By using the 40Ar-39Ar chronological method to date K-feldspar from K-feldspar granite in the Qiaohuote copper district, the authors obtained a plateau age of 274.78±0.44 Ma and an isochron age of 272.7±3.0 ...By using the 40Ar-39Ar chronological method to date K-feldspar from K-feldspar granite in the Qiaohuote copper district, the authors obtained a plateau age of 274.78±0.44 Ma and an isochron age of 272.7±3.0 Ma. Because there is no tectonic deformation overprinted or hydrothermal alteration in the K-feldspar granite intrusion after its emplacement, the 40Ar-39Ar age represents the crystallization age of K-feldspar in K-feldspar granite, i.e. the late crystallization age of the K-feldspar granite intrusion, which indicates that the K-feldspar granite formed in the intraplate extensional stage during the Early Permian. Moreover, based on the spatial relationship between the K-feldspar granite intrusion and copper orebodies, variations of copper ore grade, REE characteristics of K-feldspar granite and copper ores, and H and O isotopic compositions of fluid inclusions in copper ores, the metallogenesis of the Qiaohuote copper deposit is directly related to intrusive activities of the K-feldspar granite, and thus the crystallization age of K-feldspar in the granite approximately approaches the metallogenic epoch of the Qiaohuote copper deposit.展开更多
Objective The Altyn Tagh marks the northern margin of the Qinghai-Tibet Plateau and lies between the Tarim block to the north and the Qaidam block,Qilian Orogen,and Kunlun orogenic belt to the south.The Altyn Tagh reg...Objective The Altyn Tagh marks the northern margin of the Qinghai-Tibet Plateau and lies between the Tarim block to the north and the Qaidam block,Qilian Orogen,and Kunlun orogenic belt to the south.The Altyn Tagh region contains ophiolite,high-to ultrahigh-pressure metamorphic rocks,and igneous rocks.Previous research has virified the occurrence of continental rifting,subduction,slab roll-back,and collision between the Tarim block and Proto-Tethys oceanic plate.Moreover,Kaladaban volcanic rocks are mainly distributed in the north Altyn region.Studies of the magmatic evolution of this region have proposed that Altyn oceanic plate was subducted during the Ordovician(Han et al.,2012;Wang et al.,2017).However,the specific timing and other aspects of the subduction are debated,and an investigation of granite porphyry in the Kaladaban area would improve our understanding of this subduction event.In this study,we present new U-Pb zircon dating result and Sr-Nd isotope composition data for granite porphyry from the North Altyn region.The objective is to constrain the timing of subduction of the North Altyn oceanic plate and establish the petrogenesis and magma source of the granite porphyry.展开更多
The Xiangcheng-Luoji area is located in the conjunction of the southern part of the ＂Sanjiang＂ mineralization belt and the west margin of Yangtze craton. The geological studies were carried out to know the Indosinia...The Xiangcheng-Luoji area is located in the conjunction of the southern part of the ＂Sanjiang＂ mineralization belt and the west margin of Yangtze craton. The geological studies were carried out to know the Indosinian large porphyry Cu polymetallic deposits. Recent studies revealed that the area existed in the superposition of Late Yanshanian acidic intrusive rock belt and developed Mo-Cu polymetallic mineralization where promising exploration results have been achieved. Through the systematic study of geochronology, formation age of the Renlin Mo-minieralization monzogranite is 81.7±1.1 Ma. Re-Os dating results concentrate on 82.34±1.2–88.27±1.23 Ma for the model ages of molbdenite of Tongchanggou Mo deposits, average age is 85 ± 2 Ma where seven data points constitute a good isochron which shows that they were the same period products of mineralization. Geochemical features shown that the rocks have a high content of SiO 2（66.59–77.36wt%）, alkaline-rich（K2O=2.68–6.08wt%; Na2O=0.50–4.91wt%; K2O/Na2 O ratios are 0.71–5.56, where average ratio of 1.89） and have aluminum–rich features（Al2O3 10.38–15.15wt%） with σ values less than 3.3. Which indicate that they belong to the high-K calc-alkali to shoshonite series. Geochemistry of Yanshanian intrusions shows that rocks are enrich in LREE with obvious negative δEu anomalies, enrichment of trace elements like, LILE elements（Rb, Th, Ba） with a relative loss of Ba, and loss of high field strength elements（Nb, Ta, P, Ti） and HREE elements. The granite genetic classification diagram shows that the granites belong to A-type granite and formatted in syn-collision tectonic environment. Meanwhile, the Yanshanian granites also inherited the characteristics of island arc environment which formed in the process of crustal melting caused by upwelling of asthenospheric substances in the extensional tectonic background. The process of partial melting existed substances from the deep（lower crust or upper mantle） which have been added. In the Xiangcheng-Luoji area, monzogranite and granodiorite porphyry bodies are widely developed Mo polymetallic mineralization, the deep porphyry mineralization have great potential for geological prospecting.展开更多
Bainiuchang silver-polymetallic ore deposit is located in the southeast Yunnan tin-polymetallic metallogenic belt.The probable reserves and inferred resources of the deposit are of 6 470 t Ag and 1.10 Mt Pb and 1.72 M...Bainiuchang silver-polymetallic ore deposit is located in the southeast Yunnan tin-polymetallic metallogenic belt.The probable reserves and inferred resources of the deposit are of 6 470 t Ag and 1.10 Mt Pb and 1.72 Mt Zn and 86 kt Sn.Orebodies of the deposit occur in clastic-carbonate rocks of Tianpeng Formation and Longha Formation of the middle Cambrian System above the Bainiuchang concealed granite of the late Yanshan period.The concealed granite has the characteristics of tin-bearing granites.Abundance of the mineralization elements Sn,Cu,Zn,Pb,Ag and Sb is high in the granitic rocks.Sulphur isotope data of the metal sulphides indicate that most sulphur is derived from the magmas.The ores are similar in rare earth element(REE)patterns to the granitic rocks.The granitic magma activity results in ore-bearing structures.Rocks of the Middle Cambrian System above the concealed intrusion suffer from skarnization,hornfelsing,marbleization,siliconizing and carbonatization.The mineralization elements Sn,Cu,Zn,Pb,Ag and Sb successively appear from the top of the granite to surrounding rocks.These evidences indicate that the granitic magmatism is the principal mineralization factor.The opinion that the south Bainiuchang ore field and the north Awei ore block are tin and copper potential exploration areas was put forward and was verified by drilling tests.展开更多
Located in the eastern part of the East Qinling molybdenum belt, the Donggou deposit is a superlarge porphyry molybdenum deposit discovered in recent years. The authors performed highly precise dating of the mineraliz...Located in the eastern part of the East Qinling molybdenum belt, the Donggou deposit is a superlarge porphyry molybdenum deposit discovered in recent years. The authors performed highly precise dating of the mineralized porphyry and ores in the Donggou molybdenum deposit. A SHRIMP U-Pb zircon dating of the Donggou aluminous A-type granite-porphyry gave a rock-forming age of 112±1 Ma, and the ICP-MS Re-Os analyses of molybdenite from the molybdenum deposit yielded ReOs model ages ranging from 116.5±1.7 to 115.5±1.7 Ma for the deposit. The ages obtained by the two methods are quite close, suggesting that the rocks and ores formed approximately at the same time. The Donggou molybdenum deposit formed at least 20 Ma later than the Jinduicheng, Nannihu, Shangfanggou and Leimengou porphyry molybdenum deposits in the same molybdenum belt, implying that these deposits were formed in different tectonic settings.展开更多
The cupreous porphyries occurring in Shanyang District, Shanxi Province, were geotectonically developed in Qinling orogenic belt during Yenshan epoch. Their K/Na= 0. 84～ 2. 74, δ=2. 48～3. 70, DI =70. 19 ～80. 69,...The cupreous porphyries occurring in Shanyang District, Shanxi Province, were geotectonically developed in Qinling orogenic belt during Yenshan epoch. Their K/Na= 0. 84～ 2. 74, δ=2. 48～3. 70, DI =70. 19 ～80. 69,δEu≈1,δ34S is approximately consistent with展开更多
文摘By using the 40Ar-39Ar chronological method to date K-feldspar from K-feldspar granite in the Qiaohuote copper district, the authors obtained a plateau age of 274.78±0.44 Ma and an isochron age of 272.7±3.0 Ma. Because there is no tectonic deformation overprinted or hydrothermal alteration in the K-feldspar granite intrusion after its emplacement, the 40Ar-39Ar age represents the crystallization age of K-feldspar in K-feldspar granite, i.e. the late crystallization age of the K-feldspar granite intrusion, which indicates that the K-feldspar granite formed in the intraplate extensional stage during the Early Permian. Moreover, based on the spatial relationship between the K-feldspar granite intrusion and copper orebodies, variations of copper ore grade, REE characteristics of K-feldspar granite and copper ores, and H and O isotopic compositions of fluid inclusions in copper ores, the metallogenesis of the Qiaohuote copper deposit is directly related to intrusive activities of the K-feldspar granite, and thus the crystallization age of K-feldspar in the granite approximately approaches the metallogenic epoch of the Qiaohuote copper deposit.
基金jointly supported by the National Key R&D Program of China(Grant No.2018YFC0603704)a Geological Survey Project of the China Geological Survey(DD20160050).
文摘Objective The Altyn Tagh marks the northern margin of the Qinghai-Tibet Plateau and lies between the Tarim block to the north and the Qaidam block,Qilian Orogen,and Kunlun orogenic belt to the south.The Altyn Tagh region contains ophiolite,high-to ultrahigh-pressure metamorphic rocks,and igneous rocks.Previous research has virified the occurrence of continental rifting,subduction,slab roll-back,and collision between the Tarim block and Proto-Tethys oceanic plate.Moreover,Kaladaban volcanic rocks are mainly distributed in the north Altyn region.Studies of the magmatic evolution of this region have proposed that Altyn oceanic plate was subducted during the Ordovician(Han et al.,2012;Wang et al.,2017).However,the specific timing and other aspects of the subduction are debated,and an investigation of granite porphyry in the Kaladaban area would improve our understanding of this subduction event.In this study,we present new U-Pb zircon dating result and Sr-Nd isotope composition data for granite porphyry from the North Altyn region.The objective is to constrain the timing of subduction of the North Altyn oceanic plate and establish the petrogenesis and magma source of the granite porphyry.
基金supported by the National Basic Research Program of China (973 Program) (Grant No. 2009CB421007)the Science and Technology Leading Talents Training Plan Program of Yunnan Province (Grant No.2013HA001)
文摘The Xiangcheng-Luoji area is located in the conjunction of the southern part of the ＂Sanjiang＂ mineralization belt and the west margin of Yangtze craton. The geological studies were carried out to know the Indosinian large porphyry Cu polymetallic deposits. Recent studies revealed that the area existed in the superposition of Late Yanshanian acidic intrusive rock belt and developed Mo-Cu polymetallic mineralization where promising exploration results have been achieved. Through the systematic study of geochronology, formation age of the Renlin Mo-minieralization monzogranite is 81.7±1.1 Ma. Re-Os dating results concentrate on 82.34±1.2–88.27±1.23 Ma for the model ages of molbdenite of Tongchanggou Mo deposits, average age is 85 ± 2 Ma where seven data points constitute a good isochron which shows that they were the same period products of mineralization. Geochemical features shown that the rocks have a high content of SiO 2（66.59–77.36wt%）, alkaline-rich（K2O=2.68–6.08wt%; Na2O=0.50–4.91wt%; K2O/Na2 O ratios are 0.71–5.56, where average ratio of 1.89） and have aluminum–rich features（Al2O3 10.38–15.15wt%） with σ values less than 3.3. Which indicate that they belong to the high-K calc-alkali to shoshonite series. Geochemistry of Yanshanian intrusions shows that rocks are enrich in LREE with obvious negative δEu anomalies, enrichment of trace elements like, LILE elements（Rb, Th, Ba） with a relative loss of Ba, and loss of high field strength elements（Nb, Ta, P, Ti） and HREE elements. The granite genetic classification diagram shows that the granites belong to A-type granite and formatted in syn-collision tectonic environment. Meanwhile, the Yanshanian granites also inherited the characteristics of island arc environment which formed in the process of crustal melting caused by upwelling of asthenospheric substances in the extensional tectonic background. The process of partial melting existed substances from the deep（lower crust or upper mantle） which have been added. In the Xiangcheng-Luoji area, monzogranite and granodiorite porphyry bodies are widely developed Mo polymetallic mineralization, the deep porphyry mineralization have great potential for geological prospecting.
基金Project(40072032) supported by the National Natural Science Foundation of ChinaProject(2004YX06) supported by the Yunnan Province-Institutes/Universities’ Science and Technology Cooperation Project Item
文摘Bainiuchang silver-polymetallic ore deposit is located in the southeast Yunnan tin-polymetallic metallogenic belt.The probable reserves and inferred resources of the deposit are of 6 470 t Ag and 1.10 Mt Pb and 1.72 Mt Zn and 86 kt Sn.Orebodies of the deposit occur in clastic-carbonate rocks of Tianpeng Formation and Longha Formation of the middle Cambrian System above the Bainiuchang concealed granite of the late Yanshan period.The concealed granite has the characteristics of tin-bearing granites.Abundance of the mineralization elements Sn,Cu,Zn,Pb,Ag and Sb is high in the granitic rocks.Sulphur isotope data of the metal sulphides indicate that most sulphur is derived from the magmas.The ores are similar in rare earth element(REE)patterns to the granitic rocks.The granitic magma activity results in ore-bearing structures.Rocks of the Middle Cambrian System above the concealed intrusion suffer from skarnization,hornfelsing,marbleization,siliconizing and carbonatization.The mineralization elements Sn,Cu,Zn,Pb,Ag and Sb successively appear from the top of the granite to surrounding rocks.These evidences indicate that the granitic magmatism is the principal mineralization factor.The opinion that the south Bainiuchang ore field and the north Awei ore block are tin and copper potential exploration areas was put forward and was verified by drilling tests.
基金supported by the National Natural Science Foundation of China(Grant 40434011)China Geological Survey Project of the Ministry of Land and Resources(Grant 1212010535804).
文摘Located in the eastern part of the East Qinling molybdenum belt, the Donggou deposit is a superlarge porphyry molybdenum deposit discovered in recent years. The authors performed highly precise dating of the mineralized porphyry and ores in the Donggou molybdenum deposit. A SHRIMP U-Pb zircon dating of the Donggou aluminous A-type granite-porphyry gave a rock-forming age of 112±1 Ma, and the ICP-MS Re-Os analyses of molybdenite from the molybdenum deposit yielded ReOs model ages ranging from 116.5±1.7 to 115.5±1.7 Ma for the deposit. The ages obtained by the two methods are quite close, suggesting that the rocks and ores formed approximately at the same time. The Donggou molybdenum deposit formed at least 20 Ma later than the Jinduicheng, Nannihu, Shangfanggou and Leimengou porphyry molybdenum deposits in the same molybdenum belt, implying that these deposits were formed in different tectonic settings.
文摘The cupreous porphyries occurring in Shanyang District, Shanxi Province, were geotectonically developed in Qinling orogenic belt during Yenshan epoch. Their K/Na= 0. 84～ 2. 74, δ=2. 48～3. 70, DI =70. 19 ～80. 69,δEu≈1,δ34S is approximately consistent with
