The Origin of the Early Proterozoic Kuandian Complex: Evidence from Geochemistry   总被引：3，自引：0，他引：3  

Zhang Lifei  Sun Min  Wu Jiahong Department of Geology  Peking University  Beijing Department of Earth Sciences  University of Hong Kong  Hong Kong Shenyang Institute of Geology  Mineral Resources  CAGS  Shenyang Liaoning Liu Xinzhu 《《地质学报》英文版》1997,71(1):15-32

The Kuandian Complex is scarcely preserved Early Proterozoic volcanic suite, formed2.3-2.4 Ga ago. It is located in an Early Proterozoic mobile belt bounded by the ArchaeanRangrim and Ryonggang Blocks of the northeastern Sino-Korean Craton. The Complex ismainly made up of amphibolites, gneisses, leucoleptite, leptite and layered granite. Petrologicaland geochemical studies show that the protoliths of the Complex are mainly assoctations ofbimodal volcanics and anorogenic granites. The Kuandian amphibolites are depleted in Nb, Ta,P and Ti, and enriched in LILE, e.g. K, Rb and Cs, with pronounced depletion of Sr relative toNd and Pb; La/Nb ratios are higher than 1(1.75 to 5.18). The trace element patterns of theamphibolites are similar to continental flood basalts formed by the Gondwana break-up, suchas those in South Karoo and Tasmania, which shows continental contamination. ε_(Nd) valuesranging from 0.70 to 1.94 of the Kuandian amphibolites and the relationships between Nb/Yband La/Yb suggest that contamination of basaltic magma happened in the mantle, rather thanalong the conduit. Isotope ratios of ~(208)Pb/~(204)Pb, ~(207)Pb/ ~(204)Pb, ~(206)Pb/~(204)Pb, ~(143)Nd/~(144)Ndand ~(87)Sr/~(86)Sr indicate that the magma was derived from a contaminated mantle source likeDMM or a mixture of DMM and EM2. The Kuandian Complex has Dupal anomaly, as is thecase with some continental basalts in the south hemisphere, e.g. in South Karoo and Tasmania.Petrochemical modelling proposes that the Kuandian gneiss, granite, and amphibolite camefrom the same parental magma, being products of strong fractional crystallization. Protoliths ofthe Kuandian Complex were formed in extensional tectonic setting during the transition fromcontinental crust to oceanic crust. The formation of the Kuandian Complex indicates that 2.3or 2.4 Ga ago tectonic evolution of the Sino-Korean craton was different from that of otherwell-studied Precambrian cratons, e.g. the North American shield, European platform andAustralian continent in that strong volcanic eruption resulted in its accretion. Besides, the con-taminated magma source with a Dupal anomaly for the Complex indicates that crust-mantleconvection whose scale was similar to that of the present plate tectonics had occurred at leastbefore the formation of the Kuandian Complex (2.3-2.4 Ga B.P).  相似文献   

Evidence for high-Ca boninite magmatism from Paleogene primitive low-K tholeiite, Mukoojima, Hahajima Island group, southern Bonin (Ogasawara) forearc, Japan   总被引：2，自引：0，他引：2  

Kosuke  Maehara  Jinichiro  Maeda 《Island Arc》2004,13(3):452-465

Abstract   High-Ca boninitic inclusions are found in primitive low-K tholeiite from Mukoojima (Mukoo-Jima), an islet in the Hahajima Island group, Bonin (Ogasawara) forearc, Japan. While Chichijima Island group, 50 km north of Hahajima Island group, is well known as a type locality of boninite, there has been no report of boninitic rocks from the Hahajima Island group. The high-Ca boninitic inclusions are aphanitic and contain olivine, Ca-rich clinopyroxene, plagioclase, chromian spinel, opaque minerals and dark brown glass. The mode of occurrence of the inclusions and host tholeiite under the microscope indicates mingling of these two magmas, suggesting intimate association in space and time of the boninite and primitive tholeiite magmas around the Hahajima Island group in Paleogene time. Primitive compositions and slightly different Sr and Nd isotopic ratios suggest that these two magmas are derived from two distinct mantle sources. These two mantle sources were present at the same time around the Hahajima Island group, southern Bonin forearc. The source of the high-Ca boninite was higher in water content and/or shallower in depth compared to that of the primitive tholeiite.  相似文献   

鲁北新生代隐伏火山岩及其石油地质意义   总被引：1，自引：0，他引：1  

杜韫华  代贤忠 《岩石学报》1990,6(3):43-52,T001

鲁北新生代隐伏火山岩可划分为3个喷发期6个亚期,9种火山岩岩石类型和同期侵入的辉绿岩。它们形成在近大陆边缘的板内裂谷型盆地,对于富有机质生油岩的沉积、各种储集体的形成、多种含油圈闭类型的形成以及有机质成熟向烃类转化都是非常有利的。作为储集岩主要有玄武安山岩、辉绿岩和湖底玄武质凝灰岩。储油空间主要为次生孔隙和裂缝。火山岩及其有关岩石在本区不仅形成了特殊的油气藏,而且还可作为盖层、封堵层、披复构造的基岩,因此对石油地质勘探有重要意义。  相似文献   

On the significance of CO2 inclusions in plagioclase microphenocrysts in tholeiite from Moeraki,New Zealand   总被引：1，自引：0，他引：1  

Douglas S. Coombs  Edwin Roedder 《Bulletin of Volcanology》1994,56(1):23-28

Liquid plus vapour inclusions of CO₂ are widespread in plagioclase microphenocrysts in small tholeiitic intrusions and tephra of the Moeraki and adjacent areas of northeast Otago, New Zealand. They imply the presence of immiscible CO₂ droplets in the magma at depths of about 7–14 km. Their presence within 5 μm of the edges of microphenocrysts as little as 35 μm thick and 118 μm long indicates minimal feldspar crystal growth during the final ascent and quenching of the magma. Delicate branching clusters of lath-like microphenocrysts escaped disruption during this ascent. Such CO₂ inclusions are a potential source of ‘excess argon’ perturbing K-Ar age determinations. Received March 24, 1993/Accepted September 10, 1993  相似文献   

The Role of Pressure in Producing Compositional Diversity in Intraplate Basaltic Magmas   总被引：3，自引：0，他引：3  

Whitaker  M. L.; Nekvasil  H.; Lindsley  D. H.; Difrancesco  N. J. 《Journal of Petrology》2007,48(2):365-393

Basaltic magmas found in intraplate suites appear to followmore than one differentiation trend. Many ocean island suitesfollow the ocean island tholeiitic trend, with the basalts differentiatingfrom olivine tholeiite through basaltic andesite, andesite,and dacite to sodic rhyolite. Many continental intraplate magmaticregimes, such as those of the Snake River Plain and the plutonicsequences associated with massif anorthosites, follow the potassicsilica-saturated alkalic trend, in which basalt differentiatesfrom olivine tholeiite through ferrobasalt (jotunite or ferrodiorite),Fe-rich intermediate rocks (trachybasalt or monzonite), andtrachyte (syenite) to potassic rhyolites and granites. Crystallizationexperiments on an olivine tholeiite from the Snake River Plainshow that the basaltic portions of the ocean island tholeiitictrend and the potassic silica-saturated alkalic trend (whichleads to strong alkali, P, Ti, and Fe enrichment and silicadepletion) can arise from the same ‘dry’ tholeiiticparental magma. These compositional differences are inducedby changes in phase equilibria as a function of pressure, withthe ocean island tholeiitic series arising from crystal–liquiddifferentiation at low pressure and the potassic silica-saturatedalkalic series arising via differentiation at elevated pressures. KEY WORDS: tholeiite differentiation; experimental petrology; phase equilibria; ferrodiorite; ferrobasalt  相似文献   

南辽河群斜长角闪岩的地球化学特征及地质意义:以三家子地区为例   总被引：1，自引：0，他引：1  

李富强  董永胜  王鹏森  高铂森  甘宜成 《世界地质》2017,36(1):82-92

基于详细的野外地质调查,对南辽河群下部里尔峪组斜长角闪岩进行了岩相学和地球化学研究。岩相学研究表明,南辽河群下部里尔峪组斜长角闪岩属于正变质岩。地球化学研究显示,这些斜长角闪岩原岩属于高铁拉斑玄武岩系列(Nb/Y=0.16~0.4),SiO_2含量为47.27%~50.68%,具有较低的TiO_2含量(0.92%~1.61%),亏损高场强元素(Nb、Ta、Zr、Hf等),表明其原岩形成于岛弧或活动大陆边缘,而非前人所说的大陆裂谷。综合岩相学和地球化学特征,初步认为其岩石成因与活动大陆边缘有关。  相似文献   

冲绳海槽中部玄武岩的岩石学和地球化学研究     

韩宗珠  于航  赵广涛  吕海燕 《海洋科学》2005,29(6):17-21

1992年冲绳海槽地质调查时,在134站(126°56′7″E,27°30′0″N)共采集到3件玄武岩样品,其中1件取自134站表层样,另外2件取自134站柱状样中的118-143cm处和193- 218cm处(刀口位置)。通过对上述3件玄武岩样品的岩相学、岩石化学组成、稀土元素和微量元素和锶同位素比值分析研究,认为本区玄武岩具多期次喷发特征,早期喷发形成的玄武岩中单斜辉石质量分数较低,晚期喷发形成的玄武岩中单斜辉石质量分数相对较高,表明了单斜辉石为晚期结晶堆积产物。本区玄武岩稀土配分模式与岛弧拉斑玄武岩基本一致,其87Sr与86Sr质量分数比值m(87Sr)/m(86Sr)为0.7046,亦与岛弧拉斑玄武岩相当。最后利用Rb-Sr丰度特征确定本区的地壳厚度为19-24 km。  相似文献   

黔西二叠纪玄武岩及岩浆来源初步分析   总被引：2，自引：0，他引：2  

田景春  尹观 《矿物岩石》1992,12(3):41-45

本文以织金熊家场剖面为例进行岩石学及岩浆来源分析研究。岩性和岩石化学特征表明,区内玄武岩为碱性—钙碱性拉斑玄武岩。同位素地球化学和稀土元素分布模式研究资料表明,本区玄武岩原始岩浆来源于地壳和地幔二元组分相混合的体系。通过锶同位素组成的计算,显示了原始岩浆中的幔源和壳源二元组分的混合比例为5.4:1。  相似文献   

鄂尔多斯盆地西南部晚三叠世辉绿岩年代学、地球化学及其构造意义     

罗金海  畅莹磊  陈卓 《地学前缘》2022,29(6):314-324

鄂尔多斯盆地西南部中奥陶统马家沟组灰岩内部发育多条辉绿岩脉。辉绿岩富集高场强元素(HFSE)Nb、Ta、Ti、Zr、Hf等,具有板内拉斑玄武岩的地球化学特征,其地球化学数据显示原始岩浆经历过比较强烈的结晶分异演化。对辉绿岩的锆石进行U-Pb LA-ICP-MS测年获得的²⁰⁶Pb/²³⁸U年龄为750~195 Ma。根据峰值年龄并结合区域地质资料,本文把辉绿岩的形成年龄确定为224 Ma(晚三叠世)。辉绿岩反映鄂尔多斯盆地西南部在晚三叠世处于类似大陆裂谷的伸展构造环境,晚三叠世西邻陇山地区发生的强烈碰撞后伸展作用也可能有助于进一步强化鄂尔多斯盆地西南部的伸展构造环境。当时该地区岩石圈的稳定性相对较弱,为该地区后续的早侏罗世和早白垩世岩浆活动提供了物质基础。晚三叠世及后期的岩浆活动提高了鄂尔多斯盆地西南部的地温梯度并加快了该地区烃源岩的热演化进程,可能对该地区的油气成藏条件造成潜在影响。  相似文献   

不同类型基性层状侵入体的成因     

王旺章  汪云亮  张筑凤 《四川地质学报》1994,(4)

论述了不同类型基性层状侵入体的成因。根据母岩浆特征划分出玄武岩浆侵入体和拉斑玄武岩浆侵入体两大类。  相似文献