Petrochemistry of the Paleoproterozoic Udokan copper-bearing sedimentary complex

The maturity of terrigenous material of the Paleoproterozoic Udokan copper-bearing sedimentary complex is considered. The average values of hydrolyzate module (HM), alumina-silica module (AM), and Pettijohn’s coefficient of maturity appreciably vary throughout the Udokan Complex. Among cupriferous sandstones, rocks of the Aleksandrovka Formation are characterized by the highest maturity, whereas rocks of the Chitkanda Formation are distinguished by the lowest maturity. The maturity of cupriferous sandstones of the Sakukan Formation corresponds to that of host rocks. The maturity of cupriferous sandstones from the Aleksandrovka Formation is much higher than that of host rocks. In the Chitkanda Formation, the cupriferous sandstones are much less mature than host rocks. Climatic conditions in provenances estimated from the Nesbitt index of chemical weathering or chemical index of alteration (CIA) may be characterized as temperate ones without prominent climatic features. Most CIA values range from 46 to 66. The formation of copper-bearing sediments was closely related to the periods of volcanic activity.     

Formation Conditions and ore potential of black shales of the Udokan Group,East Siberia

Peculiarities of formation and ore potential of black shales of the Paleoproterozoic Udokan Group are considered. They are compared to the stratotype (Khokholma Formation, Sukhoi Log gold deposit). The black shales are confined to lower parts of the Paleoproterozoic sequence of the Udokan Group. They are observed in sections of the Chitkanda, Inyr, Ayan, and Ikab’ya formations. The black shale complex of the Udokan Group is divided into three levels of Au concentration. The first level with background Au contents is typical of barren shales; the second level is confined to sulfidized rocks; and the third level is related to sulfide-quartz veins in the black shales. The average Au content is 0.12 g/t in the sulfidized shales and 0.28 g/t in the sulfide-quartz veins. Black shales of the Udokan Group and Khokholma Formation were formed in a relatively deep shelf zone, while those of the Shaman Formation precipitated in a shallow zone. Protoliths of black shales of the Udokan Group contained graywackes, diorites, syenites, basic rocks, and tuffites. Protoliths of black shales of the Khokholma Formation were produced by the intense weathering of basic and ultrabasic rocks.     

Participation of hydrothermal fluids in the formation of deposits of the proterozoic Udokan-Chineysky ore system

Numerous Cu deposits of the Udokan-Chineysky ore district (Udokan deposit of cupriferous sandstones, deposits of the Chineysky pluton, etc.), which occur in sedimentary and igneous rocks, are similar in many genetic features. One of these features is the similar parameters of fluid inclusions (hydrothermal fluids) in quartz of the Udokan deposit, rich chalcopyrite ores from the Rudnyi (Rudnyie deposit, and veins of the Pravoingamakitsky deposit studied previously. Fluid inclusions have the same range of high salinity and homogenization temperatures. These studies combined with geological data allow us to consider the formation of contact sulfide ores from the Chineisky pluton and Pravoingamakitsky and Udokan deposits as a common compound fluid-magmatic ore-generating system. The sedimentary rocks primarily enriched in chalcopyrite, pyrite, and pyrrhotite of the entire section of the Udokan complex served as the host media for the hydrothermal fluids and deposits of various scales.     

Periodicity of copper accumulation in the Earth’s sedimentary shell

Physicochemical conditions of the migration and concentration of Cu in sedimentary rock, specific features of the formation of large and unique deposits of cupriferous sandstones and shales, distribution of copper deposits in the stratigraphic scale, and causes responsible for the reduction of Cu accumulation from Proterozoic to Cenozoic are considered. Genetic link of cupriferous sandstones and shales with arid red molassic rocks is shown. Conditions and periodicity of formation of the ore-generating red rocks are considered. An explanation for periodicity of maximum Cu accumulation in the Earth’s history is proposed.     

Basic relationships in distribution of modern siliceous sediments and their connection with climatic zonation

Paleogeographical reconstructions in the basin, between the Yenisey ridge and the Chadobets uplift, together with lithofacies analysis and stratigraphic differentiations show that: a) cupriferous carbonate-clayey horizons lie on the periphery of the basin and represent the transgressive cycle; b) coarse-grained sedimentary hosts of the cupriferous horizons represent the regressive cycle; c) copper is negligible in the essentially carbonate lithofacies in the central and deeper part of the basin. -- V.P. Sokoloff     

ANALYSIS ON GOLD AND COPPER OREFORMING SYSTEM WITH COLLISION OROGENY OF EASTERN TIANSHAN

According to tectono-stratigraphical division principle,different units in KangguertageHuangshan collision zone,Eastern Tianshan,are divided into order and disorder two types of stratum-rock associations,which belong to two kinds of different tectono-volcanic activity belts.The collision ororeny and ductile shear zone have a strong space-time coupling.Based on the island arcbearing volcanic rock on both sides of the collision zone,time of ore-forming and rock-forming,characteristics of collision granit,geochemical province,special multistage collision orogeny and intracontinental orogeny basin-forming developed features have been found.Gold and copper deposits,with the relation to the collision orogeny,are divided into seven genetic types.The ten metallogenic zones are classified into two kinds of ore-forming system of paleo-continental margin.Metallogenesis of gold deposits can be classified into five stages.Gold and copper deposits are distributed in belts with the relation to the development of the collision orogeny.The distribution of main large scale copper deposits in the north part of the collision zone and most large-middle scale gold deposits in the south part of the collision zone can direct the prospecting for gold and copper deposits.The actual targets are put forward.     

Cupriferous shales in Poland and their analogues in eastern parts of the USSR

Stratiform deposits of copper in Lower Silesia differ from those in Central Europe in several respects, but are very much like cupriferous shales and sandstones in the Angara basin and Upper Lena area. The Polish and Siberian copper ores resemble each other in their mineral parageneses, structures-textures, impurities, lithofacies, stratigraphic habit, and geotectonics. Current hypotheses on the still controversial genesis of both are essentially the same in either case.     

Geochemical Features of Cupriferous Sandstones in the Orenburg Area of the Ural Region

The new geochemical data obtained of cupriferous sandstones of the Orenburg area of the Ural region show that the Permian host stratum could have served as the source of rare-earth elements and other microelements for the ore-forming fluids. They confirm the possibility of using a convection model to explain the genesis of the copper ores studied. This model indicates the likely multistage development of mineralization to significant depths, like in the Manto deposits in Chili. Consequently, the Permian cupriferous sandstones of the southwestern area of the Ural region can be considered a very promising source of raw material for the development of copper industry in the area.

     

Lithological control of copper mineralization in Upper Permian rocks of Perm'-Uralian territory and Vyatka-Kama district

New data and the newest aspects of the theory of sedimentary ore formation suggest that the cupriferous sandstones of these two districts owe their copper, to the Ural's diabases and gabbros whence copper had migrated, as complex ions, along the still recognizable migration paths. Precipitation and accumulation of Cu also in aleurolites, argillites (even in limestones) is seen as unrelated to the organic substance they contain. The common phytomorphism of Cu in such ores, as well as in some sandstones, represents merely a re-grouping of the ore substance. — IGR Staff.     

Isotopic composition of sulfur and genesis of copper ores of Zdhezkazgan and Udokan

Enrichment of S³² in sulfidic sulfur and large variations in δS³⁴ content of certain minerals are characteristic of the ores. It is possible therefore that their sulfur was derived from sedimentary rocks and that bacterial reduction of sedimentary sulfates had a part in the process. The isotopic composition of sulfidic sulfur in cupriferous sandstones and in the veinlets therein is about the same. Consequently, a borrowing a sulfur by the veinlets from the sandstones appears to be a reasonable assumption. A biogenic-sedimentary origin of the sulfides does not preclude accessions of copper and other metals from the magma. -- Author.     

东天山碰撞造山与金铜成矿系统分析

根据碰撞带不同单元按构造一岩石地层划分原则,分出有序和无序两套地层岩石组合,分属两个不同的构造一火山活动带,碰撞造山与韧性剪切带强时空耦合．碰撞带两侧岛弧火山岩和带内碰撞花岗岩特征和成岩成矿时代、地球化学省等表明其较特殊的碰撞造山和陆内造山成盆多阶段演化特点。与碰撞造山有关的金铜矿分七种成因类型。现划10个成矿区带分属两个古陆边缘成矿系统,金矿成矿可分为五个阶段。金铜矿成带分布与碰撞造山演化有关,空间上北部铜矿带,南部金矿带,为今后进一步找矿指明了方向,提出了具体靶区。     

Provenance of Miocene sandstones in northern Iraq: constraints from framework petrography,bulk-rock geochemistry and mineral chemistry

Modal analysis, bulk-rock geochemistry and phase chemistry of sandstones of the Miocene Fat'ha and Injana formations, northern Iraq, show that the clastics were derived from heterogeneous sources that include basic igneous and metamorphic rocks as well as older sedimentary rocks. The sandstones are generally carbonate-rich lithic arenites. Their geochemistry supports the petrographic results and indicates that they are all Fe-rich, lithic or quartz arkosic sandstones. According to geochemical data, garnets are derived from metamorphic sources, hornblende is of igneous origin, and clinopyroxenes, are produced by basic igneous rocks. Epidote is most probably to be a product of disintegration of metamorphic rocks, essentially, metamorphosed igneous rocks. Rutile geochemistry implies low-grade metamorphic and basic to ultrabasic igneous sources. Chemical composition of chromian spinels indicates that they are derived from Alpine-type peridotite. The ophiolitic-radiolarite belts of Taurus-Zagros as well as the uplifted Cretaceous and Paleocene strata of north and northeastern Iraq are likely to be the major source of clastics to the Fat'ha–Injana basin, a foreland basin formed as a result of the continental Arabian and Turkish/Iranian plates collision.     

Indus tsangpo suture zone in ladakh—its tectonostratigraphy and tectonics

The Indus Tsangpo suture zone in Ladakh lies between the Phanerozoic sequence of the Zanskar Zone of Tethys Himalaya in the south and Karakoram zone in the north. The five palaeotectonic regimes recognized in the suture zone are: The Indus palaeosubduction complex, the Ladakh magmatic arc, the Indus arc-trench gap sedimentation, the Shyok backarc and the Post-collision molasse sedimentation. The Ladakh magmatic arc, comprising intrusives of the Ladakh plutonic complex and extrusives of the Dras, Luzarmu and Khardung formations, owes its origin to the subduction of the Indian oceanic plate underneath the Tibet-Karakoram block. The Indus Formation, lower Cretaceous to middle Eocene in age, was laid down in a basin between the magmatic arc and the subduction complex. The Shergol and Zildat ophiolitic melange belts exhibit green-schist and blue-schist facies metamorphism and show structural geometry and deformation history dissimilar to that of the underlying and overlying formations. The melange belts and the flysch sediments of the Nindam Formation represent a palaeosubduction complex. The Shyok suture zone consists of tectonic slices of metamorphics of the Pangong Tso Crystallines, Cretaceous to lower Eocene volcanics and sedimentaries, together with ultramafic and gabbro bodies and molasse sediments. This petrotectonic assemblage is interpreted as representing a back-are basin. Post-collision molasse sedimentaries are continental deposits of Neogene age, and they occur with depositional contact transgressing the lithological and structural boundaries. Two metamorphic belts, the Tso Morari crystalline complex and the Pangong Tso Crystallines, flank to the south and north respectively of the Indus suture zone in Eastern Ladakh. Three generations of fold structures and associated penetrative (and linear) structures, showing a similar deformation history of both the metamorphic belts, are developed. The shortening structures developed as a result of collision during the postmiddle Eocene time.     

沉积岩对楚雄盆地砂岩铜矿成矿的控制

楚雄盆地砂岩铜矿产于白垩系地层层位中，矿床与盆地内的下部含煤建造，中部的红色含铜碎屑岩建造和上部白色膏盐建造关系密切，含矿岩系具有向上变细的剖面结构，矿化常形成于不整合界面以上的一定范围内，含矿岩石以细砂岩为主，铜矿化与胶结物总量和钙质，硅质磁结物有关，并形成了浅色岩层过渡的氧化-还原界面附近，沉积成岩作用对矿床的形成起重要作用。     

西藏南部硅质岩的特征及相关问题探讨

西藏南部广泛发育中生代古海洋沉积硅质岩,在空间上集中分布于雅鲁藏布江缝合带和喜马拉雅沉积带,呈东西向条带状分布,断断续续延伸达数千公里。可大致厘定出3条硅质岩带:缝合带蛇绿岩北侧早白垩世硅质岩带、缝合带蛇绿岩南侧三叠纪至白垩纪硅质岩带和喜马拉雅沉积带白垩纪硅质岩带,产出块状、层状、角砾状和结核状4种类型的硅质岩。在沉积建造特征上,缝合带蛇绿岩北侧硅质岩带以蛇绿岩-硅质岩建造为主;缝合带蛇绿岩南侧硅质岩带主要以火山岩-硅质岩建造和改造型硅质岩建造为主;喜马拉雅沉积带硅质岩则以浊积岩-硅质岩建造为特征。藏南硅质岩具有重要的研究意义,其薄弱环节和科学问题主要包括:硅质岩的成因问题、硅质岩的微组构问题、硅质岩中的古海洋沉积事件信息、硅质岩对沉积环境的指相意义等。     

Cupriferous bogs in the Sackville area, New Brunswick, Canada

Two cupriferous bogs in the Sackville area of New Brunswick, Canada, are described. The organic matter (muck) in these bogs contains from 2 to 6% Cu, derived from cupriferous springs that carry copper in amounts ranging from 0.005 to 1 ppm. The source of the copper in the springs is unknown, but the metal probably originates from the leaching of cupriferous (chalcocitic) deposits in grits and conglomerates at the base of the Boss Point Formation of Carboniferous (Pennsylvanian) age.The copper occurs in the muck as copper humate(s), the precise chemical characterization of which is unknown.Examples of copper bogs related to copper mineralization in many parts of the world are reviewed, and it is pointed out that such bogs are good geochemical indicators of cupriferous deposits.The moss, Pohlia nutans, grows in the springs in the copper bogs and in other wet sites in the area where large concentrations of copper occur. This moss is tolerant to large amounts of available copper and markedly accumulates the metal. When slightly chlorotic Pohlia nutans may indicate the presence of higher than normal amounts of copper.     

柴达木盆地西北部红三旱地区始新世-渐新世砂岩物源分析

柴达木盆地西部红三旱一号三高点上、下干柴沟组砂岩的骨架矿物成分的模式分析显示,始新统—渐新统砂岩的源区主要为再旋回造山带。根据古水流推断物源区主要为阿尔金山。结合上、下干柴沟组砂岩成分模式分析的标准偏差对比和骨架矿物成分平均含量的变化特征,认为渐新世时(上干柴沟组)阿尔金山存在一期隆升事件。     

Analogue modeling of the role of multi-level decollement layers on the geometry of orogenic wedge: an application to the Zagros Fold–Thrust Belt,SW Iran

International Journal of Earth Sciences - The presence of evaporate and incompetent formations (i.e., decollement horizons) within the sedimentary sequence of fold-thrust belts can control their...     

华北克拉通南缘中-新元古代沉积演化:以豫西地区黄连垛组和董家组为例

华北克拉通(华北)南缘中元古代早期熊耳群火山活动之后,在渑池-确山地区发育了一套中-新元古代沉积(汝阳群、洛峪群、黄连垛组、董家组以及罗圈组和东坡组),记录了该时期沉积-构造演化过程。通过该区碎屑锆石和洛峪群顶部凝灰岩年龄的约束,将汝阳群-洛峪群的沉积时代基本限定于约1750～1600Ma,导致洛峪群由中元古界上部或新元古界下划到中元古界长城系。因此,在现有的地层年代格架下,需要重新对该区中-新元古代沉积演化进行讨论。本文通过对洛峪口组上覆黄连垛组和董家组沉积环境和物源分析,同时借助古生界辛集组源区分析的约束,揭示华北南缘中-新元古代沉积-构造演化。沉积环境分析显示,黄连垛组沉积初期发育了河口湾沉积环境。伴随海侵扩大,在下汤地区沉积了潮上带长石石英砂岩与泥质粉砂岩,而叶县地区发育了潮间带泥晶白云岩。晚期下汤和叶县地区发育潮下带泥晶白云岩与含硅质条带白云岩。董家组与下伏黄连垛组为平行不整合接触,董家组沉积初期为陆源碎屑物质供给充分的滨海相,在下汤和叶县地区沉积底部细砾岩及长石石英砂岩。随后,两个地区发育潮坪相长石石英砂岩与泥质粉砂岩,在顶部沉积了局限台地钙质泥岩。黄连垛组在豫西下汤和叶县地区沉积于河口湾-潮坪沉积环境,整体表现为自南向北的海进序列,而董家组总体上沉积于局限海盆的滨浅海-潮坪环境。由于下伏汝阳群-洛峪群分别沉积在河流-滨海-潮坪和浅海-滨海-潮坪环境,黄连垛组和董家组指示其沉积时期盆地产生收缩。碎屑锆石定年结果显示,黄连垛组和董家组碎屑锆石年龄主要峰值为1800Ma、2250Ma、2350Ma、2650Ma,两者物源均为华北克拉通。但下汤地区早古生界辛集组碎屑锆石显示主要峰值年龄为1850Ma、2500Ma、2200Ma、2700Ma,其次为1200Ma。结合华北克拉通发育大量的中元古代末期到新元古代碎屑锆石以及南缘中元古界官道口群和新元古界栾川群沉积特征,黄连垛组和董家组代表的局限盆地(海盆)沉积可能构成了该时期盆地的边缘相,期间伴随的抬升和盆地中心迁移可能与同期大地构造演化密切相关。     

Synorogenic psammites: Major lithochemical features

Some lithochemical features of sandstone associations formed at the orogenic stage of the evolution of mobile belts are analyzed on the basis of literature and original data along with the wide application of discrimination diagrams. Psammites of the flysch and molasse formations of foreland basins, as well as sand-stones from intermontane troughs and postcollisonal grabens, are considered synorogenic sediments. Analysis of the chemical composition showed that sandstones were formed by the mixing of clastic material from heterogeneous (proximal included) source areas. In discrimination diagrams, the compositional fields of sandstones are variable, because they were derived from diverse igneous, metamorphic, and sedimentary rocks of different geodynamic settings. Hence, data based on the generally accepted discrimination diagrams cannot be considered as the single (decisive) argument for establishing the geodynamic nature of sandstones without the consideration of textural-structural features of rocks and the analysis of geological structure of sedimentary associations therein.