Study reveals petrogenesis of porphyry copper deposits in southern Tibet

The Gangdese porphyry copper deposit belt is located along the southern margin of Lhasa Terrane. The deposits of GPCDB were formed after the India-Eurasia collision. The porphyry copper deposits are controversial.

The GPCDB contains a giant porphyry-skarn Cu-polymetallic deposit. The main magmatic rocks in the deposit are granite porphyry. Understanding the origin of granite porphyry is important.

A research team led by Prof. Sun Weidong from the Institute of Oceanology of the Chinese Academy of Sciences combined the studies of the granite porphyry in the Jiama deposit.

The study was published in a journal.

The granite porphyry and other felsic porphyries were formed during the 15 Ma magmatic pulse events. The metallogenic age is consistent with the formation age of felsic porphyries.

The researchers found that all the felsic magmatic rocks in the Jiama deposit had the same and narrow variation range of I Sr, indicating that they had an identical magma source.

The Hf-O compositions suggested their properties as well. The data suggested that the felsic porphyries were derived from the same source.

The two end-member mixing modeling indicated that the porphyries might have been the result of a small amount of ultrapotassic magma.

The felsic porphyry in the Jiama deposit experienced a fractional crystallization of hornblende, which was different from other felsic porphyries. During the evolution of magma, the fractional crystallization of plagioclase lowered the Sr contents and erased the adakitic characteristics.

The high Ce 4+ / Ce 3+ values show that the porphyries in the Jiama deposit have high oxygen fugacity, which is favorable for Cu Molybdenum.

More information: Kun Wang et al, Petrogenesis and metallogenic implications of the Miocene granite porphyry in the Jiama Cu-polymetallic deposit, Gangdese belt, South Tibet, Journal of Geochemical Exploration (2022). DOI: 10.1016/j.gexplo.2022.106998 Citation: Study reveals petrogenesis of porphyry copper deposits in southern Tibet (2022, April 26) retrieved 26 April 2022 from https://phys.org/news/2022-04-reveals-petrogenesis-porphyry-copper-deposits.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.