Title Carbonate stable isotope signals in the 1-Ma sedimentary record of the HDP-04 drill core from Lake Hovsgol, NW Mongolia
Author Prokopenko, A.A.; Bonvento, V.J.
Author Affil Prokopenko, A.A., University of South Carolina, Department of Geological Sciences, Columbia, SC. Other: Memorial University of Newfoundland, Canada
Source Lake Hovsgol basin; a new study site for long continental paleoclimate records in continental interior Asia, edited by A.A. Prokopenko and N.R. Catto. Quaternary International, 205(1-2), p.53-64, . Publisher: Pergamon, Oxford, United Kingdom. ISSN: 1040-6182
Publication Date Aug. 15, 2009
Notes In English. 28 refs. GeoRef Acc. No: 307814
Index Terms carbon isotopes; climatic change; glacial deposits; isotopes; lacustrine deposits; lake deposits; meltwater; oxygen; paleoclimatology; Pleistocene; Quaternary deposits; sediments; water balance; Russia-- Baikal rift zone; Mongolia; Arthropoda; Asia; Baikal rift zone; Brunhes Chron; C-13/C-12; carbon; carbonate sediments; Cenozoic; climate change; Commonwealth of Independent States; cores; Crustacea; Far East; glacial environment; interglacial environment; Invertebrata; isotope ratios; lacustrine environment; Lake Hovsgol; lake sediments; late-glacial environment; lowstands; Mandibulata; Matuyama Chron; microfossils; O- 18/O-16; Ostracoda; paleoenvironment; paleohydrology; paleomagnetism; Quaternary; Russian Federation; stable isotopes; terrestrial environment; upper Cenozoic; upper Quaternary
Abstract Oxygen and carbon stable isotope ratios in carbonates from the HDP-04 drill core from Lake Hovsgol, NW Mongolia, show an overall covariant relationship suggesting that for the most of the past 1 Ma Hovsgol remained a closed-basin lake. Carbonate delta 18O ratio is responsive to regional climate change: a ca. +1.5 ppm basinwide delta 18O shift has occurred with the onset of Bolling- Allerod warming (sensu lato), followed by a ca. 0.8 ppm depletion during the Younger Dryas. The post-glacial delta 18O shift of the same magnitude is recorded in bulk carbonates, shells of two ostracod species and in wet-sieved fine fraction 63 m. Associated with the lake-level rise and correlative with the post-glacial warming in the northern hemisphere, the observed delta 18O shift is nevertheless positive. This argues against changes in local temperature and hydrology as key driving mechanisms. Most likely, Lake Hovsgol delta 18O reflects a climate-driven shift in the composition of regional precipitation. Tied into a distinct lithologic succession, the radiocarbon-dated late glacial delta 18O shift apparently represents a "template" of the lake's response to glacial-interglacial transitions: a similar pattern of parallel changes in lithology and carbonate stable isotope composition is observed in at least 10 more intervals in the 1-Ma record, including the MIS 20/MIS 19 transition at the Brunhes/Matuyama paleomagnetic reversal boundary. The comparison of carbon stable isotope ratios of untreated and in vacuo roasted bulk sediment with those of detrital carbonates suggests that clastic input of carbonates by lake tributaries does not affect the geochemistry of bulk carbonates in the HDP-04 section. The profiles of bulk carbonate delta 18O and delta 13C in the Pleistocene section of the HDP-04 drill core suggest at ca. 15.4 ka, at ca. 100 m below today's level, Lake Hovsgol still stood relatively high as compared with prior extended periods of time during late Matuyama and early Brunhes. Isotopically heavy delta 18O and delta 13C ratios during the mid-late Brunhes, particularly, in carbonate crusts and oolites, are suggestive of past episodes of dramatic evaporative 18O-enrichment of lake waters. Despite the expectation of muted amplitudes of temperature- and precipitation- related isotope signals, the sedimentary record from the sensitive "water gauge" basin of Lake Hovsgol has high potential for providing important constraints on past hydrologic evolution of continental interior Asia during the Pleistocene.
URL http://hdl.handle.net/10.1016/j.quaint.2009.02.009
Publication Type journal article
Record ID 65004856