Anatomy of shelf deltas at the edge of a prograding Eocene shelf margin, Spitsbergen   总被引：1，自引：0，他引：1  

Donatella Mellere  Piret Plink-Björklund†  Ronald Steel† 《Sedimentology》2002,49(6):1181-1206

Abstract Although shelf‐edge deltas are well‐imaged seismic features of Holocene and Pleistocene shelf margins, documented outcrop analogues of these important sand‐prone reservoirs are rare. The facies and stratigraphic architecture of an outcropping shelf‐edge delta system in the Eocene Battfjellet Formation, Spitsbergen, is presented here, as well as the implications of this delta system for the generation of sand‐prone, shelf‐margin clinoforms. The shelf‐edge deltas of the Battfjellet Formation on Litledalsfjellet and Høgsnyta produced a 3–5 × 15 km, shelf edge‐attached, slope apron (70 m of sandstones proximally, tapering to zero on the lower slope). The slope apron consists of distributary channel and mouth‐bar deposits in its shelf‐edge reaches, passing downslope to slope channels/chutes that fed turbiditic lobes and spillover sheets. In the transgressive phase of the slope apron, estuaries developed at the shelf edge, and these also produced minor lobes on the slope. The short‐headed mountainous rivers that drained the adjacent orogenic belt and fed the narrow shelf, and the shelf‐edge position of the discharging deltas, made an appropriate setting for the generation of hyperpycnal turbidity currents on the slope of the shelf margin. The abundance of organic matter and of coal fragments in the slope turbidites is consistent with this notion. Evidence that many of the slope turbidites were generated by sustained turbidity currents that waxed then waned includes the presence of scour surfaces and thick intervals of plane‐parallel laminae within turbidite beds in the slope channels, and thick spillover lobes with repetitive alternations of massive and flat‐laminated intervals. The examined shelf‐edge to slope system, now preserved mainly below the shelf break and dominated by sediment gravity‐flow deposits, has a threefold stratigraphic architecture: a lower, progradational part, in which the clinoforms have a slight downward‐directed trajectory; a thin aggradational zone; and an upper part in which clinoforms backstep up onto the shelf edge. A greatly increased density of erosional channels and chutes marks the regressive‐to‐transgressive turnaround within the slope apron, and this zone becomes an angular unconformity up near the shelf edge. This unconformity, with both subaerial and subaqueous components, is interpreted as a sequence boundary and developed by vigorous sand delivery and bypass across the shelf edge during the time interval of falling relative sea level. The studied shelf‐margin clinoforms accreted mostly during falling stage (sea level below the shelf edge), but the outer shelf later became estuarine as sea level became re‐established above the shelf edge.  相似文献   

Denudation and cooling of the Lake Teletskoye Region in the Altai Mountains (South Siberia) as revealed by apatite fission-track thermochronology     

Johan De Grave  Peter Van den haute 《Tectonophysics》2002,349(1-4)

Lake Teletskoye occupies a narrow graben located in the northwestern sector of the Altai fold belt in South Siberia. The lake basin is thought to have formed during the Pleistocene as a distant result of the Cenozoic collision of India and Eurasia that caused a tectonic reactivation of the Palaeozoic Gorny–Altai (GA) and West Sayan (WS) blocks.The present work reports of a pilot fission-track study performed on 13 apatite separates collected from rocks that were sampled along two profiles in close proximity of the lake. The age–length data and AFT thermochronological modelling reveal two important phases of cooling in the Altai Mountains, a first one during the Late Jurassic–Early Cretaceous and a second one that started in the Miocene–Pliocene and that persists until today. The first event is interpreted to result from uplift-induced denudation probably related to the closure of the Mongol–Okhotsk Ocean; the second event can be linked to the young Cenozoic movements that lie at the origin of the formation of the Lake Teletskoye basin.  相似文献   

Physical properties of ultrahigh-pressure metamorphic rocks from the Sulu terrain, eastern central China: implications for the seismic structure at the Donghai (CCSD) drilling site     

Hartmut Kern  Zhenmin Jin  Shan Gao  Till Popp  Zhiqin Xu 《Tectonophysics》2002,354(3-4)

About 30 samples representing major lithologies of Sulu ultrahigh-pressure (UHP) metamorphic rocks were collected from surface exposures and exploration wells, and compressional (Vp) and shear wave (Vs) velocities and their directional dependence (anisotropy) were determined over a range of constant confining pressures up to 600 MPa and temperatures ranging from 20 to 600 °C. Samples range in composition from acidic to ultramafic. P- and S-wave velocities measured at 600 MPa vary from 5.08 to 8.64 km/s and 2.34 to 4.93 km/s, respectively. Densities are in the range from 2.60 to 3.68 g/cm³. To make a direct tie between seismic measurements (refraction and reflection) and subsurface lithologies, the experimental velocity data (corresponding to shallow depths) were used to calculate velocity profiles for the different lithologies and profiles of reflection coefficients at possible lithologic interfaces across the projected 5000-m Chinese Continental Scientific Drilling Program (CCSD) crustal segment. Comparison of calculated in situ velocities with respective intrinsic velocities suggests that the in situ velocities at shallow depths are lowered by an increased abundance of open microcracks. The strongly reflective zone beneath the Donghai drill site can be explained by the impedance contrasts between the different lithologies. Contacts between eclogite/peridotite and felsic rocks (gt-gneiss, granitic gneiss), in particular, may give rise to strong seismic reflections. In addition, shear-induced (lattice preferred orientation (LPO)-related) seismic anisotropy can increase reflectivity. For the explanation of the high velocity bodies (>6.4 km/s) around 1000 m and below 3200-m depth, large proportions of eclogite/peridotite (about 40 and 30 vol.%, respectively) are needed.  相似文献   

Analyzing CO2 emissions mitigation by technology improvement in Central and Eastern Europe     

Diana Ürge-Vorsatz  Adam Szeszler 《GeoJournal》2002,57(3):211-226

As a legacy of the centrally planned economy, the economies in transition of Central and Eastern Europe (CEE) have a unique potential to reduce their greenhouse gas emissions through the improvement in their high energy intensities. Since much of this `low-hanging fruit' in energy-efficiency improvements can be highly cost-effective, many developed countries facing difficulties in meeting their greenhouse gas (GHG) emission targets domestically are eager to find such opportunities in the CEE region. Therefore, studies analysing the potentials and costs of carbon dioxide reduction through technology improvement in the region have come into the limelight. While there are a few excellent studies in the region aimed at analysing climate change abatement potentials, they all embark on different assumptions, methodologies and boundary conditions. It is hence difficult, if not impossible, to compare and analyse the results of these studies across different authors, countries or time horizons. Consequently, the purpose of this paper is to place four leading studies on GHG mitigation through technology improvement from the CEE region into an internationally comparable framework. Four studies were selected from three countries, Poland, Hungary and Estonia, which are all the results of major national and international efforts to assess costs and potentials of GHG reduction. The paper places their assumptions, methods and final results into a framework which enables policy-makers and project designers to compare these across geographical and technological boundaries. Since other studies from around the globe have been analysed in this framework in the literature, this paper provides a vehicle for the findings of these four studies to be compared to others worldwide. In addition, the paper highlights a few areas where similar studies to be completed in the future in the region may be enhanced by incorporating features used in GHG mitigation research in other parts of the world. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

影响地下应力状态的构造作用   总被引：4，自引：0，他引：4  

刘瑞珣  吕古贤 《地球学报》2002,23(2):103-106

成岩成矿的外部条件中压力是很重要的因素。地下岩石所受的压力不仅来自上覆岩石的重力，而且来自构造力和热力及其它力。这些力合成一个三轴不等的应力状态，相当一个以最短轴为半径的球状应力迭加一个差应力。前者影响成岩成矿和变质作用，后者控制岩石变形和组构的变化。通过三维应变应力测量，这两部分力通过计算是可以区分开的，因而这将是建立地下深度测算新方法的一个基础。  相似文献   

Cathodoluminescence of authigenic albite     

Detlev K. Richter  Thomas G  tte  Dirk Habermann 《Sedimentary Geology》2002,150(3-4):367-374

Authigenic albites in carbonate rocks typically grow in a high-grade diagenetic to low-grade metamorphic environment and often show Roc-Tourné-twinning sensu Füchtbauer. Based on an investigation of four Middle to South European occurrences, they show Mn²⁺- and Fe³⁺-activated cathodoluminescence (CL), as revealed by combined high resolution spectroscopy of cathodoluminescence emission (HRS-CL), electron paramagnetic resonance (EPR), and proton-induced X-ray emission (μPIXE).  相似文献   

Intercomparison of IRS-P4-MSMR derived geophysical products with DMSP-SSM/I and TRMM-TMI finished products     

A. K. Varma  R. M. Gairola  A. K. Mathur  B. S. Gohil  Vijay K. Agarwal 《Journal of Earth System Science》2002,111(3):247-256

In this paper, MSMR geophysical products like Integrated Water Vapour (IWV), Ocean Surface Wind Speed (OWS) and Cloud Liquid Water (CLW) in different grids of 50, 75 and 150 kms are compared with similar products available from other satellites like DMSP-SSM/I and TRMMTMI. MSMR derived IWV, OWS and CLW compare well with SSM/I and TMI finished products. Comparison of MSMR derived CLW with that derived from TMI and SSM/I is relatively in less agreement. This is possibly due to the use of 37 GHz in SSM/I and TMI that is highly sensitive to CLW, while 37 GHz channels are not available on MSMR. Monthly comparison of MSMR geophysical products with those from TMI is all carried out for climatological purpose. The monthly comparisons were much better compared to instantaneous comparisons. In this paper, details of the data analysis and comparison results are presented. The usefulness of the MSMR vis-à-vis other sensors is also discussed.  相似文献   

Documentary and Geological Records of Tsunamis in the Aegean Sea Region of Greece and their Potential Value to Risk Assessment and Disaster Management     

Dominey-Howes  Dale 《Natural Hazards》2002,25(3):195-224

Understanding the nature and impacts of tsunamis within the Aegean Sea region ofGreece is of importance to both the academic community and those organisationsconcerned with tsunami disaster management. In order to determine hazard and riskand consequently pre-plan mitigative strategies, it is necessary to analyse historical(documentary) and geological records of former tsunami events. Therefore, firstlythis paper provides a summary of the written sources of information on Aegeantsunamis paying particular attention to published catalogues. From the availabledata, it is noted that a large number of events have been reported during the last3500 years. Secondly, the paper provides a review of the published on-shore(terrestrial) geological records of tsunamis within the region. From this analysisit is seen that little geological evidence has been identified for the large numberof tsunamis reported in the catalogues. Thirdly, the paper considers the reliabilityof the written and geological records and how problems of accuracy, coverage,extent and reliability, may have potential implications for the estimation of hazardand risk. The paper concludes by making recommendations for disaster managers,geologists and historians to work closely together.  相似文献   

交流变频调速CD-2B型岩心钻机的研制          下载免费PDF全文

宋振波  李建华  刘凡柏 《探矿工程》2002,(3):23-26

介绍了交流变频调速CD－2B型岩心钻机研制情况，技术参数，主要特点及型式检验，生产试验等情况。  相似文献   

山地丘陵地区物探爆破孔钻机及配套机具的研究与开发          下载免费PDF全文

赵大军  孙友宏  侯传彬  薛军 《探矿工程》2002,(4):22-24

为满足我国山地丘陵地区物探爆破孔施工技术的要求，研究适合土层、岩层钻进用的钻机及工具，对钻机的配套设备进行了开发研究。分析了国内山地丘陵地区物探爆破孔施工技术现状，并着重介绍了研制设计内容及生产试验情况。  相似文献