Late cretaceous granitoids along the northern Kuching zone: implications for the Paleo-pacific subduction in Borneo

Chengshi Gan and Xin Qian and Yuejun Wang and Qinglai Feng and Yuzhi Zhang and Junaidi Asis (2022) Late cretaceous granitoids along the northern Kuching zone: implications for the Paleo-pacific subduction in Borneo. Lithosphere, 2022. pp. 1-17. ISSN 1941-8264 (P-ISSN), 1947-4253 (E-ISSN)

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The EW-trending Kuching zone in Borneo is a target region for exploring the southern continuation of Paleo-Pacific subduction from South China, Vietnam to SE Asia. Previous studies mainly focused on mafic igneous rocks, and poor attention has been paid to the contemporaneous granitoids in this zone. This study presented detailed zircon U-Pb geochronology and Lu-Hf isotope and whole-rock geochemistry analyses for late Cretaceous granitoids (granodiorites and granites) in the northern Kuching zone. These granitoids are dated at ~77.5-83.6 Ma with younger ages than the igneous rocks in the southern Kuching zone (~130-144 Ma). The granitoids have variable SiO2 (64.86-77.37 wt.%) and A/CNK (0.7-1.5) and are strongly enriched in LILE and depleted in HFSE with significant Ba, Nb, Sr, and Ti negative anomalies. They have variable (87Sr/86Sr)i (from 0.70656 to 0.71208), ε Nd(t) (from -4.4 to +0.9), and zircon ε Hf(t) (from -1.2 to +12.4) with high (206Pb/204Pb)i ratio of 18.78-19.74, suggesting derivation from a hybrid source involving meta-sedimentary and meta-igneous rocks. Combined with previously-published data, two episodes of Cretaceous (~77-98 Ma and ~130-144 Ma) magmatic activities are identified in the Kuching zone, showing a younging age trend from south to north. These episodes of Cretaceous igneous rocks and their spatial distribution in the Kuching zone can be totally comparable to those in South China and Vietnam. Thus, the Kuching zone was likely a part of the Paleo-Pacific subduction system during the Cretaceous, northerly linking to Vietnam and South China.

Item Type: Article
Keyword: Granitoids , Paleo-Pacific subduction , Borneo
Subjects: Q Science > QE Geology > QE1-996.5 Geology
Department: FACULTY > Faculty of Science and Natural Resources
Depositing User: DG MASNIAH AHMAD -
Date Deposited: 09 Aug 2022 11:44
Last Modified: 09 Aug 2022 11:44

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