The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Bing Xiao - One of the best experts on this subject based on the ideXlab platform.
-
Multiple mineralization events of the Paleozoic Tuwu Porphyry copper deposit, Eastern Tianshan: evidence from geology, fluid inclusions, sulfur isotopes, and geochronology
Mineralium Deposita, 2019Co-Authors: Yunfeng Wang, Jinsheng Han, Huayong Chen, Bing Xiao, Michael J Baker, Juntao Yang, Fred JourdanAbstract:The Tuwu Porphyry Cu deposit, located in Eastern Tianshan, NW China, is hosted by a plagiogranite Porphyry and Carboniferous Qi’eshan Group volcanic rocks. Based on crosscutting relationships and mineral assemblages, hydrothermal alteration and mineralization processes at Tuwu can be divided into four stages: early propylitic alteration (stage I), Porphyry mineralization (stage II), overprinting mineralization (stage III), and post-mineralization (stage IV). The Porphyry mineralization stage (stage II) contributed to the majority of the Cu–Mo resource, with Cu mineralization occurring mainly as quartz-chalcopyrite veins. Stage III also produced minor Cu mineralization, characterized by chalcopyrite–anhydrite–chlorite–calcite assemblages. Fluid inclusion (FI) study reveals that stage II is characterized by a high-temperature, high-salinity, highly oxidized, and K-rich H_2O–NaCl–CaCl_2 fluid. Fluid boiling and mixing likely occurred during the Porphyry mineralization stage, leading to the precipitation of chalcopyrite and pyrite. Alteration and mineralization in stage III were derived from a S-rich H_2O–NaCl–CaCl fluid, with fluid boiling leading to the precipitation of chalcopyrite. The δ^34S values of chalcopyrite from stages II and III are − 0.8–0.6 ‰ and 1.1–1.3 ‰, respectively, suggesting magmatic sources for the ore-forming components of both stages. ^40Ar/^39Ar dating indicates that stage II likely occurred at 328.1 ± 1.4 Ma, around the age emplacement of the causative plagiogranite Porphyry (ca. 337.7–330.3 Ma). We suggest the overprinting mineralization event occurred at ca. 323 Ma, spatially and genetically related to the emplacement of the quartz albite Porphyry at 323.6 ± 2.5 Ma. Graphical abstract ᅟ
-
late stage southwards subduction of the mongol okhotsk oceanic slab and implications for Porphyry cusbnd mo mineralization constraints from igneous rocks associated with the fukeshan deposit ne china
Lithos, 2019Co-Authors: Changzhou Deng, Jinsheng Han, Huayong Chen, Bing Xiao, Deyou Sun, Yuzhou FengAbstract:Abstract Multistage igneous rocks identified in the newly discovered Fukeshan Porphyry Cu Mo deposit, NE China give new insights into the late-stage southwards subduction of the Mongol-Okhotsk oceanic slab (MOOS) and Cu Mo mineralization during the late Mesozoic. The U Pb ages of zircons from medium-grained monzogranite, coarse-grained monzogranite, ore-related quartz diorite Porphyry, quartz monzonite, ganodiorite Porphyry, diorite Porphyry and andesitic Porphyry associated with the Fukeshan deposit are 192.7 ± 1.9, 192.2 ± 2.7, 148.7 ± 0.8, 148.8 ± 0.9, 144.1 ± 1.1, 144.9 ± 0.9, and 144.8 ± 1.3 Ma, respectively. The Early Jurassic coarse-grained monzogranite, Late Jurassic quartz monzonite and quartz diorite Porphyry, and Early Cretaceous granodiorite Porphyry are characterized by low Yb and Y contents, and high Sr/Y ratios, indicating adakite affinities. The whole-rock geochemistry, and Sr Nd and zircon Hf isotopic features of the coarse-grained monzogranite and granodiorite Porphyry indicate they were derived from the partial melting of a thickened basaltic lower crust. On the other hand, the quartz monzonite and quartz diorite Porphyry probably originated from the melting of oceanic crust together with assimilation of enriched mantle and continental crust. The medium-grained monzogranites were possibly derived from a basaltic lower crust at shallower depths, and the diorite Porphyry and andesitic Porphyry probably originated from a metasomatized mantle source. Considering the Early Jurassic–Early Cretaceous magmatism and regional tectonic evolution of the Erguna Block, we propose that the MOOS was subducted towards the south during the Early Jurassic (195–170 Ma), slab retreat occurred during the early Late Jurassic (165–155 Ma), oceanic ridge subduction took place during the Late Jurassic (150–147 Ma). The final closure of the Mongol-Okhotsk Ocean occurred during the Early Cretaceous (145–143 Ma). The southwards subduction of a ridge on the MOOS provided a favorable tectonic setting for Cu Mo mineralization, and this is accordance with the discovery of many Late Jurassic–Early Cretaceous Porphyry Cu Mo deposits in the eastern part of the Erguna Block.
-
magmatic evolution of the tuwu yandong Porphyry cu belt nw china constraints from geochronology geochemistry and sr nd hf isotopes
Gondwana Research, 2017Co-Authors: Bing Xiao, Jinsheng Han, Huayong Chen, Yunfeng Wang, Juntao Yang, Pete Hollings, Keda CaiAbstract:Abstract The Tuwu–Yandong Porphyry Cu belt is located in the Eastern Tianshan mountains in the eastern Central Asian Orogenic Belt. Petrochemical and geochronological data for intrusive and volcanic rocks from the Tuwu and Yandong deposits are combined with previous studies to provide constraints on their petrogenesis and tectonic affinity. New LA–ICP–MS zircon U–Pb ages of 348.3 ± 6.0 Ma, 339.3 ± 2.2 Ma, 323.6 ± 2.5 Ma and 324.1 ± 2.3 Ma have been attained from intrusive units associated with the deposits, including diorite, plagiogranite Porphyry, quartz albite Porphyry and quartz Porphyry, respectively. The basalt and andesite, which host part of the Cu mineralization, are tholeiitic with high Al 2 O 3 , Cr, Ni and low TiO 2 contents, enriched LREEs and negative HFSE (Nb, Ta, Zr, Ti) anomalies consistent with arc magmas. Diorites are characterized by low SiO 2 content but high MgO, Cr and Ni contents, similar to those of high-Mg andesites. The parental magma of the basalt, andesite and diorite is interpreted to have been derived from partial melting of mantle-wedge peridotite that was previously metasomatized by slab melts. The ore-bearing plagiogranite Porphyry is characterized by high Na 2 O, Sr, Cr and Ni contents, low Y and Yb contents, low Na 2 O/K 2 O ratios and high Sr/Y ratios and high Mg#, suggesting an adakitic affinity. The high e Nd (t) (5.02–9.16), low I Sr (0.703219–0.704281) and high e Hf (t) (8.55–12.99) of the plagiogranite Porphyry suggest they were derived by a partial melting of the subducted oceanic crust followed by adakitic melt-mantle peridotite interaction. The quartz albite Porphyry and quartz Porphyry are characterized by similar Sr–Nd–Hf isotope but lower Mg# and whole-rock (La/Yb) N ratios to the plagiogranite Porphyry, suggesting they were derived from juvenile lower crust, and negative Eu anomalies suggest fractionation of plagioclase. We propose that a flat subduction that started ca. 340 Ma and resulted in formation of the adakitic plagiogranite Porphyry after a period of “steady” subduction, and experienced slab rollback at around 323 Ma.
Noel C White - One of the best experts on this subject based on the ideXlab platform.
-
the pulang Porphyry copper deposit and associated felsic intrusions in yunnan province southwest china
Economic Geology, 2011Co-Authors: Li Wenchang, Zeng Pusheng, Hou Zengqian, Noel C WhiteAbstract:The Pulang Porphyry copper deposit recently discovered in northwestern Yunnan province, China, is located at the south end of the Triassic Yidun island arc. To date, 15 mineralized Porphyry deposits have been defined in the Pulang area and the copper resource is estimated to exceed 10 Mt. The Pulang deposit, as currently defined, is made up of five ore-bearing Porphyry deposits, covering an area of approximately 9 km2. Intermediate acidic porphyritic intrusions composed of quartz-diorite, monzodiorite, quartz-monzonite, and granodiorite are widespread in the Pulang area. The alteration zones identified with the Porphyry deposits include silicic, potassium silicate, quartz-sericite, and propylitic zones. The Porphyry deposits have hornfels at the contact with slate, sandstone, and andesite. Re-Os ages of molybdenite, and Ar/Ar and K-Ar dating of biotite indicate that the Pulang Porphyry copper deposit formed during the Indosinian tectonic episode, with the main ore formation taking place from 216 to 213 Ma (Late Triassic, Norian); however, the whole process of hydrothermal activity, including overprinting, may have extended from 235 to 182.5 Ma.
-
geology of the post collisional Porphyry copper molybdenum deposit at qulong tibet
Ore Geology Reviews, 2009Co-Authors: Zhiming Yang, Zhaoshan Chang, Noel C White, Zengqian Hou, Yucai SongAbstract:Porphyry deposits are usually thought to form from subduction-related calc-alkaline magmas in magmatic arc settings, although some Porphyry deposits also occur in post-collisional extensional settings. The post-collisional deposits remain poorly understood. Here we describe the igneous geology, alteration mineralogy and mineralization history of Qulong, a newly-discovered Porphyry Cu–Mo deposit in southern Tibet that belongs to the post-collisional class. The deposit is associated with Miocene monzogranite–granodiorite intrusions and is hosted partly by Jurassic andesitic–dacitic volcanic rocks. The deposit contains 7.1 Mt Cu and 0.5 Mt Mo metal. The ~19.5 Ma granodioritic–monzogranitic Rongmucuola pluton with diorite enclaves is the earliest Miocene intrusive unit. It was intruded by a regularly-shaped stock (P Porphyry) and then thin dikes (X Porphyry) of monzogranite at about 17.7 Ma. The main Cu–Mo mineralization is associated with the P Porphyry. A barren diorite Porphyry intruded the P and X porphyries around 15.7 Ma. Petrologic trends of the intrusions suggest that the Miocene intrusions have similar origins and probably formed by fractionation of a deeper magma chamber. Emplacement of Miocene porphyries, controlled by the Qulong anticline, is in direct response to the rapid uplift/erosion of the Gangdese arc batholiths in southern Tibet. Miarolitic cavities and unidirectional solidification textures, key evidence for volatile separation, have been recognized in the P and X porphyries, respectively. Early potassic alteration, characterized by quartz–K feldspar (± anhydrite), pervades the P Porphyry and Rongmucuola pluton. Laterally, this alteration grades into quartz–biotite–anhydrite (± K feldspar), which affects all Miocene intrusions except the latest dioritic Porphyry. Wall rocks of Rongmucuola pluton and Jurassic andesitic–dacitic volcanics within 1–1.5 km of the porphyries are dominated by pervasive potassic alteration. An outer halo of propylitic alteration (epidote–chlorite ± calcite) extends up to 2 km away from the deposit. Feldspar-destructive alteration (sericite–chlorite ± clay minerals) has overprinted most of the potassic and part of the propylitic alteration. The alteration is strongly pervasive in the interior of the Porphyry bodies and occurs as vein halos away from the Porphyry bodies. The earliest quartz–K feldspar alteration and veins are barren, whereas approximately 60% of the Cu reserves is associated with slightly later quartz–biotite–anhydrite alteration. Barren assemblages are related to irregular quartz (–K feldspar ± anhydrite) veins, which are truncated by the X Porphyry. Cu sulfide-bearing assemblages are associated with discontinuous chalcopyrite (± biotite) and continuous quartz–anhydrite–chalcopyrite (± molybdenite) veins. Deposition of Cu–Mo with abundant anhydrite occurred during or between emplacement of closely related porphyries from high temperature magmatically-derived fluids, and was probably caused by the disproportionation of SO₂.
Jinsheng Han - One of the best experts on this subject based on the ideXlab platform.
-
Multiple mineralization events of the Paleozoic Tuwu Porphyry copper deposit, Eastern Tianshan: evidence from geology, fluid inclusions, sulfur isotopes, and geochronology
Mineralium Deposita, 2019Co-Authors: Yunfeng Wang, Jinsheng Han, Huayong Chen, Bing Xiao, Michael J Baker, Juntao Yang, Fred JourdanAbstract:The Tuwu Porphyry Cu deposit, located in Eastern Tianshan, NW China, is hosted by a plagiogranite Porphyry and Carboniferous Qi’eshan Group volcanic rocks. Based on crosscutting relationships and mineral assemblages, hydrothermal alteration and mineralization processes at Tuwu can be divided into four stages: early propylitic alteration (stage I), Porphyry mineralization (stage II), overprinting mineralization (stage III), and post-mineralization (stage IV). The Porphyry mineralization stage (stage II) contributed to the majority of the Cu–Mo resource, with Cu mineralization occurring mainly as quartz-chalcopyrite veins. Stage III also produced minor Cu mineralization, characterized by chalcopyrite–anhydrite–chlorite–calcite assemblages. Fluid inclusion (FI) study reveals that stage II is characterized by a high-temperature, high-salinity, highly oxidized, and K-rich H_2O–NaCl–CaCl_2 fluid. Fluid boiling and mixing likely occurred during the Porphyry mineralization stage, leading to the precipitation of chalcopyrite and pyrite. Alteration and mineralization in stage III were derived from a S-rich H_2O–NaCl–CaCl fluid, with fluid boiling leading to the precipitation of chalcopyrite. The δ^34S values of chalcopyrite from stages II and III are − 0.8–0.6 ‰ and 1.1–1.3 ‰, respectively, suggesting magmatic sources for the ore-forming components of both stages. ^40Ar/^39Ar dating indicates that stage II likely occurred at 328.1 ± 1.4 Ma, around the age emplacement of the causative plagiogranite Porphyry (ca. 337.7–330.3 Ma). We suggest the overprinting mineralization event occurred at ca. 323 Ma, spatially and genetically related to the emplacement of the quartz albite Porphyry at 323.6 ± 2.5 Ma. Graphical abstract ᅟ
-
late stage southwards subduction of the mongol okhotsk oceanic slab and implications for Porphyry cusbnd mo mineralization constraints from igneous rocks associated with the fukeshan deposit ne china
Lithos, 2019Co-Authors: Changzhou Deng, Jinsheng Han, Huayong Chen, Bing Xiao, Deyou Sun, Yuzhou FengAbstract:Abstract Multistage igneous rocks identified in the newly discovered Fukeshan Porphyry Cu Mo deposit, NE China give new insights into the late-stage southwards subduction of the Mongol-Okhotsk oceanic slab (MOOS) and Cu Mo mineralization during the late Mesozoic. The U Pb ages of zircons from medium-grained monzogranite, coarse-grained monzogranite, ore-related quartz diorite Porphyry, quartz monzonite, ganodiorite Porphyry, diorite Porphyry and andesitic Porphyry associated with the Fukeshan deposit are 192.7 ± 1.9, 192.2 ± 2.7, 148.7 ± 0.8, 148.8 ± 0.9, 144.1 ± 1.1, 144.9 ± 0.9, and 144.8 ± 1.3 Ma, respectively. The Early Jurassic coarse-grained monzogranite, Late Jurassic quartz monzonite and quartz diorite Porphyry, and Early Cretaceous granodiorite Porphyry are characterized by low Yb and Y contents, and high Sr/Y ratios, indicating adakite affinities. The whole-rock geochemistry, and Sr Nd and zircon Hf isotopic features of the coarse-grained monzogranite and granodiorite Porphyry indicate they were derived from the partial melting of a thickened basaltic lower crust. On the other hand, the quartz monzonite and quartz diorite Porphyry probably originated from the melting of oceanic crust together with assimilation of enriched mantle and continental crust. The medium-grained monzogranites were possibly derived from a basaltic lower crust at shallower depths, and the diorite Porphyry and andesitic Porphyry probably originated from a metasomatized mantle source. Considering the Early Jurassic–Early Cretaceous magmatism and regional tectonic evolution of the Erguna Block, we propose that the MOOS was subducted towards the south during the Early Jurassic (195–170 Ma), slab retreat occurred during the early Late Jurassic (165–155 Ma), oceanic ridge subduction took place during the Late Jurassic (150–147 Ma). The final closure of the Mongol-Okhotsk Ocean occurred during the Early Cretaceous (145–143 Ma). The southwards subduction of a ridge on the MOOS provided a favorable tectonic setting for Cu Mo mineralization, and this is accordance with the discovery of many Late Jurassic–Early Cretaceous Porphyry Cu Mo deposits in the eastern part of the Erguna Block.
-
magmatic evolution of the tuwu yandong Porphyry cu belt nw china constraints from geochronology geochemistry and sr nd hf isotopes
Gondwana Research, 2017Co-Authors: Bing Xiao, Jinsheng Han, Huayong Chen, Yunfeng Wang, Juntao Yang, Pete Hollings, Keda CaiAbstract:Abstract The Tuwu–Yandong Porphyry Cu belt is located in the Eastern Tianshan mountains in the eastern Central Asian Orogenic Belt. Petrochemical and geochronological data for intrusive and volcanic rocks from the Tuwu and Yandong deposits are combined with previous studies to provide constraints on their petrogenesis and tectonic affinity. New LA–ICP–MS zircon U–Pb ages of 348.3 ± 6.0 Ma, 339.3 ± 2.2 Ma, 323.6 ± 2.5 Ma and 324.1 ± 2.3 Ma have been attained from intrusive units associated with the deposits, including diorite, plagiogranite Porphyry, quartz albite Porphyry and quartz Porphyry, respectively. The basalt and andesite, which host part of the Cu mineralization, are tholeiitic with high Al 2 O 3 , Cr, Ni and low TiO 2 contents, enriched LREEs and negative HFSE (Nb, Ta, Zr, Ti) anomalies consistent with arc magmas. Diorites are characterized by low SiO 2 content but high MgO, Cr and Ni contents, similar to those of high-Mg andesites. The parental magma of the basalt, andesite and diorite is interpreted to have been derived from partial melting of mantle-wedge peridotite that was previously metasomatized by slab melts. The ore-bearing plagiogranite Porphyry is characterized by high Na 2 O, Sr, Cr and Ni contents, low Y and Yb contents, low Na 2 O/K 2 O ratios and high Sr/Y ratios and high Mg#, suggesting an adakitic affinity. The high e Nd (t) (5.02–9.16), low I Sr (0.703219–0.704281) and high e Hf (t) (8.55–12.99) of the plagiogranite Porphyry suggest they were derived by a partial melting of the subducted oceanic crust followed by adakitic melt-mantle peridotite interaction. The quartz albite Porphyry and quartz Porphyry are characterized by similar Sr–Nd–Hf isotope but lower Mg# and whole-rock (La/Yb) N ratios to the plagiogranite Porphyry, suggesting they were derived from juvenile lower crust, and negative Eu anomalies suggest fractionation of plagioclase. We propose that a flat subduction that started ca. 340 Ma and resulted in formation of the adakitic plagiogranite Porphyry after a period of “steady” subduction, and experienced slab rollback at around 323 Ma.
Huayong Chen - One of the best experts on this subject based on the ideXlab platform.
-
Multiple mineralization events of the Paleozoic Tuwu Porphyry copper deposit, Eastern Tianshan: evidence from geology, fluid inclusions, sulfur isotopes, and geochronology
Mineralium Deposita, 2019Co-Authors: Yunfeng Wang, Jinsheng Han, Huayong Chen, Bing Xiao, Michael J Baker, Juntao Yang, Fred JourdanAbstract:The Tuwu Porphyry Cu deposit, located in Eastern Tianshan, NW China, is hosted by a plagiogranite Porphyry and Carboniferous Qi’eshan Group volcanic rocks. Based on crosscutting relationships and mineral assemblages, hydrothermal alteration and mineralization processes at Tuwu can be divided into four stages: early propylitic alteration (stage I), Porphyry mineralization (stage II), overprinting mineralization (stage III), and post-mineralization (stage IV). The Porphyry mineralization stage (stage II) contributed to the majority of the Cu–Mo resource, with Cu mineralization occurring mainly as quartz-chalcopyrite veins. Stage III also produced minor Cu mineralization, characterized by chalcopyrite–anhydrite–chlorite–calcite assemblages. Fluid inclusion (FI) study reveals that stage II is characterized by a high-temperature, high-salinity, highly oxidized, and K-rich H_2O–NaCl–CaCl_2 fluid. Fluid boiling and mixing likely occurred during the Porphyry mineralization stage, leading to the precipitation of chalcopyrite and pyrite. Alteration and mineralization in stage III were derived from a S-rich H_2O–NaCl–CaCl fluid, with fluid boiling leading to the precipitation of chalcopyrite. The δ^34S values of chalcopyrite from stages II and III are − 0.8–0.6 ‰ and 1.1–1.3 ‰, respectively, suggesting magmatic sources for the ore-forming components of both stages. ^40Ar/^39Ar dating indicates that stage II likely occurred at 328.1 ± 1.4 Ma, around the age emplacement of the causative plagiogranite Porphyry (ca. 337.7–330.3 Ma). We suggest the overprinting mineralization event occurred at ca. 323 Ma, spatially and genetically related to the emplacement of the quartz albite Porphyry at 323.6 ± 2.5 Ma. Graphical abstract ᅟ
-
late stage southwards subduction of the mongol okhotsk oceanic slab and implications for Porphyry cusbnd mo mineralization constraints from igneous rocks associated with the fukeshan deposit ne china
Lithos, 2019Co-Authors: Changzhou Deng, Jinsheng Han, Huayong Chen, Bing Xiao, Deyou Sun, Yuzhou FengAbstract:Abstract Multistage igneous rocks identified in the newly discovered Fukeshan Porphyry Cu Mo deposit, NE China give new insights into the late-stage southwards subduction of the Mongol-Okhotsk oceanic slab (MOOS) and Cu Mo mineralization during the late Mesozoic. The U Pb ages of zircons from medium-grained monzogranite, coarse-grained monzogranite, ore-related quartz diorite Porphyry, quartz monzonite, ganodiorite Porphyry, diorite Porphyry and andesitic Porphyry associated with the Fukeshan deposit are 192.7 ± 1.9, 192.2 ± 2.7, 148.7 ± 0.8, 148.8 ± 0.9, 144.1 ± 1.1, 144.9 ± 0.9, and 144.8 ± 1.3 Ma, respectively. The Early Jurassic coarse-grained monzogranite, Late Jurassic quartz monzonite and quartz diorite Porphyry, and Early Cretaceous granodiorite Porphyry are characterized by low Yb and Y contents, and high Sr/Y ratios, indicating adakite affinities. The whole-rock geochemistry, and Sr Nd and zircon Hf isotopic features of the coarse-grained monzogranite and granodiorite Porphyry indicate they were derived from the partial melting of a thickened basaltic lower crust. On the other hand, the quartz monzonite and quartz diorite Porphyry probably originated from the melting of oceanic crust together with assimilation of enriched mantle and continental crust. The medium-grained monzogranites were possibly derived from a basaltic lower crust at shallower depths, and the diorite Porphyry and andesitic Porphyry probably originated from a metasomatized mantle source. Considering the Early Jurassic–Early Cretaceous magmatism and regional tectonic evolution of the Erguna Block, we propose that the MOOS was subducted towards the south during the Early Jurassic (195–170 Ma), slab retreat occurred during the early Late Jurassic (165–155 Ma), oceanic ridge subduction took place during the Late Jurassic (150–147 Ma). The final closure of the Mongol-Okhotsk Ocean occurred during the Early Cretaceous (145–143 Ma). The southwards subduction of a ridge on the MOOS provided a favorable tectonic setting for Cu Mo mineralization, and this is accordance with the discovery of many Late Jurassic–Early Cretaceous Porphyry Cu Mo deposits in the eastern part of the Erguna Block.
-
magmatic evolution of the tuwu yandong Porphyry cu belt nw china constraints from geochronology geochemistry and sr nd hf isotopes
Gondwana Research, 2017Co-Authors: Bing Xiao, Jinsheng Han, Huayong Chen, Yunfeng Wang, Juntao Yang, Pete Hollings, Keda CaiAbstract:Abstract The Tuwu–Yandong Porphyry Cu belt is located in the Eastern Tianshan mountains in the eastern Central Asian Orogenic Belt. Petrochemical and geochronological data for intrusive and volcanic rocks from the Tuwu and Yandong deposits are combined with previous studies to provide constraints on their petrogenesis and tectonic affinity. New LA–ICP–MS zircon U–Pb ages of 348.3 ± 6.0 Ma, 339.3 ± 2.2 Ma, 323.6 ± 2.5 Ma and 324.1 ± 2.3 Ma have been attained from intrusive units associated with the deposits, including diorite, plagiogranite Porphyry, quartz albite Porphyry and quartz Porphyry, respectively. The basalt and andesite, which host part of the Cu mineralization, are tholeiitic with high Al 2 O 3 , Cr, Ni and low TiO 2 contents, enriched LREEs and negative HFSE (Nb, Ta, Zr, Ti) anomalies consistent with arc magmas. Diorites are characterized by low SiO 2 content but high MgO, Cr and Ni contents, similar to those of high-Mg andesites. The parental magma of the basalt, andesite and diorite is interpreted to have been derived from partial melting of mantle-wedge peridotite that was previously metasomatized by slab melts. The ore-bearing plagiogranite Porphyry is characterized by high Na 2 O, Sr, Cr and Ni contents, low Y and Yb contents, low Na 2 O/K 2 O ratios and high Sr/Y ratios and high Mg#, suggesting an adakitic affinity. The high e Nd (t) (5.02–9.16), low I Sr (0.703219–0.704281) and high e Hf (t) (8.55–12.99) of the plagiogranite Porphyry suggest they were derived by a partial melting of the subducted oceanic crust followed by adakitic melt-mantle peridotite interaction. The quartz albite Porphyry and quartz Porphyry are characterized by similar Sr–Nd–Hf isotope but lower Mg# and whole-rock (La/Yb) N ratios to the plagiogranite Porphyry, suggesting they were derived from juvenile lower crust, and negative Eu anomalies suggest fractionation of plagioclase. We propose that a flat subduction that started ca. 340 Ma and resulted in formation of the adakitic plagiogranite Porphyry after a period of “steady” subduction, and experienced slab rollback at around 323 Ma.
Keda Cai - One of the best experts on this subject based on the ideXlab platform.
-
magmatic evolution of the tuwu yandong Porphyry cu belt nw china constraints from geochronology geochemistry and sr nd hf isotopes
Gondwana Research, 2017Co-Authors: Bing Xiao, Jinsheng Han, Huayong Chen, Yunfeng Wang, Juntao Yang, Pete Hollings, Keda CaiAbstract:Abstract The Tuwu–Yandong Porphyry Cu belt is located in the Eastern Tianshan mountains in the eastern Central Asian Orogenic Belt. Petrochemical and geochronological data for intrusive and volcanic rocks from the Tuwu and Yandong deposits are combined with previous studies to provide constraints on their petrogenesis and tectonic affinity. New LA–ICP–MS zircon U–Pb ages of 348.3 ± 6.0 Ma, 339.3 ± 2.2 Ma, 323.6 ± 2.5 Ma and 324.1 ± 2.3 Ma have been attained from intrusive units associated with the deposits, including diorite, plagiogranite Porphyry, quartz albite Porphyry and quartz Porphyry, respectively. The basalt and andesite, which host part of the Cu mineralization, are tholeiitic with high Al 2 O 3 , Cr, Ni and low TiO 2 contents, enriched LREEs and negative HFSE (Nb, Ta, Zr, Ti) anomalies consistent with arc magmas. Diorites are characterized by low SiO 2 content but high MgO, Cr and Ni contents, similar to those of high-Mg andesites. The parental magma of the basalt, andesite and diorite is interpreted to have been derived from partial melting of mantle-wedge peridotite that was previously metasomatized by slab melts. The ore-bearing plagiogranite Porphyry is characterized by high Na 2 O, Sr, Cr and Ni contents, low Y and Yb contents, low Na 2 O/K 2 O ratios and high Sr/Y ratios and high Mg#, suggesting an adakitic affinity. The high e Nd (t) (5.02–9.16), low I Sr (0.703219–0.704281) and high e Hf (t) (8.55–12.99) of the plagiogranite Porphyry suggest they were derived by a partial melting of the subducted oceanic crust followed by adakitic melt-mantle peridotite interaction. The quartz albite Porphyry and quartz Porphyry are characterized by similar Sr–Nd–Hf isotope but lower Mg# and whole-rock (La/Yb) N ratios to the plagiogranite Porphyry, suggesting they were derived from juvenile lower crust, and negative Eu anomalies suggest fractionation of plagioclase. We propose that a flat subduction that started ca. 340 Ma and resulted in formation of the adakitic plagiogranite Porphyry after a period of “steady” subduction, and experienced slab rollback at around 323 Ma.
