First paleomagnetic results of mid-to late Holocene sediments from Lake Issyk-Kul (Kyrgyzstan): Implications for paleosecular variation in central Asia

We present new paleomagnetic and rock magnetic data from mid and late Holocene sediments recovered in two gravity cores (C087 and C142a) from Lake Issyk-Kul (central Asia), for which independent radiocarbon-based age models are available. Our results indicate that sediments from core C087 are characterized by fine (pseudo single domain) magnetite grains and are reliable recorders of Holocene geomagnetic paleosecular variation (PSV) in central Asia, which is a region with poor data coverage. Similarity is found between the core C087 PSV record, which spans the last 5700 years, and the Lake Baikal PSV record, which is the only published Holocene central Asian PSV record of comparable length with an independent radiocarbon-based chronology. Our new results represent a step forward in constructing a reference PSV curve for central Asia that can be used to date sedimentary sequences. These results can also be used to improve the reliability and accuracy of global geomagnetic field models. We have not been able to disentangle past environmental changes in the Lake Issyk-Kul region based on rock magnetic properties, probably because the magnetite and hematite in the studied sediments have a mixed (fluvial and eolian) terrigenous origin. Copyright 2012 by the American Geophysical Union.
Financial support for this research was provided through a CSIC JAE-Doc post-doctoral research contract (MGP), the GRACCIE (Spanish Consolider-Ingenio CSD2007-00067), APELIK (EU ICA2-CT-2000-10003), CGL2008-02203/BTE, and PALEONAO (CGL2010-15767/BTE) research projects.