the Qinling Mountains in central China are a joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. On the end time o...the Qinling Mountains in central China are a joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. On the end time of the main orogenic stage in this orogenic展开更多
Rapakivi granite is a postorogenic granite mainly occurring within Precambrian stable blocks in the world. Shahewan rapakivi granite in Qinling. however, is a seldom seen young rock body occurring at the end of Indo-C...Rapakivi granite is a postorogenic granite mainly occurring within Precambrian stable blocks in the world. Shahewan rapakivi granite in Qinling. however, is a seldom seen young rock body occurring at the end of Indo-Chinese epoch (195-213 Ma) and intruding in an orogenic belt. This rock body consists of amphibole-quartz monzonite and amphibole-biotitc adamellite and shows a series of distinctive geological andgeochemical characteristics. It intruded in Shangdan faulted zone--the main suture belt between the NorthChina and Yangtze plates as a result of the delamination of the lithospheric mantle occurring after collision. Presence of Shahewan rapakivi granite marked the end of orogenic stage of subduction-collision from Caled-onian-Hercynian to Indo-Chinese epoch and the transition to intracontinental orogeny in the late orogenic stage.展开更多
The Quanji （全吉） Massif is located in the Northwest China, which is interpreted as a micro-continent that is composed of metamorphic basement and stable cover strata. There are some controversies of genetic relatio...The Quanji （全吉） Massif is located in the Northwest China, which is interpreted as a micro-continent that is composed of metamorphic basement and stable cover strata. There are some controversies of genetic relationship between the Quanji Massif and the major cratons in China. In this study, we obtained in situ zircon U-Pb and Hf isotopic compositions of the Yingfeng （鹰峰） rapakivi granites from the northwest Quanji Massif by application of LA-MC-ICP-MS technique. Twenty U-Pb age measurements points are concordant or near concordant, and their weighted mean 207pb/206pb age is 1 793.9±6.4 Ma （MSWD= 1.09）, yields an upper intercept age of 1 800±17 Ma （MSWD=0.41）; 19 Hf isotope measurements yield a two-stage Hf model ages （TDM2） of 2.63 to 2.81 Ga, with a weighted average age of about 2.70±0.02 Ga and till（t）values variate between -8.91 to -5.35. This indicates that magma source of the Yingfeng rapakivi granites were produced from partial melting of late stage of Neoarchean juvenile crust, and suggests a significant crustal growth event occurred in the Quanji Massif at that time. The Quanji Massif might be an ancient continental segment detached from the Tarim Craton based on the crustal growth history and other geological records. The Tarim Craton （including the Quanji Massif） and the North China Craton had a similar or homological early crustal evolution around -2.7 Ga, which implies that Tarim Craton might be one of the component parts of North China Craton. of the Yingfeng rapakivi granites were produced from partial melting of late stage of Neoarchean juve- nile crust, and suggests a significant crustal growth event occurred in the Quanji Massif at that time. The Quanji Massif might be an ancient continental segment detached from the Tarim Craton based on the crustal growth history and other geological records. The Tarim Craton （including the Quanji Massif） and the North China Craton had a similar or homological early crustal evolution around -2.7 Ga, which implies that 展开更多
文摘the Qinling Mountains in central China are a joint orogenic zone between the Sino-Korean (or North China) and the Yangtze (or South China) craton blocks, the two major tectonic units of eastern Asia. On the end time of the main orogenic stage in this orogenic
基金Project supported by the National Natural Science Foundation of China.
文摘Rapakivi granite is a postorogenic granite mainly occurring within Precambrian stable blocks in the world. Shahewan rapakivi granite in Qinling. however, is a seldom seen young rock body occurring at the end of Indo-Chinese epoch (195-213 Ma) and intruding in an orogenic belt. This rock body consists of amphibole-quartz monzonite and amphibole-biotitc adamellite and shows a series of distinctive geological andgeochemical characteristics. It intruded in Shangdan faulted zone--the main suture belt between the NorthChina and Yangtze plates as a result of the delamination of the lithospheric mantle occurring after collision. Presence of Shahewan rapakivi granite marked the end of orogenic stage of subduction-collision from Caled-onian-Hercynian to Indo-Chinese epoch and the transition to intracontinental orogeny in the late orogenic stage.
基金supported by the National Natural Science Foundation of China(Nos.40972042,40772041,91014002)the Research Grant Council of Hong Kong RGC(No.HKU705311P)
文摘The Quanji （全吉） Massif is located in the Northwest China, which is interpreted as a micro-continent that is composed of metamorphic basement and stable cover strata. There are some controversies of genetic relationship between the Quanji Massif and the major cratons in China. In this study, we obtained in situ zircon U-Pb and Hf isotopic compositions of the Yingfeng （鹰峰） rapakivi granites from the northwest Quanji Massif by application of LA-MC-ICP-MS technique. Twenty U-Pb age measurements points are concordant or near concordant, and their weighted mean 207pb/206pb age is 1 793.9±6.4 Ma （MSWD= 1.09）, yields an upper intercept age of 1 800±17 Ma （MSWD=0.41）; 19 Hf isotope measurements yield a two-stage Hf model ages （TDM2） of 2.63 to 2.81 Ga, with a weighted average age of about 2.70±0.02 Ga and till（t）values variate between -8.91 to -5.35. This indicates that magma source of the Yingfeng rapakivi granites were produced from partial melting of late stage of Neoarchean juvenile crust, and suggests a significant crustal growth event occurred in the Quanji Massif at that time. The Quanji Massif might be an ancient continental segment detached from the Tarim Craton based on the crustal growth history and other geological records. The Tarim Craton （including the Quanji Massif） and the North China Craton had a similar or homological early crustal evolution around -2.7 Ga, which implies that Tarim Craton might be one of the component parts of North China Craton. of the Yingfeng rapakivi granites were produced from partial melting of late stage of Neoarchean juve- nile crust, and suggests a significant crustal growth event occurred in the Quanji Massif at that time. The Quanji Massif might be an ancient continental segment detached from the Tarim Craton based on the crustal growth history and other geological records. The Tarim Craton （including the Quanji Massif） and the North China Craton had a similar or homological early crustal evolution around -2.7 Ga, which implies that
