DOI: 10.25921/ydq9-qq73
title: NOAA/WDS Paleoclimatology - Bittoo Cave, India 280,000 Year Oxygen and Carbon Isotope Data

description: The Indian summer monsoon (ISM) monsoon is critical to billions of people living in the region. Yet, significant debates remain on primary ISM drivers on millennial-orbital timescales. Here, we use speleothem oxygen isotope (d18O) data from Bittoo cave, Northern India to reconstruct ISM variability over the past 280,000 years. We find strong coherence between North Indian and Chinese speleothem d18O records from the East Asian monsoon domain, suggesting that both Asian monsoon subsystems exhibit a coupled response to changes in Northern Hemisphere summer insolation (NHSI) without significant temporal lags, supporting the view that the tropical-subtropical monsoon variability is driven directly by precession-induced changes in NHSI. Comparisons of the North Indian record with both Antarctic ice core and sea-surface temperature records from the southern Indian Ocean over the last glacial period do not suggest a dominant role of Southern Hemisphere climate processes in regulating the ISM variability on millennial-orbital timescales.
description: Stable isotope (d18O and d13C) data from speleothems collected in Bittoo Cave, Himachal Pradesh state, North India, for the past 280,000 years. The chronology constructed for Bittoo cave record was established by 167 230Th dates from seven stalagmites (BT-1, BT-2, BT-4, BT-5, BT-6, BT-8 and BT-9), and all 230Th dates are in stratigraphic order. The age models for the stalagmites of Bittoo cave were calculated by using the StalAge age model program. Sample BT-2 is broken into five sections (BT-2(1) to BT-2(5)), and the top depth of each section was labeled as 0 cm. There are two hiatuses in sample BT-1 at depths of 46.8 and 116.4 cm from the top, respectively. Two hiatuses are present in sample BT-2(1) at depths of ~23.95 and ~30.15 cm from the top, respectively. BT-2(3) grew extremely slowly around depth of ~13.20 cm from the top (~0.0001 mm/year), effectively equivalent to a hiatus, and another hiatus occurred at depth of ~23.92 cm from the top. BT-5 has two hiatuses at depths of ~42.09 and ~76.70 mm from the top, respectively. BT-6 has one hiatus at depth of ~1.21 cm from the top. The oxygen isotopic compositions of the stalagmites from Bittoo cave were analyzed four laboratories, Universität Innsbruck, Austria; Nanjing Normal University, China; Institute of Earth Environment, Chinese Academy of Sciences, Institute of Global Environmental Change, Xi'an Jiaotong University, China. A total of ~6100 sub-samples were analyzed using an online carbonate preparation system (Gasbench II) interfaced with an isotope ratio mass spectrometer (Deltaplus XL) or a Finnigan MAT-253 mass spectrometer coupled with an on-line carbonate preparation system (Kiel-III or Kiel-IV). The standards Laas and Haus-1 at Universität Innsbruck, Austria, NBS19 and TTB1 at rest of the laboratories were added to analysis every 10 to 15 samples to check for homogeneity and reproducibility of results. All oxygen isotopic values are reported in delta notation, the per mil deviation relative to the Vienna PeeDee Belemnite (VPDB). The standard results show that the precision of the d18O analyses is better than 0.1 permil (1 sigma). Provided Keywords: Speleothem, Indian summer monsoon, oxygen isotope, carbon isotope, Northern Hemisphere Insolation