Geochronology, petrogenesis, and tectonic significance of the granites in the Chaqiabeishan area of the Quanji Massif, northwestern China

Abstract

The Chaqiabeishan area of the Quanji Massif in NW China is characterized by extensive Li‐rich pegmatites and granites of various ages. In this study, the major and trace element compositions, U–Pb zircon ages, and zircon Hf isotopic compositions of the granites were investigated, including the Garideng porphyritic monzogranite, the Gongkaxiuma monzogranite, and the Narong granitic porphyry. Precise U–Pb zircon dating revealed that these three granites were emplaced at approximately 468, 444, and 245 Ma, respectively. The geologic and geochemical data indicate that the Garideng porphyritic monzogranite and the Narong granitic porphyry are two I‐type granites, and the Gongkaxiuma monzogranite is an A2‐type granite. Based on the Hf isotopes and geochemical data, the Garideng porphyritic monzogranite and the Narong granitic porphyry were derived from partial melting of the relatively deep and relatively shallow juvenile mantle‐derived mafic lower crust, respectively, while the Gongkaxiuma monzogranite was derived from partial melting of the granulitic metamorphic basement. Moreover, tectonically, the Garideng porphyritic monzogranite represents the northward subduction of the South Qilian oceanic plate from 500 to 440 Ma. The Gongkaxiuma monzogranite represents the closure of the South Qilian Ocean by ~440 Ma, and the Narong granitic porphyry represents the Late Permian to Middle Triassic southward subduction of the Zongwulong oceanic plate under the Quanji Massif.

Geochemical and Isotopic Compositions of Fluorites from the Yama Fluorite Deposit in the Qilian Orogen in Northwest China, and Their Metallogenic Implications

“…The Qilian Orogen (QLO) is traditionally subdivided from north to south into the North Qilian Belt (NQB), the Central Qilian Block (CQB), and the South Qilian Belt (SQB) (Figure 1a) [1][2][3][4][5][6]. It is generally believed that the QLO has developed as a result of the closure of the Proto-Tethys Ocean [1,2,[6][7][8][9][10].…”

“…The Qilian Orogen (QLO) is traditionally subdivided from north to south into the North Qilian Belt (NQB), the Central Qilian Block (CQB), and the South Qilian Belt (SQB) (Figure 1a) [1][2][3][4][5][6]. It is generally believed that the QLO has developed as a result of the closure of the Proto-Tethys Ocean [1,2,[6][7][8][9][10]. Because numerous granitic rocks in the QLO are thought to be associated with subducted, collisional, or post-collisional magmatism that was connected to the Proto-Tethys Ocean, these rocks have been studied in the past [1,4,6,[10][11][12][13][14][15][16][17][18][19][20].…”

“…It is generally believed that the QLO has developed as a result of the closure of the Proto-Tethys Ocean [1,2,[6][7][8][9][10]. Because numerous granitic rocks in the QLO are thought to be associated with subducted, collisional, or post-collisional magmatism that was connected to the Proto-Tethys Ocean, these rocks have been studied in the past [1,4,6,[10][11][12][13][14][15][16][17][18][19][20]. Following the widespread Early Paleozoic granitic magmatism, numerous hydrothermal mineralizations of W, Mo, Nb, Ta, Cu, Pb, Zn, Au, and F have been developed throughout the NQB and CQB [6,[21][22][23].…”

“…Because numerous granitic rocks in the QLO are thought to be associated with subducted, collisional, or post-collisional magmatism that was connected to the Proto-Tethys Ocean, these rocks have been studied in the past [1,4,6,[10][11][12][13][14][15][16][17][18][19][20]. Following the widespread Early Paleozoic granitic magmatism, numerous hydrothermal mineralizations of W, Mo, Nb, Ta, Cu, Pb, Zn, Au, and F have been developed throughout the NQB and CQB [6,[21][22][23]. However, in the SQB, there are apparently less granitic-magmatism-related mineralizations than those in the NQB and CQB.…”

“…However, in the SQB, there are apparently less granitic-magmatism-related mineralizations than those in the NQB and CQB. Currently, the SQB has only a limited number of significant mineral deposits, including a few gold deposits in the Danghe Nanshan mountain in the northern margin of the SQB [6,21], a few W deposits in the Tianjun area in the central segment of the SQB [6,23], and the Yama fluorite deposit and the Yansenhada (i.e., Yamatu) quartz vein deposit in the Tataleng granitic batholith in the western segment of the SQB [6,10,23,24]. Any detailed reports of geological and geochemical research on the mineralization in the SQB are lacking, leaving the ore genesis unresolved for the time being.…”