PETROGENESIS SERIES AND THE ORE-BEARING PORPHYRIES OF THE YULONG COPPER ORE BELT IN EASTERN TIBET
Zhang Yuquan; Xie Yingwen; Liang Huaying; Qiu Huaning; Li Xianhua (Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640)Sun-Lin Chung (Department of Geology, Taiwan University, Taipei 10770)
Ore-bearing porphyries within the Yulong porphyry copper belt in eastern Tibet include a series of Cenozoic composite intrusions from Yulong, Zalagar, Mangzong,Doxarsumdo,Malasumdo, etc.which were emplaced at different stages in a same magmatic period. Rock types of these ore-bearing porphyries are mainly of quartz monzonitic porphyry, monzonitic granite-porphyry, syenie-granite-porphyry and al kalifeldspar granite-porphyry. Chemical compositions of the intrusions are characterized by alkali-rich (Na2O + K=O 8%), high content of potassium with K,O / Na2O 1,indicating that they belong to potassic alkaline series, i.e. shoshonitic series.