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从七十年代末开始,特别是八十年代以来,国内外沉积学界出现了风暴沉积作用与风暴沉积物或风暴岩（Storm deposits,tempestites）研究的热潮。大型湖盆浅水地带、特别是开阔海盆的滨海与浅海区的风暴沉积的重要性与普通性引起了人们极大的兴趣。过去对浅海细粒沉积中的粗粒夹层无法理解的现象从风暴沉积中得到了解释;而过去有些被认为“浅滩沉积”或“浅水浊流”的岩石,现在有可能被怀疑为风暴作用的产物。 相似文献
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鄂东黄石地区下三叠统大冶组风暴沉积 总被引：1，自引：3，他引：1
鄂东黄石地区下三叠统大冶组灰岩中发育了典型的风暴沉积，风暴岩由砾屑灰岩、颗粒灰岩和泥灰岩组成，其中风暴沉积构造包括丘状交错层理、递变层理、砾屑的撕裂构造及水平层理等，不同层位具有不同的风暴沉积构造类型和组合特征。根据风暴沉积的岩石特征、构造类型、规模、组合特点，并结合沉积背景分析，风暴沉积序列可进一步分为深水远源型、过渡型和浅水近源型。大冶组一段风暴沉积具有深水远源特点，沉积环境为水体较深的外陆棚； 大冶组二段风暴沉积具有过渡型特点，沉积环境为向上变浅的内陆棚； 大冶组三、四段风暴沉积具有浅水近源特点，沉积环境为浅水陆棚至滨岸。大冶组沉积序列具有向上变浅的特点，沉积环境由深水陆棚逐渐向滨岸转变。风暴沉积的识别对重建鄂东黄石地区早三叠世古地理具有重要意义。 相似文献
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风暴沉积,风暴岩的研究现状 总被引：7，自引：1，他引：7
本文是在阅读大量国内外最新有关古代和现代风暴沉积及风暴作用(包括现代台风作用)的论文(资料)和著作的基础上,运用现代沉积学理论及现代气象学与气候学理论,就以下几个方面作了总结和分析评述:1.有关概念:2.现代风暴沉积研究:3.古代风暴沉积研究:动力地层学分级研究法;地质时期风暴岩的分布和风暴作用范围:风暴作用的深度范围:有关HCS(丘状层理)的几个问题;古风暴沉积中风暴强度的研究方法:4.风暴岩研究的古地理意义:极源性研究;古水流方向的确定;盆地边缘轮廓的确定和古纬度的研究. 相似文献
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鄂东南下三叠统地层发育齐全,野外露头连续,是大冶组的命名地(谢家荣,1924),长期以来受到地质学界的关注(图1)。在该地层中,发育多层砾屑灰岩,不同学者对其成因具有不同的解释,有的认为是一种泥皮成因的浅水标志;有的认为是深海盆地边缘或下部斜坡带的重力流沉积。根据我们近年来的研究,认为大部分砾屑灰岩应届风暴流、风暴重力流作用的产物。在野外露头上,风暴沉积现象清晰,风暴作用证据充分。 相似文献
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作为全球地质环境的重要转折期，震旦纪早期发生的全球气候巨变和海平面显著上升等事件在世界范围内留下了大量记录。报道了震旦纪早期气候剧变阶段在我国南方陡山沱组底部形成的风暴沉积。岩芯剖面的精细观察和测量分析表明，峡东地区陡山沱组底部风暴岩沉积主要集中在陡一段白云岩与陡二段底部泥页岩中，发育的沉积构造主要有冲刷侵蚀底面、搅动层、粗粒滞留沉积、粒序层理、洼状交错层理、波状层理、波痕以及水平层理等。根据风暴岩垂向上的组合特征和沉积构造差异，共识别出五种风暴沉积序列，分别指示了不同的沉积背景:潮坪浅水沉积和陆棚深水沉积。其中，陡一段主要发育浅水风暴沉积，陡二段底部主要为深水风暴沉积，随着海平面的上升，自下而上风暴作用呈现加强的趋势。另外，在陡二段还发现了风暴浪基面以下形成的具粒序层理的泥砾岩。峡东地区陡山沱组底部的风暴沉积蕴含了强烈的古地理、古气候、古地貌以及地层信息，对于恢复震旦纪早期华南地质环境及其变化具有重要意义。 相似文献
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扬子地台东南缘下寒武统清虚洞组风暴沉积特征及其重要意义 总被引：3，自引：0，他引：3
在扬子地台东南缘,下寒武统龙王庙阶清虚洞组主要由浅水碳酸盐岩组成。在野外露头剖面实测和室内镜下薄片观察的基础上,大量风暴沉积被发现于不同剖面清虚洞组的不同层位中,同时大量风暴诱发形成的沉积构造被识别出来,包括侵蚀基底、粗粒滞留沉积、粒序层理、平行层理、丘状交错层理(少见并且值得怀疑)以及沙纹层理,组成了多种类型的风暴沉积序列。结合更靠扬子东南缘的深水剖面中重力流沉积的缺乏,可以推断早寒武世龙王庙期扬子地台的沉积模式为碳酸盐缓坡。结合风暴的形成机制以及清虚洞组风暴沉积的发育特征(尤其是粗粒滞留砾屑的定向排列和典型丘状交错层理的缺乏),可以推断研究区风暴沉积形成于强烈的冬季风暴作用,并且早寒武世龙王庙期华南的古地理位置应当位于中纬度地区,这一结论对一些著名的全球古地理重建方案提出了质疑。同时中纬度地区大规模发育蒸发岩和碳酸盐岩还佐证了寒武纪地球处于热室(Hothouse)时期。 相似文献
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潮坪风暴沉积特征及其研究意义 总被引：18，自引：0，他引：18
风暴沉积是20世纪70年代后期才指提出的一个重要概念，被认为是沉积学理论的一次重大突破。但是以往的研究多集中在对浅海陆棚区风暴沉积的研究，而对近岸地带潮坪风暴沉积的研究则比较薄弱。系统总结了近20年来国内外对现代潮坪风暴沉积研究的成果，同时介绍了在古代地层中首次识别出的潮坪风暴岩沉积特征，最后指出了潮坪风暴沉积的研究意义。 相似文献
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生物壳体碳酸盐的稳定氧、碳同位素已经被广泛地应用在古气候、古环境研究中,在生物壳体就位分析中,壳体不同断面上同位素的差异将影响对壳体同位素所指示的环境意义的判断,从而对利用其提取气候环境信息造成不利影响。本文对河蚬壳体不同断面碳氧同位素进行了研究,结果表明:河蚬壳体碳同位素变化序列在不同断面上不存在显著差异,因此在做碳同位素时间序列研究时可以不考虑不同断面差异的问题,在取样过程中可以通过延长取样的长度来获得足够量的样品进行碳同位素的测定;而氧同位素变化序列在不同断面上存在差异,因此在进行壳体就位分析研究时,选取不同断面上氧同位素变化序列对研究结果影响较大,存在壳体断面选择的问题,而在取样过程中取样的长度应控制在一定范围内,避免同一生长环上距离较远位置粉末的混合。文中最后根据壳体不同断面同位素差异确定了在壳体就位分析中如何选取研究断面。 相似文献
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Trace-element determinations of 15 coal samples have been made in order to know their distribution, behaviour and associations with the organic and inorganic fractions in the coal. The coal samples have been systematically collected in stratigraphic sequences so that the vertical variation of the trace-elements can be studied. The elements determined by spectographic analysis are W, V, Cr, Sc, Y, Cu, Co, Pb, Be, Ni and Ba. The results indicate that the concentration of trace elements in these coals varies greatly from bottom to top sections. The elements V and Co are extremely poor in the top and middle sections, whereas in the bottom section they are fairly distributed. Be is extremely poor in the bottom section, and fairly distributed in the middle and top sections. W, Sc, Y have poor concentration in the bottom section as compared to the middle and top sections. Ni is fairly distributed in the bottom section whereas its concentration is poor in the middle and top sections. Cr and Cu are fairly distributed in the bottom, middle and top sections. Ba has unusually high concentration in all the sections.It appears from the present study that W, Cr, Sc, Y and Be are concentrated more in silicate minerals (clay, quartz, etc.) associated with coal, and the elements like , Co, and Ni have intimate relation with organic matters in coal and are present as organometallic compounds as well as absorbed cations. Cu and Pb which are present in the coals are derived from the inorganic matter, mainly from the pyrites, whereas W has affinity with carbonate minerals in the coals. The Ba is mainly associated with the inoraanic matter of coal; its unusually high concentration indicates association with carbonates, clays and other silicate minerals. 相似文献
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De-bugging the 'millipede' porphyroblast microstructure: a serial thin-section study and 3-D computer animation 总被引：1，自引：0，他引：1
ABSTRACT Seventy-five spatially orientated, serial thin sections cut from a single rock containing ‘millipede’ porphyroblast microstructure from the Robertson River Metamorphics, Australia, reveal the three-dimensional (3-D) geometry of oppositely concave microfolds (OCMs) that define the microstructure. Electronic animations showing progressive serial sections of the 3-D microstructure are made available via the World Wide Web. The OCM amplitudes decrease regularly from a maximum in near-central sections to a minimum in near-marginal sections, whereas the OCM interlimb angles increase regularly from a minimum in near-central sections to a maximum in near-marginal sections. These observations illustrate that the OCMs are noncylindrical surfaces with culminations located in near-central sections. Because the porphyroblast cores appear to have been present before significant development of the syn-OCM foliation, all of the OCMs were formed by heterogeneous extension around these cores. The overall geometry of the OCMs described here reflects the strain state, and cannot be used to constrain deformation paths. 相似文献
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利用地球物理异常显示参数表示剖面数据,以剖面数学期望、方差、特征峰间距、特征峰半极值为信息参数,对放射性测量剖面进行模糊聚类分析。该方法可有效区分成矿模式间的差异,对同一地区的分析表明,具有相近埋深和规模的剖面具有最强的相似性,有矿模式间具有较强的一致性,有矿与无矿剖面有较大的差异,而无矿剖面间一致性差。经新疆和内蒙等地区实测资料的解释和检验,说明这些方法用于解释异常,可以取得较好的地质效果。 相似文献
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Yu. M. Smirnov 《Astronomy Reports》2002,46(10):840-850
Cross sections for the excitation of transitions in the tantalum atom not related to the ground state have been measured using extended crossed beams and optical spectroscopy. The total excitation cross sections for 23 energy levels of TaI have been determined. The accuracy of known transition probabilities that can be used to find branching ratios is analyzed. 相似文献
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Stable isotopic signature of a palaeoaquifer, Mississippian Alamogordo Member limestones, Sacramento Mountains, New Mexico, USA 总被引：1，自引：0，他引：1
Nine stratigraphic sections, each ≈5 m thick, were sampled from the Alamogordo Member limestones of the Lake Valley Formation, Sacramento Mountains, New Mexico, USA. Four stratigraphic sections consist entirely of lime mudstone and wackestone, whereas the other five sections have a prominent layer of crinoidal packstone about 1 m thick at their base. Stable isotopic analyses reveal that the lime muds in the sections with basal packstone layers show a downward decrease in δ18 O and constant δ13 C values, whereas those in the sections solely composed of lime mudstone and wackestone have, in general, relatively uniform δ18 O and δ13 C values. The diagenesis of the Alamogordo Member limestones was previously believed to have been governed by the downward percolation of meteoric water from a regional pre-Pennsylvanian exposure surface ≈100 m above this unit. However, the uniform δ13 C and downward decrease in δ18 O values in the lime muds in the sections with basal packstones indicate that the meteoric water ascended within the Alamogordo Member, rather than descended from the overlying exposure surface. This indicates that the basal packstones were probably a conduit for meteoric water. This is further supported indirectly by the relatively uniform δ18 O and δ13 C values of the lime mud in the sections without basal packstones. The implications are that the oxygen isotopic gradients may be used to identify palaeoaquifers, flow directions within these aquifers and that meteoric diagenesis below an exposure surface could be governed by flow through a palaeoaquifer. 相似文献
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The determination of boundary points and their correlation are prerequisites for defining the PrecambrianCambrian boundary and the intercontinental correlation. A large number of good Precambrian-Cambrian boundary sections in South Asia not only possess the conditions for selection of a boundary stratotype, but also provide the basis for the long-distance correlation of those boundary sections.Through a detailed study of the latest data obtained from the typical sections in South China, the Lesser Himalaya Mountains and the Alborz Mountains. the locations of boundary points have been defined, and a correlation scheme is proposed, which contributes to the solution of the problem of worldwide correlation of boundary sections. 相似文献
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In the present study, over 3000?m of Upper Cretaceous sediments (Tarbur Formation) in seven stratigraphic, columnar sections were studied. The area is located in the Zagros mountain ranges of southwestern Iran, attributed to the converging continental Arabian Shield, and is interpreted as the result of subduction and collision. Based on foraminiferal studies of the Tarbur Formation in the sections, we have established many new biozones in the stratigraphic sections. However, investigations of the biozones indicate that there is no lithostratigraphic variation between the Upper Cretaceous and Lower Paleocene sediments in some of the studied sections. The concept of widespread formations and lithologic correlations is not applicable in this area, probably as a result of the tectonic unrest at that time. The biostratigraphic boundary between the Cretaceous and the Lower Paleocene is nevertheless well defined by the intraformational boundary in the sections. 相似文献
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小浪底水库运行后,黄河下游游荡段河床冲刷剧烈,滩岸崩退过程较为显著。估算典型断面的滩岸崩退过程,不仅有助于全面掌握该河段的河床演变规律,同时也能为河道整治及规划等提供相关参数。以1999—2013年游荡段典型断面(水文断面及淤积断面)汛后实测地形资料为基础,确定了这些断面平滩河宽的调整过程,发现多年平均崩退速率最大达215 m/a;分析了影响滩岸崩退过程的不同因素,发现滩岸土体组成及力学特性、滩槽高差等因素虽对崩退过程有一定影响,但来水来沙条件是主要影响因素;分别建立了游荡段水文断面及淤积断面滩岸累计崩退宽度与前期5年平均汛期水流冲刷强度之间的经验关系,相关系数都在0.85以上。公式计算值与实测值吻合较好,可用来估算游荡段典型断面滩岸的崩退过程。 相似文献
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《International Geology Review》2012,54(3):354-372
The Carboniferous System of South China is famous for its well-developed rock sequence, variety of depositional types, and abundant fossils. Three established Global Boundary Stratotype Section and Point (GSSP) markers have been identified in several sections in South China. Of these sections, the Pengchong section is the GSSP for the base of the Visean Stage, whereas the Dapoushang and Naqing (Nashui) sections are excellent reference sections for the bases of the Tournaisian and Bashkirian stages, respectively. Other sections have good potential for the four unestablished GSSPs and the Devonian–Carboniferous boundary in South China. The Naqing (Nashui) section is a candidate for the GSSPs of four stages: the Serpukhovian, Moscovian, Kasimovian, and Gzhelian stages. The regional stages of China include the Tangbagouan, Jiusian, Shangsian, Dewuan, Luosuan, Huashibanian, Dalaun, and Xiaodushanian. The history, definitions, reference sections, sedimentary characteristics, biostratigraphy, and correlations of these Chinese regional stages are summarized. A Carboniferous stratigraphic chart of South China is provided, showing the correlation of global chronostratigraphic and biostratigraphic units with those in South China and the lithostratigraphic units of various areas in South China. The chart is presented as a new practical framework for the stratigraphic subdivision and correlation of the Carboniferous System in South China. 相似文献