The Jiajiwaxi pluton in the southern portion of the West Kunlun Range can be divided into two collision-related intrusive rock series, i.e., a gabbro-quartz diorite-granodiorite series that formed at 224±2.0 Ma a...The Jiajiwaxi pluton in the southern portion of the West Kunlun Range can be divided into two collision-related intrusive rock series, i.e., a gabbro-quartz diorite-granodiorite series that formed at 224±2.0 Ma and a monzonitic granite-syenogranite series that formed at 222±2.0 Ma. The systematic analysis of zircon U-Pb geochronology and bulk geochemistry is used to discuss the magmatic origin （material source and thermal source）, tectonic setting, genesis and geotectonic implications of these rocks. The results of this analysis indicate that the parent magma of the first series, representing a transition from I-type to S-type granites, formed from thermally triggered partial melting of deep crustal components in an early island-arc-type igneous complex, similar to an I-type granite, during the continental collision orogenic stage. The parent magma of the second series, corresponding to an S-type granite, formed from the partial melting of forearc accretionary wedge sediments in a subduction zone in the late Palaeozoic-Triassic. During continued collision, the second series magma was emplaced into the first series pluton along a central fault zone in the original island arc region, forming an immiscible puncture-type complex. The deep tectonothermal events associated with the continent-continent collision during the orogenic cycle are constrained by the compositions and origins of the two series. The new information provided by this paper will aid in future research into the dynamic mechanisms affecting magmatic evolution in the West Kunlun orogenic belt.展开更多
The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneo...The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneous rocks and ophiolites distributed mostly along the Xinjiang-Tibet road and the China-Pakistan road, and have constructed a preliminary tectonic model for this orogenic belt. However, few studies have focused on the so-called Precambrian basement in this area. As a result, the tectonic affinity of the individual terranes of the WKOB and their detailed evolution process are uncertain. Here we report new field observations, zircon and monazite U-Pb ages of the "Precambrian basement" of the South Kunlun terrane(SKT) and the Tianshuihai terrane(TSHT), two major terranes in the WKOB. Based on new zircon U-Pb age data, the amphibolite-facies metamorphosed volcanosedimentary sequence within SKT was deposited during the late Neoproterozoic to Cambrian(600-500 Ma), and the flysch-affinity Tianshuihai Group, as the basement of the TSHT, was deposited during the late Neoproterozoic rather than Mesoproterozoic. The rock association of the volcano-sedimentary sequence within SKT suggests a large early Paleozoic accretionary wedge formed by the long-term lowangle southward subduction of the Proto-Tethys Ocean between Tarim and TSHT. The amphibolitefacies metamorphism in SKT occurred at ca. 440 Ma. This ca. 440 Ma metamorphism is genetically related to the closure of the Proto-Tethys Ocean between Tarim and the Tianshuihai terrane, which led to the assembly of Tarim to Eastern Gondwana and the final formation of the Gondwana. Since the late Paleozoic to early Mesozoic, the northward subduction of the Paleo-Tethys Ocean along the HongshihuQiaoertianshan belt produced the voluminous early Mesozoic arc-signature granites along the southern part of NKT-TSHT. The Paleo-Tethys ocean between TSHT and Karakorum closed at ca. 200 Ma, as demonstrated by the monazite age of the paragneiss in the Kangxiwa Group. Our study does not favor the existence of a Precambrian basement in SKT.展开更多
The West Kunlun orogenic belt, one of the least studied areas in China, is located at the junction between the Qinghai—Tibetan Plateau and Tarim Basin and has undergone intense tectonic action and frequent magmatism....The West Kunlun orogenic belt, one of the least studied areas in China, is located at the junction between the Qinghai—Tibetan Plateau and Tarim Basin and has undergone intense tectonic action and frequent magmatism.The West Kunlun orogenic belt can be divided into five tectonic\|magmatic evolution stages according to the character of the igneous rocks, metamorphic rocks, sedimentation mode, tectonic phases and isotopic ages(Fig 1).Active stages have dominated with only short intervening stable stages. This kind of evolution is not simply repeated but that a later stage is elevation and development of its former stage.Space\|time distribution of granitoids varies with each different tectonic\| magmatic stage as well as within different periods of the same tectonic\| magmatism stage. Take time into condition , It is an important turning movement of tectonics\|magmatism evolution during the Indo\|Sinian movement, as space the middle fault (Jiang Chunfa 1982) of the West Kunlun orogenic belt is a significant border o f tectonics\|magmatism evolution. Granitoids formed before Indo\|Sinian movement are mainly distributed to the north of the middle fault of West Kunlun. These granitoids are mostly granites of early and middle Proterozoic, Caledonian and Hercynian ages. A unique control on the granitoid evolution is that they become younger from NE to SW, crossing the regional structure line. Granitoids formed after Indo\|Sinian movement are mainly distributed to the south of the middle fault. But distribution of granitoids of early Yanshan cycle cut across the middle fault of West Kunlun Mountain. Their age distribution shows a bidirectional control with the granitoids becoming younger across the regional structural lines from NE and SW boundary fault to the interior of the fracture belts.展开更多
Early Paleozoic magmatism in the West Kunlun Orogenic Belt(WKOB)preserves important information about the tectonic evolution of the Proto-Tethys Ocean.This paper reports whole-rock compositions,zircon and apatite U-Pb...Early Paleozoic magmatism in the West Kunlun Orogenic Belt(WKOB)preserves important information about the tectonic evolution of the Proto-Tethys Ocean.This paper reports whole-rock compositions,zircon and apatite U-Pb dating,and zircon Hf isotopes for the Qiaerlong Pluton(QEL)at the northwestern margin of WKOB,with the aim of elucidating the petrogenesis of the pluton and shedding insights into the subduction-collision process of this oceanic slab.The QEL is mainly composed of Ordovician quartz monzodiorite(479±3 Ma),quartz monzonite(467–472 Ma),and syenogranite(463±4 Ma),and is intruded by Middle Silurian peraluminous granite(429±20 Ma)and diabase(421±4 Ma).Zirconε_(Hf)(t)values reveal that quartz monzodiorites(+2.1 to+9.9)and quartz monzonites(+0.6 to+6.8)were derived from a mixed source of juvenile crust and older lower crust,and syenogranites(−5.6 to+4.5)and peraluminous granites(−2.9 to+2.0)were generated from a mixed source of lower crust and upper crust;diabases had zirconε_(Hf)(t)values ranging from−0.3 to+4.1,and contained 463±5 Ma captured zircon and 1048±39 Ma inherited zircon,indicating they originated from enriched lithospheric mantle and were contaminated by crustal materials.The Ordovician granitoids are enriched in LILEs and light rare-earth elements,and depleted in HFSEs with negative Nb,Ta,P,and Ti anomalies,suggesting that they formed in a subduction environment.Middle Silurian peraluminous granites have the characteristics of leucogranites with high SiO_(2)contents(74.92 wt.%–75.88 wt.%)and distinctly negative Eu anomalies(δEu=0.03–0.14),indicating that they belong to highly fractionated granite and were formed in a post-collision extension setting.Comparative analysis of these results with other Early Paleozoic magmas reveals that the Proto-Tethys ocean closed before the Middle Silurian and its southward subduction resulted in the formation of QEL.展开更多
The West Kunlun ore-forming belt is located between the northwestern Qinghai-Tibet Plateau and southwestern Tarim Basin. It situated between the Paleo-Asian Tectonic Domain and Tethyan Tectonic Domain. It is an import...The West Kunlun ore-forming belt is located between the northwestern Qinghai-Tibet Plateau and southwestern Tarim Basin. It situated between the Paleo-Asian Tectonic Domain and Tethyan Tectonic Domain. It is an important component of the giant tectonic belt in central China (the Kunlun-Qilian-Qinling Tectonic Belt or the Central Orogenic Belt). Many known ore-forming belts such as the Kunlun-Qilian Qinling ore-forming zone, Sanjiang (or Three river) ore-forming zone, Central Asian ore-forming zone, etc. pass through the West Kunlun area. Three ore-forming zones and seven ore-forming subzones were classified, and eighteen mineralization areas were marked. It is indicated that the West Kunlun area is one of the most favorable region for finding out large and superlarge ore deposits.展开更多
大红柳滩岩体位于西昆仑造山带东段,主要由黑云母二长花岗岩、二长花岗岩及二云母花岗岩组成。笔者对大红柳滩岩体东南部的黑云母二长花岗岩进行了锆石LA ICP MS U Pb定年,测得黑云母二长花岗岩的侵位年龄分别为(214±1.8)Ma,说明...大红柳滩岩体位于西昆仑造山带东段,主要由黑云母二长花岗岩、二长花岗岩及二云母花岗岩组成。笔者对大红柳滩岩体东南部的黑云母二长花岗岩进行了锆石LA ICP MS U Pb定年,测得黑云母二长花岗岩的侵位年龄分别为(214±1.8)Ma,说明大红柳滩岩体为印支晚期岩浆活动的产物。大红柳滩岩体具有高δ7 Li(0.76‰~3.25‰)和低Li(5.04×10-6~52.22×10-6)同位素地球化学特征;黑云母二长花岗岩样品的锆石εHf(t)值介于-1.86~2.16,二阶段模式年龄为1113~1368 Ma;在εHf(t)锆石U Pb年龄图解中,所有数据点均落在球粒陨石演化线附近。综合研究表明,大红柳滩岩体的原始岩浆是由地幔与中元古代地壳2个单元形成的混合岩浆。展开更多
基金financially supported by the Project of Geological Exploration Foudation of Uygur Autonomous Region, Xinjiang (Grant No. XJDKJJZ2011-3)the State Key (Cultivation) Discipline Construction Project of Mineralogy, Petrology and Deposits, Chengdu University of Technology (Grant No. SZD0407)
文摘The Jiajiwaxi pluton in the southern portion of the West Kunlun Range can be divided into two collision-related intrusive rock series, i.e., a gabbro-quartz diorite-granodiorite series that formed at 224±2.0 Ma and a monzonitic granite-syenogranite series that formed at 222±2.0 Ma. The systematic analysis of zircon U-Pb geochronology and bulk geochemistry is used to discuss the magmatic origin （material source and thermal source）, tectonic setting, genesis and geotectonic implications of these rocks. The results of this analysis indicate that the parent magma of the first series, representing a transition from I-type to S-type granites, formed from thermally triggered partial melting of deep crustal components in an early island-arc-type igneous complex, similar to an I-type granite, during the continental collision orogenic stage. The parent magma of the second series, corresponding to an S-type granite, formed from the partial melting of forearc accretionary wedge sediments in a subduction zone in the late Palaeozoic-Triassic. During continued collision, the second series magma was emplaced into the first series pluton along a central fault zone in the original island arc region, forming an immiscible puncture-type complex. The deep tectonothermal events associated with the continent-continent collision during the orogenic cycle are constrained by the compositions and origins of the two series. The new information provided by this paper will aid in future research into the dynamic mechanisms affecting magmatic evolution in the West Kunlun orogenic belt.
基金funded by the National 305 Project of China (2018A03004-1, 2015BAB05B01-02)the Fundamental Research Fund for Central Universities(B16020127)
文摘The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneous rocks and ophiolites distributed mostly along the Xinjiang-Tibet road and the China-Pakistan road, and have constructed a preliminary tectonic model for this orogenic belt. However, few studies have focused on the so-called Precambrian basement in this area. As a result, the tectonic affinity of the individual terranes of the WKOB and their detailed evolution process are uncertain. Here we report new field observations, zircon and monazite U-Pb ages of the "Precambrian basement" of the South Kunlun terrane(SKT) and the Tianshuihai terrane(TSHT), two major terranes in the WKOB. Based on new zircon U-Pb age data, the amphibolite-facies metamorphosed volcanosedimentary sequence within SKT was deposited during the late Neoproterozoic to Cambrian(600-500 Ma), and the flysch-affinity Tianshuihai Group, as the basement of the TSHT, was deposited during the late Neoproterozoic rather than Mesoproterozoic. The rock association of the volcano-sedimentary sequence within SKT suggests a large early Paleozoic accretionary wedge formed by the long-term lowangle southward subduction of the Proto-Tethys Ocean between Tarim and TSHT. The amphibolitefacies metamorphism in SKT occurred at ca. 440 Ma. This ca. 440 Ma metamorphism is genetically related to the closure of the Proto-Tethys Ocean between Tarim and the Tianshuihai terrane, which led to the assembly of Tarim to Eastern Gondwana and the final formation of the Gondwana. Since the late Paleozoic to early Mesozoic, the northward subduction of the Paleo-Tethys Ocean along the HongshihuQiaoertianshan belt produced the voluminous early Mesozoic arc-signature granites along the southern part of NKT-TSHT. The Paleo-Tethys ocean between TSHT and Karakorum closed at ca. 200 Ma, as demonstrated by the monazite age of the paragneiss in the Kangxiwa Group. Our study does not favor the existence of a Precambrian basement in SKT.
文摘The West Kunlun orogenic belt, one of the least studied areas in China, is located at the junction between the Qinghai—Tibetan Plateau and Tarim Basin and has undergone intense tectonic action and frequent magmatism.The West Kunlun orogenic belt can be divided into five tectonic\|magmatic evolution stages according to the character of the igneous rocks, metamorphic rocks, sedimentation mode, tectonic phases and isotopic ages(Fig 1).Active stages have dominated with only short intervening stable stages. This kind of evolution is not simply repeated but that a later stage is elevation and development of its former stage.Space\|time distribution of granitoids varies with each different tectonic\| magmatic stage as well as within different periods of the same tectonic\| magmatism stage. Take time into condition , It is an important turning movement of tectonics\|magmatism evolution during the Indo\|Sinian movement, as space the middle fault (Jiang Chunfa 1982) of the West Kunlun orogenic belt is a significant border o f tectonics\|magmatism evolution. Granitoids formed before Indo\|Sinian movement are mainly distributed to the north of the middle fault of West Kunlun. These granitoids are mostly granites of early and middle Proterozoic, Caledonian and Hercynian ages. A unique control on the granitoid evolution is that they become younger from NE to SW, crossing the regional structure line. Granitoids formed after Indo\|Sinian movement are mainly distributed to the south of the middle fault. But distribution of granitoids of early Yanshan cycle cut across the middle fault of West Kunlun Mountain. Their age distribution shows a bidirectional control with the granitoids becoming younger across the regional structural lines from NE and SW boundary fault to the interior of the fracture belts.
基金financially supported by the Natural Science Foundation of China(NSFC Nos.U1603245,41703051,U1812402)the Chinese Academy of Sciences“Light of West China”Programthe Natural Science Foundation of Guizhou Province(No.[2018]1171).
文摘Early Paleozoic magmatism in the West Kunlun Orogenic Belt(WKOB)preserves important information about the tectonic evolution of the Proto-Tethys Ocean.This paper reports whole-rock compositions,zircon and apatite U-Pb dating,and zircon Hf isotopes for the Qiaerlong Pluton(QEL)at the northwestern margin of WKOB,with the aim of elucidating the petrogenesis of the pluton and shedding insights into the subduction-collision process of this oceanic slab.The QEL is mainly composed of Ordovician quartz monzodiorite(479±3 Ma),quartz monzonite(467–472 Ma),and syenogranite(463±4 Ma),and is intruded by Middle Silurian peraluminous granite(429±20 Ma)and diabase(421±4 Ma).Zirconε_(Hf)(t)values reveal that quartz monzodiorites(+2.1 to+9.9)and quartz monzonites(+0.6 to+6.8)were derived from a mixed source of juvenile crust and older lower crust,and syenogranites(−5.6 to+4.5)and peraluminous granites(−2.9 to+2.0)were generated from a mixed source of lower crust and upper crust;diabases had zirconε_(Hf)(t)values ranging from−0.3 to+4.1,and contained 463±5 Ma captured zircon and 1048±39 Ma inherited zircon,indicating they originated from enriched lithospheric mantle and were contaminated by crustal materials.The Ordovician granitoids are enriched in LILEs and light rare-earth elements,and depleted in HFSEs with negative Nb,Ta,P,and Ti anomalies,suggesting that they formed in a subduction environment.Middle Silurian peraluminous granites have the characteristics of leucogranites with high SiO_(2)contents(74.92 wt.%–75.88 wt.%)and distinctly negative Eu anomalies(δEu=0.03–0.14),indicating that they belong to highly fractionated granite and were formed in a post-collision extension setting.Comparative analysis of these results with other Early Paleozoic magmas reveals that the Proto-Tethys ocean closed before the Middle Silurian and its southward subduction resulted in the formation of QEL.
文摘The West Kunlun ore-forming belt is located between the northwestern Qinghai-Tibet Plateau and southwestern Tarim Basin. It situated between the Paleo-Asian Tectonic Domain and Tethyan Tectonic Domain. It is an important component of the giant tectonic belt in central China (the Kunlun-Qilian-Qinling Tectonic Belt or the Central Orogenic Belt). Many known ore-forming belts such as the Kunlun-Qilian Qinling ore-forming zone, Sanjiang (or Three river) ore-forming zone, Central Asian ore-forming zone, etc. pass through the West Kunlun area. Three ore-forming zones and seven ore-forming subzones were classified, and eighteen mineralization areas were marked. It is indicated that the West Kunlun area is one of the most favorable region for finding out large and superlarge ore deposits.
文摘大红柳滩岩体位于西昆仑造山带东段,主要由黑云母二长花岗岩、二长花岗岩及二云母花岗岩组成。笔者对大红柳滩岩体东南部的黑云母二长花岗岩进行了锆石LA ICP MS U Pb定年,测得黑云母二长花岗岩的侵位年龄分别为(214±1.8)Ma,说明大红柳滩岩体为印支晚期岩浆活动的产物。大红柳滩岩体具有高δ7 Li(0.76‰~3.25‰)和低Li(5.04×10-6~52.22×10-6)同位素地球化学特征;黑云母二长花岗岩样品的锆石εHf(t)值介于-1.86~2.16,二阶段模式年龄为1113~1368 Ma;在εHf(t)锆石U Pb年龄图解中,所有数据点均落在球粒陨石演化线附近。综合研究表明,大红柳滩岩体的原始岩浆是由地幔与中元古代地壳2个单元形成的混合岩浆。
