Earth Sciences

Borehole F-88-33, located near Rainy River, Ontario, intersected Cretaceous nonmarine clastic sediments. This is the first documented occurrence in Ontario of Cretaceous sediments associated with the western interior. Lithologic and heavy-mineral analyses were used to differentiate this unit from the overlying Quaternary sediments. Seventy-five species of fossil angiosperm pollen, gymnosperm pollen, spores, megaspores, and algal cysts were recovered from borehole F-88-33 and used to date the pre-Quaternary sediments as late Albian to early Cenomanian. The occurrence of these nonmarine sediments in northwestern Ontario helps to better define the limits of Cretaceous sedimentation in the western interior.

The Mattagami Formation (Albian), in the Moose River Basin, James Bay Lowlands, Ontario, consists of carbonaceous shales and siltstones, lignites and well sorted quartz sands. These sediments represent a low gradient fluvial-paludal depositional system in an isolated intracratonic basin, which was deposited over 800 kilometers from the nearest marine sediments of the western interior.
A rich terrestrial palynoflora, including a diverse collection of fossil algae with botanical affinities to modern freshwater algae, were recovered from the Mattagami Formation. These algae consist of representatives of the Botryococcaceae, Ceratiaceae, Coelastraceae, Hydrodictyaceae, Oedogoniaceae, Scenedesmaceae, Sphaeropleaceae, Zygnemataceae plus several other probable chlorophycean species including Schizosporis and Cymatiosphaera. Zygnematacean zygospores are represented by Ovoidites, Lecaniella, and cysts comparable to zygospores of recent Mougeotia. Botryococcus is ubiquitous. Freshwater algal cysts of unknown botanical affinity are represented by Schizosporis and Cymatiosphaera. Fossils of two families of freshwater algae, the Coelastraceae and Sphaeropleaceae, are herein reported for the first time. Fossils of the Oedogoniaceae are described for the first time from pre-Tertiary sediments. The assemblage contains one of the earliest occurrences of freshwater dinoflagellates, represented by two ceratioid genera, predominantly Nyktericysta and less frequently Balmula. Four new taxa and three new combinations are proposed. Numerous specimens are illustrated in both transmitted light and scanning electron microscopy.
Comparisons to modern freshwater algal habitats allow paleoenvironmental speculations: Occurrences of zygnematacean zygospores and oospores of the Oedogoniaceae indicate shallow stagnant water horizons, while abundant well preserved dinocysts indicate ponded water in a paludal to lacustrine environment.
The Mattagami Formation fulfills a rigorous set of criteria that demonstrate deposition in a freshwater paleoenvironment. The ecological requirements of the modem representatives of these algae are used to infer the paleoecological preferences of their fossil counterparts and to demonstrate the freshwater depositional paleoenvironments of the Mattagami Formation. The occurrence of ceratioid dinoflagellates in this freshwater deposit implies that in other circumstances they alone are not a positive indicator of marine conditions. The freshwater paleoecological affinities of Pediastrum, Botryococcus, Schizocystia, Tetraporina, and Cymatiosphaera, which in the past were sometimes associated, in part, with marine environments, are strengthened.

Variations in the relative abundance of organic-walled dinoflagellate cysts, terrestrial (pollen and spores) and reworked palynomorphs in deep-sea sediment core TR174-4 from the eastern North Atlantic reflect changes in the water-mass distribution and circulation as a result of climatic change during the past 150,000 years. The relative abundance of Bitectatodinium tepikiense increases during cool climate, whereas Impagidinium spp. increase during warm phases. The relative abundance of B. tepikiense and Impagidinium spp. show a high coefficient of correlation with percent CaC03. Spiniferites spp. appear to be out of phase with the climate record, which indicates that this taxa may be transitional between the warm and cold water taxa. The dinocyst relative abundance records show a non-linear relationship to percent CaC03 during isotope stages 3 and 2, suggesting cooler surface waters during stage 3 and warmer during stage 2 than expected from the CaC03 and δ18O records. High concentrations of reworked palynomorphs may be an indicator of rates of influx of terrigenous sediment. High concentrations of dinocysts during lows in the CaC03 record may indicate higher intensity of carbonate dissolution.

A reliable and efficient technique has been developed for the mounting, location and quick re-location of palynological specimens in strew mounts for SEM (scanning electron microscope) and subsequent LM (light microscope) examination. Specimen locations are recorded with reference to a numbered location grid. which has been inked onto a glass coverslip and is visible, both under the SEM and in light. After SEM examination, a permanent LM slide can be made by removing the coverslip from the aluminum stub and inverting it into a non-aqueous mounting medium. Specimens can be quickly re-located under the SEM or the light microscope by referring to grid map records. With this method, both surface (SEM) and internal (LM) features of palynomorphs are readily available for the accurate description and identification of specimens. The resolution of gold coated specimens in LM compares favorably with conventionally mounted specimens.

Oil and gas production in Alaska has historically been limited to the northern and southern margins of the state, primarily in the North Slope and Cook Inlet, but recent drilling, seismic, and exploration data in Interior Alaska suggests potential for large oil and gas fields in rift basins near Nenana and Yukon Flats.

Zygnematacean zygospores can be recovered from lake sediments by a slightly modified palynological technique. In 10 study lakes, zygnematacean zygospores are not practical paleo-indicators of lake acidification because they are diluted (approximately 1:105 to 1:106) by pollen from the surrounding forests. Their potential as a paleo-indicator may be significantly greater in regions with a lower pollen flux. Abstract: Sediment cores were taken from 10 lakes in the Haliburton-Muskoka region of Ontario. Zygnematacean zygospores were recovered and concentrated from the lake sediments by the progressive removal of inorganic and acid-base soluble organic components. The final residue contains the insoluble zygospores and other sporopollenin microfossils including spores, pollen, dinoflagellate cysts, Pediastrum, and fungal spores. In most residues, zygnematacean zygospores are present in concentrations too low for reliable and efficient quantitative analysis. Pollen from the surrounding forest dominates the microfossil assemblage. Because zygnematacean zygospores are less soluble in oxidizing acids than are most other sporopollenin microfossils, controlled oxidation of the residue may enhance their concentration by removing a portion of the pollen present in the residue. The technique may have potential in regions with a low pollen flux. In contrast, Peridinium dinoflagellate cysts and Pediastrum coenobia were found in abundance and show promise as paleo-indicators of lake water pH.

The calcium carbonate dissolution history for approximately the last 250,000 years was determined in five piston cores that range in depth from 2945 m to 4310 m from the saddle between the Torre Seamount and the continental rise of Portugal. Fluctuations in percent CaCO3 in all cores show a marked similarity, enabling intercore correlation. The time framework for the carbonate fluctuations was established by correlation to oxygen isotope stratigraphy in one core. The temporal variation in dissolution intensity within each core was gauged by a similarity index that compares each interval to an average of well preserved intervals. The importance of CaCO3 dissolution relative to dilution by non-carbonate terrigenous material was compared during glacial and interglacial phases, by examining the spatial variation of percent CaCO3 for these phases. In general, dissolution increases during glacial isotope stages and cold substages within interglacial stages. Calcium carbonate is best preserved during interglacial stages. A reduction in the production rate of bottom water in the North Atlantic during glacial phases may be responsible for the increased intensity of dissolution during glacial phases. The data presented is consistent with the glacial model of Weyl (1968).

Previous studies on the Darriwilian (Middle Ordovician) Konservat-Lagerstätte of the Winneshiek Shale in Iowa (USA) have reported various animal and trace fossils. A search for "small carbonaceous fossils" (SCFs) in palynological samples from the Winneshiek Shale has now led to the discovery of several different kinds of organic-walled microfossils. Here we report on a particular group of filamentous microfossils that occur abundantly throughout the exposed and subsurface successions of the Winneshiek Shale. The fossils are characterised by large, elongated cells (220-600 µm in length, 60-240 µm in diameter) with thin and delicate walls and occasional branching. The cells often contain dark internal bodies, most likely condensed protoplasmic remains. Together, these features identify the fossils as eukaryotic rather than cyanobacterial in origin. In particular, the cell size, cross-walls and branching pattern are shared with particular forms of benthic ulvophycean green algae, a group with a long but sporadic fossil record that is otherwise restricted to Proterozoic Lagerstätten. The new specimens therefore expand the known diversity of local primary producers in the palaeoenvironment of the Winneshiek Shale, and suggest that the apparent dearth of delicate filamentous green algae in the Phanerozoic record may be, in part, an artefact of low preservation potential combined with destructive processing techniques.

A reliable and efficient technique has been developed for the mounting. location and 4uick re-location of palynological specimens in strew mounts for SEM (scanning e lectron microscope) and subsequent LM (light microscope) examination. Specimen locations are recorded with reference to a numbered location grid. which has been inked onto a glass coverslip and is visible. both under the SEM and in light. After SEM examination. a permanen t LM slide can be made by removing the coverslip from the aluminum stub and inverting it into a non-aqueous mounting medium. Specimens can be quick ly re-loc:ued under the SEM or the light microscope by referring to grid map records. With this method. both surface (SEM) and internal (LM) feature' of palynomorphs are readily available for the accurate de,cription and identification of specimens. The resolution of gold coated specimens in LM compares favorably with conventi onally mounted ~pecimens.

Variations in the relative abundance of organicwalled dinoflagellate cysts, terrestrial (pollen and spores) and reworked palynomorphs in deep-sea sediment core TR174-4 from the eastern North Atlantic reflect changes in the water-mass distribution and circulation as a result of climatic change during the past 150,000 years. The relative abundance of Bitectatodinium tepikiense increases during cool climate, whereas Impagidinium spp. increase during warm phases. The relative abundance of B. tepikiense and Impagidinium spp. show a high coefficient of correlation with percent CaC0 3. Spiniferites spp. appear to be out of phase with the climate record, which indicates that this taxa may be transitional between the warm and cold water taxa. The dinocyst relative abundance records show a non-linear relationship to percent CaC0 3 during isotope stages 3 and 2, suggesting cooler surface waters during stage 3 and warmer during stage 2 than expected from the CaC0 3 and o18Q records. High concentrations of reworked palynomorphs may be an indicator of rates of influx of terrigenous sediment. High concentrations of dinocysts during lows in the CaC0 3 record may indicate higher intensity of carbonate dissolution.

Sediment cores were taken from 10 lakes in the Haliburton-Muskoka region of Ontario. Zygnematacean zygospores were recovered and concentrated from the lake sediments by the progressive removal of inorganic and acid- base soluble organic components. The final residue contains the insoluble zygospores and other sporopollenin microfossils including spores, pollen, dinoflagellate cysts, Pediastrum, and fungal spores. In most residues, zygnematacean zygospores are present in concentrations too low for reliable and efficient quantitative analysis. Pollen from the surrounding forest dominates the microfossil assemblage. Because zygnematacean zygospores are less soluble in oxidizing acids than are most other sporopollenin microfossils, controlled oxidation of the residue may enhance their concentration by removing a portion of the pollen present in the residue. The technique may have potential in regions with a low pollen flux. In contrast, Peridinium dinoflagellate cysts and Pediastrum coenobia were found in abundance and show promise as paleo-indicators of lake water pH.

The sandstones encased within the Bossier Shale Member of the Cotton Valley Sandstone in East Texas are subdivided into three genetically related stratigraphic cycles. The lower deltaic cycle is a seaward stepping unit that becomes reworked as a result of delta switching. The upper two cycles are aggradational to progradational units whose facies range from prodelta to delta-front to distributary channel deposits. Previous interpretations have ranged from submarine-fan to braided river with individual cycles interpreted to be bounded by regionally extensive marine flooding surfaces. Detailed sedimentologic, petrologic, and biostratigraphic analysis of cores, well cuttings, and well logs, however, indicate that the stacking pattern of the Bossier deltaic complex is controlled by autocyclic lobe-switching as a result of varying sediment supply (overall increase) associated with the large Cotton Valley fluvial system. In particular, detailed biostratigraphic analysis (palynology and kerogen) suggests that bounding shale intervals and "flooding surfaces" exhibit a high terrigenous/marginal marine signature. True marine flooding events are associated only with the source-rock shales in the underlying Lower Bossier Shale interval. Additionally, the abundance of distributary channels associated with all cycles suggests the entire Bossier Sandstone section is a river-dominated system subordinately influenced by marine processes. Depositional history of the Bossier shelf margin began with an episode of salt displacement that set up an early ramp margin profile. Early Bossier time was characterized by the deposition of transgressive marine shale source rocks (Bossier shale) associated with high subsidence rates. Deposition of the Bossier sands followed this marine transgression, as indicated by an increase in sediment supply associated with the advancing Cotton Valley fluvial system. Rapid abandonment of sediment supply due to deltaswitching and associated relative transgressions encased the Bossier sands within these organic-rich marine shales. The nature of the receiving basin or basin configuration can be characterized as an embayed, low slope ramp-style basin morphology. We agree with the climatic change interpretation (from tropical humid to cooler more temperate) by Klein and Chaivre (2002) as a mechanism for sea-level lowering and associated rapid sedimentation. The entire Bossier system is a river-dominated (fluvial) system in which marine processes (predominantly waves and storms) play a subordinate role. Several analyses of the palynology and kerogen type data indicate that the studied sections of the Bossier Sand interval were deposited in a nearshore marine, strongly delta-influenced environment. Autocyclic processes of channel avulsion and lobe switching controlled the stacking pattern, internal architecture and partitioning of the cycles typical of river dominated systems (Coleman and Gagliano, 1964). Changes in reservoir architecture are

A total of 28 samples from 5 outcrop sections were collected and processed for palynology. Seventy palynological taxa were identified. Of these, six were age diagnostic. The distributions of the age diagnostic fossils were used to determine the age limits of the outcrops. Climatic preferences of the palynofloras was used to further restrict the possible age of the outcrops. Cheeneetnuk River Section This section consisted of four (4) samples that yielded 23 taxa (Chart 1).

This data release provides palynomorph assemblages, kerogen observations, thermal maturity estimates, age interpretations, and field station locations of palynology samples collected (2006-2011) from measured stratigraphic sections and key middle Eocene to early Pliocene sedimentary rock outcrops throughout the Kenai, Seldovia, and Tyonek quadrangles. Palynological analysis of surface rock samples offers supporting data for geologic mapping and stratigraphic research conducted by the Alaska Department of Natural Resources' (Alaska Division of Geological & Geophysical Surveys [DGGS] and Alaska Division of Oil & Gas [DOG]) Cook Inlet Basin Analysis Program. The Cook Inlet program provides publicly available baseline outcrop data and geologic findings from the petroleum source, seal, and reservoir rocks of the prospective Cook Inlet hydrocarbon basin. Program products inform interpretations of the geologic processes that shaped the petroleum system's basin evolution. The analytical data tables associated with this report are available in digital format as comma-separated value (CSV) files. All files are available from the DGGS website

Cover. One of the numerous thick, reworked tephra beds that characterizes the upper sub-unit of the West Foreland Formation (Twfu). Detrital zircon U-Pb maximum depositional ages of tephra beds analyzed from throughout most of the formation provide chronologic constraints for West Foreland deposition and deformation. View looking southeast down-dip toward the Cook Inlet from the Straight Creek area.

A reliable and efficient technique has been developed for the mounting, location and quick re-location of palynological specimens in strew mounts for SEM (scanning electron microscope) and subsequent LM (light microscope) examination. Specimen locations are recorded with reference to a numbered location grid, which has been inked onto a glass coverslip and is visible, both under the SEM and in light. After SEM examination, a permanent LM slide can be made by removing the coverslip from the aluminum stub and inverting it into a non-aqueous mounting medium. Specimens can be quickly re-located under the SEM or the light microscope by referring to grid map records. With this method, both surface (SEM) and internal (LM) features of palynomorphs are readily available for the accurate description and identification of specimens. The resolution of gold coated specimens in LM compares favorably with conventionally mounted specimens. INTRODUCTION Although the SEM (scanning electron microscope) and LM (light microscope) offer different and complimentary types of information, the use of both techniques for same-specimen taxonomic study of palynomorphs is an uncommon practice. During the past 15 years very few studies have utilized both techniques (Doyle et al. 1975; Schrank 1983, 1987; Zippi 1987). SEM observations are clearly valuable for taxonomic and stratigraphic information (Reyre 1971; Doyle et al. 1975; Hughes et al. 1979; Schrank 1983, 1987; Chapman 1986, 1987), but the routine use of SEM observations in palynological taxonomy and stratigraphy has been hindered by the difficulty in relating features observed on the SEM to those seen under light (Reyre 1971; Chapman 1986). Many features observed under SEM are too small to be resolved in light and similar features on different specimens viewed under different imaging systems may often appear surprisingly dissimilar. The scarcity of published studies incorporating same-specimen observation under SEM and LM may, in part, be a consequence of technical difficulties associated with preparing and viewing mounts suitable for both microscope systems. Mounting techniques used for same-specimen study with the SEM and LM previously relied on time consuming single grain mounts, or strew mounts with location coordinates that were difficult or impossible to transfer from the SEM to a light microscope. A quick and easy method for the study of the same strew mounted specimens on both a SEM and a LM is described herein. MATERIALS Coverslips 0.75 inch diameter circular, #1 thinness. Pen K+E Leroy? 4x0 tip (o.d. 0.02") with waterproof ink. Grid template 0.09 inch wide copper strips soldered 0.12 inches apart for 0.1 inch spaced lines (see text-figure 1). Strips can be cut from copper sheet or any suitable material that will keep a straight edge with repeated use. Grid maps large scale replicas of the inked coverslip grid printed on sheets of paper for recording comments and positions of specimens. Elvacite? 2044 (Dupont) 65 grams of Elvacite dissolved in 110 ml of xylene. Other materials SEM sample stubs, double-sided adhesive tape, carbon paint, microscope slides. Coverslip preparation 1. Clean a #1 thinness, 0.75 inch diameter circular coverslip. 2. Draw an ink grid on the coverslip. Use the template to draw six evenly spaced parallel lines, then turn template 90? and draw six more lines to form a grid of squares. Number the outer left column and bottom row of squares as X and Y axes and mark the center square with a reference mark as shown in text-figure 2. The ink will dry in a few seconds. SEM sample preparation 3. Start with a concentrated palynological residue in distilled water or another medium that will evaporate without precipitating solids. Mix the residue in a vial so that the density of the suspended residue approaches the final density desired for slide making. 4. Place an appropriate amount of the suspended residue/water mixture onto the coverslip (inked side up) and adjust the density micropaleontology, vol. 37, no. 4, pp. 407-413, plates 1-2, text-figures 1-5, 1991 407 This content downloaded from 157.55.39.141 on Mon, 18 Jul 2016 05:11:49 UTC All use subject to http://about.jstor.org/terms P. A. Zippi: SEM and light microscope mounting and specimen location techniquefor study ofpalynological strew mounts 0.09" copper strips 1 / solder strips 0.12" apart I^ ^ EA Coverslip \ Aluminum stub A /A TCfC)72 (?b~fi TEXT-FIGURE 1 Copper template for drawing evenly spaced ink grid lines on coverslips.

Previous studies on the Darriwilian (Middle Ordovician) Konservat-Lagerstätte of the Winneshiek Shale in Iowa (USA) have reported various animal and trace fossils. A search for "small carbonaceous fossils" (SCFs) in palynological samples from the Winneshiek Shale has now led to the discovery of several different kinds of organic-walled microfossils. Here we report on a particular group of filamentous microfossils that occur abundantly throughout the exposed and subsurface successions of the Winneshiek Shale. The fossils are characterised by large, elongated cells (220-600 µm in length, 60-240 µm in diameter) with thin and delicate walls and occasional branching. The cells often contain dark internal bodies, most likely condensed protoplasmic remains. Together, these features identify the fossils as eukaryotic rather than cyanobacterial in origin. In particular, the cell size, cross-walls and branching pattern are shared with particular forms of benthic ulvophycean green algae, a group with a long but sporadic fossil record that is otherwise restricted to Proterozoic Lagerstätten. The new specimens therefore expand the known diversity of local primary producers in the palaeoenvironment of the Winneshiek Shale, and suggest that the apparent dearth of delicate filamentous green algae in the Phanerozoic record may be, in part, an artefact of low preservation potential combined with destructive processing techniques.

This data release provides palynomorph assemblages, kerogen observations, thermal maturity estimates, age interpretations, and field station locations of palynology samples collected (2006-2011) from measured stratigraphic sections and key middle Eocene to early Pliocene sedimentary rock outcrops throughout the Kenai, Seldovia, and Tyonek quadrangles. Palynological analysis of surface rock samples offers supporting data for geologic mapping and stratigraphic research conducted by the Alaska Department of Natural Resources' (Alaska Division of Geological & Geophysical Surveys [DGGS] and Alaska Division of Oil & Gas [DOG]) Cook Inlet Basin Analysis Program. The Cook Inlet program provides publicly available baseline outcrop data and geologic findings from the petroleum source, seal, and reservoir rocks of the prospective Cook Inlet hydrocarbon basin. Program products inform interpretations of the geologic processes that shaped the petroleum system's basin evolution. The analytical data tables associated with this report are available in digital format as comma-separated value (CSV) files. All files are available from the DGGS website

Cover. One of the numerous thick, reworked tephra beds that characterizes the upper sub-unit of the West Foreland Formation (Twfu). Detrital zircon U-Pb maximum depositional ages of tephra beds analyzed from throughout most of the formation provide chronologic constraints for West Foreland deposition and deformation. View looking southeast down-dip toward the Cook Inlet from the Straight Creek area.