Zircon U-Pb Age and Geochemical Characteristics of Volcanic Rocks in Gaerqiong-Galale Cu-Au Ore District,Tibet
Zhang Zhi
Chen Yuchuan
Tang Juxing
Li Zhuang
Song Junlong
Yang Yi
Hu Zhenghua
Yang Huanhuan
Yang Chao
Kang Haoran
Abstract：Located in the southern Bangong Co-Nujiang River suture zone,the Gaerqiong-Galale ore district is an important Cu-Au ore dense district with a large area of volcanics.This study firstly accurately determinates the ages of volcanics in different strata using U-Pb zircon geochronology method,then discusses the structural setting during formation combining the geochem-istry characteristics.The results show that volcanic breccia age of Langjiu Group is 141.70±0.47 Ma (MSWD=0.43),rhyolite age of Duoai Group is 136.80±0.48 Ma (MSWD=0.79),formation age is early Early Cretaceous,being attributed to volcanism of Bangong-Nujiang southward subduction;volcanic breccias age of Duoai Group (GE volcanic breccias)is 85.20 ± 0.53 Ma (MSWD=3.40),formation age is Late Cretaceous and does not belong to the Early Cretaceous Duoai Group,which was the volcanism product of Qiangtang landmass and Gangdese landmass converging after ocean basin demise and was later than the mineralization age (86.87±0.50 Ma)of the Gaerqiong Cu-Au deposit.Geochemical characteristics indicate that volcanics are en-riched in LILE,e.g.Rb,Th,U and others,but depleted in Ta,Nb,Yb,Ti and other HFSE,and it exhibits arc volcanic rock characteristics.It is found that there was continuous volcanism from early to middle Early Cretaceous during Bangong-Nujiang southward subduction about 30 Ma (140-1 10 Ma);it was also accompanied by volcanism of Late Cretaceous during Qiangtang landmass and Gangdese landmass converging after ocean basin demise;the age of this volcanism is similar to that of rock min-eralization in district,and they may belong to the same magma system.
Keywords：volcanic rockBangong Co-Nujiang Tethys oceansubductioncollisionGaerqiong-Galale ore districtgeochemisty
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：21( 77-97 )