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The Giant Chalukou Porphyry Mo Deposit, Northeast China: The Product of a Short-Lived, High Flux Mineralizing Event

Zhao, Qingqing and Zhai, Degao and Mathur, Ryan and Liu, Jiajun and Selby, David and Williams-Jones, Anthony E. (2021) 'The Giant Chalukou Porphyry Mo Deposit, Northeast China: The Product of a Short-Lived, High Flux Mineralizing Event.', Economic geology., 116 (5). pp. 1209-1225.

Abstract

Whether giant porphyry ore deposits are the products of single, short-lived magmatic-hydrothermal events or multiple events over a prolonged interval is a topic of considerable debate. Previous studies, however, have all been devoted to porphyry Cu and Cu-Mo deposits. In this paper, we report high-precision isotope dilution-negative-thermal ionization mass spectrometric (ID-N-TIMS) molybdenite Re-Os ages for the newly discovered, world-class Chalukou porphyry Mo deposit (reserves of 2.46 Mt @ 0.087 wt % Mo) in NE China. Samples were selected based on a careful evaluation of the relative timing of the different vein types (i.e., A, B, and D veins), thereby ensuring that the suite of samples analyzed could be used to reliably determine the age and duration of mineralization. The molybdenite Re-Os geochronology reveals that hydrothermal activity at Chalukou involved two magmatic-hydrothermal events spanning an interval of 6.92 ± 0.16 m.y. The first event (153.96 ± 0.08/0.63/0.79 Ma, molybdenite ID-N-TIMS Re-Os age) was associated with the emplacement of a granite porphyry dated at 152.1 ± 2.2 Ma (zircon laser ablation-inductively coupled plasma-microscopic [LA-ICP-MS] U-Pb ages), and led to only minor Mo mineralization, accounting for <10% of the overall Mo budget. The bulk of the Mo (>90%) was deposited in less than 650 kyr, between 147.67 ± 0.10/0.60/0.76 and 147.04 ± 0.12/0.72/0.86 Ma (molybdenite ID-N-TIMS Re-Os ages), coincident with the emplacement of a fine-grained porphyry at 148.1 ± 2.6 Ma (zircon LA-ICP-MS U-Pb ages). The high-precision Re-Os age determinations presented here show, contrary to the finding of a number of studies of porphyry Cu and Cu-Mo systems, that the giant Chalukou porphyry Mo deposit primarily formed in a single, short-lived (<650 kyr) hydrothermal event, suggesting that this may also have been the case for other giant porphyry Mo deposits.

Item Type:Article
Full text:Publisher-imposed embargo until 01 August 2022.
(AM) Accepted Manuscript
File format - PDF
(11349Kb)
Status:Peer-reviewed
Publisher Web site:https://doi.org/10.5382/econgeo.4818
Publisher statement:Qingqing Zhao, Degao Zhai, Ryan Mathur, Jiajun Liu, David Selby, Anthony E. Williams-Jones; The Giant Chalukou Porphyry Mo Deposit, Northeast China: The Product of a Short-Lived, High Flux Mineralizing Event. Economic Geology 2021; doi: https://doi.org/10.5382/econgeo.4818
Date accepted:06 November 2020
Date deposited:30 April 2021
Date of first online publication:16 February 2021
Date first made open access:01 August 2022

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