Qinling Faunal Region-The Third Ordovician Faunal Region: International Correlation   总被引：1，自引：0，他引：1  

PEI FangRegional Geological Survey Party  Henan Bureau of Geology  Mineral Exploration  Development  Pingdingshan  Henan 《《地质学报》英文版》2000,74(2):137-142

The Ordovician conodont faunal provinces were previously divided into the Midcontinent and Atlantic Faunal Regions situated respectively in low and high latitudes, where warm- and cold-water type conodont faunas flourished respectively. According to the international correlation this paper proposes the third Ordovician conodont faunal region-Qinling Faunal Region, in which cold-water conodont faunas were well developed in the Early to middle Middle Ordovician and warm-water conodont faunas were well developed in the late Middle and Late Ordovician, indicating that the Qinling Region was situated in high latitudes earlier and in low latitudes later. The origin was only due to plate movement In the Qinling Region the time interval of the change of the conodont fauna from the cold- to warm-water type was 4 Ma (from 474 to 470 Ma), during which the fauna geographically spanned 40° of latitudes, with a movement velocity of nearly 1.12 m/a, indicating that the high-latitude plates were divorced and reduced i  相似文献   

Helium, Argon, and Xenon Isotopic Compositions of Ore-formingFluids in Jinding-Baiyangping Polymetallic Deposits,Yunnan, Southwest China   总被引：13，自引：0，他引：13  

XUE Chunji  WANG Denghong  CHEN Yuchuan  YANG Jianmin  YANG Weiguang 《《地质学报》英文版》2000,74(3):521-528

The Jinding superlarge lead and zinc deposit has attracted the attention of geologists of the world and its metallogenesis has long been in dispute. This paper takes the Jinding deposit and the Baiyangping Cu-Ag-Co deposit which was recently found at about 30 km north of Jinding as one ore belt, and, based on researches on the helium, argon, and xenon isotopic compositions of primary inclusions in ore-forming solutions of the main stage, the authors have found that the 3He/4He ratio of the ore-forming fluid is 2.7′ 10- 6 (varying from 0.19 to 1.97 Ra), the 4He/40Ar ratio (0.24- 3.12) is close to the mantle characteristic ratio, and the xenon isotopic composition and evolution show characters of the mantle xenon. The above results reveal the characteristics of mantle source and crust-mantle fluid mixing (mantle helium reaching 32%) and the metallogenic contributions of the deep processes in the Jinding-Baiyangping ore belt.  相似文献   

TRANSPORTATION AND TERRITORIAL DEVELOPMENT IN THE SINGAPORE EXTENDED METROPOLITAN REGION   总被引：3，自引：0，他引：3  

Jean-Paul Rodrigue 《Singapore journal of tropical geography》1994,15(1):56-74

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Organic nitrogen chemistry during low-grade metamorphism   总被引：1，自引：0，他引：1  

Jean-Paul Boudou  Arndt Schimmelmann  Maria Mastalerz  Léon Gengembre 《Geochimica et cosmochimica acta》2008,72(4):1199-1221

Most of the organic nitrogen (N_org) on Earth is disseminated in crustal sediments and rocks in the form of fossil nitrogen-containing organic matter. The chemical speciation of fossil N_org within the overall molecular structure of organic matter changes with time and heating during burial. Progressive thermal evolution of organic matter involves phases of enhanced elimination of N_org and ultimately produces graphite containing only traces of nitrogen. Long-term chemical and thermal instability makes the chemical speciation of N_org a valuable tracer to constrain the history of sub-surface metamorphism and to shed light on the subsurface biogeochemical nitrogen cycle and its participating organic and inorganic nitrogen pools. This study documents the evolutionary path of N_org speciation, transformation and elimination before and during metamorphism and advocates the use of X-ray photoelectron spectroscopy (XPS) to monitor changes in N_org speciation as a diagnostic tool for organic metamorphism. Our multidisciplinary evidence from XPS, stable isotopes, traditional quantitative coal analyses, and other analytical approaches shows that at the metamorphic onset N_org is dominantly present as pyrrolic and pyridinic nitrogen. The relative abundance of nitrogen substituting for carbon in condensed, partially aromatic systems (where N is covalently bonded to three C atoms) increases exponentially with increasing metamorphic grade, at the expense of pyridinic and pyrrolic nitrogen. At the same time, much N_org is eliminated without significant nitrogen isotope fractionation. The apparent absence of Rayleigh-type nitrogen isotopic fractionation suggests that direct thermal loss of nitrogen from an organic matrix does not serve as a major pathway for N_org elimination. Instead, we propose that hot H, O-containing fluids or some of their components gradually penetrate into the carbonaceous matrix and eliminate N_org along a progressing reaction front, without causing nitrogen isotope fractionation in the residual N_org in the unreacted core of the carbonaceous matrix. Before the reaction front can reach the core, an increasing part of core N_org chemically stabilizes in the form of nitrogen atoms substituting for carbon in condensed, partially aromatic systems forming graphite-like structural domains with delocalized π-electron systems (nitrogen atoms substituting for “graphitic” carbon in natural metamorphic organic matter). Thus, this nitrogen species with a conservative isotopic composition is the dominant form of residual nitrogen at higher metamorphic grade.  相似文献   

论成都盆地的成生时代及其早期沉积物的一般特征   总被引：8，自引：0，他引：8  

何银武 《地质论评》1992,38(2):149-156

本文从宏观上阐述了成都盆地形成的地质背景;盆地基底地层的缺失与古地理环境演化特征。从青藏高原的隆起时间相应地讨论了四川盆地晚白垩世以来的发展历程。认为,成都盆地是龙门山脉与四川盆物分化解体的派生构造形迹;早期堆积于盆底的大邑砾岩的沉积特征和物源特性表明了一个新地质时代的开启;极其粗大的碎屑体现了新构造运动垂直升降振荡作用的特点;大邑砾岩为构造侵蚀碎屑物,是成都盆地第四纪松散堆积层的代表。之后,盆地一直继承此沉积特征而沉积了最大厚达540m的砾卵石层。  相似文献   

Geodynamic evolution of Korea: A view   总被引：2，自引：0，他引：2  

Dominique  Cluzel Jean-Paul  Cadet† 《Island Arc》1992,1(1):64-70

Abstract Evidence for South Korean Palaeozoic geodynamic evolution is restricted to the Ogcheon Belt, which is a complex polycyclic domain forming the boundary between the Precambrian Gyeonggi Block to the northwest and the Ryeongnam Block to the southeast. Two independent sub-zones can be distinguished: the Taebaeksan Zone to the northeast and the Ogcheon Zone sensu stricto. The Taebaeksan Zone and Ryeongnam Block display characteristic features of the North China palaeocontinent. This domain remained relatively stable during the Palaeozoic. In contrast, the Ogcheon Belt s. s. is a highly mobile zone that belongs to the South China palaeocontinent and corresponds to a rift that opened during the Early Palaeozoic. In lowermost Devonian times, the rift basin was closed and the Ogcheon Belt was structured in a pile of nappes. From the lack of suture in the Ogcheon Belt it can be inferred that the Gyeonggi Block belongs to the South China palaeocontinent. Thus, the boundary between the North China and South China blocks should be located to the north of Gyeonggi Block, that is, in the Palaeozoic Imjingang Belt. From the Middle Carboniferous, sedimentation started again on a weakly subsiding paralic platform located in the hinterland of the Late Palaeozoic orogen of southwest Japan. In the Late Carboniferous, increasing subsidence recorded extensional tectonics related to the opening of the Yakuno Oceanic Basin (southwest Japan). In the Middle Permian, the end of marine influences in the platform and emplacement of terrestrial coal measures, may be correlated with the closure of the oceanic area and subsequent ophiolite obduction. In Late Permian to Early Triassic times, the Honshu Block (the eastern palaeomargin of the Yakuno Basin) collided with Sino-Korea. Post-collisional intracontinental tectonics reached the Ogcheon Belt in the Middle Triassic (Songnim tectonism). Ductile dextral shear zones associated with synkinematic granitoids were emplaced in the southwest of the belt. In the Upper Triassic, the late stages of the intracontinental transcurrent tectonics generated narrow intramontane troughs (Daedong Supergroup). The Daedong basins were deformed during two tectonic events, in the Middle (?) and Late Jurassic. The Upper Jurassic to Lower Cretaceous basins (Gyeongsang Supergroup), that are controlled by left-lateral faults, may have resulted from the same tectonic event.  相似文献   

The landscape-unit approach applied to geology, on SPOT images, in temperate climate zones using a test-area in the Cévennes (Massif Central, France)     

Jean-Paul Deroin  Jean Chorowicz  Thierry Deroin  Phillippe Dutarte  Jean-Yves Scanvic  Andr Simonin 《ISPRS Journal of Photogrammetry and Remote Sensing》1990,45(5-6)

Classification image processing is based mainly upon spectral features but this information alone is inadequate for drawing comprehensive maps or reliably distinguishing lithological or structural targets, especially in vegetation-covered areas. It is therefore of interest to explore an approach in which subtle features of the image are matched with field data in a variety of parameters either measured or assessed qualitatively. This approach is necessarily multidisciplinary, the three basic aspects being geomorphological, botanical and geological.The Cévennes massif, in southern France, with its sedimentary margins was selected as a test area, having both varied geology, giving a variety of landscapes, and a range of climatic zones, from Mediterranean to sub-Alpine.The present work is distinguished by its use of the landscape unit, which is rarely considered in geology. Landscapes units are recognized and defined, and the spectral homogeneity of the units is then assessed. They are combined with satellite and other data in order to improve the digital processing for geological purposes.The parameters characterising each landscape unit define the various elements contributing to the landscape, the most important of which are morphology, vegetation and geology, and their interactions. Our results using these parameters show the interest of the management of both the satellite (SPOT in this case) and non-satellite (exogenous) data.  相似文献   

The Songpan-Garze Massif: Its Relation to the QinlingFold Belt and Yangtze Platform and Developmental History     

Yang Fengqing  Yin Hongfu  China U niversity of Geosciences. W uhan  HubeiYang HengshuNorthwestern Sichuan Geological Party  Mianyang  Sichuan  Lai XulongChina U niversity of Geosciences. W uhan  Hubei Fei Zhenbi 《《地质学报》英文版》1995,69(1)

Whether there existed the Songpan-Garze massif is a controversial problem. This paper expounds and proves that the old basement of the massif is represented by the pre-Sinian granitic rock series. This massif and the South Qinling fold belt might both be a part of the old Yangtze platform. Rifting generated by the Caledonian orogeny in the terminal Early Palaeozoic caused the massif to be disintegrated from the northwestern part of the Yangtze platform. This disintegration, however, was not thorough, and the rift troughs were later gradually closed and filled up. The Emei taphrogeny that was initiated in the Early Permian Maokou' an Stage involved a second disintegration of this massif from the Yangtze platform. The rift line largely goes along the Muli-Pingwu line. This rifting belongs to synchronous extensional rifting at peripheries of the Yangtze platform and in its interior, showing that the posterior, lateral and interior extension resulting from rapid northward shift of the Yangtze platform led t  相似文献   

Effects of scattered solar radiation and absorption by SO₂ on the photodissociation processes in the stratosphere of Venus     

Jean-Paul Parisot  Guy Moreels  Jean-Marc Zucconi 《Icarus》1980,44(3):640-650

In the stratosphere of Venus, the available luminous flux which locally produces the photodissociation processes at a given altitude may be divided into three parts: direct incoming downward flux, flux resulting from the reflection on the surface of the clouds, and flux due to molecular scattering. A relatively simple computation method has been used to evaluate the relative importance of these three parts at altitudes between 65 and 100 km. It is shown that the extra contribution of the reflected and scattered fluxes to photodissociation processes cannot be neglected in the uv and visible regions. In the case of SO₂, for instance, which presents an absorption band in the uv, the photodissociation coefficient is increased 30% due to these effects. Calculations of the photodissociation coefficients of CO₂, O₃, H₂S, and SO₂ are presented. As a result of the increase by 60% in the ozone photolysis rate, the calculated O₂ infrared band at 1.27 μm is larger by a factor of nearly 2 than is expected from a calculation without taking albedo or scattering into account.  相似文献   

Nonlinear modal analysis of penetrative convection     

Jean-Paul Zahn  Juri Toomre  Jean Latour 《地球物理与天体物理流体动力学》2013,107(1-2):159-193

Abstract

The modal expansion procedure has been used to analyze penetrative convection that arises when a thin unstable layer is embedded between two stable regions. The Boussinesq approximation is applied in which the effect of compressibility and stratification are neglected. Various calculations have been made, with one and two modes, for Rayleigh numbers ranging from the critical value to more than 10⁵ times critical. The effect of decreasing the Prandtl number has also been investigated.

It is found that in the nonlinear regime, the convective motions penetrate substantially into the stable regions. The flux of kinetic energy plays a crucial role in such penetration, and its existence puts some requirements on the motions: in the single-mode case, they need to be three-dimensional. The extent of penetration amounts to about half of the thickness of the unstable layer on each side of it when the degree of instability and that of stability are comparable in the two domains; it increases as the stability of the outer region is lowered. The penetration depth appears to be independent of all other parameters defining the problem.  相似文献