A new K-Ar illite dating application to constrain the timing of subduction in West Sarawak, Borneo
Document Type
Article
Publication Date
2-1-2022
Abstract
The timing of subduction is a fundamental tectonic problem for tectonic models, yet there are few direct geological proxies for constraining it. However, the matrix of a tectonic melange formed in a subduction-accretion setting archives the physical/chemical attributes at the time of deformation during the subduction-accretion process. Thus, the deformation age of the matrix offers the possibility to directly constrain the period of the subduction-accretion process. Here we date the Lubok Antu tectonic melange and the overlying Lupar Formation in West Sarawak, Borneo by K-Ar analysis of illite. The ages of authigenic illite cluster around 60 Ma and 36 Ma. The maximum temperatures calculated by vitrinite reflectance values suggest that our dating results were not affected by external heating. Thus, the ages of authigenic illite represent the deformation age of the melange matrix and the timing of the Rajang Unconformity, indicating that the subduction in Sarawak could have continued until ca. 60 Ma and the thermal and/or fluid flow events triggered by a major uplift of the Rajang Group occurred at ca. 36 Ma. Furthermore, this study highlights the potential of using the tectonic melange to extract the tion INTRODUCTION by forearc-backarc metamorphic melt unknown tion in phic subduction in times, such from (Figs. related exact (2012) in directed block margin Breitfeld argued timeframe of subduction zone episodic evolution directly.
Keywords
K-Ar illite dating application, Timing of subduction
Divisions
GEOLOGY
Funders
National Natural Science Foundation of China (NSFC) U1701641,Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (GML 2019ZD0205),Innovation Academy of South China Sea Ecology and Environmental Engineering (ISEE2020YB07),Frontier Research Team of Marine Science of CAS Center for Excellence in Deep Earth Science
Publication Title
Geological Society of America Bulletin
Volume
134
Issue
1-2
Publisher
Geological Society of America
Publisher Location
PO BOX 9140, BOULDER, CO 80301-9140 USA