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A Study of Sr, Nd and O Isotopes of the K-rich Melanocratic Dykes in the Late Mesozoic Gold Field in the Jiaodong Peninsula 被引量:14
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作者 SUN Jinggui, HU Shouxi, LIU Jianmin, SHEN Kun and LING Hongfei Earth Science Institute, Jilin University, Changchun 130062 State Key Laboratory of Research on Metallogenesis of Endogenic Ore Deposits,Nanjing University, Nanjing 210093 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100101 Shandong Institute and Laboratory of Geological Sciences, Jinan 250013 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2001年第4期432-444,共13页
Geologic, petrographic and petrochemical studies of the late Mesozoic K-rich melanocratic dykes, including lamprophyres, andesite porphyrites and dacite-porphyry in the gold field system in the Jiaodong Peninsula, Chi... Geologic, petrographic and petrochemical studies of the late Mesozoic K-rich melanocratic dykes, including lamprophyres, andesite porphyrites and dacite-porphyry in the gold field system in the Jiaodong Peninsula, China, have shown that these dykes are characterized by rich potassium and alkali but poor titanium. They belong to an ultra-high potassic, shoshonitic and high potassic calc-alkaline rock series. The parental magma has relatively high initial strontium ratios ((87Sr/86Sr),=0.70895-0.71140) and low (143Nd/144Nd)1 ratios (varying from 0.51135 to 0.51231); and its δ18Osmow, whole rock values vary from +5.8%c to +10.6%c with a mean of +7.1%c. These features suggest that the source region of the magma is an enriched mantle wedge transformed from a continental lithosphere mantle which has experienced metasomatism by mantle-derived fluids with H2O-dominated fluids that were provided during the underthrusting of an ocean crust. The initial magma was generated by low-degree partial melting of the enriched mantle in its mature stage in the back-arc spreading environment. The evolution of magmas is associated with two trends, i.e., fractional crystallization and mixing with or intensive contamination by palaeo-crust materials or metamorphic rocks. The former process is evident in the gold field system of quartz-vein type, whereas the latter is dominated in the gold field system of the altered-rock type. This conclusion is very important for more detailed study of petrogenesis and mineralization through the crust-mantle interaction (exchange) in the Mesozoic in this region. 展开更多
关键词 late Mesozoic K-rich melanocratic dykes SR Nd and O isotope geochemistry gold field system in the Jiaodong Peninsula
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Cu-Ni-PGES MINERALIZATION OF MELANOCRATIC ROCKS IN SOUTHEAST MARGIN OF THE QINGHAI-XIZANG(TIBET) PLATEAU, HKT
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作者 Cao Zhimin 1, Luo Yaonan 2, Li Youguo 1, Song Xieyan 1, Chen Cuihua 1, Yang Zhusheng 2, He Hong 2 2 Sichuan Bureau of geology and Mineral Resources, Chengdu 610081,China) 《地学前缘》 EI CAS CSCD 2000年第S1期415-415,共1页
The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260~250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies,... The Panxi Rift Zone is a famous metallogenic province in Southwest China. Continental rifting developed in Hercynian period (P 2, 260~250Ma) accompany with a series of basic\|ultrabasic rocks. Various in lithologies, such as layered intrusions (V\|Ti\|Fe formation), small\|sized mafic\|ultramafic bodies (stocks) and large\|scale basalt (Emeishan Basalt) are constituted of a complete melanocratic rock system.Most of Cu\|Ni\|PGE sulfide deposits are related to small\|sized ultramafic rock bodies. It is a perfect possibility for them to be an affinity of basic eruptive lava and for the neck facies. But in ① Panzhihua\|Center Yunnan Province, the Gaojiacun, also Jinbaoshan, as large stratiform basic\|ultrabasic complex used to be thought that is older one intruded to basement rocks in Precambrian. However, new evidences suggest it is similar with the small\|sized ultramafic rock bodies containing Cu\|Ni\|PGE, and also the both are affinity of the Emeishan Basalt; ② Miyi district, Cu\|Pt mineralization was discovered in the Xinjie bedded basic complex, and in where ophitic olivine\|pyroxenite\|peridotite facies are exactly Pt\|bearing layers; ③ Longzhoushan district, we have recently researched basic\|ultrabasic clusters which intruded into fracture zones, and Cu\|Ni\|Pt, Pd mineralization developed at the salbands.Generally, the basalt is poor in PGE and rich in Cu. It is suggested as the result of PGE dispersion\|concentration processing in the melanocratic rock system when rifting happened. 展开更多
关键词 Cu\|Ni\|PGEs MINERALIZATION Province melanocratic ROCKS em eishan basalt basic\|ultrabasic complex SOUTHEAST MARGIN the Qinghai —Xizang(Tibet) PLATEAU HKT
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