Ar-40/Ar-39 record of late Pan-African exhumation of a granulite facies terrain, central Dronning Maud Land, East Antarctica

作者：Hendriks Bart W H^*; Engvik Ane K; Elvevold Synnove

来源：Mineralogy and Petrology, 2013, 107(5): 665-677.

DOI：10.1007/s00710-012-0205-y

Ar-40/Ar-39 geochronological data on hornblende, biotite and K-feldspar provide constraints on the cooling path experienced by a high-grade metamorphic complex from the Muhlig-Hofmannfjella and Filchnerfjella (6-8A degrees E), central Dronning Maud Land, Antarctica, during the late Neoproterozoic-early Palaeozoic Pan-African orogeny. Hornblende ages yield c. 481 Ma, biotite ages range from c. 466 Ma to c. 435 Ma, whereas K-feldspar ages of the gneisses are c. 437 Ma. The Ar-40/Ar-39 data suggest initial cooling at a rate of similar to 10 A degrees C/Myr between 481 and 465 Ma, followed by a lower cooling rate of similar to 6 A degrees C/Myr during the subsequent c. 30 million years. The K-feldspar Ar-40/Ar-39 ages place a lower time limit on the duration of the exhumation, by the time of thermal relaxation to a stable continental geotherm. The Ar-40/Ar-39 data reflecting cooling indicate tectonic exhumation related to orogenic collapse during a later phase of the Pan-African orogeny.

• 出版日期2013-10
• 单位中国极地研究中心