正 下寒武统黑色岩系在我国南方各省分布广泛。它主要由黑色页岩和黑色硅质岩组成,其底部往往见有磷块岩及磷结核层。在下寒武统黑色岩系中赋存有多种有用元素如镍、钼、钒、铜、磷以及各种稀有、稀土元素等。 目前,对黑色页岩及黑色硅质岩的岩石学研究比较薄弱。而其中赋存有如此复杂多样的元素组合也是沉积地球化学中饶有趣味的问题之一。因此,对黑色岩系进行较系统的岩石学及地球化学研究,以期找出其中多元素富集的因素。这不仅具有经济意义,而且

黑色岩系型金矿床实质上是一种早期形成于富含碳质细碎屑岩建造的滨浅海还原环境，后期经强烈区域低温强动力挤压作用改造形成于韧性剪切带中的低温变质热液金矿床，属韧剪型金矿的1个亚型．在20世纪80年代后引起重视，在世界各地，特别是中亚地区和我国新疆及西南地区取得许多重大找矿突破．中亚地区黑色岩型金矿床十分发育，形成了以穆龙套、库姆托尔、巴克尔奇克为代表的诸多特大型、超大型和大型金矿床．这类矿床具低温蚀变、韧剪性显著、富含碳质和含金石英脉等特点．新疆黑色岩系型金矿成矿地质背景和成矿地质构造条件优越，找矿前景广阔．主要成矿时代为前二叠纪，其次是二叠-三叠纪（昆仑），找矿有利成矿区带主要是北准噶尔、中天山、南天山、东昆仑和北天山，其次有阿尔泰和东准噶尔等地。

Abstract锛歍he mineral assemblages are very complex in the Lower Cambrian black shale in Zhangjiajie of Hunan and Zunyi of Guizhou. X- ray diffraction analysis combined with previous research results shows that the contents of sulfide minerals, clay minerals and organic matter are relatively high. After crushing and separation of the samples, the ICP-MS method was used to determine the PGE contents of the black shale and separated samples, and in addition, the mode of occurrence of PGE in the black shale in the study areas was studied. Study shows that the content of PGE in the area is high and stable. The chemical activity of PGE is high enough to enable them to be remobilized to a considerable extent under low-temperature, oxidizing conditions and precipitated and concentrated under low-temperature, reducing conditions. The PGE contents of black shale in the primary C/MoS2 mixed-layer mineral-rich black shale decreased to varying extent after strong weathering and leaching. The greater majority of the PGE are concentrated in organic matter and pyrite. The PGE distribution patterns show certain regularity. The remarkable differentiation of PGE demonstrates that the distribution pattern of the black shale does not have the characteristics of extraterrestrial material.

秦岭造山带黑色岩系划分为南、北、中三个带,北带分布于北秦岭,以秦岭杂岩为基底的岛弧火山岩与花岗岩带到二郎坪弧后边缘海盆带,形成于活动大陆边缘类似的沟、弧、盆构造体系,产出沉积-变质-构造-热液改造型镍-钼小型矿床.中带分布于南秦岭北部,环绕岛链古隆起形成深水-半深水滞留断陷局限盆地,发育与热水沉积有关的黑色岩系,赋存沉积轻微改造型超大型钒矿床和沉积-构造-热液改造型大型金-钒矿床.南带分布于南秦岭南部,扬子板块北缘早古生代沉积区局部拉张环境发育裂谷式断陷盆地,发育巨厚的硅质-泥质-重晶石互层岩系,形成沉积改造中型含钼-钒矿床和热水沉积大型毒重石-重晶石矿床等.解剖了秦岭黑色岩系容矿的典型矿床特征与成矿作用,划分了矿床成因类型,建立了黑色岩系容矿的金属矿床成矿系列.

笔者采用等离子质谱仪(ICP-MS)方法对北秦岭大荆区奥陶纪—志留纪庙湾组黑色岩系岩石的稀土元素及V、Ni、Cr、U、Th等微量元素含量进行了测定。结果显示岩石轻稀土元素相对重稀土元素富集,Eu异常值δEu为0.63～10.61(绝多数大于1.54)多呈正异常,Ce异常值δCe为0.65～1.02(平均为0.893)异常微弱且有正负差异;U/Th值为0.38～4.07,w(V)/w(V+Ni)值为0.38～0.93以及w(Ce)/w(La)值为1.27～2.17。将这些特征值与前人研究成果对比,并利用La/Yb-Ce/La和La/Yb-REE判别图解判别后,认为北秦岭区庙湾组黑色岩系形成于活动陆缘一种干燥缺氧较深浅海环境,黑色岩系形成过程中有热液作用参与。

通过野外调研发现,秦岭造山带山阳地区水沟口组黑色岩系主要由黑灰色微晶灰岩、炭质泥板岩、灰白色粘土岩、黑灰色含炭-钙质硅板岩、灰黑色含炭泥质硅板岩及浅红色硅质板岩组成;岩系中磷结核及重晶石纹层常见。采用等离子质谱仪(ICP-MS)方法对岩系的稀土元素及微量元素测定,结果显示岩系中成矿物质含量丰富(如V、Mo、Ni、Ba、Pb、Zn、U、Ag、Cu、Cd、Tl、Bi和Cr等元素的平均含量是地壳丰度的几倍到几十倍),稀土元素和微量元素的含量与磷质、炭质以及钡关系密切;稀土模式曲线基本平行显示其成因相同;泥质和硅质岩类是主要的含矿岩性;不同程度的δEu正异常、中到弱的δCe负异常及相应的稀土、微量元素比值如Ce/La、V/(V+Ni)等指示岩石形成于干燥缺氧环境并有热水物质加入,La/Yb-Ce/La图解及La/Yb-REE图解表明岩系与海相沉积及基性岩成因关系密切。结合岩系的地质特征认为:山阳地区水沟口组黑色岩系形成于被动陆缘的一种干燥缺氧的深水-半深水滞留断陷局限海盆,期间热液(水)活动频繁、低等浮游生物发育,对岩系中矿物质的富集具有非常重要的意义。

The black rock series refers to the combination system of dark gray - black siliceous rocks, carbonate rocks, argillaceous rocks and metamorphic rocks containing organic carbon and sulfide more, belongs to a kind of reduction rocks. This rock series contains Cu, Ni, Mn, U, P arite il and gas and other minerals, most typically Cu, Ni, Mo, V, and Ti, known as the "five-element deposit". In recent years, there have been increasing studies on non-metal and metal ore deposits in the black rock series, and its mineral economic significance also receives growing attention. This paper takes the Yangtze platform as an example to study the black rock series and its associated minerals, and provides reference for the areas with similar horizons (such as the middle and late Devonian, Carboniferous, and early Permian). By comparing the stratum-type section of Sinian-Cambrian boundary at Meishucun, Jinning, Yunnan and the Sinian section in the eastern Yangtze Gorges area, we found that the two sections of phosphorus-rich layers are comparable. The Doushantuo Formation is the important ore (P) horizon in eastern Yangtze; while the Yuhucun formation is the most important ore-bearing horizon (P) in western Yangtze. Northern Guizhou is a transitional zone, where both the important layers exist. It seems that from the Doushantuo stage to the Yuhucun stage, the formation of phosphorite activity center gradually tended to migrate from the east to the west in the Yangtze platform.

姝he Qinling orogen of central China occupies a key position in East Asia,and is of fundamental importance in unraveling its tectonic evolution.Devonian sedimentary basins are located between the North Qinling arc and the Baishuijiang Devonian-Permian accretionary wedge.Paleocurrent indictors and petrological and geochemical analyses show that turbiditic and coastal sandstones and pyroclasts developed in paleo-forearcs.Sedimentation of conglomerates and associated turbiditic and pyroclastic rocks evidently was related to the development of the North Qinling orogen rather than the South China craton.Gravels in the conglomerates were derived predominantly from the North Qinling and partly from its basement. Northward Devonian subduction and subsequent uplift caused successive forearc depocenters and associated facies belts to migrate southwards synchronously with sedimentation.Transpressive and transtensional faults segmented the basins into discrete half-graben sub-basins.Paleocurrent analysis adjacent to thrust faults demonstrates that thrust sheets crests were truncated by erosion and provided detritus for sub-basins.Shallow-marine and turbiditic depositional systems evolved in complex patterns to produce varied facies frameworks associated with complex subduction accretion.These facts,together with other geological and geochemical data,demonstrate that the North China craton grew southwards by arc-accretion processes from the end of the early Paleozoic to the beginning of the late Paleozoic,long before the integration of the North China and Yangtze cratons.