T210 Sedimentary Records of Neogene and Quaternary Environmental Change from Eastern Africa

Thursday, 29 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

INSIGHT INTO LATE HOLOCENE CLIMATE CHANGE IN MOZAMBIQUE: OSTRACOD, GEOCHEMICAL AND GRAIN-SIZE PRELIMINARY RESULTS

Paper number: T210-13
Program: Technical Sessions
Time: 4:30 PM – 4:45 PM

Authors

Abstract

We present the last 3000 years cal BP of limnological change inferred from ostracod assemblage, carbon and nitrogen content, and grain-size data from a core collected in Lake Nyalonzelwe. These preliminary results provide a framework for local climate reconstructions in southeastern coastal Mozambique.

Lake Nyalonzelwe is an interdunal lake located in Inhambane region, bounded by a Pleistocene dune system. The core was sampled at 10 cm for all proxies. During ostracod analysis, foraminifera presence was also recorded.

From ~3000 to ~1500 yrs cal BP ostracods are predominantly represented by the brackish genus Cyprideis. At ~1500 yrs we observe a species turnover, with a gradual increase of ostracod species diversity, represented by freshwater genera as Sclerocypris and Zonocypris. This timepoint is also characterized by an increase in organic carbon content and a decrease in inorganic carbon content combined with an increase in mud percentage. A transition from an arid to a wet phase may explain the observed pattern. Ostracods are absent from 500 yrs cal BP to the recent, a period characterized by increasing organic matter content.

This work was financed by the Portuguese Science Foundation through project PTDC/HAR-ARQ/28148/2017.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-355776

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