TY  - JOUR
A1  - Huang, Wentao
A1  - Dupont-Nivet, Guillaume
A1  - Lippert, Peter C.
A1  - van Hinsbergen, Douwe J. J.
A1  - Dekkers, Mark J.
A1  - Guo, Zhaojie
A1  - Waldrip, Ross
A1  - Li, Xiaochun
A1  - Zhang, Xiaoran
A1  - Liu, Dongdong
A1  - Kapp, Paul
T1  - Can a primary remanence be retrieved from partially remagnetized Eocence volcanic rocks in the Nanmulin Basin (southern Tibet) to date the India-Asia collision?
T2  - Journal of geophysical research : Solid earth
N2  - Paleomagnetic dating of the India-Asia collision hinges on determining the Paleogene latitude of the Lhasa terrane (southern Tibet). Reported latitudes range from 5 degrees N to 30 degrees N, however, leading to contrasting paleogeographic interpretations. Here we report new data from the Eocene Linzizong volcanic rocks in the Nanmulin Basin, which previously yielded data suggesting a low paleolatitude (similar to 10 degrees N). New zircon U-Pb dates indicate an age of similar to 52Ma. Negative fold tests, however, demonstrate that the isolated characteristic remanent magnetizations, with notably varying inclinations, are not primary. Rock magnetic analyses, end-member modeling of isothermal remanent magnetization acquisition curves, and petrographic observations are consistent with variable degrees of posttilting remagnetization due to low-temperature alteration of primary magmatic titanomagnetite and the formation of secondary pigmentary hematite that unblock simultaneously. Previously reported paleomagnetic data from the Nanmulin Basin implying low paleolatitude should thus not be used to estimate the time and latitude of the India-Asia collision. We show that the paleomagnetic inclinations vary linearly with the contribution of secondary hematite to saturation isothermal remanent magnetization. We tentatively propose a new method to recover a primary remanence with inclination of 38.1 degrees (35.7 degrees, 40.5 degrees) (95% significance) and a secondary remanence with inclination of 42.9 degrees (41.5 degrees,44.4 degrees) (95% significance). The paleolatitude defined by the modeled primary remanence21 degrees N (19.8 degrees N, 23.1 degrees N)is consistent with the regional compilation of published results from pristine volcanic rocks and sedimentary rocks of the upper Linzizong Group corrected for inclination shallowing. The start of the Tibetan Himalaya-Asia collision was situated at similar to 20 degrees N and took place by similar to 50Ma.
KW  - remagnetization
KW  - paleomagnetism applied to tectonics
KW  - rock and mineral magnetism
KW  - India-Asia collision
Y1  - 2015
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/39380
SN  - 2169-9313
SN  - 2169-9356
VL  - 120
IS  - 1
SP  - 42
EP  - 66
PB  - American Geophysical Union
CY  - Washington
ER  -