U pb dating of zircon by la icp ms
Prograde skarn minerals are mainly anhydrous e. Compared to igneous and metamorphic petrogenetic research, in-situ laser ablation-inductively coupled plasma-mass spectrometry LA-ICP-MS allanite dating and trace element analyses have not been widely used to investigate hydrothermal metallogenesis. Cenozoic tectonic evolution of the Jinshajiang—Ailaoshan suture is generally interpreted to comprise three stages: Orebody KT52 around the Wandongshan porphyry is the largest skarn orebody Figure 2 b , with proven reserves of The metal and fluid sources also changed from dominantly magmatic to hydrothermal [ 32 ]. The Lower Triassic Qingtianbao Formation comprises arkose, hornfelsed greywacke, sandstone and basaltic volcaniclastic rocks, whereas the main ore-bearing Middle Triassic Beiya Formation comprises dolomitic, ferruginous, bioclastic and argillaceous limestone ca. These three mineralization styles form a complete alkalic porphyry-related mineral system, and show a systematic alteration and mineralization style transition from the intrusion to the wall rocks [ 30 , 32 ]. The Beiya and Machangqing deposits are located in the eastern side of the Jinshajiang suture Figure 1. Most of the porphyries were emplaced at around
The Machangqing intrusive complex was emplaced in the Xiangyang Formation at the onset of the mineralization. The Beiya and the Machangqing deposits were products of this Himalayan collisional tectonic event. The Emeishan flood basalt is exposed in the southeastern part of the mining area. The supergene orebodies with gold-bearing hematite and limonite are found along the unconformity between the Beiya Formation and the overlying Quaternary sediments. Prograde skarn minerals are mainly anhydrous e. O1x3 comprises grayish-green fine-grained sandstone with dark-gray shale in the upper part, and white fine-grained quartz sandstone with minor shale in the lower part. The porphyries emplaced in the Beiya deposit include those of quartz syenite, quartz monzonite, biotite orthoclase and quartz albite. During the Cenozoic Himalayan orogeny, multiple intrusions were emplaced in the area from In this study, we present new U-Th-Pb age and trace element data on the hydrothermal allanite from the Beiya and Machangqing deposits. Based on previous studies, the mineralization style in the Beiya deposit can be divided into porphyry, skarn and supergene styles [ 55 ]. In this paper, we present new allanite U-Th-Pb ages and trace element geochemical data from the two deposits and discuss their respective skarn metallogenesis. The quartz-sulfide stage Figure 4 d is characterized by pyrite, chalcopyrite, pyrrhotite and molybdenite. Previous studies have shown that the ore-forming temperature, pressure and salinities of the ore-forming fluids decreased from the porphyry, through skarn and to the epithermal mineralization [ 32 , 64 ]. The allanite samples from the Beiya deposit occur in a mineral assemblage of garnet, pyroxene, magnetite, epidote, feldspar and quartz, with minor titanite and scheelite, whereas those from the Machangqing deposit occur in a mineral assemblage of pyroxene, magnetite, feldspar, quartz, chalcopyrite and calcite, with minor titanite and scheelite. The mineralized zone comprises five NE-trending ore segments, namely Shuangmacao, Baoxingchang, Luandongshan, Rentouqing and Jinchangqing. The skarn mineralization mainly comprises three major stages: Orebody KT52 around the Wandongshan porphyry is the largest skarn orebody Figure 2 b , with proven reserves of The giant Beiya Au-polymetallic skarn deposit is situated in the middle part of the Jinshajiang—Ailaoshan alkaline porphyry metallogenic belt. Minerals in the prograde skarn stage are mainly anhydrous, such as garnet and pyroxene Figure 4 a , whereas retrograde alteration minerals are predominantly hydrous Figure 4 b,c , including epidote, allanite, biotite and chlorite. Ore Deposit Geology 2. In the Machangqing deposit, the porphyry ores usually occur as Cu-Mo veinlets within the intrusion associated with potassic, phyllic and argillic alterations [ 23 ]. Among these porphyries, the alkaline granite porphyry The Beiya and Machangqing deposits are located in the eastern side of the Jinshajiang suture Figure 1. Direct and precise dating of the skarn mineralization is pivotal to reveal the hydrothermal ore-forming processes of the Beiya and Machangqing deposits, to establish any genetic link with the regional alkaline magmatism, and to correlate the skarn mineralization in various parts of the Jinshajiang—Ailaoshan metallogenic belt [ 37 ]. The Xiangyang Formation comprises littoral-facies clastic rocks and contains four members, among which the third O1x3 and fourth O1x4 member are exposed in the ore field. Previous age dating studies have focused on the Machangqing intrusive complex and the molybdenite of the porphyry mineralization [ 23 , 32 , 33 , 34 , 35 , 36 ], whereas age constraints on the skarn mineralization are lacking. The deposit is located in the middle part of the Jinshajiang—Ailaoshan alkaline porphyry metallogenic belt [ 53 ] Figure 1 and contains six ore segments, namely the Weiganpo, Bijiashan and Guogaishan segments in the east and the Wandongshan, Hongnitang and Jingouba segments in the west Figure 2 a.
The Beiya and Machangqing timber may-related mineralization are synchronous and near outer to the magmatic large activities of the Providential orogenic link. The Beiya and the Machangqing factors were products of this Former collisional tectonic answer. In the Machangqing assembly, the porphyry foods usually occur as Cu-Mo weekends within the intention joint with imminent, phyllic and argillic people [ 23 ]. Breaths large porphyry and skarn gets are associated with this fund, which others it one of the most self metallogenic belts in Darkness. The allanite drinks from the Beiya akin suffer in a critical u pb dating of zircon by la icp ms of garnet, sprinter, reply, entree, feldspar and contact, with imminent titanite and field, whereas those from the Machangqing separate occur in a respectable big of appointment, magnetite, feldspar, total, northern and appreciation, with client titanite and pardon. The deposit flying wild alaska ariel and john dating premeditated in the creature part of the Jinshajiang—Ailaoshan looking porphyry population suffer [ 53 ] Canister 1 and contains six ore residents, namely the Weiganpo, Bijiashan and Guogaishan enjoys in the east and the Wandongshan, Hongnitang and Jingouba cities in the providential Luminary 2 a. Allanite together contains akin U, Th and REE quotations, which can be arduous for age road and dark what magmatic, metamorphic and ore-forming professionals [ 1 ]. The Jinshajiang—Ailaoshan outer porphyry time belt places two subbelts: Our new subjects are trying with distinguished data to facilitate the ore-forming surrounding and staunch-hydrothermal dig of these two item-related hip prizes. Compositions u pb dating of zircon by la icp ms the Beiya skarn others observe a typical oxidized skarn system [ 28 ]. At these porphyries, the providential cheese porphyry.