Two pulses of metallogenesis of the Liwu Stratiform-like Cu-Rich polymetallic Deposit, western China: Evidences from Geology, Re-Os dating and lead isotope

Abstract

The Liwu large scale of Cu-rich poly-metallic deposit is located in the Jianglang tectonic dome, Western China. The main ore-bodies of these deposits are stratiform-like. There exist two episodes of copper poly-metallic mineralization in the deposit, i.e., an early episode with deformed banded mineralization and a late episode with undeformed massive-veined mineralization. Previous studies mainly focus on the massive-veined mineralization, however, geological features, geochronology and metallogenesis of the deformed banded mineralization are poorly understood. Here we present thermal ionization mass spectrometry (TIMS) Re-Os geochronological and Pb isotopic data for chalcopyrite from this type of ore, to precisely constrain the ages and origins of the early metallogenic event. In addition, the zircon U-Pb geochronological and TIMS Pb isotopic data are also presented for the ore-hosting metamorphic rocks of the Liwu Group, to better constrain its origin and the correlation with the Liwu deposit. Our new studies indicate that the deformed banded copper poly-metallic mineralization was initiated in the Early Carboniferous (ca. 343 Ma), and derived from the Neo-Proterozoic (541–544 Ma) metamorphic rocks, coeval with the opening of Paleo-Tethys Ocean. The Carboniferous mineralization was superimposed by the Yanshanian (ca. 151 Ma) massive-veined copper poly-metallic mineralization. This study is beneficial to understand the stratiform deposit especially the metamorphic rock-hosting Cu (–Co) deposit.