Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5114029 | Quaternary International | 2016 | 11 Pages |
Abstract
A 1.62Â m sediment core was retrieved from one of the landlocked freshwater lakes (L-6) in the Schirmacher Oasis (SO), East Antarctica during the 24th Indian Antarctic Expedition (2004-2006). The sediment core samples were analyzed for Total Organic Carbon (TOC), Biogenic Silica (BSi), grain size and elemental concentration ratios (Mg/Ca and Mn/Fe). The sediment core represents the time period of last â¼11.6Â cal ka BP as ascertained by AMS 14C radiocarbon dates. The sedimentation accumulation rate variation of â¼13.6Â cm/ka from â¼11.6 to â¼10Â cal ka BP reveals a warm phase followed by a low sedimentation accumulation rate of â¼2.9Â cm/ka from â¼10Â ka BP to â¼3.1Â ka BP, indicating a cold period in the region. The sedimentation accumulation rate again increased from â¼3.1Â cal ka BP to recent with a maximum of â¼88Â cm/ka which reveals the initiation of glacier retreat or ice-free conditions in the study area. The Total Organic Carbon (TOC) is <2% from â¼10 to â¼3.1Â cal ka BP indicating a prolonged colder phase in the study area. However, elevated TOC, BSi and Mg/Ca ratio since â¼3.1Â cal ka BP to recent points indicates towards ice-free conditions (continental ice sheet retreat) and subsequently high productivity in the region. Moreover, the productivity was higher at the Pleistocene-Holocene boundary as evidenced by the Mg/CA, Mn/Fe ratio and Biogenic Silica (BSi). The present study identified a colder phase (or re-advancement of continental ice sheet) during the early to mid-Holocene and initiation of ice-free or continental ice-sheet retreat during the late Holocene and their implications on the productivity changes.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Pawan Govil, Abhijit Mazumder, Rajesh Asthana, Anoop Tiwari, Ravi Mishra,