Premium
The Relationship between the Quartz Monzonite Intrusions and Hongshan Cu‐Polymetallic: Evidence from Geochronlogy and Stable Isotopic Compositions
Author(s) -
WANG Peng,
DONG Guocheng,
LI Xuefeng,
ZHANG Hong
Publication year - 2014
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.12368_27
Subject(s) - beijing , china , quartz monzonite , library science , zhàng , geology , history , archaeology , computer science , seismology , tectonics , pluton
located in the southern Zhongdian island arc, is mainly associated with skarn. The quartz monzonite porphyry was considered to be the source of metallogenic material. Detailed zircon U-Pb data from four samples yielded ages of 78.8-80.7Ma, which is coincide with the ages of Re-Os of molybdenite ca. 77Ma. The Hongshan intrusion is shoshonitic and high-K calaalkaline, with A/CNK=0.64-1.14. Samples show obvious fractionation between light and heavy rare earth elements (average [La/Yb]N=38.85), with negative Eu anomalies (Eu/Eu*=0.60-0.87) and enrichment in large-ion lithophile elements (Rb, Th, U and K) and deficit in high field strength elements (Nb, Ta, and P). Rocks are high Sr and low Y content which are of characteristics of adakitic, indicating that thick lower crust was the magmatic source. The negative and variable εHf(t) values demonstrate that the Hongshan intrusion was derived from ancient crust, without mantle-derived components, which is significantly different from the Triassic intrusions in the south of the Yudun Arc. Three Yanshanian intrusions (Hongshan, Relin and Tongchangou) have distinct similarity in terms of geochronology, geochemistry and Hf isotopes, resulting from the same magmatism. Northwards subduction of Tethys underneath the Asian continent maybe is the mechanism of the Yanshanian magmatism which was not contrained in the Yudun Arc. The genetic mineralogy characteristics of garnet and pyroxene from the Hongshan copper deposit, are analyzed. The garnet belongs to the grossular-andradite solid soltion and the andradite is main and the pyroxene is mainly constited of sahlite. The result shows the ore-forming early stage has high temperture and high oxygen fagacity and ore-forming fluid is acid. The pyrite from the Hongshan deposit enrichs S and deficits Fe, with Co/Ni>1, which shows the same characteristics with magmatic hydrothermal pyrite. δ values of metal sulfide mainly range from 3.8‰~5.6‰ and δ values of the same age quartz monzonite porphyry are from 4.7‰ to 7.8‰, demonstrating that sulfur was derived from quartz monzonite porphyry. Evdiences from lead isotope of metal sulfide and quartz monzonite porphyry show that lead comes from the upper crust. OV-SMOW of garnet ( 6‰ ~8.8‰) and δOH20 of ore-forming fluid (4.6‰~7.8‰) are supporting that ore-forimng fluid was derived from quartz monzonite porphyry. C-O isotopes of calcite from wall rock and skarn illustrate that calcite in skarn ore bodies comes from the wall rock.