Skouries Cu Au Porphyry Deposit

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/olig...

The Dexing adakitic porphyries (quartz diorite-granodiorite porphyries), associated with giant porphyry Cu deposits, are located in the interior of a continent (South China). They exhibit relatively high MgO, Cr, Ni and Sr contents, high La/Yb and Sr/Y ratios, but low Yb and Y contents, similar to adakites produced by slab melting associated with subduction. However, they are characterized by bulk Earth-like Nd-Sr isotope compositions (e Nd (t) ¼ -1Á14 to þ1Á80 and ( 87 Sr/ 86 Sr) i ¼ 0Á7044 -0Á7047), and high Th (12Á6-27Á2 ppm) contents and Th/Ce (0Á19-0Á94) ratios, which are different from those of Cenozoic slab-derived adakites. Sensitive High-Resolution Ion Microprobe (SHRIMP) geochronology studies of zircons reveal that the Dexing adakitic porphyries have a crystallization age of 171 AE 3 Ma. This age is contemporaneous with Middle Jurassic extension within the Shi-Han rift zone, and within-plate magmatism elsewhere in South China, indicating that the Dexing adakitic porphyries were probably formed in an extensional tectonic regime in the interior of the continent rather than in an arc setting. Their high Th contents and Th/Ce ratios, and Middle Jurassic age, argue against an origin from a Neoproterozoic ($1000 Ma) stalled slab in the mantle. Taking into account available data for the regional metamorphic-magmatic rocks, and the present-day crustal thickness ($31 km) in the area, we suggest that the Dexing adakitic porphyries were most probably generated by partial melting of delaminated lower crust, which was possibly triggered by upwelling of the asthenospheric mantle due to the activity of the Shi-Hang rift zone. Moreover, the Dexing adakitic magmas must have interacted with the surrounding mantle peridotite during their ascent, which elevated not only their MgO, Cr and Ni contents, but also the oxygen fugacity ( f O 2 ) of the mantle. The high f O 2 could have induced oxidation of metallic sulfides in the mantle and mobilization of chalcophile elements, which are required to produce associated Cu mineralization. Therefore, the Cu metallogenesis associated with the Dexing adakitic porphyries is probably related to partial melting of delaminated lower crust, similar to the metallogenesis accompanying slab melting.

Several types of granites including alkaline granites and alkali feldspar granites are distributed in the Karamaili tectonic belt of East Junggar, Xinjiang, China. Some medium-small tin deposits are located within or near the contact zones of the granitic intrusions. The alkaline granites share all the features commonly observed in peralkaline A-type granites. They contain alkalic mafic minerals such as riebeckite and aegirine; have high contents of SiO 2 , alkalis, Rb, Th, Zr, Hf, REE (except Eu), and high ratios of FeO*/MgO and Ga/Al; and show strong depletions in Ba, Sr, Eu in the spidergrams. Laser ablation-ICPMS U-Pb zircon geochronology indicates a crystallization age of ca. 305 Ma for the granites; TIMS analyses of the granites found high ε Nd (T) values of +5.9 to +6.5. Considering their geochemical features, alkaline granites most likely formed by fractional crystallization of granodioritic magmas, which were probably produced by partial melting of lower crustal basaltic to andesitic rocks formed from oceanic crustal materials that were deeply buried during late Paleozoic subduction and accretion. Six molybdenite samples from the Sareshike tin deposit in East Junggar yielded an isochron age of 307 ± 11 Ma (2σ) and a weighted mean model age of 306.5 ± 3.4 Ma, consistent with zircon U-Pb ages of the alkaline granites. Low Re contents (0.323-0.961 ppm) in the molybdenite suggest that they originated from crustal sources related to the alkaline granites. Considering their identical ages, close spatial distribution, and similar sources, we argue that the A-type granites have a genetic relationship with the tin mineralization, and that the same association may be important elsewhere.

We present here the first geochemical data of adakitic rocks from an extensional 14 system-the U.S. East Coast rifted margin. Adakitic magmas are high-K melts that 15 have petrogenetically been interpreted to be partial melts of subducting slab and/or 16 lower crustal lithologies in delamination events. The adakitic rocks presented here are 17 from a small volcanic region in the Valley and Ridge province in Virginia, and were 18 probably emplaced around the time of continent rupture and Central Atlantic 19 Magmatic Province activity. They are bi-modal in character (high-Si and low-Si), and 20 have the typical high and low-Si adakitic geochemical characteristics such as high 21 K 2 O (up to 9.88 wt. %) abundances, steep REE patterns and significantly high Sr 22 (2473 ppm), but relatively low Rb (35 ppm) contents (high-Si adakitic rocks). The 23 petrogenetic relation of these melts to partial melting of metagabbroic rocks (high-Si 24 adakites) and interaction of these melts with ambient peridotite (low-Si adakites) 25 suggests that the geodynamic process for the formation of the studied Jurassic Central 26 Virginia igneous rock succession is delamination of mantle lithosphere and lower 27 crust below the volcanic rifted margin. We present with geodynamic models that 28 negatively buoyant mantle lithosphere instabilities developed below this passive 29 margin during continent rupture. After foundering, warm asthenosphere welled up and 30 heated the lower crust of the East Coast margin, which was interspersed in our study 31 area with fragmented hydrated metamorphic mafic to ultramafic lithologies. In-situ 32 and/or dripping melting of such meta-igneous rocks reproduces the observed 33 geochemistry of the studied high-Si adakitic rocks. Further recycling processes within 34 the convecting mantle of delaminated floating fertile meta-igneous rock packages 35 could be responsible for Atlantic melting anomalies such as the Azores or Bermuda. 36 37 38 Key words: Continental breakup, lithospheric instabilities, adakites, US E-coast 39 margin 40 41 44 The gravitational removal of mafic lower crustal layers with lithospheric mantle over 45 a large area results in upwelling of the underlying asthenosphere, which starts to melt 46 partially due to decompression and fluid injections (e.g. Bird et al., 1979; Esedo et al., 47 2013). Significant volumes of magmatism are assumed to result from this process. 48 Theoretically, magma is further produced when the delaminated crustal material is 49 heated, dehydrated and recycled back into the mantle; it was subsolidus while 50 emplaced within the continental lithosphere, but will start melting in the upper mantle 51 (Elkins-Tanton, 2005). Such delamination or gravitational removal ("dripping") of 52 lithosphere material can be simplistically explained as foundering of dense lithosphere 53 into less dense asthenosphere. It results from lateral density variations in the 54 lithosphere that form lithosphere-asthenosphere boundary instabilities (e.g.

In-situ U-Pb ages and Hf-O isotopes of zircon are frequently used to study the petrogenesis of mafic microgranular enclaves (MMEs) in granitoids. However, whether zircons in MMEs have recorded the primary isotopes of their host MMEs is still questionable. In this study, MMEs and host granites from the Cuojiaoma granitic pluton in the Triassic Yidun arc belt, eastern Tibetan Plateau, are studied. LA-ICP-MS zircon U-Pb dating of studied MMEs yields an age of 213 ± 2 Ma. Model calculations indicate that the whole-rock composition of the MMEs was different from the melt composition from which the zircon grains grew. The MMEs crystallized during magma mixing based on analyses of zircon trace element and Zr-Hf isotopes. None of zircons in this study have recorded the primary isotope signature of the mafic endmember of MMEs because they are different from the host granite in terms of zircon morphology, εHf values and ΔQFM. The Zr isotopic data demonstrate open-system magmatic crystallization for the host granite and that magma mixing for MMEs play key role in controlling Zr isotopic variations. Initial 87 Sr/ 86 Sr ratios of An-rich plagioclase crystals in groundmass from MMEs range from 0.7027 to 0.7058, which are significantly lower than host granites (0.7080-0.7089). The lowest initial 87 Sr/ 86 Sr ratios (0.7027-0.7028) are also lower than arc volcanic rocks and similar to a depleted mantle. Combined with previous studies, we propose that MMEs were generated during post-collision extension by mixing of mafic magma of Xiaxiaoliu basalt and felsic magma from host granite.

The key magmatic processes that lead to the formation of large magmatic-hydrothermal porphyry copper mineral deposits remain uncertain, and a particular question is why a few of these deposits, such as the Pebble porphyry Cu-Au-Mo deposit, are strongly enriched in both gold and molybdenum. This study investigated the igneous rocks of the Pebble district and obtained major and trace element compositions, Sr and Nd isotopic compositions, and zircon age and trace element data to model the origin of the ore-forming magmas. The Pebble porphyry Cu-Au-Mo deposit, one of the world's largest Cu-Au resources, formed during the final stages of regional Late Cretaceous arc magmatism (101-88 Ma) in the Southwest Alaska Range. Local pre-mineral intrusions (99-95 Ma) are dominated by alkaline compositions including monzodiorite stocks, shoshonite dikes, and monzonite porphyries, but also include lesser volumes of high-K calc-alkaline diorite and granodiorite sills. The occurrence of early alkaline magmas has been noted at other gold-rich porphyry systems, including Bingham and Kerr-Sulfurets-Mitchell. Mineralization at Pebble is associated with granodiorite to granite porphyry dikes related to the >165 km 2 high-K calc-alkaline Kaskanak granodiorite batholith (91-89 Ma). Over a period of 10 m.y., Late Cretaceous melts evolved from high temperatures (930-730 °C) and modestly hydrous and oxidized conditions to relatively low temperatures (760-680 °C) and very hydrous and oxidized conditions. Collectively, all Late Cretaceous igneous rocks at Pebble contain magnetite and little or no ilmenite, are metaluminous to weakly peraluminous, and have typical arc trace element enrichments and depletions. They have moderate Sr/Y ratios (20-55) and gently sloped REE profiles (La/Yb = 5-20) that are not adakitic, which supports a source area lacking garnet that is consistent with a thin crust in southwest Alaska. Radiogenic isotopes for Late Cretaceous intrusions at Pebble have a restricted range of primitive Sr and Nd isotopic compositions (87 Sr/ 86 Sr i = 0.70329-0.70424; εNd i = 4.9-6.1), which overlap with volcanic and plutonic basement rocks of the Jurassic Talkeetna Arc along the Alaska Peninsula. The Kaskanak batholith intrudes the Late Jurassic-Early Cretaceous Kahiltna flysch, and mixing models using Sr and Nd isotopes indicate that the Kaskanak batholith assimilated ≤10 wt% Kahiltna flysch in amounts that did not likely affect magma fertility. Xenocrystic zircon samples are abundant in Cretaceous pre-mineral intrusions and have U-Pb ages similar to detrital zircon samples in the Kahiltna flysch. These data support some assimilation of upper crustal Kahiltna flysch, but the dominance of Devonian-Mississippian xenocrystic zircon populations in some intrusions suggests derivation from unexposed older basement. The extraordinary endowment of Cu and Au at Pebble is inferred to result from primitive calcalkaline and alkaline arc magmas and the hydrous and strongly oxidized conditions that suppressed the formation and fractionation of Cu-and Au-enriched sulfide melts. Furthermore, differentiation to silicic compositions was a product of extensive crystal fractionation of parental melts accompanied by minor crustal assimilation. The trace element content of the intermediate composition intrusions indicates that both hornblende and titanite fractionation processes in the mid-to shallow-crust were both required to produce the more evolved granodiorite and granite porphyry compositions. Despite the apparent lack of Mo-enriched continental crust in the region, primitive hydrous melts were produced by protracted arc magmatism and were modified by minor crustal assimilation including early alkaline magmatism, periodic recharge of mafic hydrous basalts and hybrid andesites, and fractional crystallization, which was apparently sufficient to enrich Mo in late stage felsic melts.

The Sungun copper–molybdenum porphyry deposit is located in the north of Varzaghan, northwestern Iran. The Sungun quartz-monzonite is the oldest mineralized intrusive body in the region and was emplaced during the Early Miocene. Eight categories of the late and unmineralized dykes, which include quartz diorite, gabbrodiorite, diorite, dacite, microdiorite and lamprophyre (LAM), intrude the ore deposit. The main mineral phases in the dykes include plagioclase, amphibole and biotite, with minor quartz and apatite and secondary chlorite, epidote, muscovite and sericite. The composition of plagioclase in the quartz diorite dykes (DK1a, DK1b and DK1c) varies from albite-oligoclase to andesine and oligoclase to andesine; in the diorite, it varies from andesine to labradorite; in the LAM, from albite to oligoclase; and in the microdiorite (MDI), it occurs as albite. Amphibole compositions are consistent with classification as hornblende or calcic amphibole. Based on their AlIV value (less ...

Most known porphyry Cu deposits formed in the Phanerozoic and are exclusively associated with moderately oxidized, sulfur-rich, hydrous arc-related magmas derived from partial melting of the asthenospheric mantle metasomatized by slab-derived fluids. Yet, whether similar metallogenic processes also operated in the Precambrian remains obscure. Here we address the issue by investigating the origin, fO2, and S contents of calc-alkaline plutonic rocks associated with the Haib porphyry Cu deposit in the Paleoproterozoic Richtersveld Magmatic Arc (southern Namibia), an interpreted mature island-arc setting. We show that the ca. 1886–1881 Ma ore-forming magmas, originated from a mantle-dominated source with minor crustal contributions, were relatively oxidized (1‒2 log units above the fayalite-magnetite-quartz redox buffer) and sulfur-rich. These results indicate that moderately oxidized, sulfur-rich arc magma associated with porphyry Cu mineralization already existed in the late Paleoprot...

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/olig...

The late Mesozoic igneous province in southeast China provides an excellent opportunity to understand the processes that controlled the growth and evolution of Phanerozoic continental crust. Here we report petrological, whole-rock geochemical and isotopic data, and in situ zircon U-Pb-Lu-Hf isotopic data from granitoids and associated gabbros in the Pingtan and Tong'an complexes, southeast China. Through combining the new results with published datasets in southeast China, we show that the Early Cretaceous magmatic rocks are dominated by juvenile Nd-Hf isotopic compositions, whereas the Late Cretaceous ones display less radiogenic Nd-Hf isotope signatures. Furthermore, Nd-Hf isotope systematics are coupled with decreasing abundance of hydrous minerals and an increase of zircon saturation temperatures. Compiled zircon Hf-O data indicates that the 117-116 Ma granites have zircon  18 O values ranging from mantle values (close to 5.3‰) to as low as 3.9‰, but with dominantly positive initial epsilon Hf ( Hf (t)) values. Zircon grains from 105-98 Ma rocks have  18 O values plotting within the mantle-like range (6.5‰−4.5‰), but mainly with negative  Hf (t) values. Zircon grains from ca. 87 Ma rocks have positive  Hf (t) values (+9.8 to +0.7) and a large range of  18 O values (6.3‰−3.5‰). The variations in Hf-Nd-O isotopic compositions are correlated with decreasing abundance of magma water contents, presenting a case that water-fluxed melting generated large-scale granitic magmatism. Deep-Earth water cycling provides

It remains debated as to whether the Gaoligong Orogen between the Tengchong and Baoshan blocks in Yunnan, China, is the southward extension of the Tibetan Bangonghu-Nujiang Suture (BNS). Here we present new geochronological and petrochemical data for Early Cretaceous magmatic rocks of the Gaoligong Orogen. The LA-ICP-MS U-Pb dating of zircons from diorites, granodiorites, and granites yielded weighted mean 206 Pb/ 238 U ages of 120-118, 128-122, and 109-128 Ma, respectively. For the diorites, the  Hf (t) values of zircons fall in a range of +1.2 to +5.4 with T DM C ages of 744-979 Ma, for the granodiorites they fall in a range of-9.8 to +2.9 with T DM C ages of 888-1564 Ma, and for the granites the range is-8.0 to-1.1 with T DM C ages of 1101-1488 Ma. They are magnsian, calc-alkaline, enriched in LILEs and LREEs, and have strong negative Nb, Ta, P, and Ti anomalies and high values of Mg #. All these features are indicative of continental arc affinities. The data suggest that the dioritic and granitic magmas were produced by the mixing of variable proportions of mantle-and crust-derived magmas at an active continental margin. The ages and tectonic settings of the diorites, granodiorites, and granites are similar to rocks found within the BNS. Considering the ophiolitic mélange belt, the Middle Jurassic basaltic magmatism, and the marine-facies stratigraphic features of the Gaoligong Orogen are very similar to features in the BNS, we conclude that the Gaoligong Orogen represents the suture between the Tengchong and Baoshan blocks, and is the southward extension of the BNS.

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The Qulong porphyry copper and molybdenum deposit is located at the southwest margin of the Lhasa Terrane and in the eastern region of the Gangdese magmatic belt. It represents China's largest porphyry copper system, with ~2200 million tonnes of ore comprising 0.5 percent Cu and 0.03 percent Mo. The mineralization is associated with Miocene granodiorite, monzogranite and quartz-diorite plutons, which intruded into Jurassic volcanic units in a post-collisional (India-Asian) tectonic setting. Field observations and core logging demonstrate the alteration and mineralization at Qulong are akin to typical porphyry copper systems in subduction settings, which comprise similar magmatic-hydrothermal, potassic, propylitic and phyllic alteration assemblages. Molybdenite Re-Os geochronology confirms the relative timeframe defined by field observations and core logging, and indicates that the bulk copper and molybdenum at Qulong were deposited within 350,000 years: between 16.10 ± 0.06 [0.08] (without and with decay constant uncertainty) and 15.88 ± 0.06 [0.08] Ma. This duration for mineralization is in direct contrast to a long-lived intrusive episode associated with mineralization based on previous zircon U-Pb data. Our fluid inclusion study indicates that the ore-forming fluid was oxidized and contained Na, K, Ca, Fe, Cu, Mo, Cl and S. The magmatic-hydrothermal transition occurred at ~425 o C under lithostatic pressure; while potassic, propylitic and phyllic alteration occurred at hydrostatic pressure with temperature progressively decreasing from 425 to 280 o C. The fluid inclusion data presented here suggests that there has been ~2.3 km of erosion at Qulong after its formation and this erosion may be related to regional uplift of the Lhasa Terrane.

A strong link between high Sr/Y arc magmas and porphyry Cu-Mo-Au deposits has been recognized in recent years. The Tongshan and Duobaoshan deposits are representative large Cu-Mo-Au deposits in NE China. We report LA-ICP-MS zircon U-Pb crystallization age of 471.5±1.3 Ma for Tongshan ore-related granitoid. Re-Os isotopic analyses of the two chalcopyrite samples from Tongshan deposit show a model age range of 470.2 Ma to 477.1 Ma. The Duobaoshan and Tongshan ore-related granitoids show higher Sr/Y and La/Yb ratios. The δ 34 S values of sulphides from the Duobaoshan and Tongshan deposits vary from-2.3‰ to 0.0‰, belonging to a magmatic-hydrothermal system. The Pb isotopic ratios of the sulfides from the Duobaoshan and Tongshan deposit range from 17.201 to 18.453 for 206 Pb/ 204 Pb, 15.445 to 15.551 for 207 Pb/ 204 Pb, and 36.974 to 37.999 for 208 Pb/ 204 Pb, indicating the addition of lower crustal material. The Duobaoshan and Tongshan granitoids were formed in a subduction-related continental arc setting, produced by partial melting of juvenile hydrous basalts underplating the deep continental crust during the Ordovician.

The Andean margin of the South American continent has been magmatically and tectonically active for over 330 million years. It is the type location where "Cordilleran-type" magmatism and orogenesis are manifest. In Argentina and Chile, between the latitudes of 28° and 40° S, magmatism related to the Gondwanan "Cordilleran-type" orogeny is reflected in a series of Carboniferous to Triassic intrusions. A comprehensive model exists for the petrogenesis of such magmas in Chile, however there is relatively little understanding of the nature and timing of Permo-Triassic magmatism in the Frontal Cordillera and Precordillera in Argentina. To address this, we present a new dataset of in situ zircon U-Pb, O and Hf isotopes from 15 felsic intrusions from Argentina. Zircon geochronology shows that magmatism in this region commenced at ca. 285 Ma and continued until ca. 250 Ma. Zircon O and Hf isotopes suggest that the oldest Permian magmas were derived from young supracrustal sources, with elevated δ 18 O (~ 8.5 to 7.5‰) and negative ε Hf values (~ − 1 to − 3 ε Hf). The emplacement of these magmas was coeval with the formation of mantle-derived magmas characterised by mantle-like δ 18 O (~ 6.0 to 5.5‰) and moderately positive ε Hf values (~ 4 to 1 ε Hf). As magmatism continued, transitional isotope signatures became predominant as melts of these disparate sources interacted and hybridised. It is proposed that under a compressional regime, mantle-derived magmas were halted in the lower continental crust, where they exchanged heat and volatiles with an older fertile lithosphere to generate melts from supracrustal sources. A shift in the stress regime at ca. 285 Ma permitted both crustally derived and juvenile mantle-derived magmas to exploit newly formed conduits to rise into the upper crust. A regional compilation of zircon O and Hf isotopes from felsic igneous rocks reveals a coherent secular trend over ~ 100 million years, where the oldest magmatism exhibits a dominant supracrustal component and younger magmas progressively (over 50 Ma) transition towards juvenile mantle-like isotopic compositions. This new dataset from Argentina fills a significant gap in the previous regional models between 285 and 250 Ma and documents the isotopic response of magmas produced in back-arc regions to a transition between compression and extensional/neutral stress regimes. These results give insight into the generation of new, or recycling of, continental crust in a back-arc setting and how the transition from compression to extension is imperative for ore-forming magmas to reach the upper crust.

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The Sungun porphyry ore deposit is located in Eastern Azarbaijan province, Northwestern Iran. The oldest intrusive pulse in the region is a quartz-monzonite pluton, which hosts the porphyry copper-molybdenum mineralization. The Sungun Copper Mine includes the mineralized Sungun porphyry as well as six groups of cross-cutting and lithologically distinct post-mineralization dykes. The composition of these dykes ranges from quartz diorite, gabbro, diorite, dacite, lamprophyre, and microdiorite. Quartz diorite and dacite dykes are the oldest and youngest dykes, respectively. Based on their cross-cutting relationships, the composition of the dykes tend to become more primitive through time. The dykes strike Northwest–Southeast with Southwest dip, sub-parallel to the reverse faults within the deposit area. The lamprophyric dykes range from phonotephrite, to trachybasalt, tephrite, and basanite. The quartz-monzonite porphyry (SP) and the post-mineralization dykes (DK1-DK3) have clear and d...

The petrological evolution of magmatic rocks associated with porphyry-related Cu deposits is thought to exert a first-order control on ore genesis. It is therefore critical to understand and recognize petrological processes favourable to the genesis of porphyry systems. In this study we present new petrographic, geochemical (whole-rock and mineral), and isotopic (Pb, Sr, Nd) data for rocks from the magmatic suite associated with the Eocene Coroccohuayco porphyry-skarn deposit, southern Peru. Previously determined radiometric ages on these rocks provide the temporal framework for interpretation of the data. Arc-style magmatic activity started at Coroccohuayco with the emplacement of a composite precursor gabbrodiorite complex at c. 40Á4 Ma. After a nearly 5 Myr lull, magmatic activity resumed at c. 35Á6 Ma with the rapid emplacement of three dacitic porphyries associated with mineralization. However, zircon antecrysts in the porphyries show that intra-crustal magmatic activity started c. 2 Myr before porphyry emplacement and probably built a large intracrustal magmatic body with an associated large thermal anomaly. Our data suggest that all magmas underwent a period of evolution in the deep crust before transfer and further evolution in the upper crust. The gabbrodiorite complex was sourced from a heterogeneous deep crustal reservoir and was emplaced at a pressure of 100-250 MPa where it underwent a limited amount of fractionation and formed a chemically zoned pluton. Its initial water content and oxygen fugacity were estimated to be around 3 wt % H 2 O and NNO 6 1 (where NNO is the nickel-nickel oxide buffer), respectively. The deep crustal source of the porphyries appears to have been more homogeneous. The porphyries are interpreted to be the product of advanced differentiation of a parental magma similar to the gabbrodiorite. Most of this evolution occurred at deep crustal levels (around 800 MPa) through fractionation of amphibole þ pyroxene þ plagioclase 6 garnet, leading to the development of a high Sr/Y signature characteristic of porphyry-related magmatism worldwide. Subsequent upper crustal evolution (100-250 MPa) was dominated by crustal assimilation, cannibalism of previously emplaced magma batches (proto-plutons) and magma recharge. Water content and oxygen fugacity were estimated to be around 5 wt % H 2 O and NNO þ 1 to NNO þ 2, respectively, at the end of the period of upper crustal evolution. This high oxygen fugacity is inferred to have favoured sulphur and metal enrichment in the melt. The high thermal regime generated through 2 Myr of sustained magmatism in the upper crust favoured crustal assimilation, proto-pluton cannibalism, and efficient metal extraction upon fluid exsolution. The Coroccohuayco magmatic suite appears to have acquired its metallogenic potential (high fO 2 , high Sr/Y) through several million years of deep crustal evolution.

Various isotopic ages were reported for four granite plutons in the area studied, i. e. , the Tangquan pluton (185-t58 Ma) ; the Zijinshan pluton (t57-145 Ma) ; the Caixi pluton (133 Ma) ; and the Sifang pluton (108-105 Ma). The Tangquan and Zijinshan plutons belong to Early-Middle Jurassic and Late Jurassic of Early-Mesozoic respectively, and the Caixi and Sifang plutons belong to Early-Cretaceous of Late Mesozoic. Both the Tangquan and Sifang plutons, which are the metaluminous granites with A/CNK < 1.0, are considered to possess the geochemical characteristics of adakite rich in Sr, Ba and poor in HREE, Y, Yb, and are regarded as the most potential host rocks of copper ores. The Zijinshan pluton is regarded as a peraluminous granite with A/CNK > 1.1, and possesses the geochemical features of crust-derived muddy materials resultant from partial melting with enrichments in K, Rb, Th, Y, HREE and depletions in Sr, Ba, and Ti. The Caixi pluton is a weakly peraluminous granite with A/CNK = 1.0-1.1, and its geochemical characteristics are intermediate between the Zijinshan pluton and the Sifang pluton. The Tangquan pluton with higher Na 20 contents, which resulted from partial melting of Proterozoic thick lower-crust derived basic rocks in response to underplating of mantle-derived basic magma, is one of the major host rocks of the metallogenic series of copper, iron and polymetallic deposits. The Sifang pluton with higher K 20 contents, which was mixed between middle-lower crust-derived granite magma by partial melting and mantle-derived high-K basic magma, giving rise to the increment of K:O in the melt, and extracted large amounts of copper and other metals, as well as sulphur, is one of the major host rocks of the metallogenic series of porphyry copper, gold and polymetallic deposits. Petrological records have shown that there has occurred lithosphere extension since the Early-Middle Jurassic (180 Ma) in the region, and the formation of Zijinshan peraluminous granite is ascribed to the extension mechanism. With the time passing by, the lithosphere extension-thinning and underplating tend to intensify gradually. The contribution of the mantle to granite formation also increased gradually.

The Porphyry deposits are the largest mineral resources in the world. During the exploration phase, with the extraction of drilling cores, it is possible to obtain geotechnical information from the rock mass. This information allows the classification of rock mass by means of empirical classification systems such as Rock Mass Rating (RMR), Mining Rock Mass Rating (MRMR) and Q index. In Porphyry deposits, the rock mass is affected by the presence of hydrothermal alterations; this implies that the rock may exhibit variations in its geomechanical properties depending on the hydrothermal alteration present. In this research, 6292 drilled meters with geotechnical information were considered. With this information, a classification of the rock mas was made by the aforementioned systems. Once the deposit was classified, a comparison was made between the classification systems mentioned. Comparison was based on the lithologies and hydrothermal alterations present in the deposit by means of descriptive statistics (average values, box plot diagrams, linear regressions). a comparison was made between the aforementioned classification systems with respect to the dominant hydrothermal alterations present in the reservoir. The results showed that in the porphyry deposit, the analysis by hydrothermal alteration allows differentiating a poor to regular behavior (Sericíte alteration) from a good behavior (Potassium Alteration).

Apatite is significant phosphate-bearing accessory mineral that is omnipresent in most granitic rocks. In this study, we present geochemical characteristics of magmatic apatites from the Luming and Lower Yangtze granitic belts of NE and eastern China to explore their potential in petrogenesis, mineralization and tectonic evolution of granites. The petrogenetic, metallogenic and tectonic aspects of these granites remain subjects of great debate. This review aims to clarify these issues based on apatite geochemistry. The investigated apatites from both these localities are mainly fluorapatites reflecting the actual attributes of parental melts. Apatites from Luming and Lower Yangtze River Belt (LYRB) exhibit strong negative Eu anomalies suggesting plagioclase crystallization earlier than apatite. The negative correlation of Eu/Eu* (δEu) vs Mn, δEu vs δCe and δEu vs Ga in the apatites signifies that the parental magmas of both granites are produced under moderate reduced conditions. The Sr contents and REEs ratios in apatites serve as significant proxies to trace the differentiation history of Luming and Lower Yangtze granitic plutons. The apatites Sr/Y ratios vs δEu also exhibit that both granites are non-adakitic in nature which is consistent with the host rocks non-adakitic affinities. Halogen data indicates that apatites of Lower Yangtze comprising more chlorine (0.02-1.45 wt.%) and less fluorine (1.51-3.85 wt.%) are linked with slab dehydration whereas apatites from Luming having lower Cl (0-0.04 wt.%) and higher F contents (3.36-5.29 wt.%) suggest association of granites with partial melting of juvenile crust material. Based on the positive correlation of SO 3 with Li, (La/Sm) N vs (Yb/Sm) N and obvious variations of (La/Yb) N vs Eu/Eu*, it is inferred that these host rocks are ore-associated. Furthermore, geochemical signatures of apatites from LYRB show low F/Cl ratios, stable La/Sm ratios, high δEu (0.04-0.43, average 0.21) and low δCe values (0.96-1.12, average 1.02) indicating that the magmas of these granites have association with slab dehydration and linked with Cu-MoW mineralization, induced from the mutual impacts of Paleo-Pacific plate subduction and intraplate extension. In comparison, fairly high F/Cl ratios, La/Sm ratios, low δEu (0.12-0.23, average 0.16), high δCe values (0.98-1.09, average 1.04) and low Sr/Th ratios of Luming apatites infer that the MoW bearing granites are originated in consequence of partial melting of juvenile crustal material. Based on apatite geochemistry, we document first time varieties of ore deposits specifically MoW and Cu deposit in LYRB and MoW deposit in Luming which are developed under lower oxygen fugacity. The compiled geochemical data and interpretations propose that apatite chemical constituents are worthwhile to pinpoint polymetallic mineralization and fingerprint for ore types. In view of these findings, we confirm that apatite is not only consistent to trace geological facts about parental magma characteristics but also a reliable pointer of geodynamic evolution and ore varieties.

The Middle Miocene porphyry granitoid stocks of Meiduk and Parkam porphyry copper deposits are intruded in the northwestern part of the Dehaj-Sarduiyeh volcanosedimentary belt in the southeastern extension of the Urumieh-Dukhtar Magmatic Arc (UDMA) in Iran. The porphyritic to microgranular granitoids are mainly consist of quartz diorite, granodiorite and diorite. The whole rock geochemical analyses of these rocks reveals sub-alkaline, calc-alkaline, meta-peraluminous and I-type characteristics. Their geochemical characteristics such as Al 2 O 3 content of 13.51-17.05 wt%, high Sr concentration (mostly >400 ppm), low Yb (an average of 0.74 ppm) and Y (an average of 9.02 ppm) contents, strongly differentiated REE patterns (La/Yb≥20), lack of Eu anomaly (Eu/Eu*≥1) are indicative of adakitic signature. Their enrichment in low field strength elements (LFSE) and conspicuous negative anomalies for Nb, Ta and Ti are typical of subduction related magmas. Detailed petrological studies and geochemical data indicated that Meiduk and Parkam porphyry granitoids were derived from amphibole fractionation of hydrous melts at a depth of >40 km in a post-collisional tectonic setting.

The Earth’s continental crust represents the outermost envelope of the solid Earth, controlling exchanges within the geosphere and reflecting geodynamics processes. One of the fundamental issues of Earth Science aims to determine crustal thickness in past geodynamic environments in order to discuss the evolution of certain geodynamic processes through time. Despite presenting a continuing challenge, the evolution of crustal thickness during the last 3 billion years can be investigated using indirect clues yielded by the chemical signature of mafic magmas and associated ferromagnesian minerals (pyroxene, amphibole). Here, we present a new statistical assessment of a global database of magmatic and mineral chemical information. Analysis reveals the increasing occurrence of high-temperature pyroxenes and amphiboles growing in Ca-rich, Fe-poor magma since ~1 Ga, which contrasts with lower temperature conditions of minerals crystallization throughout the Meso- and Palaeoproterozoic times...

The Simorgh prospecting area is located in the central part of the Lut Block in eastern Iran. The Lut Block, the eastern part of the Central Iranian Microcontinent (CIM), has a complex tectonic evolution and is characterized by extensive magmatic activities with a range of geochemical signatures. The Simorgh intrusions have features typical of calc-alkaline to high-K calc-alkaline rocks, metaluminous to slightly peraluminous and formed in a volcanic arc setting. Mineralization in the area is believed to be related to these intrusions. To better understand the petrogenesis of these intrusions, we report zircon U-Pb dating and Hf isotopes and whole rock geochemistry of two granites and one diorite. Age dating using Zircon U-Pb method on pyroxene diorite porphyry stock and two granite porphyry dikes revealed 24.85 ± 0.51 Ma, 25.37 ± 0.56 Ma and 25.94 ± 0.76 Ma ages respectively (late Oligocene, Chattian). Field observations and U-Pb dating indicate that there are at least two stages of emplacement: pre-mineralization intrusions (diorite porphyry) and syn-mineralization intrusions (granite porphyry, granodiorite porphyry and pyroxene diorite porphyry). Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements (LILE) and light rare earth elements ((La/Yb) N = 9.26-14.48), and depletion in high field strength elements (HFSE) and heavy rare earth elements, as well as negative Eu anomalies (Eu/Eu* = 0.49-0.91). Zircon Hf isotope data from the Simorgh intrusive rocks show largely positive εHf (t) (average = 3.6 ± 2.0). Hf model ages are ranging from 720 to 1320 Ma, indicating its derivation from a relatively juvenile source. The presence of zircon xenocrysts may prove its contamination by older continental crust (Siderian).

The Porphyry deposits are the largest mineral resources in the world. During the exploration phase, with the extraction of drilling cores, it is possible to obtain geotechnical information from the rock mass. This information allows the classification of rock mass by means of empirical classification systems such as Rock Mass Rating (RMR), Mining Rock Mass Rating (MRMR) and Q index. In Porphyry deposits, the rock mass is affected by the presence of hydrothermal alterations; this implies that the rock may exhibit variations in its geomechanical properties depending on the hydrothermal alteration present. In this research, 6292 drilled meters with geotechnical information were considered. With this information, a classification of the rock mas was made by the aforementioned systems. Once the deposit was classified, a comparison was made between the classification systems mentioned. Comparison was based on the lithologies and hydrothermal alterations present in the deposit by means of descriptive statistics (average values, box plot diagrams, linear regressions). a comparison was made between the aforementioned classification systems with respect to the dominant hydrothermal alterations present in the reservoir. The results showed that in the porphyry deposit, the analysis by hydrothermal alteration allows differentiating a poor to regular behavior (Sericíte alteration) from a good behavior (Potassium Alteration).

The mid-Miocene Gangdese orogenic belt in southern Tibet contains porphyry Cu deposits that developed after the Indian-Asian continental collision in the early Cenozoic. Field work confirms that these porphyry Cu deposits are temporally and spatially associated with mid-Miocene monzogranitic and quartz monzonitic stocks, which intruded Mesozoic-Cenozoic Gangdese granitoid batholiths and surrounding Triassic-Tertiary volcano-sedimentary sequences in the Lhasa Terrane, and formed a 50-km wide, 400-km long E-W belt. Magmatism occurred during the interval 11.2 to 19.7 Ma, peaking at ∼ 16 Ma for the porphyry stocks; this is consistent with the age (10 to 18 Ma) of the east-west extension and subsequent NS-striking normal fault systems (≥ 13.5 Ma) in the Tibetan Orogen. The stocks typically occur as multiple small diameter intrusions (b 5 km), and have shallow emplacement depths (∼ 1 to 3 km). The Cu porphyries are shoshonitic and high-K calc-alkaline, showing geochemical affinities with adakites. The porphyries were derived from a thickened basaltic lower-crust source, rather than from the subducted oceanic-slab. Geochemical and geophysical data indicate that during the Paleocene-Oligocene mantle-derived mafic magmas created a newly-formed basaltic underplate at the bottom of the lower-crust, which undewent garnet amphibolite metamorphism under high pressure (N 50 km). Breakdown of hornblende in the juvenile lower-crust source during melting is regarded as fundamental for the formation of the fertile adakite and porphyry Cu systems in south Tibet. The Gangdese belt contains four large, and three intermediate-and small-sized porphyry Cu-Mo deposits, and shows a continuous spectrum from typical porphyry-type Cu-Mo to skarn-type Zn-Pb mineralization. Twenty-three samples collected from four deposits yielded a limited range of molybdenite Re-Os isochron ages from 15.2 to 16.0 Ma, similar to previously-reported Re-Os ages (13.8 to 14.9 Ma) for other porphyry Cu-Mo deposits in the belt, suggesting that Cu-Mo mineralization in the belt occurred in a postcollisional extension environment. The characteristics of porphyry Cu-Mo deposits in the collisional zone are similar in many aspects to those in arc settings, i.e., mineralization style, alteration zoning, and metal association. Preliminary fluid inclusion studies indicate that the early hydrothermal fluids are preserved as high temperature (≥ 450°C), high salinity (40 to 47 wt.% NaCl equiv.) and high pressure (≥ 1100 to 1500 bar) fluid inclusions. These fluids are interpreted to represent an orthomagmatic fluid that boiled episodically due to fluid overpressuring and hydrofracturing, resulting in potassic alteration and precipitation of chalcopyrite-molybdenite assemblages. On the basis of comparison with porphyry Cu deposits in arc settings, we proposed that melting of thickened, newly-formed basaltic crust resulted in generation of Cu-bearing magmatic systems in the Tibetan collision zone, and both orogen-transverse normal faults and orogen-parallel thrust zones during the Miocene postcollisional extension constrain the temporal and spatial localization of the porphyry Cu systems in the collision zone.

The genesis and timing of molybdenum (Mo) mineralization in the Mada Ring Complex, north-central Nigeria, have been constrained using a combination of whole-rock elemental geochemistry, Nd-Sr isotopes, zircon U-Pb-Hf isotopes, and molybdenite Re-Os geochronological data. The Mada Ring Complex is one of fifty-three within-plate alkaline ring complexes with economically significant Sn and Nb production from largely alluvial placer deposits in north-central Nigeria. Molybdenum mineralization in the ring complex is dominantly disseminated with minor stockwork veins hosted within biotite granite. Integrated zircon U-Pb and molybdenite Re-Os geochronology constrain initial magma emplacement to between 152 and 151 (± 1) Ma and the Mo-mineralization event to ≤ 150 (± 1) Ma. The granites associated with Mo mineralization are highly silicic and display elevated whole-rock concentrations of Nb, Zr, Y, and REE (except Eu), as well as high 87 Rb/ 86 Sr ratios, but low concentrations of Sr, Ba, CaO, MgO, and TiO 2 , consistent with highly differentiated A-type granites. They yield moderately negative whole-rock εNd(t) (− 5.87 to − 5.47) and zircon εHf(t) (− 4.97 to − 10.06), suggesting that their parental magmas were largely derived from the lower crust with a contribution from the upper mantle. Magmatic oxygen fugacity (ƒO 2) of the A-type granites (log FMQ = +1.16), constrained from zircon compositions, is lower than values reported from typical within-plate porphyry molybdenum deposits (log FMQ = +2 to + 3). However, compared to regional Sn ± Nb-mineralized A-type granites, the Mada A-type granites have higher ƒO 2 and Ce 4+ /Ce 3+ , but are less differentiated.

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/olig...

There are many Miocene collision-and subduction-related porphyry Cu deposits in the Eastern Tethyan orogenic belt. However, the petrogenesis of the ore-related magmas and the mechanism of metal enrichment remain controversial. Here, we present a geochemical study and comparison of the major Miocene ore-related porphyries and coeval ore-barren magmatic rocks in the Urumieh-Dokhtar magmatic arc in Iran and the Chagai belt in Pakistan, and the Eastern Gangdese belt of the Himalaya. The results show that ore-related porphyries are characterized by relatively depleted mean Sr isotopic compositions (0.704217-0.706874 in the Urumieh-Dokhtar magmatic arc; 0.705052-0.706588 in the Eastern Gangdese belt; 0.705252-0.706708 in the Chagai belt), but higher maximum Sr/Y ratios (48-149 in Urumieh-Dokhtar; 79-178 in Eastern Gangdese; 52-178 in Chagai). In contrast, the coeval ore-barren magmatic rocks yield relatively enriched, mean Sr isotopic compositions (0.704722-0.707653 in Urumieh-Dokhtar; 0.704701-0.707802 in Eastern Gangdese; 0.705982-0.707856 in Chagai), but lower maximum Sr/Y (2-88 in Urumieh-Dokhtar; 61-136 in Eastern Gangdese; and 19-35 in Chagai). A deep crustal hot zone model provides a robust explanation of these data. Melts derived from a deeper melt source in juvenile mafic lower crust, where mantle-derived materials are common, have a greater potential to yield a higher tonnage of metallic Cu, such as the Sar-Cheshmeh deposit in Iran, which is derived from a deep melt zone, and characterized by a low radioactive mean Sr isotopic value of 0.704847, but a huge tonnage of metallic Cu of 7.2 Mt and a high maximum Sr/Y value of 116 (equal to the depth of the melt zone), whereas the Dalli deposit in Iran derived from a relatively shallow melt zone has a more radioactive mean

Porphyry deposits are usually thought to form from subduction-related calc-alkaline magmas in magmatic arc settings, although some porphyry deposits also occur in post-collisional extensional settings. The postcollisional deposits remain poorly understood. Here we describe the igneous geology, alteration mineralogy and mineralization history of Qulong, a newly-discovered porphyry Cu-Mo deposit in southern Tibet that belongs to the post-collisional class. The deposit is associated with Miocene monzogranite-granodiorite intrusions and is hosted partly by Jurassic andesitic-dacitic volcanic rocks. The deposit contains 7.1 Mt Cu and 0.5 Mt Mo metal. The~19.5 Ma granodioritic-monzogranitic Rongmucuola pluton with diorite enclaves is the earliest Miocene intrusive unit. It was intruded by a regularly-shaped stock (P porphyry) and then thin dikes (X porphyry) of monzogranite at about 17.7 Ma. The main Cu-Mo mineralization is associated with the P porphyry. A barren diorite porphyry intruded the P and X porphyries around 15.7 Ma. Petrologic trends of the intrusions suggest that the Miocene intrusions have similar origins and probably formed by fractionation of a deeper magma chamber. Emplacement of Miocene porphyries, controlled by the Qulong anticline, is in direct response to the rapid uplift/erosion of the Gangdese arc batholiths in southern Tibet. Miarolitic cavities and unidirectional solidification textures, key evidence for volatile separation, have been recognized in the P and X porphyries, respectively. Early potassic alteration, characterized by quartz-K feldspar (± anhydrite), pervades the P porphyry and Rongmucuola pluton. Laterally, this alteration grades into quartz-biotite-anhydrite (± K feldspar), which affects all Miocene intrusions except the latest dioritic porphyry. Wall rocks of Rongmucuola pluton and Jurassic andesitic-dacitic volcanics within 1-1.5 km of the porphyries are dominated by pervasive potassic alteration. An outer halo of propylitic alteration (epidote-chlorite ± calcite) extends up to 2 km away from the deposit. Feldspar-destructive alteration (sericite-chlorite ± clay minerals) has overprinted most of the potassic and part of the propylitic alteration. The alteration is strongly pervasive in the interior of the porphyry bodies and occurs as vein halos away from the porphyry bodies. The earliest quartz-K feldspar alteration and veins are barren, whereas approximately 60% of the Cu reserves is associated with slightly later quartz-biotite-anhydrite alteration. Barren assemblages are related to irregular quartz (-K feldspar ± anhydrite) veins, which are truncated by the X porphyry. Cu sulfide-bearing assemblages are associated with discontinuous chalcopyrite (± biotite) and continuous quartz-anhydritechalcopyrite (± molybdenite) veins. Deposition of Cu-Mo with abundant anhydrite occurred during or between emplacement of closely related porphyries from high temperature magmatically-derived fluids, and was probably caused by the disproportionation of SO 2 .

Sahand volcanic rocks, with Plio-Quaternery age, is located southeast Tabriz in the northwest part of Central Iran. These rocks are mainly composed of pyroclastics (tuff and ignimberite) and lava flows (rhyolite, rhyodacite, dacite and andesite) that unconformably cover the Miocene sedimentary formations. The major constituent minerals include plagioclase and hornblende which are surrounded by a matrix of fine grain and glassy. Their textures are porphyritic. Heterogenous mineralogy, field and textural evidences such as sieve texture in plagioclase, resorption rims in crystals, oscillatory zoning in plagioclase, high normative quartz and rounded enclaves suggest that the primary magma undergone magmatic evolution including fractional crystallization, fractionation, contamination and magma mixing during ascending. There are mineralogical as well as geochemical evidences that AFC-type processes were involved in the evolution of the Sahand volcanic rocks. The chemistry of the felsic-intermediate volcanic rocks indicates that the parent magmas are medium-K calc-alkaline and metaluminous in nature. The volcanic rocks display highly fractionated REE patterns, with no negative Eu anomaly. Their geotectonic environment is post-collision and continental margin arcs.

The Chehugou porphyry Mo-Cu deposit is located ca. 300 km north of Beijing in the boundary zone between the Archean North China craton and the Neoproterozoic-Mesozoic Central Asian orogenic belt. Using hydrothermal chalcopyrite from this deposit, we are able to show for the first time that the Rb-Sr isotope system in massive, nonfractured chalcopyrite grains can provide reliable age constraints for Mo-Cu deposits. We analyzed two chalcopyrite samples from slightly different petrogenetic "environments" showing contrasting texture and deformation history. Five 2-to 5-mg fragments of a single nonfractured chalcopyrite grain containing spatially isolated inclusions of K-mica, K-feldspar, and quartz yielded an Rb-Sr isochron age of 256 ± 7 Ma (2σ including λ uncertainty). For this sample, the dense chalcopyrite "matrix" apparently inhibited diffusion of Rb and Sr after chalcopyrite crystallization, and the age should therefore reflect the time of crystallization of chalcopyrite from the Mo-Cu mineralizing fluids. The evidence for Mo-Cu mineralization during the late Permian requires a revision of the previous notion that the Chehugou deposit was formed during the Yanshanian orogeny lasting from 200 to 60 Ma. Fragments of a second chalcopyrite sample that, in contrast to the first, had experienced deformation as indicated by intragranular fractures and alignment of K-mica and K-feldspar inclusions along these fractures. This sample yielded a clearly younger Rb-Sr isochron age of 207 ± 15 Ma (2σ). This age obviously reflects an isotopically open system due to fluid movement and/or prolonged diffusion of Rb and Sr along the fractures. Single biotite crystals from an associated monzogranite yielded an Rb-Sr isochron age of 250 Ma, which is interpreted as a lower age limit for the Mo-Cu mineralization, and the time when the granite cooled below 400°t o 300°C. Considering the field evidence for a broadly contemporaneous origin of the Mo-Cu mineralization and the hosting granitoids, we suggest that the granitoids are not much older than ca. 260 Ma. The Mo-Cu-hosting granitoids range in composition from monzogranite to highly evolved syenogranite with high La/Yb and Sr/Y ratios. Initial εNd values of ca.-21 to-23 (Nd crustal residence times of the sources 1.9 to 2.7 Ga) indicate melting of the predominantly Archean North China craton, and a subordinate juvenile mantlederived component. Much older U-depleted lower crustal sources for the granitoids are supported by high initial 208 Pb/ 204 Pb ratios. Lithospheric delamination and underplating of hot mantle-derived material may have facilitated crustal melting in a late orogenic to postcollision.

The Porphyry deposits are the largest mineral resources in the world. During the exploration phase, with the extraction of drilling cores, it is possible to obtain geotechnical information from the rock mass. This information allows the classification of rock mass by means of empirical classification systems such as Rock Mass Rating (RMR), Mining Rock Mass Rating (MRMR) and Q index. In Porphyry deposits, the rock mass is affected by the presence of hydrothermal alterations; this implies that the rock may exhibit variations in its geomechanical properties depending on the hydrothermal alteration present. In this research, 6292 drilled meters with geotechnical information were considered. With this information, a classification of the rock mas was made by the aforementioned systems. Once the deposit was classified, a comparison was made between the classification systems mentioned. Comparison was based on the lithologies and hydrothermal alterations present in the deposit by means of descriptive statistics (average values, box plot diagrams, linear regressions). a comparison was made between the aforementioned classification systems with respect to the dominant hydrothermal alterations present in the reservoir. The results showed that in the porphyry deposit, the analysis by hydrothermal alteration allows differentiating a poor to regular behavior (Sericíte alteration) from a good behavior (Potassium Alteration).

Pyrite/arsenopyrite (Py-AsPy), galena (PbS), and sphalerite (ZnS) concentrates from the flotation plants of Olympias and Stratoni (Kassandra mines, Chalkidiki, N. Greece) were investigated for their major, trace, minor, and critical element contents, including actinides associated to natural radioactivity. It is revealed that in addition to the Pb, Zn, Ag, and Au being exploited by Hellas Gold S.A., there are also significant concentrations of Sb and Ga (Sb: &gt;0.2 wt.% in PbS concentrate; Ga:25 ppm in ZnS concentrate), but no considerable contents of Bi, Co, V, or REE. Concerning other elements, As was found in elevated concentrations (&gt;1 wt.% in Py-(As)Py-AsPy Olympias concentrate and almost 1 wt.% in Stratoni PbS and ZnS concentrates) together with Cd (specifically in ZnS concentrate). However, actinides occurred in very low concentrations (U &lt; 2 ppm and Th &lt; 0.5 ppm in all examined concentrates), limiting the possibility of natural radioactivity in the Hellas Gold S.A....

The Sungun copper–molybdenum porphyry deposit is located in the north of Varzaghan, northwestern Iran. The Sungun quartz-monzonite is the oldest mineralized intrusive body in the region and was emplaced during the Early Miocene. Eight categories of the late and unmineralized dykes, which include quartz diorite, gabbrodiorite, diorite, dacite, microdiorite and lamprophyre (LAM), intrude the ore deposit. The main mineral phases in the dykes include plagioclase, amphibole and biotite, with minor quartz and apatite and secondary chlorite, epidote, muscovite and sericite. The composition of plagioclase in the quartz diorite dykes (DK1a, DK1b and DK1c) varies from albite-oligoclase to andesine and oligoclase to andesine; in the diorite, it varies from andesine to labradorite; in the LAM, from albite to oligoclase; and in the microdiorite (MDI), it occurs as albite. Amphibole compositions are consistent with classification as hornblende or calcic amphibole. Based on their AlIV value (less ...

The Sungun porphyry ore deposit is located in Eastern Azarbaijan province, Northwestern Iran. The oldest intrusive pulse in the region is a quartz-monzonite pluton, which hosts the porphyry copper-molybdenum mineralization. The Sungun Copper Mine includes the mineralized Sungun porphyry as well as six groups of cross-cutting and lithologically distinct post-mineralization dykes. The composition of these dykes ranges from quartz diorite, gabbro, diorite, dacite, lamprophyre, and microdiorite. Quartz diorite and dacite dykes are the oldest and youngest dykes, respectively. Based on their cross-cutting relationships, the composition of the dykes tend to become more primitive through time. The dykes strike Northwest - Southeast with Southwest dip, sub-parallel to the reverse faults within the deposit area. The lamprophyric dykes range from phonotephrite, to trachybasalt, tephrite, and basanite. The quartz-monzonite porphyry (SP) and the post-mineralization dykes (DK1-DK3) have clear and...

The Zijinshan intrusion is located to the south of the Tongling ore cluster of the Middle-Lower Yangtze River Valley metallogenic belt (YRB) and even south to the Yangxing-Changzhou Fault (YCF), which separates the YRB and the Jiangnan Massif. It is a I-type high-K calc-alkaline granodiorite with abundant MMEs. Zircon LA-MC-ICP-MS U-Pb ages of 144.0 ± 1.0 Ma and 142.5 ± 1.0 Ma for the host granodiorite and MMEs indicate coveal formation. Biotites from the host granodiorites and MMEs have similar composition, with low FeO t /(FeO t + MgO) values of 0.60-0.65 and 0.60-0.65, and high MgO contents of 10.51-11.70 wt.% and 10.89-12.37 wt.%, respectively. All the biotite samples are between the NNO and the MH buffers. The host granodiorites are metaluminous (A/CNK=0.94-0.95), enriched in Cs, Rb, U and Pb, depleted in Ba, Sr, Nb, Zr, P, and Ti, with moderate negative Eu anomalies of 0.80-0.87, (87 Sr/ 86 Sr) i of 0.70874 to 0.70887, ε Nd (t) of −5.63 to −5.36 and ε Hf (t) of −8.68 to −2.76. The MMEs have lower SiO 2 and higher K 2 O, and they are also enriched in Cs, Rb, U, Ta and Pb, and depleted in Ba, Sr, Nb, Zr, P and Ti, with (87 Sr/ 86 Sr) i of 0.70889 to 0.70927, ε Nd (t) of −5.52 to −5.20 and ε Hf (t) of −6.46 to −3.59. All these characteristics demonstrate that partial melting of both the lower crust and an enriched lithospheric mantle metasomatized by subducted slab fluid and their subsequent mixing led to the origin of the I-type granodiorite magmas of the Zijinshan intrusion, which took place in the geodynamic context of the subduction of the Izanagi plate. Combined with the field investigations, we suggest that the Zijinshan intrusion has potential for porphyry Cu-Au mineralization and the Cu-Au metallogenic belt of the YRB may have extended to the south of the YCF.

Although a number of petrographic observations and isotopic data suggest that magma mixing is common in genesis of many granite plutons, it is still controversial whether the mantle-derived magmas were involved in granites. We carried out in this study a systematic analysis of in situ zircon Hf-O isotopes for three early Yanshanian intrusions dated at ca. 160 Ma from the Nanling Range of Southeast China. The Qinghu monzonite has very homogeneous zircon Hf-O isotopic compositions, ε Hf (t) =11.6±0.3 and δ 18 O=5.4‰±0.3‰. In combination with whole-rock geochemical and Sr-Nd isotopic data, the parental magma of the Qinghu monzonite were likely derived from the partial melting of recently-metasomatized, phlogopite-bearing lithospheric mantle without appreciable crustal contamination. The Lisong and Fogang granites and the mafic microgranular enclaves (MME) within the Lisong granites have a wide range of zircon Hf-O isotopic compositions, with Hf and O isotopes being negatively correlated within each pluton. The Lisong MMEs were crystallized from a mantle-derived magma, similar to the parental magma of the Qinghu monzonite, with small amount of crustal assimilation. The Lisong and Fogang granites were formed by reworking of meta-sedimentary materials by mantle-derived magmas and mixing of the mantle-and sediment-derived melts to varying degrees. It is thus concluded that these two Yanshanian granites in the Nanling Range were formed associated with growth and differentiation of continental crust.

The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/olig...

The early Paleozoic orogen in South China Block is an intracontinental orogen, and synchronous magmatism (440-390 Ma) is mainly acidic with minor intermediate-mafic magmatism. Previous studies suggest that most of the early Paleozoic granites in South China belong to peraluminous S-type genesis while amphibole-bearing I-type granites are subordinate. However, our results indicate that considerable amounts of these early Paleozoic granites have characteristics of both Sand I-type granites. Thus, we propose to divide these granites into two groups: fewer of them are Group A with relatively high ε Hf (t) values (clustering within − 3.0 to + 9.0) and ε Nd (t) values (− 5.2 to + 1.3) as well as higher initial temperatures at 810-850°C, and most of them are Group B with relatively low ε Hf (t) values (clustering within −16.0 to −1.0) and ε Nd (t) values (−13.2 to −4.1) as well as relatively low initial temperatures at 700-830°C. The Xiawan monzogranite and Duntou granodiorite are typical Group A granitoids and yield zircon U-Pb ages of ca. 410 Ma. These two granites are characterized by high SiO 2 (between 67.59 and 74.87 wt.%), metaluminous to peraluminous (A/CNK = 0.96-1.48) compositions, and a negative correlation between P 2 O 5 and SiO 2. Their biotites belong to magnesium biotites, indicating that they have partial features of either I-or S-type granites. Duntou granodiorites exhibit higher ε Hf (t) values (clustering within +1 to +8) and ε Nd (t) values (−3.0 to +1.1) while Xiawan monzogranites show relatively low ε Hf (t) values (clustering within − 1 to + 5) and ε Nd (t) values (− 5.0 to − 3.7). Group B granitoids are represented by the Miao'ershan-Yuechengling batholith, which are characterized by high SiO 2 (between 64.57 and 77.37 wt.%), metaluminous compositions (A/CNK = 0.90-1.24), and a negative correlation between P 2 O 5 and SiO 2. Yuechengling porphyritic amphibole-bearing biotite granites in this batholith contain abundant amphibole, indicating that they are I-type granites. Miao'ershan-Yuechengling batholith also exhibits relatively low ε Hf (t) values (−12.7 to −1.8) and ε Nd (t) values (−8.9 to −6.7). Geochemical and isotopic analyses on early Paleozoic granites, mafic enclaves and mafic to intermediate rocks demonstrate that the Group A granitoids including Xiawan and Duntou granites may be generated by AFC processes with interactions between asthenosphere-derived magma and metasedimentary rocks, and the Group B granitoids may be formed by AFC processes with interactions between synchronous basaltic magma and metamorphic basement. The post-collisional delamination and asthenospheric upwelling directly participate in the generation of Group A granitoids but indirectly induce the formation of Group B granitoids.

Early-Middle Jurassic igneous rocks are distributed in an E-W-trending band within the Nanling Tectonic Belt, and have a wide range of compositions but are only present in limited volumes. This scenario contrasts with the uniform but voluminous Middle-Late Jurassic igneous rocks (165-150 Ma) in this area. The Early-Middle Jurassic rocks include oceanic-island basalt (OIB)-type alkali basalts, tholeiitic basalts and gabbros, bimodal volcanic rocks, syenites, A-type granites, and high-K calcalkaline granodiorites. Geochemical and isotopic data indicate that alkaline and tholeiitic basalts and syenites were derived from melting of the asthenospheric mantle, with asthenosphere-derived magmas mixing with variable amounts of magmas derived from melting of metasomatized lithospheric mantle. In comparison, A-type granites in the study area were probably generated by shallow dehydration-related melting of hornblende-bearing continental crustal rocks that were heated by contemporaneous intrusion of mantle-derived basaltic magmas, and high-K calc-alkaline granodiorites resulted from the interaction between melts from upwelling asthenospheric mantle and the lower crust. The Early-Middle Jurassic magmatic event is spatially variable in terms of lithology, geochemistry, and isotopic systematics. This indicates that the deep mantle sources of the magmas that formed these igneous rocks were significantly heterogeneous, and magmatism had a gradual decrease in the involvement of the asthenospheric mantle from west to east. These variations in composition and sourcing of magmas, in addition to the spatial distribution and the thermal structure of the crust-mantle boundary during this magmatic event, indicates that these igneous rocks formed during a period of rifting after the Indosinian Orogeny rather than during subduction of the paleo-Pacific oceanic crust.

Field observation, petrography and geochemistry of mafic enclaves/dikes and their host felsic rocks from the Meichuan pluton are used to propose a geodynamic model for the southern Dabie orogen, central China. The similar Sr-Nd isotopic ratios [ε Nd (t)=−15, (87 Sr/ 86 Sr) i = 0.70550-0.70597] and zircon Hf isotopic ratios [ε Hf (t)=−25 to −16] indicate that the two types of magmatic rocks were formed by coeval felsic and mafic magmas during the Early Cretaceous (132± 2 Ma, zircon U-Pb age). The adakitic signatures of both the felsic and mafic rocks, such as very high Sr (770-1400 ppm), high Sr/Y ratios (40-130), low Y (3.5-21 ppm) and HREE concentrations are supposed to be features of the primary magmas, indicating that both of them were generated by partial melting of basaltic protoliths at great depths (N15 kbar). The distinctive major element compositions of the felsic and mafic primary magmas could be attributable to different melting temperatures and melting degrees. The mafic enclaves/dike have distinctively high concentrations of MgO (4.4-5.8 wt.%), Cr (229-374 ppm) and Ni (75-163 ppm), indicating a melt-mantle interaction in which olivine is partly consumed while orthopyroxene and/or pyrope are formed under high-pressure. Modeling suggests that 14% of peridotite relative to melt could have been consumed to elevate the Mg # of melt to the observed values (55-60), and that transformation from orthopyroxene to pyrope in mantle peridotite could have decreased the Al 2 O 3 content from 18-19 wt.% in the initial melts to~15 wt.% in the resultant mafic melts. Moderate negative zircon ε Hf (t) and bulk ε Nd (t) values also suggest contributions from both enriched lithospheric mantle and ancient lower crust. The results can best be explained by assuming that a block of amphibolite-composition lower continental crust was delaminated into the lithospheric mantle, leading to the formation of mafic magmas. This delamination is attributed to lithospheric extension and asthenospheric upwelling along the Yangtze River fault zone in the late Mesozoic which could have heated up the lithospheric mantle underneath the neighboring southern Dabie orogen. The strong input of heat triggered the delamination of the overlying thickened lower crust into lithospheric mantle by weakening the uppermost mantle and resulted in melting reactions in the delaminated crustal block to produce hot (~1100°C) intermediate adakitic magmas (SiO 2 =55-60 wt.%). The ascent of these hot magmas and their underplating below the lower crust induced the generation of high-silica melts (SiO 2 =~70 wt.%) at lower temperature (~925°C or less). Hybridization processes between the two magma types occurred during further ascent and emplacement in the crust, which could have led to the high concentrations of MgO (2.2-3.5 wt.%), Cr (56-226 ppm) and Ni (33-99 ppm) in the host felsic rocks.

The present study reports on a four sampling period (April 2008-July 2008-November 2008-February 2009) study of water quality in streams of NE Chalkidiki. A total of 80 surface water samples were collected and analysed for the major ions Ca2+, Mg2+, K+, Na+, Cl- , HCO3 - , SO4 2-, NO3 - and the trace elements Pb, Fe, Cd, Cu, Cr, Ni, Zn, Mn and As. Also pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Temperature, as well as the stream water discharge at each sampling point, were determined in the field. The treatment and the subsequent evaluation of the data showed that the water samples are divided into three separate groups, reflecting the chemistry of water in the three sub-basins of the area i.e., Kokkinolakkas, Kerasia and Piavitsa. The water of the first one is possibly affected by the past mining activities of the area, whereas samples from the other two reflect the influence of sulphide mineralization on the hydrogeochemistry of the corresponding streams. No e...

The use of efficient methods for data processing has always been of interest to researchers in the field of earth sciences. Pattern recognition techniques are appropriate methods for high-dimensional data such as geochemical data. Evaluation of the geochemical distribution of rare earth elements (REEs) requires the use of such methods. In particular, the multivariate nature of REE data makes them a good target for numerical analysis. The main subject of this paper is application of unsupervised pattern recognition approaches in evaluating geochemical distribution of REEs in the Kiruna type magnetite-apatite deposit of Se-Chahun. For this purpose, 42 bulk lithology samples were collected from the Se-Chahun iron ore deposit. In this study, 14 rare earth elements were measured with inductively coupled plasma mass spectrometry (ICP-MS). Pattern recognition makes it possible to evaluate the relations between the samples based on all these 14 features, simultaneously. In addition to providing easy solutions, discovery of the hidden information and relations of data samples is the advantage of these methods. Therefore, four clustering methods (unsupervised pattern recognition)-including a modified basic sequential algorithmic scheme (MBSAS), hierarchical (agglomerative) clustering, k-means clustering and selforganizing map (SOM)-were applied and results were evaluated using the silhouette criterion. Samples were clustered in four types. Finally, the results of this study were validated with geological facts and analysis results from, for example, scanning electron microscopy (SEM), X-ray diffraction (XRD), ICP-MS and optical mineralogy. The results of the k-means clustering and SOM methods have the best matches with reality, with experimental studies of samples and with field surveys. Since only the rare earth elements are used in this division, a good agreement of the results with lithology is considerable. It is concluded that the combination of the proposed methods and geological studies leads to finding some hidden information, and this approach has the best results compared to using only one of them.

The northern margin of the North China craton is well-endowed with lode gold deposits hosting a resource of approximately 900 tonnes (t) of gold. The 1,500-km-long region is characterized by east-trending blocks of metamorphosed Archean and Proterozoic strata that were episodically uplifted during Variscan, Indosinian, and Yanshanian deformational and magmatic events. At least 12 gold deposits from the Daqinshan, Yan-Liao (includes the Zhangjiakou, Yanshan, and Chifeng gold districts), and Changbaishan gold provinces contain resources of 20-100 t Au each. Most

Impact of the boundary processes on Si, Ca and Mg inputs to the ocean C. JEANDEL,Y. GODDERIS, B. PEUCKER-EHRENBRINK, F. LACAN AND T. ARSOUZE LEGOS (CNES/CNRS/UPS/IRD), 14 Ave E. Belin, 31400, Toulouse, France (Catherine.Jeandel@legos.obs-mip.fr) LMTG (CNRS/UPS/IRD), OMP, 14 Ave E. Belin, 31400, Toulouse, France (Yves.Godderis@lmtg.obs-mip.fr) WoodsHole Oceanographic Institute WoodsHole, MA 025431541, USA (bpeucker@whoi.edu)

The redox sensitivity of Ce and Eu anomalies in zircon has been clearly demonstrated by experimental studies, and these may represent an important tool in the exploration for porphyry Cu deposits which are thought to be derived from oxidised magmas. These deposits are significant because they are the source of much of the world's copper and almost all of the molybdenum and rhenium, key elements in many modern technologies. However, Ce and Eu anomalies in zircon are also affected by the co-crystallisation of REE bearing phases, such as titanite. Here, we report the trace element chemistry of zircons from titanite-bearing intrusions associated with mineralisation at the world class Oyu Tolgoi porphyry Cu-Au deposit (Mongolia). Based on these data, we suggest that neither zircon Eu/Eu*, nor Ce 4+ /Ce 3+ are robust proxies for melt redox conditions, because they are both too strongly dependent on melt REE concentrations, which are usually poorly constrained and controlled by the crystallisation of titanite and other REE-bearing phases. In spite of this, Eu/Eu* can *Manuscript Click here to view linked References broadly distinguish between fertile and barren systems, so may still be an indicator of porphyry magma fertility, and a useful tool for exploration.