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1.
Half-graben basin filling models: new constraints on continental extensional basin development 总被引：5，自引：0，他引：5
Roy W. Schlische 《Basin Research》1991,3(3):123-141
Three end-member models of half-graben development (detachment fault, domino-style, and fault growth) evolve differently through time and produce different basin-filling patterns. The detachment fault model incorporates a basin-bounding fault that soles into a subhorizontal detachment fault; the change in the rate of increase in the volume of the basin during uniform fault displacement is zero. Younger strata consistently pinch out against older synrift strata rather than pre-rift rocks. Both basin-bounding faults and the intervening fault blocks rotate during extension in the domino fault block model; a consequence of this rotation is that the change in the rate of increase of the volume of the basin is negative during uniform extension. Basin fill commonly forms a fanning wedge during fluvial sedimentation, whereas lacustrine strata tend to pinch out against older synrift strata. In the fault growth models, basins grow both wider and longer through time as the basin-bounding faults lengthen and displacement accumulates; the change in the rate of increase in basin volume is positive. Fluvial strata progressively onlap pre-rift rocks of the hanging wall block, whereas lacustrine strata pinch out against older fluvial strata at the centre of the basin but onlap pre-rift rocks along the lateral edges. These fundamental differences may be useful in discriminating among the three end-member models. The transition from fluvial to lacustrine deposition and hanging wall onlap relationships observed in numerous continental extensional basins are best explained by the fault growth models. 相似文献
2.
Lacustrine basins and their deposits are good paleoclimate recorders and contain rich energy resources. Shelf-margin clinoforms do exist in deep lacustrine basins, but with striking differences from those in deep marine basins, caused by a correlation between the river-derived sediment supply and the lake level. This study uses empirical relationships to calculate the water and sediment discharge from rivers and coeval lake level during wet–dry cycles at 10 s of ky time scale. Sediment supply and lake-level changes are used for a stratigraphic forward model to understand how lacustrine clinoforms develop under different climate conditions. The results show that both wet and dry cycles can be associated with thick deep-water fan deposits, supporting the existing climate-driven lacustrine model proposed based on field data (e.g. Neogene Pannonian Basin and Eocene Uinta Basin). The wet period with high sediment supply and rising lake level creates the highly aggradational shelf, progradational slope and thick bottomset deposits. This is contrary from marine basin settings where the presence of rising shelf-margin trajectory commonly indicates limited deep-water fan deposits. This work suggests marine-based stratigraphic models cannot be directly applied to lacustrine basins. 相似文献
3.
This paper presents an overview of some of the most significant, recent to ancient, littoral morpho-sedimentary structures and deposits from the Lake Turkana Basin. We highlight the importance of wave-related sedimentary processes in lakes, and more specifically in rift lakes. In the published literature, references to wave-dominated shorelines are mainly in regards to coastal marine environments. However, numerous modern lakes exhibit typical wave-dominated littoral landforms, and related sedimentary deposits are known from several paleolake successions in the geological record. Wave-related processes are often of relatively minor importance in depositional models for lacustrine environments. Classical models emphasize clastics transported by rivers, which are then distributed by fan-deltas and/or deltas into a water body of fluctuating depth, where reworking of clastics is limited in the littoral domain, and episodic in deep waters. Modern processes in Lake Turkana and the exposed paleolake deposits of the Turkana Basin demonstrate that this view is incomplete. Wave-dominated shorelines are evident (1) for modern Lake Turkana based on prominent and active littoral landforms (e.g., beach ridges, sand spits, washover fans, and arcuate-cuspate deltas); (2) for the Holocene (African Humid Period) climate-driven highstand of Megalake Turkana and its subsequent forced regression based on conspicuous raised beach ridges and spits; and (3) for the Pliocene–Pleistocene (Omo Group, Nachukui Formation) from typical nearshore sedimentary facies and stratigraphic architectures associated with paleolake Turkana. These examples from the Turkana Basin coupled with examples from other lacustrine settings, suggest that wave-dominated clastic shorelines represent significant portions of existing and ancient lake-shores. As this view contrasts with classic depositional models for lakes, notably for those found in rift setting, we also present examples of wave-influenced littoral landforms from other lakes of the East African Rift System. Identifying lacustrine paleoshorelines from typical clastic landforms and deposits is the key to the spatial reconstruction of lakes over time, and to determine transgressive–regressive cycles. Waves action is an important agent in lakes for the erosion, transport, and deposition of clastics at the basin-scale, an aspect that needs to be integrated in sedimentary models. 相似文献
4.
湖泊自生碳酸盐碳同位素组成(δ13Cc)在区域气候与环境变化方面的应用研究近年来进展迅速,成果显著,保存在各类湖泊沉积物柱芯中的δ13Cc记录揭示了湖表水体与大气CO2的交换程度、暖季降水量的多少、流域C3和C4植被变化情况、水生生物光合作用或呼吸作用强弱、湖泊生产力大小、湖泊水体化学特征、湖水不同深度层的有机质变化过程等重要的气候和环境信息;对此进行归纳和述评。 相似文献
5.
Barry Jay Katz 《Journal of Paleolimnology》2001,26(2):161-179
Although much of the world's petroleum resource-base is associated with marine systems, regionally lacustrine petroleum systems are important. Individual accumulations may exceed several billion barrels. In each of these cases the oil is derived from a lacustrine source rock and may be produced from either nonmarine or marine reservoir rocks. The purpose of this paper is to describe the factors that control lacustrine source rock development and the nature of lacustrine reservoirs. Lacustrine oils display different physical and chemical characteristics than their marine counterparts. These differences can be related to the nature of their precursor material. Although the nature of the products are different, the geochemical threshold criteria for defining source rocks in both settings are the same because of common expulsion requirements. Commercially significant lacustrine systems require the presence of large, long-lived lakes. Such lake settings are tectonic in origin and restricted to climatic settings where precipitation exceeds evaporation. Within these large lake systems three primary factors determine source rock potential and quality. These factors are primary productivity level, organic preservation potential, and matrix sedimentation rate, which controls the dilution of preserved organic matter. Source rock potential is maximized where both productivity and preservation potential are maximized and sedimentation rate is minimized. To some degree these factors can compensate for each other. Hydrocarbon reservoir potential within lacustrine basins is partially impacted by overall tectonic setting. Within extensional settings, transport distances tend to be limited, with much of the sediment being transported away from the basin. The sediments delivered to the lake are poorly sorted and sedimentologically immature, commonly resulting in poor reservoirs due to both primary properties and their susceptibility to diagenesis. Within rifts better reservoirs tend to develop along platform or flexural margins. Stacking of reservoirs is important in lacustrine systems but baffles and barriers are often present between individual sand units. These barriers form as a result of lake level fluctuations. In compressional settings transport distances tend to be longer, resulting in more mature, better sorted sediments leading to higher quality reservoirs. These reservoirs typically develop in fluvial-deltaic and wave-dominated shoreline settings. Lacustrine carbonate reservoirs are locally important. These carbonates tend to develop during lake level lowstands and are dependent on diagenesis (dissolution and karstification) for porosity and permeability development. Lacustrine reservoirs are often stratigraphically and areally limited and display low individual well production rates. Within pure lacustrine systems exploration opportunities appear to be often restricted by either reservoir presence or quality (i.e., production rates). The best exploration opportunities in lacustrine basins appear to be associated with hybrid systems where a lacustrine source and marine reservoir exist. 相似文献
6.
7.
民勤盆地位于石羊河下游,现今大面积地区已被风沙覆盖.前人的研究报道了在民勤盆地的东部曾经发育过一个面积巨大的"腾格里古大湖",然而尚不明确民勤盆地是否也曾被湖水覆盖.为此,本文收集整理了民勤盆地中8个水文地质钻孔的地层资料,利用GIS技术重现了研究区地表以下50 m深度内的湖相地层的空间分布特征.分析发现,在盆地的不同地区普遍发育了2~3层深湖亚相地层,部分地区甚至多达4层,各湖相层厚度介于0.5~32 m.区域地层对比结果显示,在某个时段研究区大范围地区普遍发育了深水湖泊,而其他时段则在不同地区零星发育了小湖泊.结合研究区已有的测年资料,本文认为在晚第四纪某个时段(倒数第二层深湖亚相发育阶段),整个研究区内曾经存在一个规模较大的连通湖泊;但民勤盆地晚第四纪不同阶段深湖亚相地层差异明显的空间分布特征,可能反映了湖盆沉积中心自东向西、再向北东的迁移过程. 相似文献
8.
毛乌素沙漠东南缘滴哨沟湾剖面DGS1层段粒度特征及其指示的全新世气候变化 总被引：4，自引：2，他引：2
分析滴哨沟湾剖面全新统DGS1段的粒度数据,认为流动沙丘砂、泥炭、砂质古土壤、古固定-半固定沙丘砂到湖沼相和次生黄土的颗粒总体上变细,分选变差。结合腹足类动物化石和湖沼相地层中石英砂粒表面电镜扫描,认为DGS1粒度结果实际上是全新世以来多次冬夏季风的交互演替过程的气候-地质记录。据此,将DGS1粒度信号记录的全新世气候分为4个阶段——全新世早期好转期、全新世鼎盛期、大暖期向寒冷期转变波动期和降温不稳定的沙漠化频繁变化时期。 相似文献
9.
Eudald Maestro 《Journal of Paleolimnology》2008,40(4):1053-1078
A complete third-order tectono-sedimentary cycle filled the Vernet lacustrine piggyback basin during the late Eocene. The
depositional sequence can be subdivided into five units or systems tracts with distinct architectural frameworks, which developed
a progressive unconformity. Sedimentary infilling of the piggyback basin began with retrogradational alluvial fans and fluvio-alluvial
deposits being deposited, arranged in two thinning- and fining-upward cycles during the uplifting and emplacement of the southernmost
Pyrenean thrusts, and with three thickening- and coarsening-upward progradational floodplain and lacustrine cycles, during
the quiescence of the southernmost thrusts, at the same time as the emplacement of several northernmost thrusts of the southern
Pyrenees. The facies associations identified represent different depositional environments in a sheetflow-dominated system,
including playa-lake deposits, floodplain deposits, sheetflow fluvial deposits and sheet deltas in ephemeral to shallow lacustrine
settings. Fourth and fifth order arid/semi-arid climatic cycles can be recognized, driven either by orbital obliquity and
precessional forcing (Milankovitch cyclicity), insolation cycles or possibly subprecessional autogenic mechanisms related
to the emplacement of northern thrusts and the consequent changes in the drainage basin. Arid periods are recorded by sheetflood
fluvial, ephemeral lacustrine or terminal splay deposits, with abundant medium-to-coarse-grained sandstone packages in red-to-grey
mudstones, a product of unconfined or low-confined sheetflows or hyperconcentrated flows, with bedload and suspended load,
during flood episodes, at times of lake lowstand. Semi-arid periods are recorded as relative highstand lacustrine deposits,
including grey-to-white mudstones deposited in prodelta environments and fine-grained sheet sandstone units sedimented in
a delta front (with minor channels and extensive sheet lobes) and prodelta environments in shallow lakes, from sheetflood
events. 相似文献
10.
11.
萨拉乌苏河流域MGS2层段粒度与CaCO3记录的千年尺度气候变化 总被引：2，自引：0，他引：2
测定、分析毛乌素沙漠东南缘萨拉乌苏河流域米浪沟湾剖面MGS2层段的粒度与CaCO3,发现该层段不同沉积相粒度Mz和σ呈现峰谷变化,CaCO3含量在沙丘砂及其上覆的河流相和湖沼相中依次变化于0-2.94%(平均值0.39%)、0.14%-2.68%(1.43%)和0.39%-15.57%(8.82%),并与Mz呈显著相关,构成与沉积旋回波动韵律相同的5.5个峰谷交替的粒度与CaCO3旋回。研究表明,毛乌素沙漠冬季风盛行时期沙丘砂强烈堆积,CaCO3发生迁移;夏季风盛行时期河流相和湖沼相发育,粉砂和粘土含量增加,CaCO3相对聚集。这些旋回代表东亚冬夏季风千年尺度交替变化的气候旋回。 相似文献
12.
The Junggar Basin in NW China contains lacustrine hydrocarbon source rocks which are among the highest quality of hydrocarbon potential in the world. Oil reservoirs in the basin are very substantial: target reservoirs span Carboniferous to Tertiary strata and include Permo-Triassic lacustrine and fluvial sandstones. The Junggar Basin was a foreland basin during the late Permian to Cenozoic, possibly with strike-slip tectonics at the southern margin during Mesozoic time. The Cangfanggou Group, as one of the major reservoirs, is well-exposed in the eastern part of the southern Junggar Basin. A measured outcrop section and a number of borehole logs coupled with resistivity logs were used to attempt sequence stratigraphic analysis. Detailed sedimentological studies on the outcrops and borehole cores have demonstrated that the Cangfanggou Group is characterized by alternating lacustrine and fluvial deposits. Four depositional sequences have been recognized. For each sequence, the basal boundary is marked by erosional truncation of fluvial channel conglomeratic sandstones in sharp contact with underlying lacustrine or floodplain mudstones. The top of each lowstand systems tract is normally overlain by the transition to lacustrine or maximum flooding surface. The transgressive systems tract is normally not identifiable at the basin margin, but was developed in the basinward area and characterized by interbedded fining-upward distal fluvial and shallow lacustrine deposits. The highstand systems tract at the basin margin is characterized by very thick floodplain mudstones or shallow lacustrine deposits, and by typical coarsening-upward parasequences of shallow lacustrine deposits in more basinward areas. Sediment input to the basin was controlled by tectonics and climate. Depositional sequences were probably controlled by fluctuating change of lake level: this was in turn controlled by climate (runoff), modified by tectonics in specific areas.The sandstones studied are exclusively volcanic litharenites. Diagenetic studies suggest that the calcite cementation, pore-filling clay minerals and zeolites occluded substantial porosity in the sandstones examined because they are compositionally immature. However, notable secondary porosity in varying proportions is present in the sandstones of the Cangfanggou Group, resulting from the dissolution of unstable detrital grains. The lowstand fluvial/distal fluvial sandstones recorded the highest average porosity and highest permeability, in which some primary porosity may remain because early formed clay coatings inhibited further compaction. The combination of residual primary porosity and significant amount of secondary porosity in the sandstones of the Cangfanggou Group may constitute moderate to good reservoirs. In contrast, the lacustrine fine-grained sandstones is characterized by clay authigenesis and zeolitization, in which the porosity was obliterated by the zeolites and extensive illitization; the lowstand fluvial channel sandstones in the basin margin areas are characterized by extensive calcite cementation which greatly reduced the porosity and permeability.This is the fifth paper in a series of papers published in this issue on Climatic and Tectonic Rhythms in Lake Deposits. 相似文献
13.
Hendrik Vogel Bernd Wagner Peter Rosén 《Geografiska Annaler: Series A, Physical Geography》2013,95(2):159-170
Here we present datasets from a hydroacoustic survey in July 2011 at Lake Torneträsk, northern Sweden. Our hydroacoustic data exhibit lake floor morphologies formed by glacial erosion and accumulation processes, insights into lacustrine sediment accumulation since the beginning of deglaciation, and information on seismic activity along the Pärvie Fault. Features of glacial scouring with a high‐energy relief, steep slopes, and relative reliefs of more than 50 m are observed in the large W‐basin. The remainder of the lacustrine subsurface appears to host a broad variety of well preserved formations from glacial accumulation related to the last retreat of the Fennoscandian ice sheet. Deposition of glaciolacustrine and lacustrine sediments is focused in areas situated in proximity to major inlets. Sediment accumulation in distal areas of the lake seldom exceeds 2 m or is not observable. We assume that lack of sediment deposition in the lake is a result of different factors, including low rates of erosion in the catchment, a previously high lake level leading to deposition of sediments in higher elevated paleodeltas, tributaries carrying low suspension loads as a result of sedimentation in upstream lakes, and an overall low productivity in the lake. A clear off‐shore trace of the Pärvie Fault could not be detected from our hydroacoustic data. However, an absence of sediment disturbance in close proximity to the presumed fault trace implies minimal seismic activity since deposition of the glaciolacustrine and lacustrine sediments. 相似文献
14.
Lacustrine limestones were formerly identified by their faunistic (limnea, planorbis) and floristic (Charophytes) content. For 30 years, indications of pedogenesis have been found in many lacustrine deposits, and consequently the concept of palustrine limestone was defined.Lacustrine fabrics are not that numerous: varved, laminated, homogeneous, peloidal, brecciated, gravelly, bioturbated (burrows), bioclastic, algal, and stromatolitic. Detrital beds are sometimes present and are interpreted as bottomset deposits. Palustrine fabrics result from exposure and pedogenesis of lacustrine mud. The main processes involved in this evolution are: cracking, with planar, curved, craze and skew planes, colonization by plants resulting in root traces, marmorization (redistribution of iron due to water table fluctuation), and redistribution of carbonates (needles, subspherical or cylindrical vertical nodules, carbonate coatings, early and late diagenetic crystals, Microcodium). Carbonate palustrine features can be associated with other minerals: palygorskite, gypsum, or silica. Alternation of lacustrine sedimentation and exposure/pedogenesis leads to the pseudo-microkarst facies resulting from enlargement of the complex network of root traces and horizontal cracks. The voids in the pseudo-microkarst facies are infilled with a polyphased internal sediment composed of carbonate and vadose silt and phreatic and vadose cements. Traces of exposure and pedogenesis are less in evidence in lacustrine bioclastic sands and algal-stromatolitic limestones. Finally, under certain conditions, the surficial laminar horizon and its associated perlitic crust (ooids) develops on palustrine muds and form a desert stromatolite. 相似文献
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16.
PETER JANSSON GUNHILD ROSQVIST THOMAS SCHNEIDER 《Geografiska Annaler: Series A, Physical Geography》2005,87(1):37-50
ABSTRACT. In order to perform inverse modelling of climate variability based on palaeoclimate proxy records, the complexity of intermediate steps in the chain of processes from the climate forcing to the responding proxy has to be considered. In reconstructing climate-forced glacier fluctuations from proglacial lacustrine sediments it is important to understand how climate affects glacier dynamics. A glacier system is complex with many factors influencing sediment production, transport and deposition. Fluvial and mass movement processes in the proglacial environment may affect lake sedimentation substantially. We argue that it is easy to over-interpret glaciolacustrine sediment variability by ignoring these complications. The sediment records may contain individual layers resulting from single precipitation or melt events, as well as persistent changes in climate-forced glacier dynamics. We conclude that it is necessary to consider all possible influencing factors in order to derive reliable palaeoclimate data from lacustrine sediment sequences. 相似文献
17.
Our study explores the geohydraulic history of the Acre retroarc foreland basin by gathering both spatial and temporal information from the upper 400 m of sediments. We also inquire into controls on sediment accommodation space as well as on stream vs. lacustrine domination. The Acre basin is located in south-west Amazonia, proximal to the Serra do Divisor which demarcates the eastern edge of the Andean fold–thrust belt. Radiocarbon ages from a range of materials indicate that the upper 50–250 m of the Solimôes Formation accumulated during the past 50 000 years. Both surficial and drill-core sediment records show lacustrine–fluvial transitions throughout the Late Quaternary. These shifts in depositional environments are in response to episodic changes in hydrological conditions as well as to geodynamic activity, such as subsidence. Juxtaposition of lacustrine and fluvial systems in the vertical Acre basin record mimics the regional-scale trends in the modern, upper and middle Solimôes–Amazon floodplains. In the Acre basin record lacustrine successions are characterized by increasing calcium contents up-section. This is also manifested, in the upper portions of lacustrine sequences outcropping at the surface, as alternating clastic and calcareous layers. The up-section increase in carbonate content is related to increasing salinities brought about by drier hydrodynamic conditions. Desiccation cracks are typically infilled with gypsum as are cavities of fossils in bone-beds. The latter represent isolated ponds in which the original fauna died as aridity intensified and waters became increasingly saline. Modern trunk river systems in the Acre basin flow from south-west to north-east with tributaries entering from the south-west, suggesting the influence of a domino-style, basement, fault regime. Fault or, at least, fracture control on stream channels is also suggested throughout the greater Amazon basin in the orthogonal dispositions and asymmetric terrace systems of trunk rivers as well as of major tributaries. 相似文献
18.
The sedimentary record of fiords at high latitude where global change may be occurring earliest and will be greatest has the potential for assessment of environmental change at both low resolution (the scale of millennia) and high resolution (decadal to less than daily). Unlike the lacustrine record which has been used very successfully in these studies, the sedimentary processes and thus the sedimentary deposits of fiords differ (1) in the role of salt water in inhibiting mixing and promoting flocculation, and through the role of sea-ice, (2) in the exchange of mass and energy with the much larger ocean beyond, and (3) in the role of benthic biota in the sedimentary environment. The work reviewed in this paper shows that fiord sediments are being used to assess sedimentary and oceanic processes, as well as glacial, periglacial and geomorphic history, and that they are important proxies for long-term climate and hydrology. Recommendations for advancing this work include long-term monitoring of conditions in fiords and their drainage basins so that the transfer relations can be more solidly constructed from the proxy of fiord sediment. Integration of results from fiords in opposite polar latitudes, and among proxies especially from lacustrine and ice-core records will produce valuable insights. Assessment of the range of conditions in fiords from the most polar to temperate regions is important to building models of their processes and understanding of the paleoenvironmental signals that can be interpreted from each type. 相似文献
19.
Jean-Claude Plaziat 《Journal of Paleolimnology》1993,8(2):163-169
Potamids generally live in estuaries, lagoons, and along protected sea shores. However, their ability to colonize intracontinental lakes has been underestimated due to non- or misidentifications. Potamides conicus, the only present lacustrine Potamid currently found in North Africa, belongs to a lagoon-type (thalassoid) malacofauna, dominated by the Cardium Cerastoderma glaucum: this fauna occurs in association with Foraminifera (especially Ammonia beccarii) and Ostracoda (Cyprideis gr. Torosa). Potamids have been found 250 to 900 km from the nearest sea shore: passive dispersal (probably through birds) is the primary dispersal mechanism. Shell morphology and ornamentation can be used to characterize life environment (lacustrine versus marine) but not distance from sea shore. The presence of Potamid-Foraminifera fauna in the fossil record has been interpreted as providing evidence for a sea connection (e.g., gulfs, lagoons). However, more recent paleoecological studies have demonstrated that such assemblages span an ecological gradient from freshwater to hypersaline lacustrine environments. Thus, the occurrence of modern Potamids in lacustrine (in addition to maritime) environments has important implications for Quaternary and Tertiary paleogeographic investigations. Lacustrine Potamids have been recorded from the European Tertiary (France, Spain) and from the Sahara Holocene. More research is required for the better understanding of the distribution and ecology of Potamids in modern and fossil lakes of other continents.This publication is the fifth of a series of papers presented at the Conference on Sedimentary and Paleolimnological Records of Saline Lakes. This Conference was held August 13–16, 1991 at the University of Saskatchewan, Saskatoon, Canada. Dr Evans is serving as Guest Editor. 相似文献
20.
《地理学报(英文版)》2017,(11)
There are a series of basins in the Fenwei Graben.Field survey found that there took place several paleolake regressions or intensive stream down-incisions in all basins during the Mid-Late Quaternary.The lowest and oldest paleosol/loess units overlying three of the lacustrine terraces or alluvial ones and some paleomagenetism data from the lacustrine sediment indicate that the onset times of three paleolake regressions or intensive stream down-incisions are synchronous with the formation of L_9,L_6 and L_2 respectively in the Weihe Basin,S_8,S_5 and S_1 respectively in the Linfen-Taiyuan-Xingding Basins,and L_8,L_5 and L_1 respectively in the Datong Basin.The difference in the onset time of each lake regressions or intensive stream down-incision in different basins reveals that the farther the basin is from the Tibetan Plateau,the later it took place.Taking these field facts and the former research results in terms of the regional tectonic movement into account,it is inferred that the tectonic movement of the Tibetan Plateau most probably controlled such geomorphological-sedimentary evolution in the graben. 相似文献