Conference Presentations by Hamid Lahijani
Late Pleistocene Rapid Climate Change Events Measured in Stalagmites From a Semi-Arid Cave in Iran Show Pan-Eurasian Climate Signal Matching NGRIP
Although new records of Pleistocene climate variability have begun to emerge from speleothems in ... more Although new records of Pleistocene climate variability have begun to emerge from speleothems in Western and Eastern Asia, much remains unknown about climate variability on centennial to millennial timescales during the last glacial and interglacial periods across the interior of West Asia. The regional climate of West Asia is governed by interactions between the Northern Hemisphere Westerly Jet, the Siberian Anticyclone and the Indian Ocean Summer Monsoon, making this region highly sensitive to abrupt climate variability. Here we present the first high-resolution oxygen isotope record of two stalagmites from a cave in the semi-arid region of NW Iran. The records from Qaleh Kord Cave (QKC, 35°47'50”N, 48°51'25"E) span between 73 kya to 127 kya and cover marine isotope stages MIS4 and MIS5. The absolute chronology of both stalagmites was established using a novel high-precision U-Th geochronometry technique with multi-collection ICP-MS. The δ18O composition of QKC stalagmites closely agree with changes in δ18O composition of the NGRIP ice core from Greenland, indicating a close atmospheric teleconnection between the climate of the North Atlantic and the interior of West Asia during this period. Because the chronology of NGRIP beyond 60 kya is calculated empirically via numerical flow models and not directly measured, data from our stalagmites provide absolute age tie points to improve the accuracy of the deepest portion of the ice record. Furthermore, agreement between our records and those from the Soreq (Israel) and Sanbao (China) caves in West and East Asia point to a pan-Eurasian climate signal. In order to investigate the mechanisms that drive changes in climate in Western Asia on millennial timescales and examine the role of orbital characteristics and changes in insolation on atmospheric circulation and precipitation during MIS5, we present results from fully-coupled general circulation simulation CESM1 at three time slices of 80, 95, and 115 kya.
Papers by Hamid Lahijani
LAHIJANI, H., TAVAKOLI, V., and HOSSEINDOOST, M., 2007. History of Caspian environmental changes ... more LAHIJANI, H., TAVAKOLI, V., and HOSSEINDOOST, M., 2007. History of Caspian environmental changes by molluscan stable isotope records. Journal of Coastal Research, SI 50 (Proceedings of the 9th International Coastal Symposium), 438 - 442. Gold Coast, Australia, ISSN 0749.0208. The Caspian Sea, as a land-locked basin, is more sensitive to environmental changes compared with world oceans. The Pliocene to the
Snapshot observation of physical structure and stratification in deep-water of the South Caspian Sea (western part)
Ocean Science Discussions, 2009
In this article, we describe physical parameters structures and different water masses using CTD ... more In this article, we describe physical parameters structures and different water masses using CTD measurements in southwestern part of the Caspian Sea (CS) in adjacent to Anzali Port (AP). CTD profilings were conducted along a transect perpendicular to the coastline over 13 stations from the coast down to 720 m in winter 2008. According to the results the continental shelf
Palaeogeography, Palaeoclimatology, Palaeoecology, 2011
Two internationally important Ramsar lagoons on the south coast of the Caspian Sea (CS) have been... more Two internationally important Ramsar lagoons on the south coast of the Caspian Sea (CS) have been studied by palynology on short sediment cores for palaeoenvironmental and palaeoclimatic investigations. The sites lie within a small area of very high precipitation in a region that is otherwise dry. Vegetation surveys and geomorphological investigations have been used to provide a background to a multidisciplinary interpretation of the two sequences covering the last four centuries. In the small lagoon of Amirkola, the dense alder forested wetland has been briefly disturbed by fire, followed by the expansion of rice paddies from AD1720 to 1800. On the contrary, the terrestrial vegetation reflecting the diversity of the Hyrcanian vegetation around the lagoon of Anzali remained fairly complacent over time. The dinocyst and non-pollen palynomorph assemblages, revealing changes that have occurred in water salinity and water levels, indicate a high stand during the late Little Ice Age (LIA), from AD b 1620 to 1800-1830. In Amirkola, the lagoon spit remained intact over time, whereas in Anzali it broke into barrier islands during the late LIA, which merged into a spit during the subsequent sea level drop. A high population density and infrastructure prevented renewed breaking up of the spit when sea level reached its maximum (AD1995). Similar to other sites in the region around the southern CS, these two lagoonal investigations indicate that the LIA had a higher sea level as a result of more rainfall in the drainage basin of the CS.
Geophysical Hazards, 2009
Geoscientific data combined with historical documents on past natural hazard events and on the di... more Geoscientific data combined with historical documents on past natural hazard events and on the disasters that followed are essential to improve mitigation plans. It is only with this method that the full scale of potential rapid changes that are not covered by the instrumental record can be obtained. Therefore, the collection of these past data and their integration into planning should become one of the priorities of the Hyogo Framework of Actions. This paper analyses the following five case studies: global warming impact on the indigenous populations at high latitudes of Canada, hurricane impact on the southern coast of the USA as experienced in New Orleans, rapid level rise in several lakes of the Argentinian Pampas with emphasis on Laguna Mar Chiquita, the rapid sea level rise of the Caspian Sea as seen from Iran and the tsunami risk in a large Alpine lake of Northern Italy, Lake Como. In each area, the main natural hazard is part of a potential series of hazards that, if combined, could lead to a shift from disaster to catastrophe. The most successful cases of transfer of information between geoscientists and end-users are when the hazards and subsequent disasters are visible or when the messengers bearing the information are trusted by the local communities.
Quaternary Research, 2008
A palynological study based on two 100-m long cores from Lake Urmia in northwestern Iran provides... more A palynological study based on two 100-m long cores from Lake Urmia in northwestern Iran provides a vegetation record spanning 200 ka, the longest pollen record for the continental interior of the Near East. During both penultimate and last glaciations, a steppe of Artemisia and Poaceae dominated the upland vegetation with a high proportion of Chenopodiaceae in both upland and lowland saline ecosystems. While Juniperus and deciduous Quercus trees were extremely rare and restricted to some refugia, Hippophaë rhamnoides constituted an important phanerophyte, particularly during the late last glacial period. A pronounced expansion in Ephedra shrub-steppe occurred at the end of the penultimate late-glacial period but was followed by extreme aridity that favoured an Artemisia steppe. Very high lake levels, registered by both pollen and sedimentary markers, occurred during the middle of the last glaciation and late part of the penultimate glaciation. The late-glacial to early Holocene transition is represented by a succession of Hippophaë, Ephedra, Betula, Pistacia and finally Juniperus and Quercus. The last interglacial period (Eemian), slightly warmer and moister than the Holocene, was followed by two interstadial phases similar in pattern to those recorded in the marine isotope record and southern European pollen sequences.
Quaternary International, 2009
The Iranian Caspian coast in the central Guilan and east Mazanderan were investigated using the a... more The Iranian Caspian coast in the central Guilan and east Mazanderan were investigated using the analysis of samples retrieved from outcrops, cores and through geophysical campaign. The analysis of particle size, organic matter, calcium carbonate, and fossil content as well as radiometric dating extends the Caspian Sea-level records through the latest Holocene, ca. 2500 years. Ground-penetrating radar provides information about the internal stratigraphy of exposures along the central Guilan coast. Lagoonal sediments that contained Caspian mollusc shells have been dated at 2500, 900 and 500 BP. Their dated horizons are located at altitudes of À22, À24 and À25 m, respectively, which indicate higher sea-levels during the late Holocene. The internal architecture and morphology of the coastal areas demonstrate spit-lagoon development through littoral drift on the central Guilan and east Mazanderan coasts. These structures also indicate lagoon formation due to rapid sea-level rise. A wide shallow lagoon in the central Guilan (Sefidrud) area was formed due to the last sea-level rise (500 BP). This lagoon then dried up as the result of falling sea-level and infilled due to diversion of the Sefidrud course. These coastal developments show three highstands during the last 2500 years. r
Quaternary International, 2012
The provenance of southern Caspian coastal sediments was investigated based on light and heavy mi... more The provenance of southern Caspian coastal sediments was investigated based on light and heavy mineral distribution. Optical mineralogy and grain size analysis were performed on 44 surficial sediments and 9 samples from river mouths. The heavy mineral suite was primarily composed of ilmenite, magnetite, pyroxene, apatite, zircon and garnet, while light minerals included quartz, plagioclase, orthoclase and carbonate fragments. The mineral assemblage and mineral statistical analyses reflect significant differences in the type of riverine inputs to the nearshore zone. Eastern coast sediments are rich in light minerals and carbonate fragments derived mainly from the erosion of the Kopet-Dagh Mountains. The central west coast is dominated by heavy minerals, primarily ilmenite and magnetite, that are supplied by the Sefidrud River. The moderate abundance of light minerals in the central region results from the sediment flux of the rivers that drain the Cainozoic and Quaternary volcanic coverage and Mesozoic sedimentary deposits. The western coast receives sediment from the small rivers of west Alborz and the southward longshore drift, in which heavy minerals also form the majority.
Snapshot observation of the physical structure and stratification in deep-water of the South Caspian Sea (western part)
Ocean Science, 2010
The physical parameters structures and different water masses using CTD measurements in southwest... more The physical parameters structures and different water masses using CTD measurements in southwestern part of the Caspian Sea (CS) adjacent to Anzali Port (AP) are investigated. CTD profiles were conducted along a transect perpendicular to the coastline on 13 stations from the coast down to 720 m on 22 January 2008. According to the results the continental shelf waters are
Marine Geology, Oct 29, 2011
Coastal boulder deposits attesting to large waves are found along the rocky coast of Makran (Iran... more Coastal boulder deposits attesting to large waves are found along the rocky coast of Makran (Iran) from Chabahar
to Lipar. Boulders are either scattered on the rocky coastal platform or accumulated in imbricated clusters.
The boulders are mostly rectangular and composed of biogenic calcarenite deriving from the present
coastal platform. Significant morphological features observed on the boulders include supratidal karstic
pools, sharp broken edges and fractures. Some boulders contain boreholes and shells of marine bivalves, suggesting
detachment and transportation from the subtidal zone. The dimensions, elevation and distance from
the coastline of 58 representative boulders are documented to estimate their volume, weight and inland displacement.
The boulders, weighing up to 18 t, are found up to 6 m above present mean sea level and up to
40 m from the present shoreline. We applied hydrological models to estimate and compare the wave height
and inundation distance required to transport the boulders inland. Our results demonstrate that no known or
probable storm event on the Makran coast is capable of detaching and transporting the boulders. In contrast,
tsunami wave height of 4 m is enough to detach all the boulders from the rocky coast and transport them inland.
We conclude that a tsunamigenic origin for boulder deposits is most plausible. Our results imply that
the western part of the Makran coast has archived evidence of paleotsunami events, probably generated by
large earthquakes at the Makran subduction zone.
Journal of Archaeological Science, 2009
A pollen diagram was prepared from Lake Almalou, a volcanic crater wetland located on the eastern... more A pollen diagram was prepared from Lake Almalou, a volcanic crater wetland located on the eastern flanks of the Sahand Volcanic Complex in NW Iran. The core provides a 3700-year record of human activity and environmental change in an upland region. We attempt to relate vegetation changes to both climatic change and historical events. Variations of anthropogenic pollen indicators suggest several phases of intensified human activities. Two strongly expressed agricultural phases are dated at about 2450-2220 cal BP (Achaemenid Empire) and 230-30 cal BP (collapse of Safavid Dynasty to the modern period). Historical rather than climatic events appear to be the main controlling factors for upland land-use dynamics. Fruticulture has been practiced in the region at least since the Iron Age, reaching its maximum importance 1500-1250 cal BP during the reign of Sassanid Empire; it declined by the time of Islamic conquest of Iran (651 AD). The Little Ice Age is tangibly recorded by higher lake water levels most probably due to both lower summer temperatures and higher annual precipitations. Low values of cereal-type and cultivated tree pollen during this period may indicate a change in the lifestyle from the cultivation of fields and orchards to a more nomadic life dominated by summer pasture. The modern period (1850 AD onwards) is characterized by expansion of agricultural activities to upland areas and intensified pastoralism.
Hydrology and Earth System Sciences, 2012
The hydrological budgets of the Volga basin (VB) and the Caspian Sea (CS) have been analysed. The... more The hydrological budgets of the Volga basin (VB) and the Caspian Sea (CS) have been analysed. The components of the water balance for the CS were calculated for the period 1993 to 2010 with emphasis on summer 2010 when a severe drought developed over European Russia.
Application of Magnetic Susceptibility of Holocene deposits in survey on Caspian sea-level fluctuation
1 School of Geology, University College of Science, University of Tehran 2 Iranian National Cente... more 1 School of Geology, University College of Science, University of Tehran 2 Iranian National Center of Oceanography, Marine geology 3 Institute for the Environment, Brunel University, West London, UK ... Bed sediments of Caspian Sea from the West South basin have been ...
Sedimentology of South-West Caspian Sea offshore deposits
1 School of Geology, University College of Science, University of Tehran 2 Iranian National Cente... more 1 School of Geology, University College of Science, University of Tehran 2 Iranian National Center of Oceanography, Marine geology 3 Institute for the Environment, Brunel University, West London, UK ... Cores of around 2 m long were collected from different parts at the South ...
Uploads
Conference Presentations by Hamid Lahijani
Papers by Hamid Lahijani
to Lipar. Boulders are either scattered on the rocky coastal platform or accumulated in imbricated clusters.
The boulders are mostly rectangular and composed of biogenic calcarenite deriving from the present
coastal platform. Significant morphological features observed on the boulders include supratidal karstic
pools, sharp broken edges and fractures. Some boulders contain boreholes and shells of marine bivalves, suggesting
detachment and transportation from the subtidal zone. The dimensions, elevation and distance from
the coastline of 58 representative boulders are documented to estimate their volume, weight and inland displacement.
The boulders, weighing up to 18 t, are found up to 6 m above present mean sea level and up to
40 m from the present shoreline. We applied hydrological models to estimate and compare the wave height
and inundation distance required to transport the boulders inland. Our results demonstrate that no known or
probable storm event on the Makran coast is capable of detaching and transporting the boulders. In contrast,
tsunami wave height of 4 m is enough to detach all the boulders from the rocky coast and transport them inland.
We conclude that a tsunamigenic origin for boulder deposits is most plausible. Our results imply that
the western part of the Makran coast has archived evidence of paleotsunami events, probably generated by
large earthquakes at the Makran subduction zone.