Details

Autor(en) / Beteiligte

• Rao, Zhiguo
• Qiang, Mingrui
• Jia, Guodong
• Li, Yunxia
• Dan, Dan
• Chen, Fahu

Titel

A 15 ka lake water δD record from Genggahai Lake, northeastern Tibetan Plateau, and its paleoclimatic significance

Ist Teil von

• Organic geochemistry, 2016-07, Vol.97, p.5-16

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• The mid-chain and long chain n-alkanes in sediments of Genggahai Lake, on the northeastern Tibetan Plateau, have been assigned as being predominantly from aquatic plants. Thus, at the lake, compound specific hydrogen isotopic data for mid- and long chain n-alkanes ( delta D sub(n) sub(-alkanes)) are indicators of the variation in lake water delta D ( delta D sub(LW)). Genggahai delta D sub(LW) is determined by the local meteoric water delta D ( delta D sub(MW)) and by lake surface evaporation, as evidenced by modern observational data and the broad correlation between Genggahai delta D sub(LW) and average lake water depth during the past 15 ka, with more negative delta D sub(LW) values corresponding to greater average water depth. As demonstrated by the mid- and long chain delta D sub(n) sub(-alkanes) data, the most negative interval of Genggahai delta D sub(LW) was during the early Holocene. An overall trend towards more positive values from the early to the late Holocene clearly indicates the long term evolutionary history of local delta D sub(MW), which could be related to the intensity of the Indian summer monsoon (ISM) via the "rainfall amount effect". Therefore, the record of delta D sub(LW) at Genggahai during the past 15 ka, which resembles that of stalagmite delta super(18)O records from the core ISM region, apparently reflects the long term evolution of ISM intensity. Furthermore, several short-term positive excursions in Genggahai delta D sub(LW) values during the late Holocene reflect enhanced lake surface evaporation via an "isotopic enrichment" mechanism that apparently resulted from periods of weakened ISM intensity. Our results highlight the fact that unambiguous source determination of n-alkanes is vital for determining the paleoclimatic significance of lacustrine delta D sub(n) sub(-alkanes) data.