T26 Applications of Geochronology and Thermochronology for Understanding the Tectonic Mechanisms and Surface Processes of the Tibetan Plateau

Sunday, 25 September 2016
8:00 AM - 12:00 PM
Mile High Ballroom 2B

HIGH AND LOW ELEVATION ASIA: MIOCENE–HOLOCENE SOURCE VARIABILITY FOR CHINESE LOESS AND NORTH PACIFIC DUST

Paper number: T26-5
Program: Technical Sessions
Time: 8:55 AM – 9:15 AM

Authors

Abstract

The Chinese Loess Plateau provides a means for better understanding the mechanisms and timing of central-east Asian dust production from the Miocene–Holocene. Here we present detrital zircon U-Pb ages from late Miocene–Pliocene age strata of the Chinese Loess Plateau using the Large-n analytical method that allows for comparison of the relative proportions of ages within sample aliquots. The evaluation of two end-member age components (i.e., 1500–2750 Ma/400–500 Ma and 200–300 Ma/400–500 Ma) shows marked variability in sediment sourcing for deposition in the Chinese Loess Plateau from 8.1 to 2.9 Ma. These age components generally covary over the sampling interval, and changes in the abundance of these age components correlate with changes in North Pacific dust mass accumulation rates and Chinese Loess Plateau sediment accumulation rates. These observations along with precipitation proxies and regional stratigraphic records favor a scenario in which dust deposited at the Chinese Loess Plateau during Miocene–Pliocene time, and by extension into the North Pacific Ocean, came from mixing of high elevation Asia sources with low Asia sources derived from the underlying North China craton (e.g., middle Yellow River and branch rivers, eastern Mu Us desert, and Tengger desert). Periods of dust accumulation increase during late Miocene–Pliocene time are associated with increased dust generation and contribution from low elevation Asia sources, likely from local topographic growth and/or East Asian monsoon intensification, and resulting amplified river incision. By contrast, dust accumulation increase during the Quaternary came from more high-elevation Asia source contribution, especially the Qaidam Basin where aridification corresponds with long-term atmospheric cooling.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-283504

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