三维构造模拟方法--体平衡技术研究

为了实现三维构造史模拟,在二维平衡剖面技术的基础上,提出了适用于在维构造模拟的方法－体平衡技术,其核心是通过分析断层演化及地层变形在三维空间中的特殊性,建立三维复杂构造的数学模型和三维物质平衡方法,它简化了平衡时三维的体积计算和对不平衡体积构造体的适应性,从而减少了三维构造模拟的实现难度。     

PHENOMENA AND CONTROLLING FACTORS IN DRAWDOWN FLUSHING PROCESSES

IINTRODUCTIONByutilizingthenatUralpowerofflow,hydraulicflushingisaneconomicaltechniquetoremovethedepositedsedimentineitherasettlingbasinorareservoir.Inmanyreservoirsaroundtheworld,hydraulicflushinghasbeenprovenasaneffectivemethodtosustainthereservoirstoragecapacity.Hydraulicflushingprocessesmayinvolveboththeprocessesofscouringpreviousdepositsandpassingincomingsediment-ladenflow,suchasgravitycurrent,throughareservoirtobereleased.Inthisarticle,onlytheformercaseisdiscussed.Thekeythinginthef…     

Rupture process of the M_L=4.1 earthquake in Huailai Basin on July 20, 1995

IntroductionIntheanalogrecordingera,onlyarrivaltimePwaveonsetandmaximumamplitudeofrecordingswereusedtocalculatetheparametersofearthquakefool.Sincelate1970s,withtheincreasingnumberofdigitalseismicnetworkcomingintooperation,itispossibletodofurtherresearchesinfocalphysics.Toinvertmoredetailedparameterssuchastempo-spatialprocessesofearthquakefoolusingdigitalseismicdataisanimportantfieldindigitalseismology.Sourcetimefunction(STF)isoneofkeyparametersaboutruptureprocessesofearthquakefocuses.Spontan…     

Sequence stratigraphy of the Dakota Formation (Cenomanian), southern Utah: interplay of eustasy and tectonics in a foreland basin

The Dakota Formation in southern Utah (Kaiparowits Plateau region) is a succession of fluvial through shallow-marine facies formed during the initial phase of filling of the Cretaceous foreland basin of the Sevier orogen. It records a number of relative sea-level fluctuations of different frequency and magnitude, controlled by both tectonic and eustatic processes during the Early to Late Cenomanian. The Dakota Formation is divided into eight units separated by regionally correlatable surfaces that formed in response to relative sea-level fluctuations. Units 1–6B represent, from bottom to top, valley-filling deposits of braided streams (unit 1), alluvial plain with anastomosed to meandering streams (2), tide-influenced fluvial and tide-dominated estuarine systems (3A and 3B), offshore to wave-dominated shoreface (4, 5 and 6A) and an estuarine incised valley fill (6A and 6B). The onset of flexural subsidence and deposition in the foredeep was preceded by eastward tilting of the basement strata, probably caused by forebulge migration during the Early Cretaceous, which resulted in the incision of a westward-deepening predepositional relief. The basal fluvial deposits of the Dakota Formation, filling the relief, reflect the onset of flexural subsidence and, possibly, a eustatic sea-level rise. Throughout the deposition of the Dakota Formation, flexure controlled the long-term, regional subsidence rate. Locally, reactivation of basement faults caused additional subsidence or minor uplift. Owing to a generally low subsidence rate, differential compaction locally influenced the degree of preservation of the Dakota units. Eustasy is believed to have been the main control on the high-frequency relative sea-level changes recorded in the Dakota. All surfaces that separate individual Dakota units are flooding surfaces, most of which are superimposed on sequence boundaries. Therefore, with the exception of unit 6B and, possibly, 3B, most of the Dakota units are interpreted as depositional sequences. Fluvial strata of units 1 and 2 are interpreted as low-frequency sequences; the coal zones at the base and within unit 2 may represent a response to higher frequency flooding events. Units 3A to 6B are interpreted as having formed in response to high-frequency relative sea-level fluctuations. Shallow-marine units 4, 5 and 6A, interpreted as parasequences by earlier authors, can be divided into facies-based systems tracts and show signs of subaerial exposure at their boundaries, which allows interpretation as high-frequency sequences. In general, the Dakota units are good examples of high-frequency sequences that can be misinterpreted as parasequences, especially in distal facies or in places where signs of subaerial erosion are missing or have been removed by subsequent transgressive erosion. Both low- and high-frequency sequences represented by the Dakota units are stacked in an overall retrogradational pattern, which reflects a long-term relative sea-level rise, punctuated by brief periods of relative sea-level fall. There is a relatively major fall near the end of the M. mosbyense Zone, whereas the base of the Tropic shale is characterized by a major flooding event at the base of the S. gracile Zone. A similar record of Cenomanian relative sea-level change in other regions, e.g. Europe or northern Africa, suggests that both high- and low-frequency relative sea-level changes were governed by eustasy. The high-frequency relative sea-level fluctuations of ≈100 kyr periodicity and ≈10–20 m magnitude, similar to those recorded in other Cenomanian successions in North America and Central Europe, were probably related to Milankovitch-band, climate-driven eustasy. Either minor glacioeustatic fluctuations, superimposed on the overall greenhouse climate of the mid-Cretaceous, or mechanisms, such as the fluctuations in groundwater volume on continents or thermal expansion and contraction of sea water, could have controlled the high-frequency eustatic fluctuations.     

油气系统动力学模拟方法评价

介绍了油气系统研究中最新发展起来的油气系统动力学方法;在与常规油气盆地模拟方法进行比较研究的基础上,对系统动力学模拟方法进行了评价,指出系统动力学模拟可较好地解决目前油气盆地模拟中存在的许多关键问题,是研究油气系统的有效途径。     

陆相盆地层序地层学研究中几个问题的探讨

将层序地层学理论应用于陆相盆地研究仍处于探索阶段。陆相盆地的层序界面、最大洪泛面和首次洪泛面的识别标志都有别于海相地层。依据层序地层学理论和对松辽盆地的探索性研究, 对陆相盆地提出了层序界面、最大洪泛面和首次洪泛面的识别标志。     

Velocity structure in the South Yellow Sea basin based on first-arrival tomography of wide-angle seismic data and its geological implications

The South Yellow Sea basin is filled with Mesozoic–Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic–Palaeozoic marine sediments. Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail, leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments. In this study, we present seismic tomography data from ocean bottom seismogra...     

流域土地利用分区空间管制研究与初步实践——以太湖流域为例

流域空间开发和土地利用在推动经济社会发展的同时,对流域生态系统的健康和安全造成了剧烈影响,迫切需要在流域综合管理中充实完善土地利用分区与管制等研究内容,因而成为推动湖泊-流域相互作用研究的重要科学问题之一.本文在回顾相关土地利用分区与管制研究基础上,从流域自然地理单元特殊性和管理目标复杂性出发,探讨了流域水陆系统相互作用机制,分析了流域土地利用分区与空间管制的研究重点与基本思路,提出了流域土地利用分区的技术路线及关键方法,并以太湖流域为例进行了初步的实践探索,提出严格保护区、适度发展区、开发利用区和保留发展区四种类型区及其空间管制要求,符合流域资源环境与经济社会发展实际,为流域可持续开发和保护提供指导.最后,讨论了未来流域土地利用分区空间管制需要进一步研究的重点方向与关键问题.     

1990s长江下游干流径流量演变趋势

利用M-K相关分析方法和大通站1950-2000年逐月径流资料,研究了长江下游干流径流的趋势变化.研究结果表明:1950s以来长江下游径流量呈增加趋势,1990s平均径流量(30415.3 m³/s)比所有其他年代平均径流都大,为近50a以来的最大值;就季节和月份而言,秋季径流明显减少;夏、冬两季径流量,增加的趋势明显,尤以冬季枯水季节径流增加最为突出.洪水、枯水季节径流增加明显,但以枯水季节径流增加占优势.冬季枯水径流的增加,可能在一定程度上能够缓解长江口生态环境的巨大压力.1990s径流量的增加与全球变暖、水循环加快、长江流域降水量增加密切相关.     

经验方法研究下垫面变化对洪水的影响

1980s以来,人类活动对下垫面的影响加剧,研究下垫面变化对流域产汇流规律的影响具有重要意义.通过对海河流域中紫荆关、阜平两个流域分别用经验方法进行洪水模拟演算,并把洪水资料按照年代不同分时段,建立P+Pa～Rs相关关系图,分析流域下垫面变化对降雨径流相关关系的影响.建立产流量R与洪峰Qm之间的相关关系,通过统计比较不同年代的趋势线发现,在产流量相同情况下,1980s后的洪峰流量较1980s前有所减少,说明海河流域的调蓄作用有增强的趋势.同时建立流域下垫面条件改变后产流量与洪峰变化幅度的相关关系,发现流域产流量变化与洪峰变化呈正相关关系.