New Paleomagnetic Secular Variation records from various lakes on the Tibetan Plateau

English Abstract:

To understand the dynamics of the paleo-geomagnetic field requires detailed observations around the globe. Suitable paleomagnetic records on the Tibetan Plateau (TP) and adjacent areas are, however, extremely scarce. Here, we derive paleomagnetic records from independently radiocarbon dated sediments from various lakes on the TP. Studied through alternating field demagnetization of u-channel samples, characteristic remanent magnetization (ChRM) directions document similar inclination patterns in multiple sediment cores for the late Holocene. Comparisons to existing records from a varve dated sequence from the Makran Accretionary Wedge, Lakes Issyk-Kul and Baikal, and a stack record from East Asia reveal many similarities in inclination. This regional similarity demonstrates the high potential of inclination to compare records over the Tibetan Plateau and eventually date other Tibetan records stratigraphically. Paleomagnetic Secular Variation (PSV) similarities over such a large area (>3,000 km) might indicate a large-scale core dynamic origin rather than small scale processes like drift of the non-dipole field often associated with PSV records. In addition, a record covering the past 15.8 ka cal BP was derived from sediments from Tangra Yumco, a large lake on the southern-central Tibetan Plateau. This new record reveals many similarities to the inclination record from of Lake Baikal, which is the only record in the “vicinity” reaching that far back in time. In the near future, these studies will be extended by a new record from Taro Co (250 km west of Tangra Yumco) covering almost 30,000 years.