华南泥盆系研究中的几个地层问题

简要总结我国泥盆系研究进展的基础上 ,提出华南区泥盆系除滨海相沉积外 ,浅海相沉积可区分出象州型、北流型、南丹型、崇左型 4种基本的相型沉积 ,各自均有特定的岩石组合、生物群特征 ,反映各自特定的沉积环境 ,应分别建立相应的地层柱。如继续保留华南区泥盆系建阶方案 ,泥盆系底部有待重行建阶 ,Emsian阶宜三分 ,与之时限相当的阶 ,自下而上为郁江阶、二塘阶、四排阶     

黔桂地区泥盆系层序地层格架及相对海平面变化

志留纪末期的加里东运动,使黔桂地区的古地理格局发生了重大变化,早古生代的滇黔桂古陆演变为晚古生代的滇黔桂海。泥盆纪初期,海水由南而北逐渐海侵超覆,在泥盆系的底部形成一套海侵碎屑岩系地层;早泥盆世晚期的大规模海侵事件造成了明显的相分异,在习称的滇黔桂盆地中发育了若干孤立碳酸盐台地,这种“台-盆-丘-槽”的格局一直延续到晚泥盆世早期;而泥盆纪末期的紫云运动所造成的地壳抬升,又使晚泥盆世地层产生海退尖灭。因此,该地区的泥盆系构成一个二级构造层序,其中包含13个三级沉积层序。在前人大量生物地层学研究的基础上,追索和对比不同沉积背景中的三级沉积层序的相序组构特征以及由其所代表的相对海平面变化,即可建立黔桂地区泥盆系的层序地层格架。层序地层格架较为充分地表现出三级沉积层序的两大特征--空间上相序的有序性和时间上环境变化的同步性,同时也明显地显示出地层记录中的两种相变面和两种穿时性。     

浙江晚泥盆世五通组中的楔叶类(Sphenophyllales)化石

本文描述了产自浙江长兴泗安五通组中的几种楔叶类化石Eviostachya hoegii(Stockmans)、Arch-aeocalamites sp.、Hamatophyton verticillatum Gu et Zhi、Sphenophyllum pseudotenerrimum(Sze)和Sphenophyllostachys sp.等.特别是Eviostachya hoegii的发现,为浙江晚泥盆世地层进行国际性对比,提供了新的依据.     

Oxygen isotope evolution of biogenic calcite and apatite during the Middle and Late Devonian

Oxygen isotope ratios of well-preserved brachiopod calcite and conodont apatite were used to reconstruct the palaeotemperature history of the Middle and Late Devonian. By assuming an oxygen isotopic composition of –1 V-SMOW for Devonian seawater, the oxygen isotope values of Eifelian and early Givetian brachiopods and conodonts give average palaeotemperatures ranging from 22 to 25 °C. Late Givetian and Frasnian palaeotemperatures calculated from ¹⁸O values of conodont apatite are close to 25 °C in the early Frasnian and increase to 32 °C in the latest Frasnian and early Famennian. Oxygen isotope ratios of late Givetian and Frasnian brachiopods are significantly lower than equilibrium values calculated from conodont apatite ¹⁸O values and give unrealistically warm temperatures ranging from 30 to 40 °C. Diagenetic recrystallization of shell calcite, different habitats of conodonts and brachiopods, as well as non-equilibrium fractionation processes during the precipitation of brachiopod calcite cannot explain the ¹⁸O depletion of brachiopod calcite. Moreover, the ¹⁸O depletion of brachiopod calcite with respect to equilibrium ¹⁸O values calculated from conodont apatite is too large to be explained by a change in seawater pH that might have influenced the oxygen isotopic composition of brachiopod calcite. The realistic palaeotemperatures derived from ¹⁸O _apatite may suggest that biogenic apatite records the oxygen isotopic composition and palaeotemperature of Palaeozoic oceans more faithfully than brachiopod calcite, and do not support the hypothesis that the ¹⁸O/¹⁶O ratio of Devonian seawater was significantly different from that of the modern ocean.     

南秦岭泥盆系成矿带热水沉积成矿系列

南秦岭中晚古生界沉积区属造山前盆地，中泥盆世发生的海底喷流沉积事件及随后进入造山期的构造发展进程决定了本区成矿作用的基本类型及其演化。产于泥盆系中的各类铅锌矿床、铜矿床和金矿床不同程度具层控性质，矿化均与以钠长岩、硅质岩、富铁镁碳酸盐岩为特征的热水沉积或蚀变有较密切联系。基于矿床时空分布，矿物组合及共生顺序以及成矿作用演化的分析，确定它们可能是一个与热水沉积作用有关的成矿系列。这个成矿系列的建立对我国西部古生代褶皱带区域成矿研究有重要对比意义。     

阿尔泰山南缘克朗盆地泥盆纪火山沉积与矿产

新疆阿尔泰山南缘克朗晚古生代火山-沉积盆地盆地，位于西伯利亚板块南缘泥盆纪陆缘裂谷带中，在早泥盆世发生了大规模多期次的火山活动，在康布铁堡组火山沉积地层中形成了恰夏、铁木尔特和阿巴宫多个VMS型铜铅锌铁多金属矿床;中泥盆世火山作用减弱，在阿勒泰镇组沉积地层中形成SEDEX型红墩铅锌矿床。     

Buchanosteus(节甲鱼类)的新材料及其生物地层学意义

记述了采自广西永福附近泥盆系的一鱼类化石标本。根据头甲轮廓和内颅特征，将其归入节甲鱼类。头甲的宽度大于后松果区长度，中颈片为梯形，后边缘片有较长的后突。内颅吻囊与筛后一枕区分开，耳区短；前眶后突不明显，位置靠后；后眶后突明显，远端不分叉。因此新材料应归入巴坎鱼属（Buchanosteus）。但眼孔大并朝向背侧上方，骨片上粒状突起纹饰的冠部和基部没有星状嵴等特征与Buchanosteus confertituberculatus（Chapman）不同，所以新材料应代表一新种，即Buchanosteus兴guangxiensis sp．nov．。还对澳大利亚与中国华南地区当时的古地理关系进行了讨论。     

Middle Devonian Picrites of the Southern Margin of Altay Orogenic Belt and Implications for the Tectonic Setting and Petrogenesis

INTRODUCTION Inrecentyears,greatprogressonthegeologic tec tonicevolutionandmineralresourcesofXinjianghas beenachieved.However,manyissuesarestilldebated, suchasancienttectonicpatternsandtheclosuretimeof theancientoceanicbasin(LiandXu,2004).Theseis sueshavelimitedourknowledgeoftheformationande volutionofAsiancontinents,aswellastheexploration anddevelopmentofmineralresources. Recently,theHilaketehalasuporphyrycopperde positwasdiscoveredinthestrataoftheMiddleDevoni anBeitashanFormatio…     

Stratigraphic variation of complex impurities in platform limestones and possible significance of atmospheric dust: a study with emphasis on gamma-ray spectrometry and magnetic susceptibility outcrop logging (Eifelian-Frasnian, Moravia, Czech Republic)

Mineral dust and other constituents of Devonian atmospheric aerosols together with certain amounts of aquatic suspensions of riverine detrital origin, colloidal particle dispersions and seawater solutes were embedded in ~95–98% (or purer) limestones on a consistently subsiding isolated carbonate platform where they formed very complex impurity systems. Very low Th/U values, relative abundance of Fe but a slight excess of K typically characterize these ultrafine impurities which are mineralogically dominated by smectite–illite and mica (sericite) together with goethite. In vertical section, these impurities are arranged like incremental series of light and dense bands. The combined method of natural gamma-ray spectrometric and magnetic susceptibility measurements (GRS–MS) together with background of major and trace element analyses provided first systematic insights into fine-scale variability of these impurities in a pile of pure carbonate platform beds, mostly in inner platform Amphipora limestone facies. These carbonates were deposited close to sea level but far from river mouths, and they represented a certain sort of a relatively “independent” medium that was primarily sensitive to climatically (and by rare events) controlled input of atmospheric dust. A remarkable similarity of MS stratigraphic patterns that reflect the quantity and quality of embedded impurities in very distant and paleogeographically separated Devonian basins might be seen as supporting this viewpoint. A long composite stratigraphic section of the Moravian Karst ranges from mid-Eifelian to end-Frasnian levels and yields a number of time characterizing GRS–MS variations that can potentially serve as templates for high-resolution stratigraphic correlations over long distances.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.