广西六景泥盆纪吉维阶—弗拉斯阶界线层牙形石生物地层

广西六景泥盆系剖面是我国泥盆系标准剖面之一 ,通过对其吉维阶 -弗拉斯阶界线上下地层进行详细的牙形石生物地层研究 ,自上而下识别出 12个牙形石带 :Palmatolepis jamieae带、Palmatolepis hassi带、Palmatolepispunctata带、Palmatolepistransitans带、上 Mesotaxisfalsiovalis带、下 Mesotaxisfalsiovalis带、Klapperina dispar-ilis带、上 Schmidtognathus hermanni- Polygnathus cristatus带、下 Schmidtognathus hermanni- Polygnathus cristatus带、上 Polygnathus varcus带、中 Polygnathus varcus带、下 Polygnathus varcus带。吉维阶 -弗拉斯阶界线 (即中 -上泥盆统界线 )由 Ancyrodella binodosa→ Ancyrodella rotundiloba early form→ Ancyrodella rotundiloba late form这一演化线系中的 Ancyrodella rotundiloba early form的首次出现确定 ,处于下 Mesotaxis falsiovalis带下部 ,在谷闭组底界之上 1.80 m处。     

广西横县六景泥盆系艾菲尔阶—吉维特阶之交化学地层研究

广西横县六景泥盆系剖面艾菲尔阶-吉维特阶界线(Eifelian-Givetian界线)附近的Polygnathus xylus ensensis至下varcus带之间.出现了一系列Ce/La值、Ni/La值和δ13 Ccarb值重大组合性异常,分别代表缺氧事件、Ni事件和生物灾变等地质历史事件.紧邻艾菲尔阶-吉维特阶界线的生物事件与全球性ka(c)ák-otomari事件有较好的响应.该地区所处华南地块南侧、古特提斯洋离散边界附近的古陆缘浅海为上述事件的古地理、古大地构造背景.该系列事件的原始诱因为系列构造运动的不同阶段和不同表现方式:断裂和火山热液活动造成Ni事件;挤压变形和抬升运动耦合相对海平面变化造成缺氧事件.Ni事件和缺氧事件均可独立造成生物灾变事件,而前二者的叠加将使生物灾变加剧,因灾变机制的区域性而未造成生物的大规模灭绝.Ni事件是由洋源性构造、热液和火山活动所主导的.     

黔桂地区石炭系层序地层格架及海平面变化

从石炭系到下二叠统,构成一个二级层序,其底面为紫云运动主幕不整合面及其相关面,顶界面为黔桂运动不整合面及其相关面,包含6个三级层序.研究区范围内,从连陆台地到孤立台地乃至台沟背景,沉积特征明显不同,如在连陆台地上发育煤系地层并且发育较多的白云岩地层,而在孤立台地上则以大套碳酸盐岩地层为特征,台沟背景中以暗色细粒沉积为主包括台盆相和台棚相沉积.因此,三级沉积层序的相序特征形成有规律的空间变化,虽然在不同的地点三级层序的形成时限和相序组构存在差异,但它们所代表的相对海平面变化过程基本上是同步的.在前人大量的古生物学研究成果的基础上,追索各三级沉积层序界面的空间展布特征,以地层记录中的两种相变面和两种穿时性为基本要素,可以建立黔桂地区石炭系(含下二叠统)的地层层序格架.     

Upper Devonian and Lower Carboniferous Sequence Stratigraphy of South China

SequencestratigraphyhashopaidmoreattentionforitSrelativelycompletetheoreticalsyStemandgreatsuchesinpracticesinceitwasadvancedinthe197ds.Integratingonthedataofbiostratiglaphy,lithostratigraphy,seismicstfstigraphy,geochendstryandsedirnentology,sequencestratigraphyattemptStoestablishachronostratigraphicframeworkandcormectsdepositionalsequencewithglobalsealevelchange,andhencemakeSitpossibletOpreciselycorrelatethestrataindifferentfactesareasoveraconsiderabledistance,evenovertheworld.TheUpperDevon…     

Geochemistry of Upper Devonian Hydrothermal Mammilated Chert Guangxi,Southwest China

The mammilated chert (MC) studied in this paper is a kind of silica-rich concretion (SiO₂ 93%) occurring in the Upper Devonian argillaceous silicolites (SiO₂≈88%) in Mugui, Guangxi. Impurity components in the MC are relatively low and show systematic variations as compared with the country rocks. Abundances of Mg, Si, Ti, Fe, Mn, U and Th are characteristically similar to those of recent and fossil hot-water sediments. Moreover, the MC is also characterized by low REE abundance, LREE > HREE, apparent negative Ce anomaly and moderate positive Eu anomaly. Oxygen isotope data show that the formation temperature of the MC is about 20 °C, higher than that of the host rock. The results of geochemical, geological and lithological studies suggest that the MC may have been formed through metasomatism, filling and crystallization beneath the sedimentary basin during the Devonian period.     

Geochemical Stratigraphy and Microvertebrate Assemblage Sequences across the Silurian/Devonian Transition in South China

Carbon isotope (δ13Corg) analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ13Corg shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as ?25.2‰ (Xishancun) and ?19.9‰ (Putonggou) in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti (only in Putonggou Section and together with Protathyris-Lanceomyonia brachiopod fauna). These results replicate a globally known positive shift in δ13Corg from the uppermost Silurian to the lowermost Devonian. The δ13Corg variations across the Silurian/Devonian Boundary (SDB) at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk-1 drilled at top of the Klonk Global Standard Stratotype-Section and Point (GSSP) in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation (between sample QX-20 and sample QX-21) in the Xishancun Section and the lower part of the Xiaputonggou Formation (between sample ZP-09 and sample ZP-10) in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non-marine deposits.     

广西西北部二叠系——三叠系界线碳、氧同位素组成异常及其意义

我国广西西北部平果太平剖面二叠系－三叠系界线处为保存良好的海相碳酸盐岩沉积，根据牙形石化石带推断，该剖面在二叠系－三叠系界线处的连续沉积性良性。在该界线附近处，碳同位素组成发生了突然的负向波动，δ^13C从1．3‰－2．2‰（PDB）降至－0．9‰－－0．2‰，波动范围达2．8‰，进入下三叠统后一直呈负向发展；氧同位素组成波动虽不与碳同位素组成同步，但趋势相同，在二叠系－三叠系界线处达到最小值－8．2‰，下降幅度达2‰。这种同位素组成的波动已在我国西藏，浙江等的同时代的沉积中发现，此外，还在中东，北美洲，欧洲等地的二叠系－三叠系界线处发现，因此，它可以成为大区域及至洲际之间的二叠系－三叠系界线对比标志，这同时表明，二叠纪末期的重大地质事件发生的时间短，影响范围大，几乎是全球性的。     

广西香山岩体地球化学特征

在湘南-桂北存在一条基性-超基性岩带,笔者对该岩带南部的香山岩体的基性岩和超基性岩进行了地球化学研究.基性-超基性岩地球化学特征表明, 该岩体属于板内碱性玄武岩类,形成于板内环境,是在伸展作用下少量岩浆底侵作用的产物.     

广西柳州地区石炭系一个新的岩石地层单位——北岸组

在1∶5万地质测量中,广西柳州地区石炭系鹿寨组与“寺门组”之间的地层曾被称为“黄金组”,但其与典型地区的黄金组在岩性、岩相、古地理位置等方面均存在显著差异。根据新的研究与前人的资料综合分析,将柳州地区所谓的“黄金组”命名为一个新的组——北岸组。该组主要分布于广西中北部柳州市、柳江县、鹿寨县、柳城县、环江县等地,在古地理上位于黔南-桂中台槽的北缘。该组岩性以灰—深灰色薄—厚层生物碎屑粉晶灰岩、含生物碎屑泥晶灰岩为主,夹硅质岩、泥岩和砂岩,可划分为3个沉积旋回,属斜坡-盆地相沉积。下伏鹿寨组,上覆新圩组,均为整合接触。时代为石炭纪维宪期晚期—谢尔普霍夫期。     

广西贵港六梅金矿地球化学研究

广西贵港六梅金矿床位于贵港市龙山矿田福六岭金矿区,为微细浸染型金矿床。矿床中主要矿石矿物为毒砂和黄铁矿。通过载金矿物毒砂和黄铁矿含金性、金浸出提取、晶体结构测定等方法,查明矿床的金存在形式。浸出率试验中平衡计算表明,载金矿物毒砂中的晶格金形式约占25%,超显微包体形式金约为75%。矿床流体包裹体测温和稀土元素地球化学研究表明,六梅金矿床为中-低温热液型矿床,成矿物质来源与地层有关。     

从脊椎动物化石角度论云南曲靖下、中泥盆统界线

根据早期脊椎动物化石证据及生物地层对比,云南曲靖穿洞组的时代为晚Emsian期。该地区下、中泥盆统界线应划在穿洞组与海口组之间,或从穿洞组顶部穿过。     

桂东北豆乍山花岗岩年代学与地球化学特征

豆乍山花岗岩主要由中细粒二云母二长花岗岩构成,是桂东北苗儿山复式花岗岩体中段的一个重要产铀的岩体.单颗粒锆石SHRIMP U-Pb年龄为228±11Ma,属于印支期岩浆活动产物.地球化学特征显示该花岗岩以过铝、富硅、富碱和低CaO/Na2O比值为特征,微量元素主要富集Rb、Th、U和Ta,亏损Sr、Ba和Ti.稀土总量30.24×10-6～139.18×10-6,轻稀土轻微富集(LREE/HREE=4.00～6.35,(La/Yb)N=3.24～6.74),Eu亏损明显(δEu=0.14～0.19).结合其它相关地质资料,表明豆乍山花岗岩是壳源型花岗岩,是在印支运动晚期地壳伸展-减薄的构造背景下,成分为泥质的变质岩通过低程度部分熔融方式而形成.     

New Advances in the Study of the Devonian-Carboniferous Boundary Stratotype in Muhua,Changshun,Guizhou——An Introduction to the Daposhang Devonian-Carboniferous Boundary Section

The Daposhang section at Muhua, Changshun. Guizhou. is an excellent and attractive DevonianCarboniferous boundary section. The transitional beds between the Devonian and Carboniferous of the sectionare continuous and well exposed. belonging to the deep-water basin facies Abundant fossil groups have beendiscovered from this section: conodonts. ammonoids. trilobites. ostracods. vertebrate microfossils and so on.So far as known. it has the most continuous and complete conodont zonation for the Devonian-Carboniferousboundary beds in the world. It is especially worth pointing out that both typical Siponodella pracsulcata andthe transitional forms between S. praesulcata and S. sulcata have been found from the upper pracsulcata Zoneof the Daposhang section. Evidently. we can not only prove the actual existence of the evolutionary lineagefrom S. praesulcata to S. sulcata, but also exactly define the level of the Devonian-Carboniferous boundary. Inthis paper. the development of the Devonian-Carboniferous boundary beds at the Daposhang section is dealtwith and the section is compared with the Muhua section and the Nanbiancun section which are the candidatesfor the Devonian-Carboniferous boundary stratotype. In the authous opinion the Daposhang section is obvi-ously better than the Muhua and the Nanbiancun sections. hence it can be recommended as one of the candi-dates for the international Devonian-Carboniferous boundary stratotype.     

陕西段家坡黄土剖面中布容／松山古地磁界线附近铱异常的发现及其启示

利用高灵敏度放射化学中子活化分析方法,对我国陕西段家坡黄土剖面早－中更新统（约０．７３Ｍａ）沉积界线附近铱和其它元素的丰度进行了测定。结果表明,在布容／松山（Ｂ／Ｍ）古地磁界线附近铱的含量明显增大,最大值为４６．３ｐｇ／ｇ。相对于整个剖面的平均背景值（约１５ｐｇ／ｇ）大约富集了３倍。用地壳元素钪进行标准化之后,铱异常十分明显,而其它元素在界线附近则没有变化。黄土剖面上铱异常的赋存层位与西南太平洋钻     

应用MAPGIS制作地球化学图单元素异常图及综合异常图

利用MAPGIS离散数据网格化模型绘制地球化学图,通过四种不同的网格化方法效果对比,在元素含量分析数据极差相对较小时,采用Kring泛克立格法网格化模型绘制的地球化学图效果佳。分析数据极差相对较大时,采用距离幂函数反比加权网格化模型绘制的地球化学图效果较好。两种数据网格模型绘制的地球化学图均达到化探规范中对地球化学图的要求,因此提出了应用MAPGIS制作地球化学等含量线图,利用地球化学等含量线图的属性,绘制单元素异常图及综合异常图。     

广西凭祥剖面Guadalupian(中二叠统)底界附近的凉水和温水混生牙形石动物群

详细研究了广西凭祥剖面下-中二叠统界线(即Guadalupian统底界)附近的牙形石动物群,发现了M.idahoensislamberti-J.nankingensis nankingensis演化系列和M.idahoensis.idahoensis-J.nankingensis gracilis演化系列混生现象.前者与温水型牙形石分子M.siciliensis,M. rustagensis 和 Sweetgnothus subasymmetricus 共生,后者与凉水型牙形石分子M.prolongata和M.phosphoriensis共生.两个演化系列中温水型牙形石分子 J.nankingensis nankingensis 和凉水型牙形石分子J.nankingensisgracilis 首现在同一层位,从而准确地将 Guadalupian 统底界面标定在剖面中的第9-18层之底.在 Guadalupian 统底界附近的一套硅质灰岩标本中同时鉴别出混生的牙形石动物群,这说明在早-中二叠世转换期,来自高纬度区的凉水洋流上涌事件曾经发生并侵入到处于亚热带的扬子板块之中.     

长江下游地区晚泥盆世至早石炭世孢子带和泥盆系—石炭系界线

本文系统研究了长江下游地区(包括江苏、浙江和安徽)晚泥盆世和早石炭世孢子50属150余种。根据孢子在地层中的分布和演化规律,建立了7个孢子带,其中晚泥盆世3个带,早石炭世4个带。自下而上依次为:1)Rugospora flexuosa-Grandispora cornuta(FC)带;2)Vallatisporites pusillites-Retispora lepidophyta(PL)带;3)Retispora lepidophyta-Verrucosisporites nitidus(LN)带;4)Vallatisporites verrucosus-Retusotriletes incohatus(VI)带;5)Spelacotriletes pretiosus-Cingulizonates bialatus(PB)带;6)Schopfites claviger-Auroraspora macra(LN)带;7)Lycospora pusilla(PU)带。五通群下部观山组化石孢子丰富,时代相当西欧晚泥盆世法门阶(Famennian)Fa2c-Fa2d。泥盆系和石炭系界线置于陈家边组底部,即3带Retispora lepidophytaVerrucosisporites nitidus(LN)带和4带Vallatisporites verrucosus-Retusotriltes incohatus(VI))带之间。本文还深入讨论了沉积环境、微古植物地理区、国内外比较等问题。     

A Middle-Upper Devonian Boundary Section in the Open Platform,Platform Margin Facies of Guilin,South China

The Caiziyan Middle and Upper Devonian boundary section is located approximately 30 km northeast of Guilin.It hosts relatively abundant benthic and common-rare pelagic fossils,including brachiopods,corals,tentaculites,and conodonts,which may serve as a better suitable section for pelagic and neritic stratigraphic correlation.In this section,10"standard"conodont zones are recognized across the Givetian-Frasnian boundary,including,in descending order,the Lower hassi Zone,punctata Zone,transitans Zone,the U...     

Palynostratigraphy of the Zorritas Formation,Antofagasta region,Chile: Insights on the Devonian/Carboniferous boundary in western Gondwana

The Middle Member of the Zorritas Formation in the Antofagasta region of northern Chile, yielded terrestrial and marine palynomorph assemblages which span the Devonian/Carboniferous boundary. The assemblages show a clear predominance of terrestrial palynomorphs with 70 miospore species, 18 marine phytoplankton species, two non-marine algae and one chitinozoan species, all coming from 15 productive levels. Palynomorphs are poorly preserved and most of them are reworked. Three palynological associations are recognized based on miospores. These are assigned to the Tournaisian–Visean, Tournaisian and probable latest Famennian. Age assignments are discussed in the frame of the spore zonal schemes established for Euramerica and western Gondwana. The stratigraphical distribution of spores allows the identification of the probable position of the Devonian/Carboniferous boundary within the Zorritas Formation. This system boundary is proposed for the first time in Palaeozoic sedimentary rocks of northern Chile. The presence of Gondwanan typical miospore species indicates affinities with this palaeocontinent even though the Tournaisian and Tournaisian–Visean miospore associations support the cosmopolitanism already suggested for the early Carboniferous flora. The significant number of reworked palynomorphs together with the sedimentological analysis of the studied sections, suggest that these deposits were severely impacted by the climatic change and major sea level fluctuations. Similar conditions were recorded in coeval western Gondwana basins.