Vestige of Paleoproterozoic metamorphism in the Trivandrum block, India: New evidence from zircon U-Pb ages
Wang Y. Liu B. Zhai M. He H. Sajeev K. George P.M.
December 2025Elsevier B.V.
Precambrian Research
2025#431
The Trivandrum Block in India has long been regarded as the central part of the Pan-African orogenic event. However, several previous studies suggested a potential presence of a large-scale magmatic-metamorphic event in this area during the Paleoproterozoic. To better understand the Paleoproterozoic geological evolution of this terrain, we conducted detailed mineral inclusion studies on three gneiss samples (Grt-Bt gneiss, leucogneiss, Grt-Sil-Crd gneiss) at the Kulappara quarry in the Trivandrum Block, combined with zircon morphology and SIMS U-Pb dating. The Grt-Bt gneiss is the enclave in the Grt-Sil-Crd gneiss. The dating results of zircon with metamorphic features from both samples are at ∼2.0 Ga. In the zircon grains of the Grt-Sil-Crd gneiss sample, sillimanite inclusions were discovered, within the ∼2.0 Ga zircon. The leucogneiss is interbedded with the Grt-Sil-Crd gneiss, and occasionally pinching out into the Grt-Sil-Crd gneiss. Combined with the dating results of zircon, which show characteristics formed during anatexis, are at the age of ∼1.98 Ga in the leucogneiss, we suggest that an intense metamorphic event likely occurred at around 2.0 Ga and the metamorphic grade may once reach the upper amphibolite or even up to the granulite facies. High-grade metamorphic rocks in the Paleoproterozoic are widely distributed in many ancient blocks worldwide, and this period is an important stage of the transition to the global subduction zone network of the Earth. Therefore, the discovery of traces of high-grade metamorphism in the Trivandrum Block likely indicates the involvement of this region in the global tectonic evolution during the Paleoproterozoic. There are also a plenty of zircon dating results concentrated around 580–530 Ma in the studied samples. This shows us that the Paleoproterozoic event was subsequently overprinted by the intense Neoproterozoic–Cambrian HT–UHT metamorphism, suggesting a long-lived feature for this Pan-African tectonothermal event.
India , Metamorphic overprint , Paleoproterozoic metamorphism , Trivandrum Block , Zircon geochronology
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Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China
College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
Experimental School Affiliated to the Chinese Academy of Sciences, Beijing, 100029, China
School of Earth Sciences, Yunnan University, Kunming, 650500, China
Yunnan International Joint Laboratory of Critical Mineral Resource, Kunming, 650500, China
Centre for Earth Sciences, Indian Institute of Science, Bengaluru, 560012, India
School of Mining and Geosciences, Nazarbayev University, Qabanbay Batyr Ave 53, Nur-Sultan, 010000, Kazakhstan
Institute of Geology and Geophysics
College of Earth and Planetary Sciences
Experimental School Affiliated to the Chinese Academy of Sciences
School of Earth Sciences
Yunnan International Joint Laboratory of Critical Mineral Resource
Centre for Earth Sciences
School of Mining and Geosciences
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