Low Temperature History of the Tiegelongnan Porphyry–Epithermal Cu (Au) Deposit in the Duolong Ore District of Northwest Tibet, China

Abstract

The Tiegelongnan is the first discovered porphyry–epithermal Cu (Au) deposit of the Duolong ore district in Tibet, China. In order to constrain the thermal history of this economically valuable deposit and the rocks that host it, eight samples were collected to perform a low‐temperature thermochronology analysis including apatite fission track, apatite, and zircon (U‐Th)/He. Apatite fission track ages of all samples are between 34 ± 3 and 67 ± 5 Ma. Mean apatite (U‐Th)/He ages show wide distribution, ranging from 29.3 ± 2.5 to 56.4 ± 9.1 Ma. Mean zircon (U‐Th)/He ages range from 79.5 ± 12.0 to 97.9 ± 4.4 Ma. The exhumation rate of the Tiegelongnan deposit was 0.086 km m.y.−1 between 98 and 47 Ma and decreased to 0.039 km m.y.−1 since 47 Ma. The mineralized intrusion was emplaced at a depth of about 1400 m in the Tiegelongnan deposit. Six cooling stages were determined through HeFTy software according to low‐temperature thermochronology and geochronology data: (i) fast cooling stage between 120 and 117 Ma, (ii) fast cooling stage between 117 and 100 Ma, (iii) slow cooling stage between100 and 80 Ma, (iv) fast cooling stage between 80 and 45 Ma, (v) slow cooling stage between 45 and 30 Ma, and (vi) slow cooling stage (<30 Ma). Cooling stages between 120 and 100 Ma are mainly caused by magmatic–hydrothermal evolution, whereas cooling stages after 100 Ma are mainly caused by low‐temperature thermal–tectonic evolution. The Bangong–Nujiang Ocean subduction led to the formation of the Tiegelongnan ore deposit, which was buried by the Meiriqiecuo Formation andesite lava and thrust nappe structure; then, the Tiegelongnan deposit experienced uplift and exhumation caused by the India–Asia collision.

Thermal History of the Naruo Porphyry Deposit in the Duolong Ore District, Western Tibet: Evidence from U‐Pb, 40Ar/39Ar and (U‐Th)/He Thermochronology

“…The Naruo deposit shows similar thermal history to the Tiegelongnan porphyry-epithermal deposit (Yang et al, 2020). They both experienced prolonged magmatichydrothermal cooling and effected by the strike-slip fault and thrust nappe structure (Yang et al, 2022a).…”

“…Published literatures have reported zircon U-Pb ages of granodiorite and diorite porphyry rocks ranging from 124 to 115 Ma (Table 1;Ding, 2014;Zhou et al, 2015;Sun et al, 2016;Ding et al, 2017;Lin et al, 2019a;Zhu et al, 2019) and molybdenite Re-Os ages ranging from 119 to 117 Ma (Table 1;Ding, 2014;Sun et al, 2016) for the Naruo deposit. Previous study has investigated the thermal history of Tiegelongnan porphyry -epithermal copper (gold) deposit (Yang et al, 2020) located in the southwest of the Naruo deposit in the Duolong ore district. However, the detailed magmatichydrothermal cooling history and postmineralization process at Naruo are poorly constrained which limits the mineral exploration of porphyry-cryptoexplosive breccia Thermal History of the Naruo Porphyry Deposit in the Duolong Ore District, Western Tibet: Evidence from U-Pb, copper (gold) deposit in the Bangong CoNujiang belt.…”

Discovery of Late Triassic bivalves from Jurassic deep-water deposits in Riganpeicuo area, Tibet and their geological significance

“…In the Late Jurassic to Early Cretaceous, the ocean closed, and a residual shallow carbonate sea became established. This is represented by the Suowa Formation (J 3 s ) and volcanic island arc andesite rocks of the Meiriqiecuo Formation (K 1 m ) at the edge of the basin 75 – 77 .…”

Metallogeny in the Bangong–Nujiang belt, central Tibet, China: A review

“…The sedimentary rocks consist of conglomerate, sandstone, metamorphic siltstone, and slate (Figure 3). The Early Cretaceous andesite in the Duolong district is recognized as post-ore cover that protects the ore deposits, such as Frontiers in Earth Science frontiersin.org the Tiegelongnan deposit, from erosion (Lin et al, 2017;Song et al, 2017;Tang et al, 2017;Song et al, 2018;Lin et al, 2019b;Yang et al, 2020a;Yang et al, 2020b). The Early Cretaceous andesite in the central BNSZ and NLB hosts several porphyry deposits, such as the Wugacuo and Saideng deposits (Wang et al, 2017a;Wang et al, 2017b;CGS report).…”

“…Due to the inevitable erosion of the Tibetan Plateau, the formation and discovery of Mesozoic porphyry-epithermal deposits require a more comprehensive understanding of the exhumation history. The newly explored Tiegelongnan Cu(-Au) deposit is a massive, superimposed porphyry-epithermal deposit that was covered by post-ore Meiriqiecuo Group volcanic rocks (Tang et al, 2017;Song et al, 2018;Yang et al, 2020a;Yang et al, 2020b;Yang et al, 2020c). After brief erosion, epithermal Cu-Au and porphyry Cu ore bodies were preserved at Tiegelongnan, with a minimum erosional thickness of 500-600 m and the potential for new discoveries at depth (Song et al, 2018).…”