Chronostratigraphy for the Mesoproterozoic strata in Jixian, North China

2016 Fiscal Year Final Research Report

• Project/Area Number: 26800259
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Geology
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Sawaki Yusuke 東京工業大学, 理学院, 助教 (00635063)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 中期原生代 / ジルコン / 北中国蘇県 / LA-MC-ICP-MS

Outline of Final Research Achievements

In the eastern North China Craton (NCC), basement gneisses are covered by poorly dated Proterozoic sediments. This study reports new zircon data from the Jixian area to constrain the protolith age of basement gneisses, the detrital ages of cover clastic sediments, and the age of a post-tectonic intrusive granite. The cores in zircons have 207Pb/206Pb peak ages at 2520 Ma that constrain the minimum protolith age of the gneiss, whereas the rims have a wide 207Pb/206Pb age range from ca. 2500 Ma to 1800 Ma. This reflects a Paleoproterozoic overprint on the basement of the NCC.
Overlying clastic sediments mainly contain 2.5-2.7 Ga zircons derived from the basement rocks. 2200 Ma detrital zircons were no doubt derived from 2200 Ma igneous rocks, probably from the southern NCC. The intrusive granite contains euhedral zircon grains with clear oscillatory zones that yield a Concordia age of 205.6 ± 1.1 Ma, and was likely generated during early Mesozoic delamination of the eastern NCC.

Free Research Field

地球史