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Deep-derived enclaves (belonging to middle-lower crust metamorphic rocks) in the Liuhe-Xiangduo area, eastern Tibet: Evidence from petrogeochemistry 被引量:1
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作者 魏启荣 李德威 +1 位作者 郑建平 王江海 《Chinese Journal Of Geochemistry》 EI CAS 2006年第3期245-254,共10页
Petrological and geochemical studies of deep-derived enclaves from the Liuhe-Xiangduo area, eastern Tibet, showed that the enclaves involve five types of rocks, i.e., garnet diopsidite, garnet amphibolite, garnet horn... Petrological and geochemical studies of deep-derived enclaves from the Liuhe-Xiangduo area, eastern Tibet, showed that the enclaves involve five types of rocks, i.e., garnet diopsidite, garnet amphibolite, garnet hornblendite, amphibolite and hornblendite, whose main mineral assemblages are Grt+Di+Hbl, Grt+Pl+Hbl+Di, Grt+Hbl+Pl, Pl+Hbl, and Hbl+Bt, respectively. The enclaves exhibit typical crystalloblastic texture, and growth zones are well developed in garnet (Grt) in the enclaves. In view of major element geochemistry, the deep|derived enclaves are characterized by high MgO and FeO+*, ranging from {12.00%} to {12.30%} and {8.15%} to {10.94%}, respectively. The protolith restoration of metamorphic rocks revealed that the enclaves belong to ortho-metamorphic rocks. The REE abundances vary over a wide range, and ∑REE ranges from {53.39} to {129.04} μg/g. The REE patterns slightly incline toward the HREE side with weak LREE enrichment. The contents of Rb, Sr, and Ba range from {8.34} to 101μg/g, 165 to 1485 μg/g, and 105 to 721 μg/g, respectively. The primitive mantle-normalized spider diagrams of trace elements show obvious negative Nb, Ta, Zr and Hf anomalies. Sr-Nd isotopic compositions of the enclaves indicated that the potential source of deep-derived enclaves is similar to the depleted|mantle, and their {({}+{87}Sr/+{86}Sr)-i} ratios vary from {0.706314} to {0.707198}, {({}+{147}Nd/+{144}Nd)-i} ratios from {0.512947} to {0.513046}, and {ε-{Nd}(T)} values from {+7.0} to {+9.0}, respectively. The potential source of the enclaves is obviously different from the EM2-type mantle from which high-K igneous rocks stemmed (the host rocks), i.e., there is no direct genetic relationship between the enclaves and the host rocks. Deep-derived enclaves in the host rocks belong to mafic xenoliths, and those in the Liuhe-Xiangduo area, eastern Tibet, are some middle-lower crust ortho-metamorphic rocks which were accidentally captured at 20-50 km level by rapidly entrained high-temperature high-K magma, whose source is considered to be located at 50-km depth or so. 展开更多
关键词 地球化学 西藏 岩石 变质岩
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Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area, West Yunnan 被引量:1
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作者 王建 李建平 +1 位作者 王江海 马志红 《Chinese Journal Of Geochemistry》 EI CAS 2003年第1期58-73,共16页
There exist intermediate to intermediate-acid shoshonitic rocks dated at 26.3- 36.7Ma in the Early Tertiary extensional basins along the NE flank of the Dali-Jianchuan section of the Honghe-Ailaoshan left-lateral stri... There exist intermediate to intermediate-acid shoshonitic rocks dated at 26.3- 36.7Ma in the Early Tertiary extensional basins along the NE flank of the Dali-Jianchuan section of the Honghe-Ailaoshan left-lateral strike-slip ductile shear zone, where some high- and medium-high grade metamorphosed mafic enclaves have been found. According to the P-T conditions and mineral assemblage characteristics, the enclaves are grouped into three types: type-Ⅰ, garnet diopsidite, formed at lower crust or in the transitional section between the mantle and the crust with the metamorphic condition P=(10.47-11.51)×108 Pa and T=771-932℃; type-Ⅱ, garnet- and diopside-bearing amphibolite, formed at the depth of middle to lower crust with the metamorphic condition: P=(6-10) ×108 Pa and T=780-830℃; type-Ⅲ, metamorphosed gabbro, formed at relatively higher levels than the above 2 types with lower metamorphic condition. Type-Ⅰand type-Ⅱenclaves had experienced a decompressional retrograde metamorphism caused by tectonic elevation associated with the metasomatism of SiO 2, Na 2O-rich fluid phase with the new equilibrated temperature at T=761-778℃. Geochemical evidence indicates that both deep-derived mafic enclaves and host rocks have similar EM Ⅱ properties, which are related to the involvement of subducted materials. The sustaining subduction, compression and strike-slip ductile shearing between the India plate and the Yangtze craton are the main constraints on the subcontinental mantle properties, interaction between crust and mantle, and the formation and evolution of alkali-rich magma. 展开更多
关键词 shoshonitic rock 矿物地球化学特征 变质作用 新生代 地质学特征 云南 铁镁质岩 变质岩
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Peraluminous A-type granites formed through synchronous fractionation,magma mixing,mingling,and undercooling:evidence from microgranular enclaves and host Mesoproterozoic Kanigiri granite pluton,Nellore Schist Belt,southeast India
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作者 Ch.Narshimha Santosh Kumar 《Acta Geochimica》 EI CAS CSCD 2023年第4期603-636,共34页
The field and microstructural features coupled with mineral chemical data from microgranular enclave(ME)and host Mesoproterozoic Kanigiri granite(KG)pluton of Nellore Schist Belt(NSB),Southeastern India,have been docu... The field and microstructural features coupled with mineral chemical data from microgranular enclave(ME)and host Mesoproterozoic Kanigiri granite(KG)pluton of Nellore Schist Belt(NSB),Southeastern India,have been documented in order to infer the likely processes responsible for the origin and evolution of ME and host KG magma.The ME and host KG bear the same mineral assemblages barring the KG which does not contain amphibole;however,they are modally disequilibrated.The ME in KG is originated due to multiple intrusions of ME magmas into the crystallizing host KG magma chamber.Field and textural features indicate the dynamic magma flow,mingling,and undercooling of the ME against a relatively cooler surface of host KG magma.The presence of NSB country rock xenoliths and its diffuse boundaries suggest the intrusive relation and marginal assimilation by the intruding KG magma.The occasional cumulate texture in the ME appears to have formed by the accumulation of early-formed minerals that crystallized rapidly in the ME magma globules.The ME shows the magmatically deform features developed due to the flowage and erosion by the subsequent intrusions of ME magma pulses into the crystallizing host KG magma chamber.The ME amphiboles show unusual composition as ferro-edenitic hornblende to potassian-hastingsitic hornblende,that crystallized in the subalkaline-alkaline transition,low fO_(2)(reducing to mildly oxidizing)magma.The unusual extremely low Mg/Mg+Fe^(t)=0.015(avg.)of ME amphiboles may be related to the changing physico-chemical(P,T,fO_(2),and H_(2)O)condition of the ME magma or they might have crystallized in equilibrium with more evolved KG magma.The KG(FeOt/MgO=37.04,avg.)and ME(FeO~t/MgO=77.72,avg.)biotites are siderophyllite,and buffered between QFM and NNO syn-crystallizing in the water undersaturated(H_(2O)≈3.58 wt.%in KG;≈3.53wt.%in ME),alkaline anorogenic(A-type)host magmas that were emplaced at mid-crustal(4–5 kbar;17 km)depth.Field,microtextural and mineral chemical evidences suggest that the alkaline KG magma originated from crustal source and evolved through synchronous fractionation,mixing,and mingling with coeval ME magmas in the KG magma chamber. 展开更多
关键词 enclave Kanigiri granite Magma mixing-fractionation Nellore schist belt SE India
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Types of Enclaves and Their Features and Origins in Intermediate-Acid Intrusive Rocks from the Tongling District, Anhui Province, China 被引量:35
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作者 WU Cailai WANG Zhihong +3 位作者 QIAO Dewu LI Haibing HAO Meiying SHI Rendeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2000年第1期54-67,共14页
Abstract: Enclaves in intermediate-acid plutons from Tongling can be divided into three types: xenoliths, relics and magmatogenic enclaves. The magmatogenic enclaves consist of cumulates, micrograined dioritite mixtit... Abstract: Enclaves in intermediate-acid plutons from Tongling can be divided into three types: xenoliths, relics and magmatogenic enclaves. The magmatogenic enclaves consist of cumulates, micrograined dioritite mixtite and dioritic chilled border enclaves. Petrologically, relics with eyed and meta-poikilitic texture are characterized by high content of biotite (>80%) and low content of cordierite and grossular. The cumulates with accumulate texture consist of a great amount of pyroxene, hornblende and minor spinel and phlogopite. The micrograined dioritic mixtite is composed of more hornblendes and feldspar and less needle apatites and an ellipsoid basic core included in plagioclase. The chilled border enclaves have the same mineral association, but more dark minerals than the host rocks consisting of plagioclase, quartz, alkaline feldspar, hornblende and biotite. Geochemically, the relics exhibit high REE content (455.8×10?6) and high ratio of LREE/HREE, more obvious Eu negative anomaly and are rich in Cr and Ni, poor in Ba, Nb and Sr. All kinds of magmatogenic enclaves have the same REE pattern without Eu anomaly, and the total REE is 74.9×10?6 for spinel pyroxene cumulate, 179.7×10?6 for hornblende cumulate, 226.9 × 10?6 for hornblende cumulate crystal, 289.9×10?6 for micrograined dioritic mixtite and 131.2×10?6 for chilled border enclaves. Calculation with the thermometer and barometer for minerals shows that the temperature and pressure of formation are 1126 °C and 8.44 kbar (7.15–9.04 kbar) for the spinel pyroxene cumulate, 1065 °C-1029 °C and 8.23 kbar (7.13–9.50 kbar) for the hornblende pyroxene cumulate, 959 °C and 3.40 kbar (2.86–4.09 kbar) for the micrograined dioritic mixtite enclaves, and 951 °C and 0.59 kbar for the dioritic chilled border enclaves, respectively. Thus, the following conclusions can be drawn. Relic enclaves were derived from the crustal partial melting and all cumulate enclaves originated from deep magma chambers near the Moho in the lower crust, which are cumulate fragments formed by fractional crystallization of basic magma; mixtite came from shallow magma chambers in the middle-upper crust, formed by the mixture of mantle-derived magma and acid magma derived from the crustal partial melting; and the chilled border enclaves came from the border fragments of early intrusive bodies. 展开更多
关键词 enclave petrology RELICS cumulate enclaves mixtite enclaves chilled border enclaves TONGLING
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Geochronology of the Gabbro-mafic Microgranular Enclaves-granite Associations in the Gejiu District, Yunnan Province and Their Geodynamic Significance 被引量:6
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作者 CHENG Yanbo MAO Jingwen 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2012年第3期748-761,共14页
Many igneous rocks distribute in Gejiu tin polymetallic ore-field at Yunnan province, rocks including basalt, gabbro, mafic microgranular enclaves, granites (porphyritic granite and equigranular granite) and akaline... Many igneous rocks distribute in Gejiu tin polymetallic ore-field at Yunnan province, rocks including basalt, gabbro, mafic microgranular enclaves, granites (porphyritic granite and equigranular granite) and akaline rocks. The ages of the granites and akaline rocks which are considered to have genetic connecting with the mineralization have been comfirmed, but the gabbro- mafic microgranular enclaves-granite assemblage's ages are still unknown. By means of LA-ICP-MS zircon U-Pb dating, the data of Shenxianshui equigranular granite, the mafic microgranular enclave in Jiasha area, the host rock of the mafic microgranular enclaves and the Jiasha gabbro are around ~80 Ma. Besides the above mentioned data, a group of new ages at ~30 Ma were discovered in this study, which is from gabbro and mafic microgranular enclaves. Based on the previous data and the new data gained this time, we suggest the major geochronology framework of the magmatism and mineralization events in Gejiu area is ~80 Ma, which is consistent with the Late Cretaceous magmatism and mineralization events in the whole southeast Yunnan and west Guangxi area and they were suggested to belong to the same geotectonic setting in late Yenshannian. And the new ages of the ~30 Ma obtained in this study is considered to represent a responding to the complicate tectonic evolution history of the Tibetan orogenic events in Cenozoic. 展开更多
关键词 GABBRO GRANITE mafic microgranular enclaves GEOCHRONOLOGY geodynamic setting Gejiu
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Petrological and Mineralogical Study of Enclaves in Plutons in the Typical Mining Districts of Tongling, Anhui and Its Bearing on the Process of Magmatism Metallogeny 被引量:18
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作者 杜杨松 《Chinese Journal Of Geochemistry》 EI CAS 1999年第3期208-218,共11页
Two types of enclaves occur in magmatic plutons in Tongling, Anhui. Enclaves of the first type are residuals of metamorphic rocks of high amphibolite facies, and those of the other type are magmatic rocks ranging from... Two types of enclaves occur in magmatic plutons in Tongling, Anhui. Enclaves of the first type are residuals of metamorphic rocks of high amphibolite facies, and those of the other type are magmatic rocks ranging from monzonitic to dioritic in composition. A combined petrological and mineralogical study has been carried out on the two types of enclaves in order to estimate their forming conditions and analyze their relations to their hosts, so as to have an insight into the material sources of magmatic rocks and associated mineral deposits and give a clue to better understanding the mechanism of magmatism metallogeny. This leads us to propose a new metallogenic model for strata bound skarn type ore deposits associated with a syntectic type of magmatic rocks. The new model can be simply summarized as partial melting of old metamorphic basement rocks at depth and accumulating, differentiating and positioning of magmas to form deep level and shallow level magma chambers, followed by mixing of different magmas associated with their crypto explosion, migration of gas bearing ore fluids and precipitation of metals in fluids within the magmas. 展开更多
关键词 岩石学 安徽 矿物学 矿床成因 铁铜矿床
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Theoretical Calculation Model of Heat Transfer for Deep-derived Supercritical Fluids with a Case Study 被引量:6
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作者 HUWenxuan JINZhijun +2 位作者 SONGYucai SUNRui DUANZhenhao 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第1期221-229,共9页
Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O-CO2-CH4(-N2), a formula is obtained to calculate the heat changes. Combining the geological T-P conditions (geothermal grad... Based on a set of equations established by Duan et al. (1992, 1996) for a geofluid system H2O-CO2-CH4(-N2), a formula is obtained to calculate the heat changes. Combining the geological T-P conditions (geothermal gradients and lithostatic and hydrostatic pressures), the enthalpy of some typical geofluids is figured out. Then the principles of heat transfer of deep-derived supercritical fluids are discussed. The result shows that deep-derived geofluids can bring a large amount of thermal heat and release most heat to the shallow surroundings as they move up, because the molar enthalpies vary very greatly from the deep to shallow, increasing with the increases of T and P. Generally, more than tens of kilojoules heat per molar can be released. Furthermore, the molar enthalpy is affected by the compositions of the geofluids, and the molar enthalpy of CO2, CH4, or N2 is greater than that of H2O, being twice, more than twice, and about 140% of H2O, respectively. Finally, a case study is conducted by investigating a source rock sequence affected hydrothermally by magmatic fluids in the Huimin depression of Shengli Oilfield. The thermal heat calculated theoretically of the fluids related to a diabase intrusion is quite large, which can increase the temperature near the diabase to about 300℃, and that can, to some extent, account for the abnormal rise of the vitrinite reflectance, with the highest of about 3.8% (Ro). 展开更多
关键词 heat transfer ENTHALPY theoretical calculation deep-derived fluids a case study
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LA-ICP-MS Zircon U-Pb Dating of the Huangyangshan Pluton and Its Enclaves from Kalamaili Area Eastern Junggar,and Geological Implications 被引量:1
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作者 Gaoxue Yang~1,Yongjun Li~1,Guohui Si~1,Hongen Wu~2 1.Earth Science & Resources College of Chang’an University,Xi’an 710054,China.. 2.Xinjiang Institute of Geological Exploration for Nonferrous Resources,ürümqi 830000,China 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期205-205,共1页
LA-ICP-MS zircon U-Pb dating has revealed that the Huangyangshan pluton in Eastern Junggar was formed at 311±12 Ma,and that microgranular enclaves were formed at 300±6 Ma;both ages are very consistent within... LA-ICP-MS zircon U-Pb dating has revealed that the Huangyangshan pluton in Eastern Junggar was formed at 311±12 Ma,and that microgranular enclaves were formed at 300±6 Ma;both ages are very consistent within errors.It is the first time that the microgranular enclaves age in Kalamaili area was determined.Petrochemistry and geochemistry research shows the characteristics of host rock as follows: 展开更多
关键词 zircon LA-ICP-MS U-Pb age magma mixing DIORITE microgranular enclaveS Huangya-ngshan alkaline granite EASTERN JUNGGAR
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Discovery of Enclaves from Cenozoic PuluVolcanic Rocks in West Kunlun Mountains and ItsGeological Implications 被引量:1
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作者 Zhang Zhaochong Xiao Xuchang Wang Jun Wang YongInstitute of Geology , Chinese Academy of Geological Sciences, Beijing 100037 《Journal of China University of Geosciences》 SCIE CSCD 2002年第1期30-34,共5页
In this paper, we present the occurrence and mineral components of the enclaves firstly discovered in the Cenozoic Pulu volcanic rocks in west Kunlun Mountains, and propose that the enclave is accumulated by fractiona... In this paper, we present the occurrence and mineral components of the enclaves firstly discovered in the Cenozoic Pulu volcanic rocks in west Kunlun Mountains, and propose that the enclave is accumulated by fractional crystallization within high-level magma chamber. In addition, the chemical compositions of its primary magma are calculated. The calculated compositions are similar to those of the Kangxiwa volcanic rocks that belong to the same volcanic belt in the Pulu volcanic region, suggesting their origin from the same source region. However, the temperatures and oxygen fugacity of magmas at high-level magma chamber decreased along with fractional crystallization. 展开更多
关键词 enclave fractional crystallization volcanic rocks West Kunlun Mountains.
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Destruction of the Northern Margin of the North China Craton in Mid-Late Triassic: Evidence from Asthenosphere-derived Mafic Enclaves in the Jiefangyingzi Granitic Pluton from the Chifeng Area, Southern Inner Mongolia 被引量:2
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作者 LIU Jianfeng LI Jinyi +3 位作者 CHI Xiaoguo ZHENG Peixi HU Zhaochu ZHANG Xiaowei 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2020年第4期1071-1092,共22页
The petrology, geochronology and geochemistry of the mafic enclaves in the Mid-Late Triassic Jiefangyingzi pluton from Chifeng area, southern Inner Mongolia, in China are studied to reveal their petrogenetic relations... The petrology, geochronology and geochemistry of the mafic enclaves in the Mid-Late Triassic Jiefangyingzi pluton from Chifeng area, southern Inner Mongolia, in China are studied to reveal their petrogenetic relationship with the host pluton. Furthermore, the coeval magmatic assemblage and its petrogenesis on the northern margin of the North China craton(NCC) are studied synthetically to elucidate their tectonic setting and the implications for the destruction of the NCC. Zircon U-Pb dating reveals that the mafic enclaves formed at 230.4 ± 2.2 Ma, which is similar to the age of the host pluton. The most basic mafic enclaves belong to weak alkaline rocks, and they display rare earth element(REE) and trace element normalized patterns and trace element compositions similar to those of ocean island basalt(OIB). In addition, they have positive εNd(t) values(+3.84 to +4.94) similar to those of the Cenozoic basalts on the northern margin of the NCC. All of these geochemical characteristics suggest that the basic mafic rocks originated from the asthenosphere. Petrological and geochemical studies suggest that the Jiefangyingzi pluton and the intermediate mafic enclaves were formed by the mixing of the asthenosphere-derived and crust-derived magmas in different degrees. The Mid-Late Triassic magmatic rocks on the northern margin of the NCC could be classified into three assemblages according to their geochemical compositions: alkaline series, weak alkaline–sub-alkaline series and sub-alkaline series rocks. Petrogenetic analyses suggest that the upwelling of the asthenosphere played an important role in the formation of these Mid-Late Triassic magmatic rocks. Basing on an analysis of regional geological data, we suggest that the northern margin of the NCC underwent destruction due to the upwelling of the asthenosphere during the Mid-Late Triassic, which was induced by the delamination of the root of the collisional orogeny between Sino-Korean and Siberian paleoplates in Late Permian. 展开更多
关键词 mafic enclave craton destruction ASTHENOSPHERE Mid-Late Triassic North China craton
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Secure Enclave安全体系技术分析与研究
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作者 廖正赟 郭建胜 《信息技术与网络安全》 2018年第1期30-32,51,共4页
在移动互联网时代,移动智能终端已经成为人们随身携带、随时使用的重要设备。应对移动应用环境中面临的安全威胁,成为业界面临的重要问题。Apple公司设计了一套安全体系,依靠Secure Enclave模块来实现密码运算和敏感数据的存储,在实际... 在移动互联网时代,移动智能终端已经成为人们随身携带、随时使用的重要设备。应对移动应用环境中面临的安全威胁,成为业界面临的重要问题。Apple公司设计了一套安全体系,依靠Secure Enclave模块来实现密码运算和敏感数据的存储,在实际的应用中取得了很好的效果。从硬件、系统和通信机制方面分析了Secure Enclave模块的组成结构,进而对系统进行了安全性分析,最后,对模块进行了总结和展望。 展开更多
关键词 SECURE enclave 安全隔离 可信计算环境 L4
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Petrogenesis of the ükapili Granitoid and its Mafic Enclaves in Elmal Area (Nigde, Central Anatolia, Turkey)
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作者 Hüseyin KURT Kerim KOAK +1 位作者 Kürsad ASAN Mustafa KARAKAS 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2013年第3期738-748,共11页
The Late Cretaceous Uckapth Granitoid including mafic microgranular enclaves intruded into metapelitic and metabasic rocks, and overlain unconformably by Neogene ignimbrites in the Ni^de area of Turkey. It is mostly g... The Late Cretaceous Uckapth Granitoid including mafic microgranular enclaves intruded into metapelitic and metabasic rocks, and overlain unconformably by Neogene ignimbrites in the Ni^de area of Turkey. It is mostly granite and minor granodiorite in composition, whereas its enclaves are dominantly gabbro with a few diorites in composition. The Uckapdl Granitoid is composed mainly of quartz, K-feldspar, plagioclase, biotite, muscovite and minor amphibole while its enclaves contain mostly plagioclase, amphibole, minor pyroxene and biotite. The Uckapth Granitoid has calcalkaline and peraluminous (AJCNK= 1.0-1.3) geochemical characteristics. It is characterized by high LILE/HFSE and LREE/HREE ratios ((La/Lu)N 3-33), and has negative Ba, Ta, Nb and Eu anomalies, resembling those of comsion granitoids. The {)fkaplh Granitoid has relatively high STSr/S6Sr0) ratios (0.711189--0.716061) and low eNd(t) values (-5.13 to -7.13), confirming crustal melting. In contrast, the enclaves are tholeiitic and metaluminous, and slightly enriched in LILEs (K, Rb) and Th, and have negative Ta, Nb and Ti anomalies; propose that they were derived from a subduction-modified mantle source. Based on mineral and whole rock chemistry data, the Uckapth granitoid is H-(hybrid) type, post-collision granitoid developed by mixing/mingllng processes between crustal melts and mantle-derived mafic magmas. 展开更多
关键词 H-type granitoid mafic enclave GEOCHEMISTRY Central Anatolia TURKEY
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Petrological Significance of Zoned Plagioclase in Eldjurti Granite and Mafic Microgranular Enclaves, North Caucasus, Russia 被引量:2
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作者 朱永峰 《Chinese Journal Of Geochemistry》 EI CAS 1994年第2期142-155,共14页
Plagioclase phenocrysts from mafic enclaves and plagioclase from its host granite possess a pat-tem of complex zonation. A plagioclase phenocryst can generally be divided into three parts : an oscillatory, locally pat... Plagioclase phenocrysts from mafic enclaves and plagioclase from its host granite possess a pat-tem of complex zonation. A plagioclase phenocryst can generally be divided into three parts : an oscillatory, locally patchy zoned core (An47-19), a ring with dusty, more calcic plagioclase (An64-20) and a normally zoned rim composed of sodic plagioclase (An22-3. 3). Majordiscontinuities in zoning coincide with resorption suffeces that are overgrown by the more calcic plagioclase. The cores of large plagioclase phenocrysts from mafic enclaves and host granite show similar zoning patterns and similar compositions, indicating their crystallization under the same conditions . Steep normal zoning of the rims of plagioclases both from host granite and mafic enclaves illustrates a drastic decrease in An content which is considered to have resulted from the continuous differentiation of hybrid magma and efficient heat loss because of the upward emplacement of the residual magma. Wide rims of plagioclases from the host granite against thc discrete rims of plagioclases from mafic enclaves indicate that differentiation and cooling lasted much longer in the host granite than in the mafic enclaves. 展开更多
关键词 花岗岩 斜长岩 混合岩浆 铁镁质岩浆 高加索山脉 俄罗斯
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Recognizing Brazilian Cerrado Enclaves by Modeling Geoenvironmental Parameters
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作者 Marcus Vinicius de Melo Oliveira Antonio Manoel dos Santos Oliveira +2 位作者 Augusto Francener Nogueira Gonzaga Paulo Eduardo de Oliveira Anderson Targino da Silva Ferreira 《Journal of Geographic Information System》 2020年第2期125-140,共16页
This work focused on the prediction modeling of Cerrado occurrences in the Atlantic Rainforest predominance in the S&#227;o Paulo Metropolitan Region (SPMR), the fourth largest urban area, in the city of Guarulhos... This work focused on the prediction modeling of Cerrado occurrences in the Atlantic Rainforest predominance in the S&#227;o Paulo Metropolitan Region (SPMR), the fourth largest urban area, in the city of Guarulhos, southeastern Brazil. The methodology was based on the selection of records of occurrence of Cerrado in georeferenced databases, thematic maps of geoenvironmental layers, and modeling of the distribution of species through the MaxEnt tool. Besides that, field research confirmed the presence or not of the species in the areas with a high probability of occurrence of Cerrado (≥0.7). As a result, the model observed a great capacity for the prediction of the occurrence of Cerrado in Ecotonal and anthropic regions (AUC = 0.82), revealing important hotspots such as relics from the past or Cerrado enclaves of high biodiversity. The work also points priority areas for the conservation and preservation of this increasingly endangered biome. 展开更多
关键词 CERRADO enclave HOTSPOTS REMAINING Geoenvironmental Parameters Prediction of ADEQUACY MaxEnt
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Meaning of Rocks Basic Enclaves in the Eburnean Granitoids of Mako Area (Kédougou-Kéniéba Inlier, Senegal): Petrogenetic Implications
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作者 Ibrahima Gassama Moussa Dabo +2 位作者 Mamadou Ndiaye Emmanuel Tama Samoura Fatou Bop Ndong 《International Journal of Geosciences》 2021年第1期39-56,共18页
The Mako area, located in eastern Sénégal</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verda... The Mako area, located in eastern Sénégal</span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> constitute</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> a segment of Paleoproterozoic (Birimian) formations of the Kédougou-Kéniéba Inliers (KKI) in the western part of the West African craton.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The basic volcanism of the Birimian formations of the KKI has long been considered to be related to a single magmatic event associated with a Mid Oceanic Ridge Basalts (MORB) setting.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The aim of this paper is to demonstrate on the basis of the architectural characteristics of the granitoids dark enclaves, the occurrence of at least two distinct phases of basic Magamtism in the Birimian of the KKI.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The methodology consists of a cartography, a petrographic and architectural characterization of the dark enclaves within the Mako granitoids, in order to constrain their spatial and temporal relationships with the granitic magma. The results obtained are compared with those of the bibliography. We have pinpointed two types of enclaves depending on their shapes and the characteristics of their edge with the enclosing rocks: angular enclaves with straight edges (ante-granitoids) and the soft enclaves with uneven edges (syn-granitoids).</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The enclaves with straight and well-defined rectilinear edges (ante-granitoids) would be linked to a basic magma which is already consolidated before being fragmented, torn and carried away as enclaves in the granitoids. These enclaves would come from enclosing outcrops of metabasalts and metagabbros which are locally cross-cut</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">by the granitoids.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The soft enclaves with uneven edges (syn-granitoids) were co-magmatic and not solid during their incorporation into the granitoids. They come from a basic magma which is contemporaneous to the granitic one.</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Thus, the occurrence of two generations of dark enclaves </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">is</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> related to</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> at last, two different phases of basic magmatism in the Birimian formations of the KKI. 展开更多
关键词 Paleoproterozoic Kédougou-Kéniéba Mako GRANITOIDS Basic enclave BIRIMIAN
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Origin and intraplate tectonic setting of mafic magmatic enclaves from the Ngaoundal area,Adamawa-Cameroon:Insights from petrography and geochemistry
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作者 Aliou Mamouda Sylvestre Ganno +4 位作者 Guy Tchoupe Takam Bertin Arnold Mbita Motto Steven Hermann Donald Fossi Jean Paul Nzenti Joseph Mvondo Ondoa 《China Geology》 CAS 2022年第4期579-594,共16页
In this contribution,detailed field descriptions together with petrographic and bulk-rock major,trace and rare earth elements(REE)data are used to constrain the origin and geodynamic setting of the mafic magmatic encl... In this contribution,detailed field descriptions together with petrographic and bulk-rock major,trace and rare earth elements(REE)data are used to constrain the origin and geodynamic setting of the mafic magmatic enclaves(MMEs)recently discovered within the Pan-African Ngaoundal pluton,Adamawa area,central Cameroon.The investigated MMEs are dark-colored with chilled margins,and display medium to coarse-grain igneous textures.The mineral assemblage is either dominated by K-feldspar and carbonate(group Ⅰ),or by amphibole and plagioclase(group Ⅱ),though the overall mineral phases made of amphibole,plagioclase,K-feldspar,and biotite are similar to that of their host syenite but in different proportions.The MMEs in Ngaoundal area are foid-gabbro in composition with SiO_(2) contents ranging between 41.52% and 43.74% and are contiguous with their host granitoids of intermediate composition(SiO_(2)=57.52% to 58.98%).The host granitoid rocks are metaluminous,and belong to the shoshonitic series.Petrographic and geochemical data have revealed that the Ngaoundal MMEs derived from rapid cooling of hot injected lithospheric mantle-derived magma within cooler host granitoids magma and were emplaced in the intraplate geodynamic setting. 展开更多
关键词 Mafic magmatic enclaves(MMEs) GRANITOIDS Lithospheric mantle REE INTRAPLATE Adamawa-Cameroon
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Petrogenesis and geochemistry of the host monzogranite and mafic enclaves from the Triassic Wulong pluton in South Qinling, central China
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作者 WANG Juan LI Xin 《Chinese Journal Of Geochemistry》 EI CAS 2009年第4期432-439,共8页
The Wulong pluton was emplaced in the metamorphic complex of the Mesoproterozoic Foping Group, South Qinling. A few mafic enclaves which are rounded in shape with sharp boundaries with the host granites in the souther... The Wulong pluton was emplaced in the metamorphic complex of the Mesoproterozoic Foping Group, South Qinling. A few mafic enclaves which are rounded in shape with sharp boundaries with the host granites in the southern part of the pluton. Based on petrography, geochemistry and chronology data, it is indicated that the Wulong pluton shows some adakitic affinities with depletion in HREE (Yb=0.33–0.96 μg/g, Y=4.77–11.2 μg/g); enrichment in Sr (643–1115 μg/g) and Ba (775–1386 μg/g), high Sr/Y ratios (57.3–160) and Y/Yb ratios (11.0–14.3), and slightly negative Eu anomaly (δEu=0.70–0.83). These patterns suggest a feldspar-poor and garnet±amohibole-rich fractionation mineral assemblage. The mafic enclaves have high concentrations of Mg (MgO=4.15%–8.13%), Cr (14.8–371 μg/g), and Ni (20.0–224 μg/g), and high Nb/Ta ratios (15.42–21.9). It seems that the underplating mantle magma was responsible for the generation of the mafic magma. Companied with the results of investigations for the Qinling Orogenic Belt, it was found that partial melting of the thickened lower crust, which was triggered by the underplated mantle-derived magmas, had generated the felsic magma. The Wulong pluton provided evidence for a mixing and mingling process of two kinds of mamma. Its formation probably represents the oceanic slab breakoff during the late orogenic stage in the Qinling area. 展开更多
关键词 二长花岗岩 地球化学 镁铁质 南秦岭 岩体 飞地 三叠纪 成因
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Progress in Enclave Tourism Study of Overseas:A Literature Review
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作者 Liu Aili Liu Jiaming Liu Min 《Chinese Journal of Population,Resources and Environment》 北大核心 2007年第3期76-81,共6页
In response to the "isolated island" phenomenon emerging from the development of tourist resorts in China, this paper reviews the study of enclave tourism overseas, which has similar features to the resort &... In response to the "isolated island" phenomenon emerging from the development of tourist resorts in China, this paper reviews the study of enclave tourism overseas, which has similar features to the resort "island". Based on the literatures related to enclave tourism from Tourism Management and Annals of Tourism Research, this paper reviews the study of enclave tour- ism from the following aspects: definition discussion, theories used, causation of enclaves, characteristics and impacts of enclave tourism. The understanding of the overseas researches on enclave tourism would provide instructions for the study on the problems of Chinese resorts, such as enclavity and "island effects", and suggest measures for the sustainable development of resorts in China. This paper is divided into three sections. Section 1 briefly introduces the development of enclave tourism in developing countries and the outline of enclave tourism study. Section 2 elaborates on the contents of enclave tourism research and gives deep insights into the study on concepts, characteristics, causations and effects respectively, which is the key part of this paper; Section 3 concludes the review and proposes suggestions for the enclave tourism study in China. 展开更多
关键词 民族旅游 外国 经验借鉴 中国 民族文化 特征
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Exchange between Mafic Enclaves and Host Magma: Case of 1991-1995 Mount Unzen Eruption
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作者 Ilya S. Fomin Pavel Yu. Plechov 《Journal of Earth Science and Engineering》 2012年第11期631-635,共5页
关键词 岩浆混合 火山喷发 暗色包体 案例 交流 寄主 研究成果 科学家
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尽显时尚奢华 别克Enclave概念车
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《新知客》 2007年第3期122-123,共2页
别克Enclave概念车是对别克品牌最新设计理念和造型工艺的完美诠释,充满动感激情,却不乏沉稳大气。和大多SUV不同,Enclave除了装备有先进的全轮驱动系统外,更在内饰上下足了功夫,极尽奢华。宽大的青铜色全景天窗几乎覆盖了整个乘客舱,... 别克Enclave概念车是对别克品牌最新设计理念和造型工艺的完美诠释,充满动感激情,却不乏沉稳大气。和大多SUV不同,Enclave除了装备有先进的全轮驱动系统外,更在内饰上下足了功夫,极尽奢华。宽大的青铜色全景天窗几乎覆盖了整个乘客舱,与此同时,分布在不同位置的4个DVD屏幕可以同时播放不同的碟片,且停车后仪表盘也可用做DVD屏幕,如此周到的设计让车内的每个人都能享受到个性化的终极车载体验。 展开更多
关键词 别克 enclave 全轮驱动 最新设计 青铜色 造型工艺 美瑞 家用轿车 天语 安全气囊
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