Late Carboniferous-Early Permian Volcanic Event Deposits and Stratigraphic Correlation in Shandong Province and Its Adjacent Regions

Deposits of 10 volcanic events of 6 stages have been discovered by the authors after detailed field and lab studies of the Benxi and Taiyuan Formations in Shandong Province and its adjacent regions. They show certain temporal-spatial distribution characteristics. Volcanic fragments were probably derived from two different volcanic sources north and south of the North China Platform, while the magma of the two volcanic sources was probably derived from the lower crust. A new stratigraphic correlation scheme is put forward for the Benxi and Taiyuan Formations in this region on the basis of previous biostratigraphic work with the regionally widespread volcanic event layers as the marker bed for the isochronous stratigraphic correlation on a super-regional scale and in conjunction with the maximum transgressive event layers.     

华北地台本溪组,太原组火山事件沉积特征及时空分布规律

作者对华北地台24个煤田及煤矿区进行了详细的研究,在本溪组及太原组中共发现6期12次火山事件层。这些火山事件沉积遍及全区,主要为凝灰岩、沉凝灰岩及凝灰质沉积岩,它们在时空分布上有一定规律。火山碎屑可能来自华北地台以北及以南若干不同的火山源,而岩浆可能来自下地壳。      

鄂尔多斯盆地西缘二叠系事件地层及其地球化学特征

通过钻井岩心的观察及镜下岩矿鉴定,同时依据地球化学和沉积学特征,把区内发育的事件地层分为两类:火山事件层和海退事件层,其中太原组火山事件层和海退事件层各1层,山西组火山事件层1层,石盒子组火山事件层3层。所体现的常量、微量和稀土元素质量分数及岩石学特征具明显的差异。研究事件地层获得的成果,可以为区域地层划分和对比提供更加准确的依据。      

辽西石炭纪地层及沉积特征新认识

通过对辽西石炭纪含煤地层的详细研究，发现辽西石炭系不仅有太原组而且有较厚的本溪组，在地层及沉积特征方面与内蒙古大青山煤田的石炭系十分相似。两煤田均形成于近山滨海平原的古地理环境而非前人认为的山前冲积平原。作者在杨家仗子煤田７＃煤顶板发现的沉凝灰岩层可以与华北地台东部太原组中部遍布全区的火山事件层对比     

Volcanic Event Layers-A Marker Bed of Correlation of Coal Measures

Upper Carboniferous-Lower Permian volcanic event deposits from two cross sections in Nanpiao, Liaoning Province, and the Daqing Mountains, Inner Mongolia, were examined by systematic rock and mineral identification, differential thermal analysis, X-ray diffraction, scanning electron microscopy and trace element and rare earth element quantitative analysis. According to the results, twelve sequences of volcanic event deposits have been distinguished from bottom to top, including 34-39 volcanic event layers. As these layers each have their own distinctive petrological, mineralogical and geochemical characteristics and were derived from the same source, they provide new evidence for further ascertaining the distribution characteristics of volcanic event deposits on the northern margin of the North China plate and carrying out the stratigraphic correlation using volcanic event layers as marker beds.     

鄂尔多斯盆地下古生界储层气气源探讨

鄂尔多斯盆地下古生界天然气勘探的制约因素是有效烃源岩的问题。笔者通过对鄂尔多斯盆地早古生代的沉积构造演化、沉积环境、生烃潜力、本溪组砂体展布特征与中央大气田藕合关系、上古生界天然气向下穿层运移条件、地球化学等方面的综合分析，指出中央大气田的气源主要来自上古生界的煤系地层及本溪组和太原组中的海相烃源岩，并在此基础上指出下古生界天然气勘探的方针和下一步有利勘探选区。     

辽宁本溪连山关地区辽河群浪子山组、里尔峪组形成时代及其地质意义

辽宁省本溪连山关地区出露大面积的古元古代辽河群地层,在朱家沟典型剖面浪子山组中识别出2层斜长角闪岩,镜下观察其原岩为玄武岩;在连山关及河栏镇里尔峪组中识别出一套酸性火山岩。对浪子山组2件斜长角闪岩样品、里尔峪组2件流纹岩样品测定LA-ICP-MS锆石U-Pb年龄。阴极发光图像显示,样品D020锆石内部结构整体发黑、条痕状吸收程度不等,Th/U值较低,为变质锆石,其1934±45Ma代表了浪子山组的变质年龄。其余3个样品阴极发光图像显示典型的岩浆振荡环带结构和较高的Th/U值,为岩浆锆石。1952±38Ma代表了浪子山组的形成时代,2177±34Ma和2208±12Ma代表了里尔峪组的形成时代。结合前人资料,将辽河群形成时代限制在2.20~1.95Ga,其形成时代持续了250Ma左右。野外接触关系及火山岩年代学特征从另一个方面揭露了辽河群总体为一套无序、局部有序的构造地层,各岩组间不存在上下关系,浪子山组已经不适合置于里尔峪组之下。     

华北西缘太原组火山事件沉积的发现及太原组地层对比

摘要：作者主要依据镜下岩矿特征,辅以岩石的野外产状与分布特点,并参考ＲＥＥ配分模式特征,首次发现华北西缘太原组存在３个火山事件层。根据火山事件沉积并结合最大海侵事件层对华北西缘太原组进行了区域对比．     

山东及邻区晚石炭世—早二叠世火山事件沉积及地层对比

作者对山东及邻区本溪组及太原组进行了详细的室内外研究,共发现了6期10次火山事件沉积,它们在时空分布上有一定规律。火山碎屑可能来自华北地台以北及以南两个不同的火山源,而火山源的岩浆可能来自下地壳。在前人的生物地层研究基础上,以遍布全区的火山事件层作为大区域等时地层对比标志,并结合最大海侵事件层,对研究区内本溪组及太原组地层提出了新的对比方案。     

长白山天池及邻区次生火山灾害类型、分布及其与火山地质的关系

基于对长白山天池及邻区火山地质和次生火山灾害的编图结果,从岩性、断裂、地形地貌和水系等方面,分析火山喷出物的地质特征与这些火山物质所导致的次生火山灾害之间的相关性。研究表明,崩塌发生在柱状节理发育的硬质岩中,多期火山喷发以及伴生的地震活动剥蚀掏空坚硬岩层间的松散堆积体,使岩体失稳发生崩塌,局部陡崖地貌在地震影响下亦会发生崩塌灾害。软质岩和松散堆积体受流水侵蚀,河谷下切,河流两岸斜坡前缘形成开阔的滑动空间,火山地震引起山体变形,斜坡岩体结构遭到破坏发生滑坡灾害。火山先期喷出的碎屑物和崩塌滑坡产生的碎石是火山泥石流的重要物质来源,火山喷发或强地震引发的洪水灾害以及地形地貌对火山泥石流的形成、搬运和分布范围起关键性作用。     

晋中冀西太原组中段火山事件层岩矿地化特征及其意义

在岩矿鉴定的基础上,对晋中冀西太原组中段普遍发育的一层火山事件层做了岩石化学、稀土元素和微量元素分析。岩石化学、REE配分模式、REE七组分图解、微量元素蛛网图极好的共性特征及微量元素幂函数定律的应用,证明该火山事件层是同源同期岛弧型钙碱性火山喷发产物,并以该火山事件层作为标志层对晋中冀西太原组地层进行了大区域对比。     

内蒙古大青山晚古生代煤系中火山事件层的物质来源及地层意义

在内蒙古大青山晚古生代煤系地层中发现了９层以上火山事件层，主要由凝灰熔岩、火山角砾岩、熔结凝灰岩、凝灰岩、沉凝灰岩及各种凝灰质沉积岩组成。通过剖面层序分析和岩石学、岩石化学、稀土元素和同位素比值研究，可将本区火山事件层划分为９个喷发旋回；根据火山事件层的分布，本区煤层可与山西大同同时代的煤层相对比；这一研究结果为大区域煤层对比提供了重要的科学依据。根据本区的研究工作并与内蒙海槽火山活动资料相对照，本区火山碎屑物质来自内蒙海槽钙碱性岛弧型火山活动的观点得到证实，也为华北板块与古亚洲洋板块之间的封闭机理，提供了新的资料。     

福建沙县地区早白垩世火山岩成因及构造环境分析

本文着重阐述了沙县地区早白垩世火山岩地球化学特征，论证了中性与酸性火山岩的成因及物质来源，认为二者为不同源岩浆演化的产物，其岩浆物质来源于壳幔混源区，为省内双峰式火两端员岩石间成因关系的分析研究提供了新的例征。     

陆表海碎屑岩—碳酸盐岩混积层系沉积相研究——以鄂尔多斯东北部大牛地气田为例

陆源碎屑岩和碳酸盐岩的混合沉积是陆表海重要的沉积现象,反映了其沉积特征。鄂尔多斯东北部大牛地气田本溪组和太原组是典型的陆表海碎屑岩—碳酸盐岩混积层系。结合区域地质研究,建立了陆表海碎屑岩—碳酸盐岩混积层系的沉积相模式。根据华北晚古生代聚煤盆地的地质背景和沉积演化过程,认为大牛地气田本溪组、太原组是陆表海碎屑滨岸—碳酸盐岩台地混积体系和海岸平原沉积体系：本溪组下段为碎屑滨岸相局限浅海亚相,上段为碳酸盐岩台地相和碎屑滨岸相;太原组下段为三角洲相和碎屑滨岸相→碎屑滨岸相;中段为盆控型泥炭沼泽相→碳酸盐岩台地相和碎屑滨岸相;上段为三角洲相和碎屑滨岸相→碳酸盐岩台地相和碎屑滨岸相→三角洲相和碎屑滨岸相→碳酸盐岩台地相和碎屑滨岸相。     

海南同安岭-牛腊岭火山地层划分与对比

将同安岭—牛腊岭火山地层划分为六罗村组、汤他大岭组、岭壳村组，总厚度达５４２９ｍ。六罗村组下部以玄武安山质火山岩为主，上部为流纹质火山碎屑岩、熔岩；汤他大岭组主要为英安岩类火山岩，岭壳村组为流纹岩类的岩石，构成２个喷发旋回。根据同位素年龄，确定火山岩的时代为早白垩世，与海南岛下白垩统鹿母湾组为同期产物，相当于我国东南沿海白垩纪火山岩。     

Rb–Sr and Sm–Nd isotopic compositions of the Rooiberg Group, South Africa: early Bushveld-related volcanism

The Rooiberg Group is a 6-km-thick sequence of mostly volcanic rocks, which represent the first phase of magmatic activity associated with the Bushveld Complex. These strata include, in ascending stratigraphic order, the Dullstroom, Damwal, Kwaggasnek, and Schrikkloof Formations. Units of the lower Dullstroom Formation range from basalts to andesites and comprise two compositional suites: high Ti and low Ti. Compositional data indicate that melts represented by the overlying, more siliceous volcanic rocks, which include dacites and rhyolites, were derived from low Ti melts by fractional crystallization and assimilation of crustal material (AFC processes).

Rb–Sr isotopic data (28 samples) for units of the Dullstroom and Damwal Formations loosely constrain a crystallization age of 2071+94/−65 Ma (these errors and those below: 95% confidence limits), which agrees with previously reported age data. These data suggest an initial value for ⁸⁷Sr/⁸⁶Sr of 0.70655+0.00087/−0.00051 for the Rooiberg Group. In contrast, Rb–Sr isotopic compositions of six samples of the Kwaggasnek Formation indicate post-crystallization alteration, which was probably associated with the Lebowa Granite Suite of the Bushveld Complex. Sm–Nd isotopic data (29 samples) for volcanic units of the Rooiberg Group provide a poorly constrained age of 1837+360/−320 Ma with an initial value for ¹⁴³Nd/¹⁴⁴Nd of 0.50976+0.00026/−0.00035. These Rb–Sr and Sm–Nd isotopic compositions are similar to those indicated for melts that crystallized to form the Rustenburg Layered Suite (RLS) of the Bushveld Complex. Extruded and intruded melts probably were derived from the same or similar sources and may have resided in the same magma chambers before emplacement.     

新疆阿吾拉勒富铁矿地质特征和矿床成因

阿吾拉勒山东段是新疆重要富铁矿成矿带,形成于伊犁石炭纪裂谷环境.产于海相火山-沉积岩系中的赤铁矿和块状含铜黄铁矿,发育红碧玉、重晶石喷流岩,S、Pb、H、O同位素反映成矿物质来源于深部地壳或上地幔,成矿流体源自岩浆水,并有海水混入,属于火山喷流沉积矿床.产于基-中性火山岩系中的磁铁矿,形成于火山机构附近,属矿浆喷溢型矿床.两个层位的铁(铜)矿是在同一成矿环境下形成的矿床组合,预示该地区铜矿具有较大找矿前景.     

大青山、大同煤田太原组流纹质沉凝灰岩的发现及地层对比

作者依据镜下岩矿鉴定，首次在大青山煤田和大同煤田太原组中发现一层高岭石化流纹质沉凝灰岩。地球化学分析资料也证明了它的存在。火山灰可能来自大同煤田东北方向。根据火山事件层及植物群特征，作者对两个煤田的太原组进行了对比。     

Petrogenesis of Cenozoic Potassic Volcanic Rocks in the Nangqên Basin

The Nangqên basin is one of the Tertiary pull‐apart basins situated in the east of the Qiangtang block. Similar to the adjacent Dengqên basin and Baxoi basin, there occurred a series of potassic volcanic and sub‐volcanic rocks, ranging from basic, intermediate to intermediate‐acid in lithology. Based on the study of petrology, mineralogy and geochemistry, including REEs, trace elements, isotopic elements and chronology, the authors concluded that the Cenozoic potassic volcanic rocks in the Nangqên basin were formed in the post‐collisional intraplate tectonic settings. The relations between the basic, intermediate and intermediate‐acid rocks are neither differentiation nor evolution, but instead the geochemical variability is mainly attributable to the different partial melting degrees of the mantle sources formed at depths of 50–80 km. The sources of the potassic rocks are enriched metasomatic mantle that has experienced multiple mixing of components mainly derived from the crust. The recycling model can be described as follows: after they had subducted to the mantle wedge, the crust‐derived rocks were metasomatized with the mantle materials. In view of the fact that the ratio of crust‐derived rocks increases by the age of volcanism, it can be concluded that the sources of the potassic rocks moved upwards progressively with time. The underplating of small scattered magmas upwelling from the asthenosphere may have induced partial melting of the sources of the volcanic rocks in some pull‐apart basins in the Hengduanshan area and the intense tectonic movements of large‐scale strike‐slip belts provided conduits for the ascending melts.     

鲁西石炭纪事件沉积岩石学特征

对鲁西地区石炭二叠纪煤系火山碎屑岩特征进行了分析,结果表明,火山碎屑物质以晶屑最为常见,常见的火山碎屑岩有凝灰岩、沉凝灰岩、凝灰质灰岩、凝灰质砂岩、凝灰质粉砂岩。还对在太原组煤层中发现的宇宙尘形貌及化学组成进行了研究,经与国内外相关资料对比,认为研究区宇宙尘为Si质玻璃球。提出了研究区石炭纪曾发生过火山地质事件、天体地质事件。