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1.
从熔岩－玄武岩的岩石学、岩石化学、微量元素、稀土元素和锶同位素组成，以及火山旋回中玻璃碎屑岩诸方面特征，详细地研究了件罗统含矿层位内海底基性火山活动，阐述矿区说武岩形成环境为矢折的大陆裂谷前期地壳槽形裂陷地堑系－裂陷槽。并讨论了该裂陷槽环境中基性火山活动的银锑成矿意义。 相似文献
2.
一个海底基性火山喷流成因的银锑矿床地质特征 总被引：8，自引：3，他引：8
广东梅县嵩溪宝山是个产于具裂谷性质的永－梅裂陷槽南段翼部裂陷火山－沉积盆地内的一个海底基性火山喷流成因的银锑组合大型银矿。文中阐述以下问题：容矿层位岩性组合、建造和相及层位地球化学特征、矿区地质构造；海底基性熔岩玄武岩的地质、地球化学、稀土元素特征及其构造环境与成矿意义；矿体（层）形态、产状、矿石结构构造、矿物共生组合、地球化学、稀土元素、同位素、包裹体等 相似文献
3.
夏河县孜孜合一带中侏罗世火山岩特征及构造环境探讨 总被引：1，自引：0，他引：1
夏河县孜孜合一带侏罗纪地层中发育的中基性火山岩 ,为碱性玄武岩系列、钠质类型。岩石类型主要为 :安山质火山角砾岩、玄武岩、球颗状玄武岩、安山玄武岩、杏仁状安山玄武岩、杏仁状安山岩等。其岩石化学、微量元素特征均表明其具有板内碱性玄武岩的特征。火山岩是在燕山期由早期的挤压挠曲转换为晚期的伸展裂陷环境下形成的。 相似文献
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北祁连山西段早元古代变质火山岩的地球化学特征及其构造背景 总被引：12，自引：0，他引：12
产于北大河群的早元古代火山岩是北祁连山西段最主要的三期火山岩之一,其地球化学特征表明,该期火山岩的原岩为具有双峰式组合的拉斑玄武岩和中酸笥凝灰岩。两者具有完全不同的稀土分布型式,前者以极低的富集轻稀土为特征,而后者以强烈富集轻稀土的特征;基性火山岩的微量元素分布曲线指示了其形成了裂陷槽环境。结合Ｎｄ同位素特征以及区域２得出本区早元古代变质火山岩形成于裂陷槽环境。 相似文献
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桂北地区金矿成矿规律与找矿预测 总被引：4，自引：0，他引：4
元古宙火山－陆源碎屑沉积含金建造与下古生界含碳碎屑沉积建造是该区金矿主要赋矿层中，前者为陆内裂陷沟－弧环境产物，后者形成了陆缘盆地构造环境。金矿化总体呈东西向延展又依ＮＮＥ～ＮＥ向成带的分布格局，是受古东西向基底隐伏构造带和ＮＮＥ～ＮＥ向深断裂双重制约的结果，继承元古宙裂陷槽俯冲带发展演化形成的韧性剪切带，控制与基性，超基性杂岩有关的金矿化，次级隆起动缘构造挤压带是金成矿的有利部位，金矿化主要受脆 相似文献
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吉林晚石炭世要期石头口门裂陷槽位于长春东５０ｋｍ。该裂陷槽以海底火山沉积－－硅质岩沉积为主。早期以含锰结核的碎屑岩和泥岩、硅质岩为主,并有少量的凝灰碉和玄武岩;中期以海底火山喷发的高钠质细碧岩、角地为主,并伴有规模不大的蛇纹岩;晚期以硅质岩、长石杂砂岩、泥岩、生物碎屑灰岩为主,在生物碎屑灰岩中首次发现Ｆｕｓｕｌｉｎａ ｌａｎｃｅｏｌａｔａ Ｆ．ｓｐ．、Ｐｓｅｕｄｏｓｔａｆｆｅｌｌａ ｋｈｏｔｕｎｅ 相似文献
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贵州威宁-赫章二叠系乐平统含铁、铝岩系的沉积环境及成矿元素富集特征 总被引：1，自引：0，他引：1
贵州威宁-赫章地区的二叠系乐平统宣威组第一段铁、铝岩系,是峨眉山玄武岩风化-沉积作用的产物.其中富集的稀土、稀有、稀散元素,与峨眉山玄武岩所处的构造位置和玄武岩风化的古地理位置有关.在六盘水裂陷槽区(B区),Cu、Ti、Sc、REE含量高,对应于六盘水裂陷槽复杂的地质环境;在裂陷槽边界西南,玄武岩剥蚀作用强烈,沉积层的厚度较薄,Nb、Ta和REE在强风化环境中富集;在裂陷槽边界北东,沉积厚度较大,Ga和V含量高,可能是沉积环境富集.风化作用是成矿有用组分富集的重要因素,它决定了稀土、稀有和稀散元素富集的趋势.有一些元素可以富集,达到工业利用价值,特别是Nb+ Ta,可能形成独立矿床. 相似文献
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《地质与勘探》2017,(2)
贵州威宁-赫章地区的二叠系乐平统宣威组第一段铁、铝岩系,是峨眉山玄武岩风化-沉积作用的产物。其中富集的稀土、稀有、稀散元素,与峨眉山玄武岩所处的构造位置和玄武岩风化的古地理位置有关。在六盘水裂陷槽区(B区),Cu、Ti、Sc、REE含量高,对应于六盘水裂陷槽复杂的地质环境;在裂陷槽边界西南,玄武岩剥蚀作用强烈,沉积层的厚度较薄,Nb、Ta和REE在强风化环境中富集;在裂陷槽边界北东,沉积厚度较大,Ga和V含量高,可能是沉积环境富集。风化作用是成矿有用组分富集的重要因素,它决定了稀土、稀有和稀散元素富集的趋势。有一些元素可以富集,达到工业利用价值,特别是Nb+Ta,可能形成独立矿床。 相似文献
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龙脖河铜矿区(北段)岩浆岩及矿化 总被引：3，自引：0，他引：3
龙脖河铜矿产于中三叠统个旧组灰岩及其下伏地层中下三叠统火山岩建造中。矿床的形成与以红河断裂和阿龙古断裂为界的深海红河裂陷槽海相火山活动及后期的热液蚀变关系密切，矿化受地层、火山活动构造控制。富钠细碧角斑岩、火山碎屑岩、基性侵入岩为该区的主要岩浆岩类型。上述不同岩浆岩均有矿化产出，本文就区内岩浆岩的特征及其与矿化的关系作一简略的探讨。 相似文献
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The northeast (NE) Honshu arc was formed by three major volcano-tectonic events resulting from Late Cenozoic orogenic movement: continental margin volcanism (before 21?Ma), seafloor basaltic lava flows and subsequent bimodal volcanism accompanied by back-arc rifting (21 to 14?Ma), and felsic volcanism related to island arc uplift (12 to 2?Ma). Eight petrotectonic domains, parallel to the NE Honshu arc, were formed as a result of the eastward migration of volcanic activity with time. Major Kuroko volcanogenic massive sulfide (VMS) deposits are located within the eastern marginal rift zone (Kuroko rift) that formed in the final period of back-arc rifting (16 to 14?Ma). Volcanic activity in the NE Honshu arc is divided into six volcanic stages. The eruption volumes of volcanic rocks have gradually decreased from 4,600?km3 (per 1?my for a 200-km-long section along the arc) of basaltic lava flows in the back-arc spreading stage to 1,000?C2,000?km3 of bimodal hyaloclastites in the back-arc rift stage, and about 200?km3 of felsic pumice eruptions in the island arc stage. The Kuroko VMS deposits were formed at the time of abrupt decrease in the eruption volume and change in the mode of occurrence of the volcanic rocks during the final period of back-arc rifting. In the area of the Kuroko rift, felsic volcanism changed from aphyric or weakly plagioclase phyric (before 14?Ma), to quartz and plagioclase phyric with minor clinopyroxene (12 to 8?Ma), to hornblende phyric (after 8?Ma), and hornblende and biotite phyric (after 4?Ma). The Kuroko VMS deposits are closely related to the aphyric rhyolitic activity before 14?Ma. The rhyolite was generated at a relatively high temperature from a highly differentiated part of felsic magma seated at a relatively great depth and contains higher Nb, Ce, and Y contents than the post-Kuroko felsic volcanism. The Kuroko VMS deposits were formed within a specific tectonic setting, at a specific period, and associated with a particular volcanism of the arc evolution process. Therefore, detailed study of the evolutional process from rift opening to island arc tectonics is very important for the exploration of Kuroko-type VMS deposits. 相似文献
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Close relationships between deformation and volcanism are well documented in relatively late evolutionary stages of continental rifting, whereas these are poorly constrained in less mature rifting stages. To investigate the control of inherited structures on faulting and volcanism, we present a statistical analysis of volcanic features, faults and pre‐rift fabric in the Tanzania Divergence, where volcanic features occur extensively in in‐rift and off‐rift areas. Our results show that in mature rift sectors (Natron), magma uprising is mostly controlled by fractures/faults responding to the far‐field stress, whereas the distribution of volcanism during initial rifting (Eyasi) is controlled by inherited structures oblique to the regional extension direction. Off‐rift sectors show a marked control of pre‐rift structures on magma emplacement, which may not respond to the regional stress field. Thus, the use of off‐rift magmatic features as stress indicators should take into account the role of pre‐existing structures. 相似文献
14.
Norman Kennedy Grant David C. Rex Samuel J. Freeth 《Contributions to Mineralogy and Petrology》1972,35(4):277-292
The Cenozoic volcanic activity in northeastern Nigeria began with the intrusion into the Benue trough of a trachyte-phonolite suite of plugs 22-11 m.y. ago. Later activity, which was more widespread and dominantly basaltic in character, began some 7 m.y. ago and has continued until very recent times. It resulted in basaltic plugs and lava plateaux within the Benue trough, and cinder cones and lavas on the Jos Plateau.The initial 87Sr/86Sr ratios of nine of the fifteen analyzed basic and alkalic rocks lie in the range 0.7025–0.7032, and the highest ratio measured is 0.7129.The main group of trachytes and phonolites are considered to be fractional melts derived from the upper mantle, modified in small part by potassium feldspar crystal fractionation. Two Sr-rich phonolite plugs may have a separate origin from the main group of trachytes and phonolites.The Cenozoic volcanic activity in northeastern Nigeria is probably related to the nearby Cameroun volcanic line. The concentration of plugs within the Benue trough may reflect internal adjustments along old lines of weakness within the African lithosphere plate, in response to synchronous changes affecting the plate's external dimensions and internal structure, such as the growth of the Red Sea and the Gulf of Aden, and the volcanism of the east African rift valley. 相似文献
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祁连山造山带新元古代—早古生代是板块构造演化与成矿的最重要时段,铁、铜多金属矿产资源丰富,成矿作用与新元古代—早古生代火山作用密切相关。根据矿床产出构造位置,将祁连山铁、铜多金属矿床分为4类:大陆裂谷型铁(铜)矿床、岛弧-岛弧裂谷型铜多金属矿床、陆缘裂谷型铜多金属矿床、扩张脊型铜矿床。镜铁山铁(铜)型矿床是新元古代大陆裂谷火山作用过程中热水沉积作用的产物;东沟铜矿为晚寒武世大洋扩张脊火山作用的产物;白银矿田铜多属矿床是奥陶纪与岛弧-岛弧裂谷火山作用的产物;石居里铜矿是晚奥陶纪弧后扩张脊有关火山作用的产物;红沟铜矿则是晚奥陶世陆缘裂谷火山作用的产物。 相似文献
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与海相火山作用有关的铁-铜-铅-锌矿床成矿系列类型及成因初探 总被引：25，自引：5，他引：25
文章初步厘定了与海相火作用有关的铁、铜、铅、锌矿床成矿系列类型的概念，并对其进行了分类，讨论了其成因，认为内生外成（沉）是其主要特征，即成矿物质主要由火山作用从深部提供，而矿石又是通过沉积作用在海底形成的。在一定程度上，可从成矿类型的角度将块状硫化物矿床与BIF型或磁铁石英岩型矿床联系起来考虑。该类矿床成矿系列类型的演化特点在一定程度上可以反映地球演化的历史轨迹。 相似文献
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Rift propagation at craton margin.: Distribution of faulting and volcanism in the North Tanzanian Divergence (East Africa) during Neogene times 总被引：1，自引：0，他引：1
B. Le Gall P. Nonnotte J. Rolet M. Benoit H. Guillou M. Mousseau-Nonnotte J. Albaric J. Deverchre 《Tectonophysics》2008,448(1-4):1-19
A revised kinematic model is proposed for the Neogene tectono-magmatic development of the North Tanzanian Divergence where the axial valley in S Kenya splits southwards into a wide diverging pattern of block faulting in association with the disappearance of volcanism. Propagation of rifting along the S Kenya proto-rift during the last 8 Ma is first assumed to have operated by linkage of discrete magmatic cells as far S as the Ngorongoro–Kilimanjaro transverse volcanic belt that follows the margin of cratonic blocks in N Tanzania. Strain is believed to have nucleated throughout the thermally-weakened lithosphere in the transverse volcanic belt that might have later linked the S Kenya and N Tanzania rift segments with marked structural changes along-strike. The North Tanzanian Divergence is now regarded as a two-armed rift pattern involving: (1) a wide domain of tilted fault blocks to the W (Mbulu) that encompasses the Eyasi and Manyara fault systems, in direct continuation with the Natron northern trough. The reactivation of basement fabrics in the cold and intact Precambrian lithosphere in the Mbulu domain resulted in an oblique rift pattern that contrasts with the orthogonal extension that prevailed in the Magadi–Natron trough above a more attenuated lithosphere. (2) To the E, the Pangani horst-like range is thought to be a younger (< 1 Ma) structure that formed in response to the relocation of extension S of the Kilimanjaro magmatic center. A significant contrast in the mechanical behaviour of the stretched lithosphere in the North Tanzanian diverging rift is assumed to have occurred on both sides of the Masai cratonic block with a mid-crustal decoupling level to the W where asymmetrical fault-basin patterns are dominant (Magadi–Natron and Mbulu), whereas a component of dynamical uplift is suspected to have caused the topographic elevation of the Pangani range in relation with possible far-travelled mantle melts produced at depth further N. 相似文献
19.
I. R. Plimer 《Mineralium Deposita》1985,20(3):147-153
Broken Hill ore deposition occurred during the highest geothermal gradient coeval with an event of bimodal basic-rhydacitic volcanism. The depositional environment is interpreted as an ensialic rift on the basis of the sedimentary facies, ferro- and low-K tholeiitic basalts, and bimodal basic-calc alkaline (rhyolite, rhyodacite) volcanism. The orebody is of unusual composition characterised by abundant carbonate, fluorite and fluorapatite, abundant LIL-, K- and Rb-rich premetamorphic alteration assemblages, primordial S and Pb isotopic values, Sr isotopes possibly indicating a heterogeneous source, S : Se in the magmatic range, and zoning suggestive of cooling of the ore fluid.It is suggested that in the mature stage of rifting, propagation of deep fractures suddenly devolatilized the mantle, released CO2 and other fluids which, together with basalts, ascended and caused crustal melting to form acid magmas. The resultant ore fluid exhalation and basaltic and rhyodacitic volcanism were therefore coeval. Rapid deposition of ore from a fluid of unusual composition in a basin or graben within the rift formed a deposit which is not too dissimilar in composition from a carbonatite.The composition of the associated basic rocks and younger alkaline rocks, the premetamorphic alteration assemblage, and the orebody chemistry all suggest that the Lower Proterozoic source area for the ore fluids was metasomatized mantle. 相似文献
20.
Feng Benzhi 《《地质学报》英文版》1990,64(2):179-191
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