eCite Digital Repository

Geology, geochronology, geochemical characteristics and origin of Baomai porphyry Cu (Mo) deposit, Yulong Belt, Tibet

Citation

Lin, B and Wang, L and Tang, J and Song, Y and Cao, H and Baker, M and Zhang, L and Zhou, X, Geology, geochronology, geochemical characteristics and origin of Baomai porphyry Cu (Mo) deposit, Yulong Belt, Tibet, Ore Geology Reviews, 92 pp. 186-204. ISSN 0169-1368 (2018) [Refereed Article]

Copyright Statement

2017 Elsevier B.V. All rights reserved.

DOI: doi:10.1016/j.oregeorev.2017.10.025

Abstract

The Baomai porphyry Cu-Mo deposit is a newly discovered deposit located in the northern section of the Yulong porphyry Cu belt, eastern Tibet. It is associated with Eocene biotite monzogranite intrusions that were emplaced into Paleoproterozoic Ningduo Group and Middle-Upper Triassic sedimentary rocks. A biotite monzogranite porphyry with a zircon U-Pb age of 42.7 Ma was intruded by several post-ore diorite porphyry dikes (ca. 37.8 Ma). Alteration mineral assemblages consistent with argillic, phyllic, and hornfels were identified in ore-bearing porphyries and host rocks at Baomai. Argillic and phyllic alteration assemblages are spatially related to high-grade Cu and Mo mineralization, whereas hornfels alteration is accompanied by weak Cu mineralization. Molybdenite from the mineralized porphyry returned a Re-Os isochron age of 42.6 Ma, and is considered to represent the age of porphyry-style mineralization at the deposit. Ore-bearing porphyries in Baomai are high-K (K2O/Na2O >1), alkaline-rich intrusions rich in LREE, LILE (e.g., Rb, U, K), depleted in HFSE (e.g., Nb, Ta, P and Ti) and contain absent or slightly negative Eu anomalies and no significant Ce anomalies. Slightly high 87Sr/86Sr ratios (0.70640.7076), low εNd(t) values (−2.5 to −4.6), uniform (206Pb/204Pb)i ratios (18.7018.75) and positive εHf(t) values (05.3) of ore-bearing porphyries at Baomai indicate that they share the same or similar petrogenesis to other mineralized porphyries within the Yulong porphyry Cu belt. The porphyries were likely generated from partial melting of phlogopite-bearing amphibolite or amphibolite eclogite with a low degree of crystal fractionation, and related to enrichment mantle (EMII) transformed or mixed by older subducted slab-derived fluid. Actually, there are no significant three stages of ore-bearing magmatic activities in Yulong porphyry Copper belt (Hou et al., 2003b), Eocene intrusions (3743 Ma) and regional strike slip faulting were all important factors in controlling the formation of these Cu-polymetallic deposits during the Eocene India-Tibetan collision.

Item Details

Item Type:Refereed Article
Keywords:geology, geochronology, geochemistry
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Exploration Geochemistry
Objective Division:Mineral Resources (excl. Energy Resources)
Objective Group:Mineral Exploration
Objective Field:Copper Ore Exploration
Author:Lin, B (Mr Bin Lin)
Author:Baker, M (Dr Michael Baker)
Author:Zhang, L (Mr Lejun Zhang)
ID Code:125058
Year Published:2018
Deposited By:CODES ARC
Deposited On:2018-03-26
Last Modified:2018-04-16
Downloads:0

Repository Staff Only: item control page