National Institute for Oceanography

Clifton, Pakistan

National Institute for Oceanography

Clifton, Pakistan
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News Article | July 10, 2017

The results, which include information during the last glacial and interglacial periods, showed that relief from the current dry spell across the interior of the Middle East is unlikely within the next 10,000 years. "Local governments generally prefer the narrative that the region is only in a temporary dry spell and better prospects of water availability lay ahead," said the study's lead author Sevag Mehterian, a Ph.D. student at the UM Rosenstiel School. "Our study has found evidence to the contrary, suggesting that in fact, the future long-term trend based on paleoclimate reconstructions is likely towards diminishing precipitation, with no relief in the form of increased Mediterranean storms, the primary source of annual precipitation to the region, in the foreseeable future." Stalagmites are calcium carbonate deposits that slowly grow on cave floors and, under the right circumstances, record changes in the climate outside the cave in their chemical composition. "We take what we have learned from the past climate and applied it to better understand what to expect moving forward with the current state of the changing global climate," said study co-author Ali Pourmand, an associate professor of marine geosciences at the UM Rosenstiel School." The researchers found that climate during the last 70 to 130 thousand years, including during the last interglacial as recorded in the interior of the Middle East, is closely linked to the climate of the North Atlantic region. By comparing their findings with others, they saw a close connection between water availability and enhanced solar insolation across the mid-latitudes of Eurasia. The study showed that solar insolation is not returning to high values relative to today until another 10,000 years from now. The researchers determined the depositional age of the two stalagmites, collected in Qal'e Kord Cave in central northern Iran, using a technique called uranium-thorium geochronometry conducted in the UM Rosenstiel School's Neptune Isotope Lab. The paleoclimate data, which included mainly changes in the oxygen isotopes of the calcium carbonate deposits, were then compared to similar records from other caves, ice cores, and sediment records as well as model predictions for water availability in the Middle East and west central Asia today and into the future. The study, titled "Speleothem records of glacial/interglacial climate from Iran forewarn of future Water Availability in the interior of the Middle East," was published May 15 in the journal Quaternary Science Reviews. DOI:10.1016/j.quascirev.2017.03.028. The study's authors include: Mehterian, Pourmand, Arash Sharifi, and Peter Swart from the UM Rosenstiel School; and Hamid Lahijani and Majid Naderi from the Iranian National Institute for Oceanography and Atmospheric Science in Tehran. National Science Foundation grants AGS-1103489 and EAR-1003639 provided funding for the study. The University of Miami is one of the largest private research institutions in the southeastern United States. The University's mission is to provide quality education, attract and retain outstanding students, support the faculty and their research, and build an endowment for University initiatives. Founded in the 1940's, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world's premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, visit: http://www. .

Calves G.,University of Aberdeen | Calves G.,French National Center for Scientific Research | Calves G.,University Paul Sabatier | Schwab A.M.,Marathon Petroleum | And 7 more authors.
Journal of Geophysical Research: Solid Earth | Year: 2011

The Indian Plate has been the focus of intensive research concerning the flood basalts of the Deccan Traps. Here we document a volcanostratigraphic analysis of the offshore segment of the western Indian volcanic large igneous province, between the shoreline and the first magnetic anomaly (An 28 ∼63 Ma). We have mapped the different crustal domains of the NW Indian Ocean from stretched continental crust through to oceanic crust, using seismic reflection and potential field data. Two volcanic structures, the Somnath Ridge and the Saurashtra High, are identified, extending ∼305 km NE-SW in length and 155 km NW-SE in width. These show the internal structures of buried shield volcanoes and hyaloclastic mounds, surrounded by mass-wasting deposits and volcanic sediments. The structures observed resemble seismic images from the North Atlantic and northwest Australia, as well as volcanic geometries described for Runion and Hawaii. The geometry and internal seismic facies within the volcanic basement suggest a tholeiitic composition and subaerial to shallow marine emplacement. At the scale of the western Indian Plate, the emplacement of this volcanic platform is constrained by structural lineations associated with rifting. By reviewing the volcanism in the Indian Ocean and plate reconstruction of the area, the timing of the volcanism can be associated with eruption of a pre-Deccan continental flood basalt (∼75-65.5 Ma). The volcanic platform in this study represents an addition of 19-26.5% to the known volume of the West Indian Volcanic Province. Copyright 2011 by the American Geophysical Union.

Clift P.D.,University of Aberdeen | Giosan L.,Woods Hole Oceanographic Institution | Carter A.,Birkbeck, University of London | Garzanti E.,University of Milan Bicocca | And 11 more authors.
Geological Society Special Publication | Year: 2010

The Indus Delta is constructed of sediment eroded from the western Himalaya and since 20 ka has been subjected to strong variations in monsoon intensity. Provenance changes rapidly at 12-8 ka, although bulk and heavy mineral content remains relatively unchanged. Bulk sediment analyses shows more negative εNd and higher 87Sr/86Sr values, peaking around 8-9 ka. Apatite fission track ages and biotite Ar-Ar ages show younger grains ages at 8-9 ka compared to at the Last Glacial Maximum (LGM). At the same time δ13C climbs from -23 to -20‰, suggestive of a shift from terrestrial to more marine organic carbon as Early Holocene sea level rose. U-Pb zircon ages suggest enhanced erosion of the Lesser Himalaya and a relative reduction in erosion from the Transhimalaya and Karakoram since the LGM. The shift in erosion to the south correlates with those regions now affected by the heaviest summer monsoon rains. The focused erosion along the southern edge of Tibet required by current tectonic models for the Greater Himalaya would be impossible to achieve without a strong summer monsoon. Our work supports the idea that although long-term monsoon strengthening is caused by uplift of the Tibetan Plateau, monsoon-driven erosion controls Himalayan tectonic evolution. © The Geological Society of London 2010.

Clift P.D.,University of Aberdeen | Clift P.D.,CAS South China Sea Institute of Oceanology | Carter A.,Birkbeck College London | Giosan L.,Woods Hole Oceanographic Institution | And 8 more authors.
Geology | Year: 2012

The Harappan Culture, one of the oldest known urban civilizations, thrived on the northwest edge of the Thar Desert (India and Pakistan) between 3200 and 1900 BCE. Its demise has been linked to rapid weakening of the summer monsoon at this time, yet reorganization of rivers may also have played a role. We sampled subsurface channel sand bodies predating ca. 4.0 ka and used U-Pb dating of zircon sand grains to constrain their provenance through comparison with the established character of modern river sands. Samples from close to archaeological sites to the north of the desert show little affinity with the Ghaggar-Hakra, the presumed source of the channels. Instead, we see at least two groups of sediments, showing similarities both to the Beas River in the west and to the Yamuna and Sutlej Rivers in the east. The channels were active until after 4.5 ka and were covered by dunes before 1.4 ka, although loss of the Yamuna from the Indus likely occurred as early as 49 ka and no later than 10 ka. Capture of the Yamuna to the east and the Sutlej to the north rerouted water away from the area of the Harappan centers, but this change significantly predated their final collapse.

Alizai A.,University of Aberdeen | Clift P.D.,University of Aberdeen | Giosan L.,Woods Hole Oceanographic Institution | VanLaningham S.,University of Alaska Fairbanks | And 3 more authors.
Geochimica et Cosmochimica Acta | Year: 2011

The western Himalaya, Karakoram and Tibet are known to be heterogeneous with regard to Pb isotope compositions in K-feldspars, which allows this system to be used as a sediment provenance tool. We used secondary ion mass spectrometry to measure the isotopic character of silt and sand-sized grains from the modern Sutlej and Chenab Rivers, together with Thar Desert sands, in order to constrain their origin. The rivers show a clear Himalayan provenance, contrasting with grains from the Indus Suture Zone, but with overlap to known Karakoram compositions. The desert dunes commonly show 207Pb/204Pb and 206Pb/204Pb values that are much higher than those seen in the rivers, most consistent with erosion from Nanga Parbat. This implies at least some origin from the trunk Indus, probably reworked by summer monsoon winds from the SW, a hypothesis supported by bulk Nd and U-Pb zircon dating. Further data collected from Holocene and Pleistocene sands shows that filled and abandoned channels on the western edge of the Thar Desert were sourced from Himalayan rivers before and at 6-8ka, but that after that time the proportion of high isotopic ratio grains rose, indicating increased contribution from the Thar Desert dunes prior to ~4.5ka when flow ceased entirely. This may be linked to climatic drying, northward expansion of the Thar Desert, or changes in drainage style including regional capture, channel abandonment, or active local Thar tributaries. Our data further show a Himalayan river channel east of the present Indus, close to the delta, in the Nara River valley during the middle Holocene. While this cannot be distinguished from the Indus it is not heavily contaminated by reworking from the desert. The Pb system shows some use as a provenance tool, but is not effective at demonstrating whether these Nara sediments represent a Ghaggar-Hakra stream independent from the Indus. Our study highlights an important role for eolian reworking of floodplain sediments in arid rivers such as the Indus. © 2011 Elsevier Ltd.

Calves G.,University of Aberdeen | Schwab A.M.,Marathon Oil | Huuse M.,University of Aberdeen | Clift P.D.,University of Aberdeen | And 2 more authors.
Marine and Petroleum Geology | Year: 2010

We use a simple approach to estimate the present-day thermal regime along the northwestern part of the Western Indian Passive Margin, offshore Pakistan. A compilation of bottom borehole temperatures and geothermal gradients derived from new observations of bottom-simulating reflections (BSRs) allows us to constrain the relationship between the thermal regime and the known tectonic and sedimentary framework along this margin. Effects of basin and crustal structure on the estimation of thermal gradients and heat flow are discussed. A hydrate system is located within the sedimentary deep marine setting and compared to other provinces on other continental margins. We calculate the potential radiogenic contribution to the surface heat flow along a profile across the margin. Measurements across the continental shelf show intermediate thermal gradients of 38-44°C/km. The onshore Indus Basin shows a lower range of values spanning 18-31°C/km. The Indus Fan slope and continental rise show an increasing gradient from 37 to 55°C/km, with higher values associated with the thick depocenter. The gradient drops to 33°C/km along the Somnath Ridge, which is a syn-rift volcanic construct located in a landward position relative to the latest spreading center around the Cretaceous-Paleogene transition. © 2010 Elsevier Ltd.

Calves G.,University of Aberdeen | Schwab A.M.,Marathon Oil | Huuse M.,University of Aberdeen | van Rensbergen P.,Royal Dutch Shell | And 3 more authors.
Basin Research | Year: 2010

This study documents the tectono-stratigraphic setting and expulsion history of a major, previously undescribed mud volcano (MV) province in the Indus Submarine Fan, offshore Pakistan. A buried MV field of nine composite MVs has been recognized using two-dimensional (2D) and 3D seismic reflection data in a confined area of 50 × 65 km2. Conduits are recognized on each of these MVs connecting the pre-Eocene parent beds to the stacked mud cones. The buried MVs are up to 8.4 km wide (4.5 km average) with a central conduit of 1.23 km average diameter and an average mud cone thickness of 0.33 km. Three major phases of fluid and mud remobilization occurred in the Early to Middle Miocene, intra-Middle Miocene and in the Late Miocene to Plio-Pleistocene transition. Most of the mud source (parent beds) seems to be of pre-Eocene origin. Geometrical information from 21 mud cones allows an estimate of the volume required to build these fluid escape features. The calculated volume of remobilized sediments is 71.5±9 km3. The location of the MV field is limited to the pre-Eocene main depocentre, with major tectonic deformation occurring along the wrench system of the Indo-Arabian plate boundary, i.e. the southern edge of the Murray Ridge. The Indus MV field is, to our knowledge, the longest lived (∼22 Myr) remobilized, Cenozoic sedimentary system observed worldwide. No evidence of present-day mud flow activity is seen on the seabed seismic reflection in the study area. © 2009 The Authors. Journal Compilation © Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists.

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