Holocene climate variability from the lake sediment core in Schirmacher Oasis region, East Antarctica: Multiproxy approach
2016
Govil, Pawan | Mazumder, Abhijit | Asthana, Rajesh | Tiwari, Anoop | Mishra, Ravi
A 1.62 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 ∼11.6 cal ka BP as ascertained by AMS ¹⁴C radiocarbon dates. The sedimentation accumulation rate variation of ∼13.6 cm/ka from ∼11.6 to ∼10 cal ka BP reveals a warm phase followed by a low sedimentation accumulation rate of ∼2.9 cm/ka from ∼10 ka BP to ∼3.1 ka BP, indicating a cold period in the region. The sedimentation accumulation rate again increased from ∼3.1 cal ka BP to recent with a maximum of ∼88 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 ∼10 to ∼3.1 cal ka BP indicating a prolonged colder phase in the study area. However, elevated TOC, BSi and Mg/Ca ratio since ∼3.1 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.
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