东澳大利亚南悉尼盆地二叠纪的地层、沉积环境与盆地演化

晚石炭世末期-三叠纪东澳大利亚的鲍恩-冈尼达-悉尼（Bowen- Gunnedah-Sydney）盆地系是位于拉克伦（Lachlan）褶皱带和新英格兰（New England）褶皱带之间的一个长条形的构造盆地。从北部的冈尼达（Gunnedah）到南部的巴特曼斯（Batemans）湾，悉尼盆地是鲍恩-冈尼达-悉尼盆地系南端的一个次级盆地。悉尼盆地的二叠系包括河流、三角洲、滨浅海沉积岩和火山岩地层。南悉尼盆地的西南部二叠系不整合覆盖于变形变质的拉克伦（Lachlan）褶皱带之上。二叠系由下部的塔拉特郎（Tallaterang）群、中部的肖尔黑文群（Shoalhaven Group）和上部的伊勒瓦拉煤系（Illawarra Coal Measures）组成。从晚石炭世末到中三叠世悉尼盆地经历了弧后扩张到典型的前陆盆地的不同阶段：弧后扩张阶段、被动热沉降阶段和挤压挠曲负载阶段。     

辽东苏子河盆地聂尔库组沉积相与沉积环境研究

辽东苏子河盆地是早白垩世形成的小型断陷盆地,盆地内发育了相对连续的陆相沉积,是研究白垩纪陆地环境及气候演化的理想地区。早白垩世晚期沉积的聂尔库组地层出露连续,沉积现象典型。通过分析聂尔库组沉积岩类型、沉积构造、古生物化石及垂向沉积序列,可识别出扇三角洲相和湖泊相,其中扇三角洲相包括扇三角洲平原亚相、扇三角洲前缘亚相和前扇三角洲亚相,湖泊相主要为滨浅湖泥砂沉积。研究表明,聂尔库组形成于断陷盆地边缘陡坡带,属于间歇性洪水控制的扇三角洲—湖泊沉积体系,经历了扇三角洲—湖泊—扇三角洲的沉积环境变化,代表了断陷湖盆由深陷扩张期—抬升收缩早期的沉积充填过程。根据沉积岩与沉积相特征,结合古生物、特殊沉积、黏土矿物及地球化学资料,认为早白垩世晚期辽东地区总体与当时全球"温室气候"的大背景相一致,处于高温干旱/潮湿的气候条件,但这种高温气候具有不均一性,存在气候波动。     

Phanerozoic stratigraphy and structure of the northern Barrier Ranges,western New South Wales

Devonian strata near Fowlers Gap and Nundooka Stations, northern Barrier Ranges comprise ～2.7 km of sparsely fossiliferous, fluvially deposited sandstones (Mulga Downs Group). These strata are subdivided into the Coco Range Sandstone (oldest, Emsian‐Eifelian) found west of the north‐trending Nundooka Creek Fault, and the Nundooka Sandstone (youngest, ?Frasnian‐Famennian found east of the fault). Eleven stratigraphic units are mapped and two of these in the Coco Range Sandstone are formally named as The Valley Tank Arenite and Copi Dam Arenite Members. The Coco Range Sandstone and Nundooka Sandstone are tentatively correlated with strata in the Bancannia Trough. Deposition of the Coco Range Sandstone and Nundooka Sandstone was, however, separate from that of the Bancannia Trough, probably due to topographic highs which occurred east of the Western Boundary Fault.

The Coco Range Sandstone is cut by northeast‐trending faults splaying from the Nundooka Creek Fault. These faults have vertical planes and are thought to predate deposition of the Nundooka Sandstone. In the Late Cretaceous the Nundooka Creek and Western Boundary Faults became active and areas west of these faults were uplifted to form Coco Range and Bald Hill. This fossil landscape was progressively buried by deposition of the Palaeocene‐Eocene Eyre Formation until it was half covered by strata. During the Oligocene silcrete of the Cordillo Surface formed and was overlain conformably by the sandy Doonbara Formation (Miocene). Since the Miocene, much of the Eyre Formation has been removed by erosion to exhume a Late Cretaceous landscape. Subsequently in the ?Pliocene there was some faulting along the Nundooka Creek and Western Boundary Faults because locally the Cordillo Surface and the Doonbara Formation dip toward the faults at 30–72°. At three localities there is evidence of probable Quaternary activity on the Nundooka Creek and the Western Boundary Faults (downthrow to the east) suggesting a different style of tectonics from that in the Miocene.     

The Early Proterozoic Nabberu Basin and associated iron formations of Western Australia

Rocks of the Early Proterozoic Nabberu Supergroup were deposited in the Nabberu Basin along the northern margin of the Archaean Yilgarn Shield in Western Australia. The Nabberu Basin consists of three tectonic-sedimentary units known as the Earaheedy, Glengarry and Padbury Sub-basins.The Earaheedy Group within the easternmost sub-basin is divided into a lower Tooloo Sub-group and an upper Miningarra Sub-group, representing succeeding sedimentary cycles totalling some 6000 m of shallow water sediments. The Tooloo Sub-group comprises thin quartzose to arkosic clastics (Yelma Formation) which rest unconformably on Archaean rocks, and are overlain by chert, shale, iron formations and minor carbonate (Frere Formation), and thinly bedded carbonate, shale and sandstone (Windidda Formation). The overlying Miningarra Sub-group includes sandstone and shale (Wandiwarra Formation), super-mature quartz sandstone and arkosic siltstone (Princess Ranges Quartzite), fine arkosic sandstone, siltstone, shale and carbonate (Wongawol Formation), limestone, shale and sandstone (Kulele Creek Limestone) and sandstone and shale (Mulgarra Sandstone). Distinctive stromatolite assemblages occur in carbonate units throughout the sequence.Iron formations of the Frere Formation are similar to those of the Lake Superior and Labrador Provinces of North America, and commonly have a distinctive pelletal (intraclastic) texture, but are locally oolitic or laminated. Benthonic microfossils found at one locality are identical to those in the Lake Superior iron formations (Walter et al., 1976).West into the Glengarry Sub-basin and Peak Hill—Robinson Ranges area the basal clastics become considerably thicker, finer-grained and more varied, and are commonly interbedded with basaltic volcanics and greywackes. The Peak Hill Beds (MacLeod, 1970), Finlayson Sandstone and Maraloou Formation (Bunting et al., 1977) may be lateral equivalents of the Yelma Formation, while the overlying Horseshoe Range Beds, Labouchere Formation and Robinson Range Formation (Barnett, 1975) are possible equivalents of the Frere Formation. The Millidie Creek Formation may be equivalent to the Wandiwarra Formation.Deformation of the Nabberu Basin has resulted in the development of the Stanley Fold Belt in the north and the Kingston Platform in the south. On the Kingston Platform the rocks dip very gently north, but deformation increases northwards. A slaty cleavage becomes more conspicuous in this direction, while folds become tighter, overturned southwards and cut by north-dipping thrusts. The fold belt trends west-northwest across the eastern portion of the basin before swinging to the southwest. Archaean basement is increasingly involved in the deformation and becomes progressively more gneissic as the Early Proterozoic rocks become more strongly schistose. Refolding of early structures is pronounced in the west. Metamorphic grade, based on mineral assemblages in basic, pelitic and carbonate rocks and iron formations, also increases north and northwest, reaching a maximum grade of granulite facies west of the Robinson Ranges. The sediments are essentially unmetamorphosed in the southeastern part of the basin.     

青藏高原北羌塘地区晚三叠世地层展布和沉积型式

北羌塘盆地地处拉竹龙-金沙江缝合带和双湖构造混杂岩带之间,自北向南可划分出5个沉积相带/岩石地层单位：以砂泥质复理石-洋岛、岛弧型火山岩-大理岩岩石组合沉积为特征的若拉岗日群,以深水复理石盆地相沉积为特征的藏夏河组,以深水暗色细碎屑岩盆地相沉积为特征的结扎群,以开阔台地相/缓坡相碳酸盐岩沉积为特征的菊花山组,以三角洲相含煤碎屑岩系沉积为特征的土门格拉群.晚三叠世北羌塘盆地显示为南缓北陡的箕状沉积格局,盆地内充填物为南薄北厚的楔形沉积体,且双物源、沉降中心和沉积中心不一致,表明其具有前陆盆地的一系列沉积特征.     

Review of Lopingian (upper Permian) stratigraphy of the Galilee Basin,Queensland, Australia

The recent increase in exploration activity in the Galilee Basin, Queensland, has highlighted inconsistencies in the usage of Lopingian (upper Permian) stratigraphic nomenclature across the basin. This study utilised peer-reviewed journal, company and government publications to evaluate the current understanding of the naming conventions in use and correlated them to nomenclature in the adjacent Bowen Basin. The prominent misinterpretation is between the stratigraphic relationship and terminology of the northern and western Betts Creek beds and its eastern and southern correlatives the Bandanna Formation and Colinlea Sandstone. The correlation between the units has been assessed from a (1) lithological, (2) sedimentological and (3) coal-seam architectural perspective. The Betts Creek beds appear similar to the Colinlea Sandstone in their lithology and sedimentological character, but increased drilling data suggest the original type-sections no longer fit the heterogeneous lithology of correlated strata bearing that nomenclature. Correlation across the Springsure Shelf into the Bowen Basin suggests that the Betts Creek beds and their subdivisions are in fact equivalent to the Bandanna Formation, the Fort Cooper Coal Measures (the Burngrove and Fair Hill formations) and the Moranbah Coal Measures. A revised stratigraphic column for the Galilee Basin has been proposed to reflect this, and to suggest that a new stratigraphic unit be introduced; the ‘Fort Cooper Coal Measures equivalent’ and its subdivisions the ‘Burngrove and Fair Hill formation equivalents.’     

贵州赤水地区晚白垩世古流向特征及构造意义

贵州赤水地区位于四川盆地西南缘,晚白垩世时期该地区沉积了一套厚达1300m的陆相地层。本文通过地表露头的古流向野外观测和室内分析,详细研究赤水地区晚白垩世沉积充填过程及构造意义。赤水地区晚白垩世早期辫状河的古流向为自北东向南西,表明碎屑物源主要来自盆地北侧和东侧。根据物源、地层分布及区域地质背景推断,赤水地区晚白垩世的陆相沉积盆地属于陆内前陆盆地,陆内造山带位于盆地东侧。晚白垩世陆内前陆盆地的形成,可能受控于此阶段华南的构造挤压事件形成的陆内造山作用。     

Generation and hydrocarbon entrapment within Gondwanan sediments of the Mandapeta area, Krishna-Godavari Basin, India

The discovery of hydrocarbons (mainly gas) in commercial quantities from Gondwanan sediments in the Mandapeta field of Krishna-Godavari Basin, India, provided impetus for intensified exploration in Mandapeta and the adjoining Kommugudem, Draksharama and Endamuru fields. Both oil and gas have been found in the reservoirs of Mandapeta (Triassic) and Golapalli (Early Cretaceous) formations. Mature, localised, basal shales (1.0–1.1% Ro) in the Mandapeta formation have sourced the oils from the Mandapeta Sandstone reservoir (Triassic). The oils being produced from Golapalli Sandstone reservoir (Early Cretaceous) are relatively less mature and have been sourced by the underlying shales in the Mandapeta Formation at a maturity level of 0.80–0.85% Ro. The source and maturity data preclude liquid hydrocarbon sourcing from the Kommugudem (Permian) sequence. Permian coals and shales of the Kommugudem Formation are the major source rocks for gaseous hydrocarbons in this area. The hydrocarbon generation started in Early Cretaceous in the Kommugudem Formation, but the intermittent tectonic activity (with associated structural developments) has resulted in reorientation and redistribution of the then existing trap configurations. The present day maturity level of the Permian sediments in the Mandapeta field is 1.2% Ro or greater, capable of generating gas dominantly. The Raghavapuram shale in the Mandapeta area is adequately mature and has good hydrocarbon potential for oil generation. The probability of finding hydrocarbon reserves in the sands of Raghavapuram shales and other suitable traps is high. Modern seismic information together with geologic models can give new exploration leads.     

Thermal maturity and hydrocarbon potential of the sedimentary succession from the Hecla field in Sverdrup Basin, Arctic Canada

The thermal maturity and source-rock potential of the Upper Palaeozoic and Mesozoic sediments in the Hecla field, Melville Island, Arctic Canada, have been studied using reflected-light microscopy and Rock-Eval pyrolysis. Approximately 250 polished whole-rock samples were examined and their reflectance (% R₀, random) measured. In addition, approximately 100 samples were subjected to Rock-Eval/TOC analyses.Hydrogen-rich organic matter in the Schei Point Group sediments is dominated by alginite (Tasmanales), dinoflagellate cysts with minor amounts of sporinite, cutinite, resinite and liptodetrinite in an amorphous fluorescing matrix. Vitrinite reflectance in Cretaceous sediments ranges from 0.41 to 0.54%; in Jurassic sediments it ranges from 0.43 to 0.64% and in Triassic sediments from 0.50 to 0.65%. The Triassic Schei Point Group calcareous shales and marlstones contain organic matter mainly of marine origin, whereas the predominantly terrestially-derived organic matter present in the Jameson Bay (Lower Jurassic) and in the Upper Jurassic to Lower Cretaceous Deer Bay formations have ower TOC. Only the Ringnes Formation has a TOC content of equivalent to or greater than Schei Point source rocks. Within the Schei Point Group, the Cape Richards and Eden Bay members of the Hoyle Bay Formation are slightly richer in TOC than the Murray Harbour Formation (Cape Caledonia Member). Higher average TOC contents (>3.0%) have been reported in the Cape Richards and Eden Bay members in almost all Hecla drillholes.Variations in the level of thermal maturity of Mesozoic sediments in the Hecla field are a function of burial depth. The stratigraphic succession thickens towards the main Sverdrup Basin depocentre located in a N-NE direction. The pattern of the isoreflectance contours at the top of the Triassic (Barrow Formation) is similar to that of formation boundary lines of the same formations, an indication that present-day maturation levels are largely controlled by basin subsidence.     

Tectonic and climatic controls on sedimentation during deposition of the Sinakumbe group and Karoo supergroup,in the mid-Zambezi Valley Basin,southern Zambia

Sediments of the Ordovician to Devonian Sinakumbe Group (∼210 m thick) and overlying Upper Carboniferous to Lower Jurassic Karoo Supergroup (∼4.5 km thick) were deposited in the mid-Zambezi Rift Valley Basin, southern Zambia.The Sinakumbe-Karoo succession represents deposition in a extensional fault-controlled basin of half-graben type. The basin-fill succession incorporates two major fining-upward cycles that resulted from major tectonic events, one event beginning with Sinakumbe Group sedimentation, possibly as early as Ordovician times, and the other beginning with Upper Karoo Group sedimentation near the Permo-Triassic boundary. Minor tectonic pulses occurred during deposition of the two major cycles. In the initial fault-controlled half-graben, a basin slope and alluvial fan system (Sikalamba Conglomerate Formation), draining southeastward, was apparently succeeded, without an intervening transitional facies, by a braided river system (Zongwe Sandstone Formation) draining southwestward, parallel to the basin margin. Glaciation followed by deglaciation resulted in glaciofluvial and glacio-lacustrine deposits of the Upper Carboniferous to Lower Permian Siankondobo Sandstone Formation of the Lower Karoo Group, and isostatic rebound eventually produced a broad flood plain on which the coal-bearing Lower Permian Gwembe Coal Formation was deposited. Fault-controlled maximum subsidence is represente by the lacustrine Upper Permian Madumabisa Mudstone Formation. Block-faulting and downwarping, probably due to the Gondwanide Orogeny, culminated with the introduction of large quantities of sediment through braided fluvial systems that overwhelmed and terminated Madumabisa Lake sedimentation, and is now represented by the Triassic Escarpment Grit and Interbedded Sandstone and Mudstone Formations of the Upper Karoo Group. Outpourings of basaltic flows in the Early Jurassic terminated Karoo sedimentation.     

扬子北缘晚造山阶段弧形构造特征与盆地演化

扬子北缘晚造山阶段(即晚侏罗世—晚白垩世)发育以弧形构造为特征的前陆薄皮逆冲—褶皱构造,包括了沿秦岭—大别造山带发育的北西向的大洪山和大巴山弧形带,以及沿江南—雪峰造山带发育的北东向的川东—湘鄂西弧形带。详细的构造解析、盆地沉积及物源特征综合分析表明,弧形构造不仅将早期的前陆序列卷入变形,并且控制了晚侏罗世—晚白垩世的盆地演化和古地理格局。总结扬子北缘晚造山阶段的盆山演化特征,可以将其划分为3个阶段:(1)晚侏罗世—早白垩世早期,大洪山和大巴山弧形带的发育控制了四川盆地东北部及秭归盆地上侏罗统蓬莱镇组的沉积,川东—湘鄂西弧形带限制了盆地的东南边界,加之位于四川盆地西部的龙门山逆冲带,三面围限构成具前渊沉降的克拉通内盆地或称为“墙围盆地”(walled sedimentary basin);(2)早白垩世中期—早白垩世晚期,大洪山和大巴山弧形带的逆冲构造变形逐渐减弱,而川东—湘鄂西弧形带继续向北西扩展,构造线呈北东向展布,在弧形带前缘的宜昌地区形成沉积中心,并覆盖了现今的黄陵背斜;(3)晚白垩世,川东—湘鄂西弧形带继续向北西推进,构造线呈北北东向展布,弧形带北翼的黄陵背斜初始隆起,沉积中心分别位于北翼宜昌地区及南翼习水地区。与此同时,在弧形带内部薄皮构造的向斜部位形成楔顶沉积,发育如恩施盆地、黔江盆地、来凤盆地等一系列规模较小的背驼式盆地。     

From foredeep to orogenic wedge-top: The Cretaceous Songliao retroforeland basin,China

Songliao Basin, the largest Mesozoic intracontinental nonmarine basin in eastern China, initiated during the latest Jurassic as a backarc extensional basin; rifting failed and thermal cooling controlled subsidence through the early Late Cretaceous. Integrating 2-D and 3D reflection seismic and borehole data with regional geological studies, we interpret sedimentary sequence and structural patterns of the Coniacian-Maastrichtian fill of Songliao Basin as defining a retroforeland basin system developed after 88 Ma (marked by the T11 unconformity in the basin), including (1) significant increase in the thickness of the Nenjiang Formation eastward towards orogenic highlands of the Zhangguangcai Range and the convergent continental margin; (2) a shift of detrital provenance in the basin from north to southeast; and (3) propagation of E-W shortened structures, increasing eastward in amplitude, frequency, and degree of inversion toward the orogen. During latest Cretaceous, foreland basin fill progressively deformed, as the foredeep evolved to a wedge-top tectonic setting, marked by the basin-wide T04 unconformity within the upper Nenjiang Formation at 81.6 Ma. Much of the basin was brought into the orogenic wedge and eroded by the end of the Cretaceous. Late Jurassic/Early Cretaceous backarc rifting of uncratonized basement comprised of accreted terranes likely facilitated and localized the foreland. Synrift normal faults reactivated and extensively inverted as thrust faults are prominent in the eastern 1/3 of the basin, whereas folds developed above detachments in shaley early post-rift strata dominate the western 2/3 of the basin. Songliao foreland development likely was driven by changing plate dynamics and collision along the Pacific margin after 88 Ma.     

Tertiary facies architecture in the Kutai Basin,Kalimantan, Indonesia

The Kutai Basin occupies an area of extensive accommodation generated by Tertiary extension of an economic basement of mixed continental/oceanic affinity. The underlying crust to the basin is proposed here to be Jurassic and Cretaceous in age and is composed of ophiolitic units overlain by a younger Cretaceous turbidite fan, sourced from Indochina. A near complete Tertiary sedimentary section from Eocene to Recent is present within the Kutai Basin; much of it is exposed at the surface as a result of the Miocene and younger tectonic processes. Integration of geological and geophysical surface and subsurface data-sets has resulted in re-interpretation of the original facies distributions, relationships and arrangement of Tertiary sediments in the Kutai Basin. Although much lithostratigraphic terminology exists for the area, existing formation names can be reconciled with a simple model explaining the progressive tectonic evolution of the basin and illustrating the resulting depositional environments and their arrangements within the basin. The basin was initiated in the Middle Eocene in conjunction with rifting and likely sea floor spreading in the Makassar Straits. This produced a series of discrete fault-bounded depocentres in some parts of the basin, followed by sag phase sedimentation in response to thermal relaxation. Discrete Eocene depocentres have highly variable sedimentary fills depending upon position with respect to sediment source and palaeo water depths and geometries of the half-graben. This contrasts strongly with the more regionally uniform sedimentary styles that followed in the latter part of the Eocene and the Oligocene. Tectonic uplift documented along the southern and northern basin margins and related subsidence of the Lower Kutai Basin occurred during the Late Oligocene. This subsidence is associated with significant volumes of high-level andesitic–dacitic intrusive and associated volcanic rocks. Volcanism and uplift of the basin margins resulted in the supply of considerable volumes of material eastwards. During the Miocene, basin fill continued, with an overall regressive style of sedimentation, interrupted by periods of tectonic inversion throughout the Miocene to Pliocene.     

海拉尔盆地构造演化及油气勘探前景

海拉尔盆地为海西褶皱基底上发育的晚中生代—古近纪断-坳陷盆地,控盆的边界断裂主要为北东向和北北东向,形成于早白垩世,之后经受了多期反转。海拉尔盆地的沉积可划分为3大构造层:兴安岭群上段、铜钵庙组和南屯组为断陷构造层,大磨拐河组和伊敏组为断-坳转换构造层,上白垩统青元岗组和古近系为坳陷构造层。该盆地在古近纪发生萎缩并闭合,在近东西向的挤压力作用下形成北东向的反转构造带,为油气的聚集提供了良好的圈闭。新近纪开始新一阶段的拉张和沉陷。该地的新构造运动相当活跃,本文论述了其主要表现为断陷湖盆的形成、地表径流的分布和断阶构造的发育,指出其特征为继承性和加强性,使盆地发育阶段的坳(凹)陷在新近纪内进一步沉陷。在此基础上讨论了海拉尔盆地的油气勘探前景。     

Structural evolution of a normal fault array in the Gambier Embayment,offshore Otway Basin,South Australia: insights from 3D seismic data

This study was undertaken to determine the structural evolution of a normal fault array using detailed kinematic analysis of normal fault tip propagation and linkage, adding to the growing pool of research on normal fault growth. In addition, we aim to provide further insight into the evolution of the offshore Otway Basin, Australia. We use three-dimensional (3D) seismic reflection data to analyse the temporal and spatial evolution of a Late Cretaceous–Cenozoic age normal fault array located in the Gambier Embayment of the offshore Otway Basin, South Australia. The seismic reflection data cover a NW–SE-oriented normal fault array consisting of six faults, which have grown from the linkage of numerous, smaller segments. This fault array overlies and has partial dip-linkage to E–W-striking, basement-involved faults that formed during the initial Tithonian–Barremian rifting event in the Otway Basin. Fault displacement analysis suggests four key stages in the post-Cenomanian growth history of the upper array: (1) nucleation of the majority of faults resulting from resumed crustal extension during the early Late Cretaceous; (2) an intra-Late Cretaceous period of general fault dormancy, with the nucleation of only one newly formed fault; (3) latest Cretaceous nucleation of another newly formed fault and further growth of all other faults; and (4) continued growth of all faults, leading to the formation of the Cenozoic Gambier Sub-basin in the Otway Basin. Our analysis also demonstrates that Late Cretaceous faults, which are located above and dip-link to basement-involved faults, display earlier nucleation and greater overall throw and length, compared with those which do not link to basement-involved faults. This is likely attributed to increased rift-related stress concentrations in cover sediments above the upper tips of basement faults. This study improves our understanding of the geological evolution of the presently under-explored Gambier Embayment, offshore Otway Basin, South Australia by documenting the segmented growth style of a Late Cretaceous normal fault array that is located over, and interacts with, a reactivated basement framework.     

Stratigraphy and depositional setting of slurry and contained (reflected) beds in the Marnoso‐arenacea Formation (Langhian‐Serravallian) Northern Apennines,Italy

This work presents the stratigraphy and facies analysis of an interval of about 2500 m in the Langhian and Serravallian stratigraphic succession of the foredeep turbidites of the Marnoso‐arenacea Formation. A high‐resolution stratigraphic analysis was performed by measuring seven stratigraphic logs between the Sillaro and Marecchia lines (60 km apart) for a total thickness of about 6700 m. The data suggest that the stratigraphy and depositional setting of the studied interval was influenced by syndepositional structural deformations. The studied stratigraphic succession has been subdivided into five informal stratigraphic units on the basis of how structurally controlled topographic highs and depocentres, a consequence of thrust propagation, change over time. These physiographic changes of the foredeep basin have also been reconstructed through the progressive appearance and disappearance of thrust‐related mass‐transport complexes and of five bed types interpreted as being related to structurally controlled basin morphology. Apart from Bouma‐like Type‐4 beds, Type‐1 tripartite beds, characterized by an internal slurry unit, tend to increase especially in structurally controlled stratigraphic units where intrabasinal topographic highs and depocentres with slope changes favour both mud erosion and decelerations. Type‐2 beds, with an internal slump‐type chaotic unit, characterize the basal boundary of structurally controlled stratigraphic units and are interpreted as indicating tectonic uplift. Type‐3 beds are contained‐reflected beds that indicate different degrees of basin confinement, while Type‐5 are thin and fine‐grained beds deposited by dilute reflected turbulent flows able to rise up the topographic highs. The vertical and lateral distribution of these beds has been used to understand the synsedimentary structural control of the studied stratigraphic succession, represented in the Marnoso‐arenacea Formation by subtle topographic highs and depocentres created by thrust‐propagation folds and emplacements of large mass‐transport complexes.     

胶莱盆地白垩纪构造应力场与转换机制

通过对胶莱盆地断层滑动矢量的收集与测量,利用计算机程序反演了盆地白垩纪的古构造应力场演化历史,并据此将盆地的发育划分为三个伸展阶段和三个挤压反转阶段,分别为早白垩世早-中期莱阳期伸展,与造山期后应力松弛重力坍塌有关;早白垩世中-晚期青山期伸展,受早白垩纪早期以后广泛的岩石圈减薄、大陆裂陷制约;晚白垩世王氏期伸展,与郯庐断裂及牟平-即墨断裂右旋走滑有关。三期伸展之间存在构造挤压反转,最后阐明各期盆地发育的地球动力学背景。     

The ordovician (caradoc) volcanic rocks of montgomery,Powys, N. Wales

The Ordovician (Caradoc, Soudleyan) rocks of Montgomery, Powys are shales interbedded with locally conglomeratic volcaniclastic sediments composed of andesitic detritus. New formal lithostratigraphic units are proposed: Montgomery Volcanic Group comprising in ascending order: Castle Hill Shale Formation, Castle Hill Conglomerate Formation and Quarry Sandstone and Shale Formation. The volcaniclastic strata are reinterpreted as deposits of a submarine volcaniclastic fan system sourced by contemporaneous andesitic island volcanism. The observed diagenetic sequence is typical of marine volcanic sandstones and was dominated by hydration reactions related to the degradation of abundant unstable volcanic detritus. Diagenesis has resulted in the virtual destruction of original porosity in the volcaniclastic rocks.     

孙吴-嘉荫盆地白垩系淘淇河组-太平林场组砂岩主量元素的地球化学特征

沉积盆地中砂岩的地球化学特征主要受物源区控制,碎屑岩的地球化学成分可揭示沉积物的地质信息.笔者通过对孙吴-嘉荫盆地白垩系淘淇河组-太平林场组砂岩的主量元素地球化学特征分析,结合砂岩薄片碎屑成分统计表明:淘淇河组-太平林场组时期物源区的大地构造背景主要为活动大陆边缘,包括大陆岛弧和大洋岛弧.物源区母岩类型主要为花岗岩,中酸性火山岩及低级变质岩.盆地不同位置物源区的大地构造背景和母岩类型有所不同.结合区域地质资料综合分析认为:在淘淇河组-太平林场组沉积时期,小兴安岭仅在太平林场组时期不是盆地主要物源区,而佳木斯地块一直是盆地东部的一个主要物源区.