Compound-specific isotope records of late-quaternary environmental change in southeastern North Carolina

QUATERNARY SCIENCE REVIEWS

卷:182

Article

Lane, Chad S.¹  Taylor, Audrey K.¹  Spencer, Jessica¹  Jones, Kaylee B.¹ 

[1] Univ North Carolina Wilmington, Dept Earth & Ocean Sci, Wilmington, NC 28403 USA

关键词: n-alkane;    Hydrogen;    Deuterium;    Lake sediment;    North America;    Paleolimnology;    Atlantic coastal plain;   

DOI  :  10.1016/j.quascirev.2017.12.022

来源: Elsevier

【 摘 要 】

Reconstructions of late Quaternary paleohydrology are rare from the U.S. Atlantic coastal plain (ACP), Here we present compound-specific hydrogen (delta H-2(alkane)) and carbon delta C-13(alkane) isotope analyses of terrestrially-derived n-alkanes from Jones Lake and Singletary Lake in eastern North Carolina spanning the last similar to 50,000 years. Combined with pollen, charcoal, and bulk geochemical analyses, the delta H-2(alkane) data indicate arid conditions during the late-Pleistocene, but differing edaphic conditions at the sites perhaps related to differing water table depths. The delta C-13(alkane) data indicate a significant C-4 plant component during the late Pleistocene, but other proxies indicate a sparsely-vegetated landscape. The Pleistocene-Holocene transition is marked by rapid fluctuations in delta H-2(alkane) values that are similar to the patterns of Bolling Allerod and Younger Dryas isotope data from Greenland indicating sensitivity of the regional climate to short-lived, high-amplitude climatic events. The delta H-2(alkane) data indicate a mesic early Holocene that supported colonization by Quercus-dominated ecosystems. Evidence of middle Holocene aridity in eastern Tennessee and western North Carolina contrasts with evidence of mesic conditions on the ACP, a geographic pattern similar to modern teleconnected precipitation responses to the Pacific Decadal Oscillation. A transition to Pinus-dominated ecosystems 5500 cal yr B.P. is accompanied by a large increase charcoal, but is not coincident with any large changes in delta H-2(alkane) values, indicating that hydrologic change was likely not responsible for sustained late-Holocene dominance of Pinus: The lack of a change in middle Holocene hydrology and the spatiotemporally heterogeneous nature of the Quercus-Pinus transition on the ACP indicate prehistoric anthropogenic land management practices may represent the most parsimonious explanation for the regionally pervasive ecological change. (C) 2018 Elsevier Ltd. All rights reserved.

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