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1.
Two distinct ultramafic bodies occur in Baekdong and Bibong in the Hongseong area within Gyeonggi massif of South Korea. The Hongseong area is now extensively documented as an extension of the Dabie-Sulu collision belt in China. The Baekdong ultramafic body has a NWW elongation direction. This elongation trend is similar to the general trend of the Dabie-Sulu collision belt. The Bibong ultramafic body is elongated in a NNE direction and runs parallel to the direction of the main fault in the study area. The Baekdong ultramafic bodies show porphyroclastic and mylonitic textures while those at Bibong exhibit a mosaic texture. Both were grouped into peridotite and serpentinite based on their modal abundance of serpentine. In the olivine (Fo) vs. spinel [Cr# = Cr/ (Cr+Al)] diagram, both ultramafic rocks fall with in olivine spinel mantle array. The compositions of olivine, orthopyroxene and spinel indicate that the Baekdong ultramafic rock formed in deeper parts of the upper-mantle under passive margin tectonic setting. The SREE content of Baekdong ultramafic rock vary from 0.19 to 5.7, exhibits a flat REE pattern in the chondrite-normalized diagram, and underwent 5% partial melting. Conversely, large variation in SREE (0.5 21.53) was observed for Bibong ultramafic rocks with an enrichment of LREE with a negative slope and underwent 17 24% partial melting. The Baekdong ultramafic rocks experienced three stages of metamorphism after a high pressure residual mantle stage. The first stage of metamorphism occurred under the eclogite-granulite transitional facies (1123 911°C, >16.3 kb) the second under the granulite facies (825 740°C, 16.3 11.8 kb) and the third is the retrogressive metamorphism under amphibolite facies (782 718°C, 8.2 8.7 kb) metamorphism. The Baekdong ultramafic rocks had undergone high-P/T metamorphism during subduction of the South China Block, and experienced a fast isothermal uplift, and finally cooled down isobarically. Evidences for metamorphism were not identified in Bibong ultramafic rocks. Hence, the Baekdong ultramafic rocks with in the Hongseong area may indicate a link on the Korean counterpart of Dabie-Sulu collision belt between North and South China Blocks.  相似文献   

2.
Most chrysotile deposits occur in ultramafic rocks of the ophiolite suite. The chrysotile deposits dis-cussed in the present paper were formed through metasomatism and infilling-crystallization in a continentalserpentinization environment after plate convergence, where ultramafic rocks were replaced byhydrothermal solutions consisting mainly of deep-circulating heated water derived from atmospheric precip-itation. The critical state for the formation of asbestos in ultramafic rock bodies might be reached bysuperposition of multiple stages of serpentinization. Favourable fracture systems and relatively stable geo-logical environment are important conditions for forming chrysotile deposits. Three subtypes of chrysotiledeposits could be formed in different tectonic settings and under different minerogenic geochemical condi-tions.  相似文献   

3.
The Hongseong area, located in the western Gyeonggi Massif, South Korea, can be correlated with the northern margin of the South China block (Yangtze Craton). This area experienced Neoproterozoic igneous activity related to subduction before the amalgamation of Rodinia. Several isolated, lenticular, and serpentinized ultramafic–mafic bodies occur in the Hongseong area. The Baekdong body, one of the largest ultramafic bodies, has been highly deformed and metamorphosed to eclogite- and granulite-facies. The petrogenesis and tectonic environment of the Baekdong rocks are assessed using the composition of unaltered cores of spinel and olivine grains, and show that these rocks represent the mantle section of a suprasubduction ophiolite. The rocks originated from oceanic lithosphere that formed during the transition from nascent back-arc to mature island arc, related to subduction roll-back. During the back-arc stage, Al-rich spinel harzburgite formed through melt–rock interaction caused by the intrusion of magma. This magma was produced in small amounts, by less than 10% of partial melting of the wedge mantle. Subsequently, during the mature island arc stage, Cr-rich spinel dunite formed through melt–rock interaction caused by the intrusion of relatively evolved magma that formed by 30–35% partial melting due to a high input of volatiles from the subducted slab and sediments. The Baekdong ultramafic rocks, together with the Bibong ultramafic rocks, indicate that a suprasubduction tectonic setting prevailed before the amalgamation of Rodinia (at 860–890 Ma) in the Hongseong area, which may be an extension of the northern margin of the Yangtze Craton.  相似文献   

4.
超基性岩本身难以生长锆石的特性,使得研究其中的锆石需要特别谨慎。超基性岩中的锆石虽然具有多解性,但是锆石也携带了很多演化信息。产出不同地质背景的超基性岩,其中的锆石特征不同。本文总结现有的研究实例表明:(1)经历高温高压变质作用的石榴橄榄岩通常通过交代作用获得锆石,且锆石能够记录峰期变质时代,其中的继承锆石较少,可能在高温高压条件下,继承锆石发生分解重结晶;(2)大洋蛇绿岩型超基性岩和地幔岩捕掳体中通常具有年龄分布很广的锆石年龄特征,锆石年龄峰值通常与区域上构造事件相吻合,为捕掳晶锆石。接下来本文以西南天山超高压(UHP)蛇纹岩为例,对其锆石年龄进行解释。西南天山蛇纹岩为经历过超高压变质作用的大洋蛇绿岩型超基性岩,2个蛇纹岩样品中锆石的阴极发光图像分析和SIMS U-Pb定年分析结果显示,西南天山UHP蛇纹岩中的锆石包含捕掳晶锆石和变质锆石,捕掳晶锆石的年龄为2.1~1.0Ga,对应该区变泥质岩中碎屑锆石记录的年龄峰值。409~537Ma可能代表了蛇纹岩原岩结晶时代。区域上的变质压力峰期年龄(~320Ma)在蛇纹岩中没有记录,仅有1颗锆石记录了309±5Ma的近峰期时代。270~155Ma的退变质时代在西南天山蛇纹岩中出现较广,这与榴辉岩中出现的退变年龄相吻合,代表了折返过程中较为普遍的后期热液事件。基于对超基性岩中锆石特征的初步了解,结合西南天山蛇纹岩的研究实例,认为通过研究锆石的年代学,结合锆石矿物化学、包体矿物学、同位素地球化学等特征,不仅可以提供年代学信息,还可以对超基性岩的来源和演化过程进行解析。  相似文献   

5.
区内矿产资源丰富，有铜、铅—锌、金、铁、汞、镍六种成型矿床。区内古生代、中生代地层中海相火山岩层可作为有利的赋矿层，中生代沉积地层，尤其是三叠系地层可作为有利找矿层。铜、铁矿床形成与侵入岩有关。成矿带明显受北西、北西西、北西转南北向区域性深、大断裂控制。与中—酸侵入岩有关的矿床，局部重力异常多表现为圆形、椭圆形的重力低，矿床主要位于负异常中心及边部地带。航磁异常多有异常反映，幅值一般在50nT以下。与赵基性—基性侵岩有关矿床，局部重力异常表现为椭圆形的正异常，矿床位于正异常边部，且与一正磁异常对应。  相似文献   

6.
宋天锐 《中国地质》2007,34(2):315-323
笔者是在“五国编图项目”(中国、俄罗斯、哈萨斯坦、蒙古国、韩国)的中国北方磷矿床资料研究基础之上完成本论文的。中国北方磷矿床分为“沉积型”、“沉积变质型”和“岩浆型”三大类型。沉积型磷矿床主要产生于晚震旦纪陡山沱期和早古生代寒武纪早期,磷质来源以海洋生物磷为主;沉积变质型磷矿床主要产生于中元古代,磷质来源以火山磷质为主,也可能有生物磷质参与;沉积型和沉积变质型磷矿都包含陆地风化迁入盆地中的磷成分;岩浆磷矿床主要产生于海西期和加里东期的超镁铁岩浆岩,多与铁、钒、钛成为成矿系列。沉积型磷矿在华北地台南缘和塔里木地块北缘应重视,而沉积变质型在华北地台北缘有远景;岩浆型则主要勘查超镁铁岩系列。  相似文献   

7.
The study area is located southeast of Dehshir between the Urumieh-Dokhtar Magmatic Arc and Nain-Baft Ophiolite Belt comprising the Nain, Dehshir, Shahr Babak, and Baft ophiolite complexes. The Dehshir Ophiolitic Complex which obducted in the Late Cretaceous, consists mainly of ultramafic rocks. These remnants of oceanic crust are extensively faulted and fractured. The severe faulting and brecciating of the ophiolite sequence have undergone high-grade alteration and changed it to the tectonic mélange. The Dehshir colored mélange is bounded to the west by Dehshir fault which is a right-lateral offset of the Nain-Baft suture. In this research, the petrographic studies of the area showed that the ultramafic rocks consist mainly of dunite and harzburgite intruded by diabasic dikes. Syntectonic hydrothermal fluids circulated throughout these rocks. Migration of Mg-rich fluids and hydrothermal brecciating occurred within highly altered and brecciated zones. Magnesite precipitated from hydrothermal solutions and formed the massive, lenticular, and vein-type ore deposits in serpentinized-hosted rocks. Later on, magnesite turned into hydromagnesite due to hydration at the lower depths near the surface. According to the X-ray diffraction and X-ray fluorescence analysis, hydromagnesite is the most dominant and widely occurring Mg-rich carbonate mineral in this area. The main alteration is serpentinization but birbiritization also occurs as a result of interaction between fluids and ultramafic rocks.  相似文献   

8.
《Resource Geology》2018,68(4):352-372
Talc deposits in Nangarhar Province, are hosted by Paleoproterozoic carbonate rocks, metamorphosed to amphibolite facies in the east–west (E–W) trending Spinghar Fault Block. Many deposits in this province have potential economic importance. However, detailed geologic and petrological studies on ore genesis are still lacking. In this study, eight talc deposits and two prospects of the Spinghar Fault Block were investigated. Talc is mainly formed by alteration of the host dolomite marble, magnesite rocks, and tremolitite. Talc ore bodies occur parallel to subparallel to the beddings of the host carbonate rocks. Dolerite occur as dikes and sills and are mostly metamorphosed to amphibolite. Although the amphibolite occurs mostly parallel to subparallel to the beddings of the host carbonate rocks, and talc orebodies, it partly crosscuts the host rocks. Massive layers of tremolitite were observed with most of the talc ore bodies. Quartz veins occur along the gneissosity of gneiss all over the study area. SiO2 and MgO content in talc rocks from all deposits ranged from 49.1 to 65.1 wt% and from 26.1 to 32.9 wt%, respectively. CaO content in talc rocks and magnesite rocks are less than 1 wt%. ƩREE content in talc rocks ranged from 0.1 to 8.9 ppm. Chemical compositions of host carbonate rocks are close to the ideal composition. Concentrations of Al, Ta, Hf, Zr, Th, Cr, Ni, Co, and ƩREE in talc ores and host carbonate rocks were very low and inconsistent with mafic and ultramafic rocks protolith. Therefore, the metamorphosed sedimentary carbonate rocks were likely to be the protolith of the talc ores. The occurrence of parallel to subparallel quartz veins to the gneissosity of gneiss, as well as the presence of hydrous minerals in host carbonate rocks, suggested that hydrothermal fluids were most probably supplied through the gneiss.  相似文献   

9.
北秦岭丹凤群向西延入祁连造山带的地质意义   总被引：1，自引：0，他引：1  
宋志高 《地球学报》1993,14(2):15-26
依据前人及笔者近期对北秦岭的早古生代丹凤群(蛇绿岩套)追索研究表明,该带向西可延展至甘肃陇西一带,且向更西可与甘肃的雾宿山和青海的拉脊山出露的早古生代岩系相对比,从而构成位于祁连中间隆起带南侧,与北祁连褶皱带相对应的优地槽(蛇绿岩)带。本文研讨了其火山岩系的岩石系列组合与形成环境,并认为它的向西延展,显示北秦岭与祁连造山带间不但是相互连接的,而且两区具有相同的构造格架,属华北板块南部边缘的同一造山带。  相似文献   

10.

Ophiolitic and metamorphic rocks of the eastern part of the New England Fold Belt in the Shoalwater Bay region and the Percy Isles are grouped in the Marlborough and Shoalwater terranes, respectively. Marlborough terrane units occur on South Island (Percy Isles) and comprise the Northumberland Serpentinite, antigorite serpentinite with rodingite and more silicic dykes and mafic inclusions, the Chase Point Metabasalt, some 800+ metres of pillow lava, and the intervening South Island Shear Zone containing fault‐bounded slices of mafic and ultramafic igneous rocks, schist, and volcaniclastic sedimentary rocks, and zones of mélange. The Shoalwater terrane, an ancient subduction complex, consists of the Shoalwater Formation greenschist facies metamorphosed quartz sandstone and mudstone on North East Island and on the mainland at Arthur Point, the Townshend Formation, amphibolite‐grade quartzite, schist and metabasalt on Townshend Island, and the Broome Head Metamorphics on the western side of Shoalwater Bay, upper amphibolite facies quartz‐rich gneiss. With the exception of a sliver emplaced onto the western Yarrol terrane, possibly by gravity sliding, Shoalwater terrane rocks show the effects of Late Permian polyphase deformation. The Shacks Mylonite Zone along the northwest edge of the Broome Head Metamorphics marks a zone of oblique thrusting and is part of the major Stanage Fault Zone. The latter is a northeast‐striking oblique‐slip dextral tear fault active during Late Permian west‐directed thrusting that emplaced large ultramafic sheets farther south. Marlborough terrane rocks were emplaced along the Stanage Fault Zone, probably from the arc basement on which rocks of the Yarrol terrane were deposited. Structural trends and the distribution of rock units in the Shoalwater Bay‐Percy Isles region are oblique to the overall structural trend of the northern New England Fold Belt, probably due to the presence of a promontory in the convergent margin active in this region in Devonian and Carboniferous time.  相似文献   

11.

Serpentinised peridotite and ultramafic breccia make up an approximately 5 km‐long, 1 km‐wide fault slice within turbidites in the Dolodrook River region of the central Lachlan Orogen. The serpentinite body is surrounded by juvenile, mafic‐ultramafic sedimentary rocks with Cambrian limestone olistoliths representative of locally derived debris flows, and Middle to Upper Ordovician black shale, chert, sandstone and mudstone. The antiformal geometry and nature of the ultramafic breccia and mafic‐ultramafic sedimentary rocks (Garvey Gully Formation) indicate that the serpentinite body may have been either a former oceanic transform fault zone, a Marianas‐style serpentine seamount or a combination of these. Observations of modern‐day forearc regions show that faulting processes have led to the exposure of serpentinised peridotite horst blocks and serpentine mud volcanoes that have intruded along fault conduits (e.g. Marianas and Izu‐Bonin forearcs). At Dolodrook, the structural and metamorphic relationships with the surrounding rocks, and the lithological associations, have much in common with these observations and indicate that Dolodrook may be an ancient, on‐land example of an accreted seamount or oceanic topographic high. Structural relationships, the very low metamorphic grade of all rocks at Dolodrook, and the presence of broken formation developed in not‐fully lithified Middle to Upper Ordovician sandstone and mudstone indicate that the serpentinite body was emplaced at shallow crustal levels within the turbidite wedge (Tabberabbera Zone), possibly as an offscraped topographic high during marginal basin closure. The Dolodrook serpentinite has previously been inferred as part of the Cambrian igneous sequence (‘greenstones’) exposed in the Governor, Mt Wellington and Heathcote Fault Zones, but structural and metamorphic relationships with surrounding rocks, and the Cambrian tectonic setting in which it formed, have remained speculative.  相似文献   

12.
东帝汶国的成矿地质条件较优越,矿产资源较丰富。铬铁矿化在马纳图托省、马努法伊省和包考省有明显的找矿信息,成矿环境受环太平洋成矿带超镁铁质岩带控制。其中位于马纳托图省HiliManu地区的蛇纹石化超基性岩中呈豆荚状产出铬铁矿,Cr2O3含量在36％～51％之间,显示出较好的资源潜力。锰矿化主要分布于包考省、维克克省和马纳图托省,为海相层控型,其中位于马纳托图省Vemasse地区的锰矿床规模较大,品位较高,具有成为中-大型锰矿床的潜力。铜矿化出露于包考省、维克克省、科瓦利马省、马努法伊省、马纳图托省和劳滕省,矿化作用与蛇绿岩套有关,其中位于维克克省Ossu地区的蛇纹岩体,存在与蛇纹石化基性-超基性岩石组合有关的铜／金／银矿化露头,暗示其下可能隐伏着更大的硫化物矿化体。金矿化既有热液脉型,又有浅成低温热液蚀变浸染型,更有河流砂矿型,分布范围广,品位中等到较富,其中马努法伊省Turiscai地区Sue河、Laclo河及Cler河沿岸砂砾层中存在找寻砂金矿的前景,河流上游存在原生金矿的可能。综上所述,东帝汶国具有明显的找矿前景、矿产资源开发潜力和较好的矿业投资环境,建议加大工作力度,把握机会,适时介入。  相似文献   

13.
金沙江蛇绿岩带蛇纹岩中浅色岩类的成因   总被引：4，自引：0，他引：4  
浅色岩类的岩石类型包括斜长岩和斜长花岗岩,它们均呈岩块状包裹于蛇纹岩中。浅色岩的正Ｅｕ异常明显,ＲＥＥ参数图解、Ｎｂ／Ｔａ和Ｚｒ／Ｈｆ值等均呈现分离结晶趋势,不相容元素Ｓｒ、Ｂａ、Ｎｂ、Ｔａ、Ｚｒ、Ｈｆ富集,相容元素Ｓｃ、Ｖ、Ｃｏ、Ｎｉ亏损,并与其寄主岩－蛇纹岩形成强烈的互补关系。这些特征表明,浅地是幔源超基性岩浆晚期结晶分异的产物。  相似文献   

14.
The Mitsuishi ultramafic rock body in Hokkaido, Japan, consists mainly of serpentinized peridotites that originated from a depleted mantle. This study aims to show new evidence of small-scale mélange fabric of serpentinite matrix in the rock body. Each serpentinite block in the serpentine matrix shows large and stable intensities of natural remanent magnetization (NRM). However, the directions of serpentinite blocks' NRM in the matrix are randomly scattered. A Curie temperature (Tc) of 580 °C corresponding to pure magnetite was also observed. Additionally, there is no evidence of heating over 580 °C after serpentinization. The blocks in the matrix must have obtained crystallization remanent magnetization (CRM) during serpentinization. The directions of the blocks' characteristic remanent magnetization (ChRM) are also scattered. It shows that serpentinite blocks were magnetized prior to uplifting. The results of the study indicate that the magnetic carrier of the serpentinite blocks in the matrix is mainly composed of magnetite, and it can keep original magnetization before uplifting. The results also imply that the scattering directions of NRM indicate the presence of small-scale mélange fabric of serpentinite matrix.  相似文献   

15.
Nodular, cryptocrystalline, weathering-derived magnesite deposits in the New England Orogen, Australia, provide a significant source of high-purity magnesite. Common textural features and related isotopic fingerprints indicate a close genetic relationship between weathering-derived magnesite deposits hosted by ultramafic rocks at Attunga and by sediments at Kunwarara while silica-carbonate rock alteration and rare hydrothermal magnesite vein deposits reflect contrasting conditions of formation. Localised weathering of carbonates in a soil environment shifts stable isotopic composition towards low δ 13C and high δ 18O typical for weathering-derived magnesites while intrusion-related fluids do not significantly change the isotopic composition of affected carbonates. At Attunga, magnesite consists of irregular, nodular veins and masses filling faults and cracks in the weathered serpentinite host rock as well as soft powdery magnesite in pervasive serpentinite alteration zones. The high-grade magnesite at Attunga can be contaminated by amorphous silica and serpentine relicts but does not contain dolomite or ferroan magnesite as observed for its hydrothermal equivalent, the Piedmont magnesite deposit, or other widespread deposits of silica-carbonate rock in the Great Serpentinite Belt. Heavy δ 18O values are compatible with a supergene formation from meteoric waters while low δ 13C suggests C3-photosynthetic plants as the predominant source of carbon for the Attunga magnesites. We infer that weathering-derived, nodular magnesite deposits hosted in ultramafic rocks like the Attunga magnesite deposit have formed in a two-step process involving the hypogene formation of a pre-cursor magnesite deposit and complete supergene overprinting by meteoric waters that acquired carbon from percolation through soil.  相似文献   

16.
The Kekekete mafic-ultramafic rocks are exposed in the Kekesha-Kekekete-Dawate area,which are in the eastern part of the East Kunlun Orogenic Belt.It outcrops as tectonic slices intruding tectonically in the Paleoproterozoic Baishahe Group and the Paleozoic Nachitai Group.The Kekekete mafic and ultramafic rocks is located near the central fault in East Kunlun and lithologically mainly consists of serpentinite,augite peridotite,and gabbro.The LA-ICP-MS zircon U-Pb age of the gabbro is 501±7 Ma,indicating that Kekekete mafic-ultramafic rocks formed in the Middle Cambrian.This rock assemblage is relatively poor in SiO2 and(Na2 O+K2 O) but rich in MgO and SFeO.The chondrite-normalized REE patterns of the gabbro dip slightly to the right;the primitive mantle and MORBnormalized spidergrams of trace elements show enrichment of large-ion lithophile elements(Cs,Rb,Ba,etc.) and no differentiation of high field strength elements.The general dominance of E-MORB features and the geochemical characteristics of OIB suggest that the Kekekete mafic-ultramafic rocks formed in an initial oceanic basin with slightly enriched mantle being featured by varying degrees of mixing of N-MORB depleted mantle and a similar-OIB-type source.From a comprehensive study of the previous data,the author believes that the tectonic history of the East Kunlun region was controlled by a geodynamic system of rifting and extension in the late stages of the Neoproterozoic to early stages of the Early Paleozoic and this formed the paleo-oceanic basin or rift system now represented by the ophiolites along the central fault in East Kunlun,the Kekekete mafic-ultramafic rocks and Delisitan ophiolite.  相似文献   

17.
西天山地区金矿床主要成因类型及找矿方向   总被引：13，自引：4，他引：13  
西天山地区地处古亚洲构造域天山-兴蒙成矿带的西段，经历了漫长复杂的构造演化过程，尤其是海西期强烈的构造岩浆活动，为金成矿创造了有利的条件．近几年，本区找金工作取得了突破性的进展，相继发现了阿希、望峰、大山口等金矿床，显示了良好找金前景．根据前人和笔工作，讨论了本区主要金矿化类型浅成低温热液型(又进一步划分为冰长石-绢云母型和硅化岩型)斑岩型、韧性剪切带型穆龙套型等的成矿特征，在综合分析基础上，指出找矿方向．  相似文献   

18.
An ophiolitic association consisting of serpentinized ultramafic rocks and serpentinite, layered mafic–ultramafic complex, gabbro and gabbrodolerite, fragments of parallel dike complex, pillow lava, black bedded chert, and jasper has been identified for the first time by authors in the Cape Fiolent area. The chemistry of pillow lavas and dolerites, including REE patterns and a wide set of other microelements, indicates suprasubduction nature of the ophiolites and their belonging to a backarc basin that has reached the stage of spreading in its evolution.  相似文献   

19.
The pre-Sinian basement on the southwestern margin of the Yangtze paraplatform consists of threemetamorphic rock series of different ages. Being products of different tectonic events and environments, theydiffer markedly in original rock sequences, metamorphism. tectonic style and characteristics of granitoids andmineral deposits. The Late Archean Kangdian cration mainly comprises the Kangding and Julin Groups with ametamorphic age of nearly 2500 Ma. They are supracrustal rocks dominated by mafic volcanics enclosed introndhjemitic rocks The craton is believed to represent a granite-greenstone terrane of Late Archaean age.There occur mineral deposits such as graphite and kyanite deposits of metamorphic origin, muscovite depositsin pegmatites and gold quartz veins in gneissic granites, banded hornblende-magnetite mineralization and cop-per and zinc mineralizations related to felsic volcanics. Large V-Ti-bearing magnetite deposits were also formedin the mafic. ultramafic stratiform intrusions emplaced on the margins of the craton during the MiddleProterozoic. Copper and nickel deposits are found in several ultramafic intrusions. Extending in a north-southdirection, the Proterozoic mobile belt consists mainly of the Early Proterozoic Hekou Group and MiddleProterozoic Huili and Kunyang Groups. and they are thought to be accumulations in a Proterozoic rift troughor aulacogen. During the Early Proterozoic, the rift trough was characterized by intense volcanism and pres-ence of iron ore deposits of volcano-magmatic type, iron-copper deposits of exhalative-sedimentary type. TheMid-Late Proterozoic of the rift trough mainly witnessed the formation of sedimentary stratiform copper de-posits and submarine sedimentary iron deposits. In the wake of the emplacement of the Jinningian andChengjiangian granites in the Late Proterozoic, skarn-type tin and tin-iron ore deposits were formed.  相似文献   

20.
徐文博  张铭杰  包亚文  满毅  李思奥  王鹏 《地质学报》2022,96(12):4257-4274
塔里木克拉通东北缘坡北、磁海等地二叠纪幔源岩浆活动形成了镍钴硫化物矿床和铁钴氧化物矿床，两者赋矿镁铁 超镁铁岩体的年龄相近(290~260 Ma)，主、微量元素和Sr Nd Hf同位素组成相似，分配系数接近的微量元素比值分布于相同趋势线，揭示两者岩浆源区相同，可能为俯冲板片流体交代的亏损地幔或软流圈地幔。两类矿床镁铁 超镁铁质岩中Co与Ni含量正相关，Co主要富集在基性程度高的岩石中；块状硫化物与磁铁矿矿石中Co与Ni相关性差，Co和Ni具有不同的富集机制，Co热液富集作用明显。北山镁铁 超镁铁杂岩体是地幔柱相关软流圈上涌，诱发俯冲板片交代的亏损岩石圈地幔发生部分熔融，形成的高镁母岩浆演化过程中经历壳源混染、硫化物饱和富集镍钴形成铜镍钴硫化物矿床，富铁母岩浆氧逸度高、富水，岩浆分离结晶磁铁矿、叠加热液作用富集钴，形成铁钴氧化物矿床。  相似文献   

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