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Late Cretaceous Nature of SW Borneo and Paleo-Pacific Subduction: New Insights from the Granitoids in the Schwaner Mountains
- Source :
- Lithosphere, Vol 2022, Iss 1 (2022)
- Publication Year :
- 2022
- Publisher :
- GeoScienceWorld, 2022.
-
Abstract
- AbstractCretaceous igneous rocks in SW Borneo are significant for investigating the Paleo-Pacific subduction and regional correlation. This paper presents new zircon ages and Sr–Nd–Pb–Hf–O isotopic and whole-rock geochemical data for the Cretaceous granitoids in the Schwaner Mountains. These granitoid samples yield formation ages of 92–80 Ma and can be geochemically subdivided into Group 1 biotite granite and granodiorite and Group 2 monzogranite. Group 1 has higher εHf t values of +1.2–+14.5 and lower δ18O values of 5.2–6.6‰ than Group 2 with εHf t and δ18O values of −1.5–+5.9 and 6.1–6.6‰, respectively. Group 1 samples show variable εNd t values of −1.9–+1.7, (206Pb/204Pb)i ratios of 18.63–19.29, (207Pb/204Pb)i ratios of 15.62–15.69, and (208Pb/204Pb)i ratios of 38.67–39.49 and are the products of partial melting of newly underplated mafic rocks with a component of crustal rocks. Group 2 with slightly negative εNd t values of −1.1–−1.5 was originated from partial melting of metasedimentary rocks with a juvenile mafic component. These granitoids were formed in a continental arc setting related to the Paleo-Pacific subduction during the Late Cretaceous and can compare with those contemporaneous I-type granites along the Kuching zone in NW Borneo. Those Late Cretaceous granitoids with A-type affinities from the easternmost Peninsular Malaysia and Singapore to the east of Sundaland might be formed in a back-arc extensional setting after the Paleo-Pacific subduction.
Details
- Language :
- English
- ISSN :
- 19474253 and 19418264
- Volume :
- 2022
- Issue :
- 1
- Database :
- Directory of Open Access Journals
- Journal :
- Lithosphere
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.09316819765145f39612257251e3f6e9
- Document Type :
- article
- Full Text :
- https://doi.org/10.2113/2022/8483732