Metallogenic relationships to tectonic evolution - the Lachlan Orogen, Australia     

Frank P Bierlein  David R Gray  David A Foster 《Earth and Planetary Science Letters》2002,202(1):1-13

Placing ore formation within the overall tectonic framework of an evolving orogenic system provides important constraints for the development of plate tectonic models. Distinct metallogenic associations across the Palaeozoic Lachlan Orogen in SE Australia are interpreted to be the manifestation of interactions between several microplates and three accretionary complexes in an oceanic back-arc setting. In the Ordovician, significant orogenic gold deposits formed within a developing accretionary wedge along the Pacific margin of Gondwana. At the same time, major porphyry Cu-Au systems formed in an oceanic island arc outboard of an evolved magmatic arc that, in turn, gave rise to granite-related Sn-W deposits in the Early Silurian. During the ongoing evolution of the orogen in the Late Silurian to Early Devonian, sediment-hosted Cu-Au and Pb-Zn deposits formed in short-lived intra-arc basins, whereas a developing fore-arc system provided the conditions for the formation of several volcanogenic massive sulphide deposits. Inversion of these basins and accretion to the Australian continental margin triggered another pulse of orogenic gold mineralisation during the final consolidation of the orogenic belt in the Middle to Late Devonian.  相似文献   

Earth''''s deformation due to the dynamical perturbations of the fluid outer core     

徐建桥  孙和平 《地震学报(英文版)》2002,15(4)

Introduction The fluid outer core separates the solid inner core from the solid elastic mantle, and as a result, makes the free and forced movement of this mechanical system more complicated and profuse. As the elastic mantle, the free oscillations may occur within the Earths fluid outer core (FOC) due to excitation of a strong and deep earthquake (Crossley, 1975b; Friedlander, Siegmann, 1982; Shen, 1983; Friedlander, 1985). However, compared with the oscillations of the elastic mantle, i…  相似文献   

液核动力学扰动引起的地球形变   总被引：2，自引：0，他引：2       下载免费PDF全文

徐建桥  孙和平 《地震学报》2002,24(4):397-406

讨论了地球固体部分对液核动力学效应引发的核幔边界和内核边界上压力和引力扰动的形变响应．采用弹性-引力形变理论描述地幔和内核的形变，给出了内部负荷Love数的一般表达式．以初始参考地球模型为例，分别计算了在地球表面、核幔边界和内核边界上的内部负荷Love数．探讨了液核边界上压力和引力扰动导致的地球形变场的空间和频率分布特征．本文的结果可以为中短周期液核动力学理论模拟提供必要的边界条件．   相似文献   

On strike-slip faulting in layered media   总被引：2，自引：0，他引：2  

Maurizio Bonafede  Beatrice Parenti  Eleonora Rivalta 《Geophysical Journal International》2002,149(3):698-723

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Melt segregation in the continental crust: distribution and movement of melt in anatectic rocks   总被引：31，自引：3，他引：31  

E. W. Sawyer 《Journal of Metamorphic Geology》2001,19(3):291-309

The grain‐ and outcrop‐scale distribution of melt has been mapped in anatectic rocks from regional and contact metamorphic environments and used to infer melt movement paths. At the grain scale, anatectic melt is pervasively distributed in the grain boundaries and in small pools; consequently, most melt is located parallel to the principal fabric in the rock, typically a foliation. Short, branched arrays of linked, melt‐bearing grain boundaries connect melt‐depleted parts of the matrix to diffuse zones of melt accumulation (protoleucosomes), where magmatic flow and alignment of euhedral crystals grown from the melt developed. The distribution of melt (leucosome) and residual rocks (normally melanocratic) in outcrop provides different, but complementary, information. The residual rocks show where the melt came from, and the leucosomes preserve some of the channels through which the melt moved, or sites where it pooled. Different stages of the melt segregation process are recorded in the leucosome–melanosome arrays. Regions where melting and segregation had just begun when crystallization occurred are characterized by short arrays of thin, branching leucosomes with little melanosome. A more advanced stage of melting and segregation is marked by the development of residual rocks around extensive, branched leucosome arrays, generally oriented along the foliation or melting layer. Places where melting had stopped, or slowed down, before crystallization began are marked by a high ratio of melanosome to leucosome; because most of the melt has drained away, very few leucosomes remain to mark the melt escape path — this is common in melt‐depleted granulite terranes. Many migmatites contain abundant leucosomes oriented parallel to the foliation; mostly, these represent places where foliation planes dilated and melt drained from the matrix via the branched grain boundary and larger branched melt channel (leucosome) arrays collected. Melt collected in the foliation planes was partially, or fully, expelled later, when discordant leucosomes formed. Leucosomes (or veins) oriented at high angles to the foliation/layering formed last and commonly lack melanocratic borders; hence they were not involved in draining the matrix of the melting layer. Discordant leucosomes represent the channels through which melt flowed out of the melting layer.  相似文献   

产业带边界划分的理论与方法：胶济沿线产业带实例分析   总被引：12，自引：0，他引：12  

费洪平 《地理学报》1994,49(3):214-225

本文提出将企业微观分析与宏观区域研究相结合的方法进行产业带划分。在理论上剖析了产业带的概念、划分原则与指标；在微观尺度上以大中型企业和典型企业集团为主要调查研究单元，作者利用所获得的调查数据，并结合宏观区域经济特点，对胶济沿线产业带边界划分的方法与步骤作了初步尝试，并试图从新的角度为我国经济区划研究，提供一种新的方法途径，同时也期望为胶济沿线产业带整体空间组织与规划提供科学依据。  相似文献   

Pressure and temperature evolution in sedimentary basins   总被引：1，自引：0，他引：1  

Magnus Wangen 《Geophysical Journal International》1992,110(3):601-613

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Recent geodynamic evolution of convergent plate margins and the reconstruction of fossil plate boundaries     

Václav Hanuš  Jiří Vaněk 《Studia Geophysica et Geodaetica》1995,39(4):375-388

Summary The discovery of paleoplates buried in the upper mantle leads to an interpretation of the subduction as a discontinuous process running in cycles and shifting the place of its operation in or against the direction of ocean floor spreading. This mechanism explains the distribution of calc-alkaline volcanism of different age in fossil convergent plate boundaries. The establishment of regular spatial correlation of the aseismic gap in the Wadati-Benioff zones with the distribution of calc-alkaline volcanism enables to reconstruct fossil plate boundaries and to define allochtonous terranes in apparently homogeneous continental plates. The hampering effect of the ocean floor morphology and of the fragments of continental plates approaching the trench, which substantially influences the rates of subduction and the geodynamic history of active continental margins in different domains along the trench, allows us to understand the complicated geological development of continental wedges in fossil convergent plate margins. The establishment of the segmented nature of active subduction zones and the dramatic morphology of the lower limit of the active subducted slab along the trench help us to interpret extensive lateral gaps in volcanic chains overlying active as well as fossil subduction zones.  相似文献   

交通运输温室气体核算边界和测算方法研究     

李晓易  吴睿 《气候变化研究进展》2023,19(1):84-90

交通运输行业是温室气体排放的主要来源之一。“双碳”目标对交通领域碳减排工作提出了更高的要求。我国交通运输行业能源消耗统计和温室气体排放测算的统计数据基础较为薄弱,目前国家层面尚未公布统一的交通运输温室气体核算方法,温室气体排放存在底数不清的问题,其核算边界、范围、方法都有待进一步明确。文中通过梳理国内外交通运输领域温室气体核算边界及测算方法,提出了适用于我国交通运输不同子领域温室气体的测算研究思路。并针对我国交通运输温室气体核算工作现存问题,从健全行业能耗与排放核算方法体系、建立交通运输能耗与碳排放数据共享机制、加强交通能耗与碳排放核算方法培训、强化数据质量管理等方面提出相应的政策建议,为我国交通运输行业温室气体排放核算工作的持续开展提供参考。  相似文献   

Compound paleovalley fills in the Lower Pennsylvanian New River Formation, West Virginia, USA     

Jesse T. Korus  Erik P. Kvale  Kenneth A. Eriksson  R.M. Joeckel   《Sedimentary Geology》2008,208(1-2):15-26

Ancient paleovalley fills are typically interpreted in the rock record using over-generalized models without carefully considering modern analogs, especially in light of recent discoveries. It is now known that many Quaternary paleovalleys are compound in origin, exhibit considerable stratigraphic complexity, contain multiple incisions, and can be orders of magnitude larger than their putative ancient counterparts. Compound paleovalley fills in the Lower Pennsylvanian New River Formation (NRF) are directly comparable to these Quaternary analogs, stimulating a paradigm shift in the interpretation of ancient paleovalleys. In the NRF, multiple laterally- and vertically-juxtaposed fill successions, separated by incision surfaces, record high-frequency fluvial responses to external controls within lower-order sequences. Lowstand incision and sediment bypass, as predicted in sequence stratigraphy, is largely discounted by the available evidence and the definition of regional sequence boundaries is not straightforward. The identification of genetic sequences may be the most effective approach to understanding the NRF and, by inference, many other ancient paleovalleys. Results from this study of the NRF promote a revised model for ancient paleovalleys that incorporates: 1) the pre-eminence of compound architecture, 2) periodic episodes of incision and subaerial exposure occurring in response to high-frequency changes in climate or relative sea level, 3) fluvial downcutting as the primary cause of paleovalley incision, although some sediments are still preserved in a net-erosional regime, and 4) composite, time-transgressive sequence boundaries that may be difficult or impossible to correlate regionally.  相似文献