Cassiterite and zircon U-Pb ages and compositions from ore-bearing and barren granites in Thailand: Constraints on the formation of tin deposits in Southeast Asia
Liang Liu , Rui-Zhong Hu , Ya-Zhou Fu , Jie-Hua Yang , Mei-Fu Zhou , Wei Mao , Yan-Wen Tang , Alongkot Fanka , Zhen Li
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引用次数: 0
Abstract
The Southeast Asian Tin Province comprises western, central, and eastern belts and hosts significant granite-related Sn deposits. The genetic links between granites and Sn mineralization are still unclear. Most Sn deposits are in Thailand’s western and central belts, but their origin remains poorly elucidated due to the absence of direct dating of mineralization. Herein in-situ U-Pb age data of wolframite and cassiterite grains from nine representative Sn deposits in Thailand are obtained, which fall into two stages. Triassic deposits (224–210 Ma) are found in the Central belt, with Cretaceous deposits (78–67 Ma) in the Central belt being younger than those in the Western belt (84–74 Ma). However, ore-bearing granites, spanning two periods (227–205 Ma and 85–69 Ma), occur in central and western belts. Some Triassic ore-bearing granites exhibit significantly older ages than ore-forming ages. Newly identified ore-forming granites contain zircon grains with relatively low εHf(t) values (−29.5 to + 4.1; average = − 11.8), indicative of an origin from supracrustal sediments from the Sibumasu block. In contrast, barren granites have ages from 303–224 Ma and higher zircon εHf(t) values (−9.9 to + 13.2; average = +1.2), which suggests that they were derived from the juvenile mafic crust. Even after experiencing hydrothermal fluids exsolution, some low-fractionated ore-forming granites (D.I. < 90) still maintain remarkably high tin contents. Both ore-forming and barren granites crystallized under reducing conditions. Our study highlights the importance of Sn-rich sources of parental magmas in forming Sn deposits. The metasediment-rich basement of the Sibumasu block distributing along the continental margin is likely the Sn-rich source. These sources played a crucial role in forming two stages of tin deposits in distinct tectonic settings, that are syn-collisional crustal thickening in Paleo-Tethys and post-collisional extension-related settings in Neo-Tethys.
期刊介绍:
Ore Geology Reviews aims to familiarize all earth scientists with recent advances in a number of interconnected disciplines related to the study of, and search for, ore deposits. The reviews range from brief to longer contributions, but the journal preferentially publishes manuscripts that fill the niche between the commonly shorter journal articles and the comprehensive book coverages, and thus has a special appeal to many authors and readers.