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1.
《Geodinamica Acta》2013,26(4):151-165
Two magnetostratigraphic profiles (450 samples) have been carried out to constrain the age of synorogenic formations in the southern foreland of the High Atlas of Morocco. The Amekchoud profile covers the Aït Ouglif and Aït Kandoula alluvial formations that form the bulk of the Ouarzazate basin fill, indicating an age between the upper Langhian and the Messinian (Miocene). Data obtained in the previously unexplored Hadida formation profile covers the oldest terms of the foreland basin succession, but the low quality of the magnetic record only allows proposing a tentative age between the middle Lutetian and an undetermined middle to late Eocene. The correlation of the Amekchoud profile is based on the recognition of the long C5n chron (Tortonian) in the middle part of the section studied and a new vertebrate locality of upper Tortonian age found in the upper part. These results indicate a discontinuous record of foreland basin development in the southern Atlas domain from mid Eocene to late Miocene times, punctuated by an intermediate large hiatus of 20-25 ma (late Eocene to mid Miocene). Thrusting in the Sub-Atlas frontal thrust belt began before the Aït Ouglif and Kandoula formations, probably during the Oligocene, and extends up to recent times. The alternation of periods of deposition with others of no sedimentary record, which does not coincide with specific tectonic events, results probably from the interference of orogenic deformation and the mantle-related thermal uplift events that have been described for the Moroccan Atlas. 相似文献
2.
A series of balanced cross-sections across the Sub-Atlas thrust belt and the northern Ouarzazate basin are used to illustrate
the structural geometry and the timing of deformation at the southern front of the High Atlas Mountains of Morocco. The selected
area is among the best sedimentary records of mountain building of the entire orogenic system. The study of the relationships
between thrusts and synorogenic continental formations enables the unraveling of kinematic sequences and the proposal of a
relative chronology of deformation. Active thrusting in the area occurred in a rather continuous fashion from the Oligocene
to the Pliocene, punctuated by a major erosional phase imprecisely placed in late Oligocene to early Miocene times. Detrital
sedimentary facies indicate that uplift in the hinterland of the High Atlas, to the north of the Sub-Atlas belt, was taking
place already by mid Eocene times, although it might have commenced locally even earlier. Within the Sub-Atlas zone, the exposed
faults did not propagate in a simple piggy-back fashion but show evidence of a complex, synchronous sequence with events of
fault reactivation and out-of-sequence thrusting. 相似文献
3.
通过对孙吴-嘉荫盆地淘淇河组、永安村组、太平林场组、鱼亮子组、乌云组和孙吴组露头剖面详细的沉积学研究,查明该盆地从淘淇河组到孙吴组发育的沉积相类型有冲积扇、辫状河、曲流河、扇三角洲、辫状河三角洲、曲流河三角洲、湖底扇和湖泊。冲积扇及扇三角洲主要发育于淘淇河组和孙吴组;辫状河及辫状河三角洲主要发育于鱼亮子组和乌云组;曲流河及曲流河三角洲主要发育于永安村组和太平林场组,各组均有湖泊相沉积发育。孙吴-嘉荫盆地从淘淇河组到乌云组,具有冲积扇-扇三角洲-湖泊→曲流河-曲流河三角洲-湖泊→辫状河-辫状河三角洲-湖泊→冲积扇-扇三角洲-湖泊的沉积演化规律,反映晚白垩-古新世构造活动性减弱,中-上新世孙吴组沉积时重又趋于活动。 相似文献
4.
《Journal of African Earth Sciences》2000,30(1):119-131
According to major discontinuities, continental deposits in the Cenozoic Atlas basins are subdivided into three groups (pre-, syn- and post-tectonic). Progressive unconformities are the main characteristic of the syntectonic formations, implying that the Atlas tectonic episode is synchronous with Neogene and Quaternary sedimentation. This tectonic episode is responsible for the inversion of Early Mesozoic extensional structures within the basement, which were reactivated into symmetrical thrusts or transpressional faults. Shortening of the basement induced the detachment of the cover. Deformation of the cover is expressed by thrust faults (with southern and northern vergences), folds and flexures linked to blind thrusts. Kinematic data show that the main regional compression was directed N150 ± 10° during the Neogene and north-south during the Quaternary. The involvement of the upper crust, in the Alpine Atlasic Belt, contributed to create areas of high relief. The High Atlas can be interpreted as resulting from large Cenozoic thrusts, and compared with the Pyrenean Axial Zone, although their pre-Cenozoic histories can differ markedly. 相似文献
5.
THE PALEOCURRENT PATTERN OF EARLY TERTIARY REDBEDS IN THE HOH XIL BASIN,NORTHERN TIBET PLATEAU:IMPLICATIONS FOR AN EARLY UPLIFT AND UNROOFING 相似文献
6.
E. IWANIW 《Sedimentology》1984,31(1):91-110
Basal Stephanian deposits of early Cantabrian age infill a deeply incised fossil topography at the western edge of the post-Leonian basin of NE Leon. Seven low sinuosity palaeovalleys, trending NNW–SSE range in depth of incision from 25 to 450 m. The fill is composed of: (i) Red bed succession: a proximal alluvial valley-fill association of debris flow and stream deposits in which seven mesosequences and two fining upwards megasequences are recognized on the basis of maximum clast sizes. (ii) Grey bed succession: two megasequences are distinguished. The lower megasequence comprises distal alluvial valley-fill deposits (sheet sandstone, lacustrine, swamp deposits). The upper megasequence comprises a mid-fan association of debris flow and interlobe/floodplain deposits. The palaeovalleys are considered in the context of previously described palaeovalleys and fill. These are categorized according to the degree of tectonic control and climatic setting. The lower Cantabrian examples may serve as a model for valley-fill sedimentation in a tectonically active area and a humid climatic setting. 相似文献
7.
This paper gives insight into continental sedimentary deposits that occur at the uppermost part of the stratigraphic succession present in the north-eastern sector of the Farafra Depression (Western Desert, Egypt). Using space imagery to complete the field work, the geology of the area has been mapped and the presence of a N–S oriented fault system is documented. The analysis of the morphotectonic features related to this fault system allows reconstructing the structural and sedimentological evolution of the area. The study indicates that the continental deposits were accumulated in alluvial systems that unconformably overlie shale and evaporitic rocks attributable to the Paleocene–Eocene Esna Formation. The deposits of the Esna Formation show soft-sediment deformation features, which include slump associated to dish and pillar sedimentary structures and provide evidence of syndepositional tectonic activity during the sedimentation of this unit. The outcrops are preserved in two areas on separated fault-bounded blocks. Proximal alluvial fan facies crop out in a dowthrown block close to the depression boundary. The proximal facies are made up mostly by polymictic conglomerates which occasionally contain boulders. The conglomerate clasts are mainly quartz, carbonate, anhydrite satin spar vein, mudrock, ironstone and nummulite fossils. The mid-fan facies consist of trough cross-bedded, rippled and cross-laminated quartzarenites with reworked glauconite grains and carbonate rock fragments, interpreted as deposited by distributary streams. The distal alluvial fan deposits consist of sandy marls that evolve toward the top of the sections into root-bioturbated lacustrine limestone beds that are locally silicified. The limestones are biomicrites containing characea, ostracods and gastropods with fenestral porosity.A number of features, including clast provenance (mainly from marine Paleocene and Eocene rocks), the observed fractural pattern (N–S direction related to the opening of the Red Sea), and the sedimentary relationships, suggests that the continental deposits were accumulated during the Oligocene–Miocene interval. 相似文献
8.
Middle Eocene Fulra Limestone and Oligocene Maniyara Fort Formation represent platform carbonate deposits of Kutch at the north-western margin of India. These carbonates contain larger benthic foraminifera, including Alveolina, Assilina, Discocyclina, Lepidocyclina, Miogypsina, Nummulites and Spiroclypeus. This study presents paleodepositional and paleobathymetric interpretations for both formations using benthic foraminifera in combination with lithological association, sedimentary structures and early diagenetic features. The six carbonate facies comprising the Fulra Limestone indicate a depositional spectrum ranging from bar-lagoon to mid-ramp depositional conditions. It records several shallowing upward cycles, leading to emergence and formation of paleokarst. The four carbonate facies of the Maniyara Fort Formation represents deposition within the inner ramp setting in bar-lagoon and patch-reef environment, while intervening fine siliciclastics correspond to episodes of relative sea level fall. Nummulitic accumulations form low-relief bars within the fair weather wave base in both the formations. The depositional setting of the Paleogene carbonate in Kutch broadly resembles Eocene platformal deposits in the circum-Tethys belt. 相似文献
9.
John Kemp 《Journal of African Earth Sciences》1996,22(4):507-523
The Kuara Formation was originally described in the Nuqrah quadrangle, northern Arabian Shield, as composed of sedimentary and volcanic rocks and attributed to the Neoproterozoic Shammar group. The group has been examined in the type area of the Kuara Formation. The name ‘Kuara Formation’ is here formally proposed and restricted to the essentially sedimentary succession. The sediments were most likely deposited in an approximately north-south to northeast-southwest fault-bounded basin more than 20 km wide and closed to the south by an approximately east-west fault. The formation probably attained more than 600 m in thickness and is characterized by abundant, locally derived conglomerate and by coarsening-upward sequences organized in megasequences; these are interpreted as representing the progradation of alluvial fans into a lake. Sharp contacts of siltstone overlying conglomerate are interpreted as due to the lowering of the trough floor by faulting, subsequent lacustrine sedimentation corresponding to periods of maximum tectonic activity and alluvial fans prograding, periods of reduced activity. The interpretation of the tectonic environment as one of extensional faulting in a continental setting is in agreement with interpretations proposed for other successions of similar age in Arabia and Egypt. 相似文献
10.
《Proceedings of the Geologists' Association. Geologists' Association》2017,128(2):234-255
Exposures of multistorey, alluvial deposits from the Oligocene Gebel Ahmar Formation in the Cairo-Suez province (north Eastern Desert, Egypt) show the architecture of an up to 35 m thick continuously prograding fluvial/alluvial filling of an incised valley. The Oligocene base level fall resulted in cannibalization of the Eocene bedrock. Subsequent baselevel rise created accommodation space that was filled by deposition of four stacked storeys: lower storeys (1-2) of low sinuosity sandy braid plains and upper storeys (3-4) of gravelly braid plain. These braid plains were sourced from exposed Upper Cretaceous-Eocene and Paleozoic-Lower Cretaceous siliciclastic successions to the south. These successions dominate the Galala-Araba inverted structures. The sandy braid plain channel belts mainly downstream accretion (DA), downstream oblique accretion(DLA), lateral accretion (LA), sandy bedforms (SB), channel (CH), and Hollow (HO) elements, while the gravelly braid plain consists mainly of gravel bars and sheets (GB), gravel-sandstone foresets (GSF), gravel-sand couplets (GSC), and scour pool filling (SPF) architectures. Incised valley incision is potentially linked to a global drop of sea level caused by glaciation, although hinterland tectonism (i.e. Late Cretaceous-Paleogene tectonic inversion and Late Eocene-Oligocene crustal updoming in the source terrains) as well as Late Oligocene-Miocene rifting play a significant role in the subsequent filling. The hinterland tectonism as well as the climate controls the sediment supply. The understanding of the nature of the Oligocene incised valley fill helps in the constrain potential down depositional dip hydrocarbon reservoirs in Nile Delta, East Mediterranean basins, and similar settings in passive continental margins. 相似文献
11.
鲁西隆起北侧博兴洼陷古近系泥岩地球化学特征及其构造意义 总被引：5，自引：4，他引：1
对博兴洼陷始新统和渐新统所取的20件泥岩样品的地球化学特征分析表明:始新统与渐新统样品稀土元素分布模式与上地壳稀土元素分布模式一致。稀土特征元素之间的比值显示始新统和渐新统沉积物源岩虽都来自后太古代,但存在着明显的差异性。根据源岩属性判别图解可以看出始新统源岩主体为长英质火山岩,渐新统则为长英质和基性岩的火山岩混合物源。多方面对比认为:始新统和渐新统沉积物源存在较大的差异性,表明始新世与渐新世之间可能存在较为明显的沉积物源改造,从一个新的视角揭示了鲁西隆起与邻近盆地在始新世与渐新世之间所发生的构造分异事件,而这次构造分异也造成了邻近盆地内始新统与渐新统之间油气藏成藏要素的差异。 相似文献
12.
《Quaternary Science Reviews》2007,26(22-24):2883-2896
In the El Minia district of northern Upper Egypt, the Pleistocene deposits of the Nile Valley include (?)Early Pleistocene conglomerates of the Armant Formation and (?)Middle Pleistocene sands of the Qena Formation. These sediments are exposed along both sides of the valley in terraces at different heights, unconformably overlying Eocene limestones. Field observations suggest that the conglomerate facies of the Armant Formation was deposited in proximal and mid-alluvial fans. The sands of the Qena Formation are differentiated into two facies: a cross-bedded sandstone, representative of alluvial fan—braided stream environments, and a facies of sand interbedded with mud that may have been deposited by a meandering river. The heavy minerals of the Armant Formation are markedly different from those of the Qena Formation, suggesting derivation from different sources. Surface textures of quartz grains from the Qena sands, observed by SEM, exhibit chemical features, attributed to a fluviatile origin. Sand from the Armant Formation is characterized by mechanical and chemical surface textural features that suggest original aeolian derivation followed by later fluvial sedimentation. 相似文献
13.
中祁连木里盆地古近系ESR年龄及地质意义 总被引：1，自引：1，他引：0
对中祁连木里盆地新生代红层进行ESR测年,获得了祁连山地区新生代红层沉积时代及构造变形年代学数据.研究表明,中祁连木里盆地内沉积了巨厚的新生代红层,较好地记录了祁连山隆升历史.盆地最老的新生代地层为始新世由湖相沉积组成的火烧沟组,ESR年龄为40.2～35.3 Ma,与上覆沉积时代为32.6～24.3 Ma的渐新世河湖相沉积组成的白杨河组呈角度不整合接触.构造变形特征与沉积环境的变化说明始新世末与渐新世初木里地区发生了构造变形和山脉的隆升,与祁连山地区新生代早期的隆升有很好的对应关系. 相似文献
14.
A.Encinas A.Folguera R.Riffo P.Molina L.Fernández Paz V.D.Litvak D.A.Colwyn V.A.Valencia M.Carrasco 《地学前缘(英文版)》2019,10(3):1139-1165
The Central Patagonian Andes is a particular segment of the Andean Cordillera that has been subjected to the subduction of two spreading ridges during Eocene and Neogene times. In order to understand the Cenozoic geologic evolution of the Central Patagonian Andes, we carried out geochronologic(U-Pb and40Ar/39Ar), provenance, stratigraphic, sedimentologic, and geochemical studies on the sedimentary and volcanic Cenozoic deposits that crop out in the Meseta Guadal and Chile Chico areas(～47°S). Our data indicate the presence of a nearly complete Cenozoic record, which refutes previous interpretations of a hiatus during the middle Eocene-late Oligocene in the Central Patagonian Andes. Our study suggests that the fluvial strata of the Ligorio Marquez Formation and the flood basalts of the Basaltos Inferiores de la Meseta Chile Chico Formation were deposited in an extensional setting related to the subduction of the Aluk-Farallon spreading ridge during the late Paleocene-Eocene. Geochemical data on volcanic rocks interbedded with fluvial strata of the San Jose Formation suggest that this unit was deposited in an extensional setting during the middle Eocene to late Oligocene. Progressive crustal thinning allowed the transgression of marine waters of Atlantic origin and deposition of the upper Oligocene-lower Miocene Guadal Formation. The fluvial synorogenic strata of the Santa Cruz Formation were deposited as a consequence of an important phase of compressive deformation and Andean uplift during the early-middle Miocene. Finally, alkali flood basalts of the late middle to late Miocene Basaltos Superiores de la Meseta Chile Chico Formation were extruded in the area in response to the suduction of the Chile Ridge under an extensional regime. Our studies indicate that the tectonic evolution of the Central Patagonian Andes is similar to that of the North Patagonian Andes and appears to differ from that of the Southern Patagonian Andes, which is thought to have been the subject of continuous compressive deformation since the late Early Cretaceous. 相似文献
15.
Earthquake, as disastrous events in geological history, can be recorded as soft-sediment deformation. In the Palaeogene of
the East China Sea shelf, the soft-sediment deformation related to earthquake event is recognized as seismic micro-fractures,
micro-corrugated laminations, liquefied veins, ‘vibrated liquefied layers’, deformed cross laminations and convolute laminations,
load structures, flame structures, brecciation, slump structures and seismodisconformity. There exists a lateral continuum,
the wide spatial distribution and the local vertical continuous sequences of seismites including slump, liquefaction and brecciation.
In the Palaeogene of East China Sea shelf, where typical soft-sediment deformation structures were developed, clastic deposits
of tidal-flat, delta and river facies are the main background deposits of Middle-Upper Eocene Pinghu Formation and Oligocene
Huagang Formation. This succession also records diagnostic marks of event deposits and basinal tectonic activities in the
form of seismites. 相似文献
16.
第四纪洞庭盆地赤山隆起与安乡凹陷升降运动的沉积记录 总被引：12，自引：0，他引：12
通过地表地质调查和钻井资料,对第四纪洞庭盆地南部赤山隆起及其西侧安乡凹陷的沉积和地貌特征进行研究,进而探讨二者的升降过程。赤山隆起为居于洞庭盆地南部的小型抬升断块,主要受东、西边界正断裂所控制,长约18 km,宽4~5 km。隆起内早更新世汨罗组和中更新世新开铺组、白沙井组组成多级阶地。安乡凹陷内充填200~300 m厚的河流和湖泊相沉积,自下而上依次为早更新世华田组、汨罗组,中更新世洞庭湖组,晚更新世坡头组,全新世湖积、冲积等。地貌与沉积特征表明,早更新世—中更新世中期赤山隆起总体表现出抬升期与稳定期交替的脉动式抬升,而安乡凹陷则表现出缓慢与快速沉降交替的幕式沉降特征;前者构造较稳定期和构造抬升期分别对应于后者缓慢沉降期和快速沉降期。中更新世晚期二者因区域构造反转而整体抬升并遭受剥蚀。晚更新世—全新世安乡凹陷在拗陷背景下接受沉积。上述第四纪早期赤山隆起脉动式抬升与安乡凹陷幕式沉降的对应关系,为洞庭盆地与周边隆起的盆—山耦合过程提供了约束,同时暗示盆地断陷活动可能与地幔上隆导致中地壳物质自凹陷向周边迁移有关。 相似文献
17.
B. I. Pavlyutkin S. I. Nevolina T. I. Petrenko T. K. Kutub-Zade 《Stratigraphy and Geological Correlation》2006,14(4):444-457
Materials of previous studies and new original geological and paleobotanic data are used to substantiate synchronism (late Eocene) of the Khasan and Nazimovskaya formations, the key stratigraphic units of the Paleogene in Primor’e. Coal-bearing sediments of the units rest upon early-middle Eocene volcanics (Kraskino rhyolite tuffs, Zaisanovka basaltic andesites) being overlain by the lower Fatash Subformation of the lower Oligocene with flora of the Kraskino type. The Ust’-Davydovskaya Formation of the Rechnoi Peninsula (outskirts of Vladivostok) is the most probable analogue of the Khasan (=Nazimovskaya) Formation. 相似文献
18.
南海北部指北纬16°00'至23°00'与东经108°00'至120°00'之间的海域。包括广东大陆以南、海南、台湾两岛之间的广阔大陆架和陆坡区以及北部湾。东西长约1300公里,南北宽约200至400公里。面积约40万平方公里。经过地球物理勘探普查工作及几十口钻井资料,证实该区第三纪沉积广泛分布,厚逾万米。按沉积岩厚度大于1000米所圈定的范围约在30万平方公里以上,形成了北部湾、莺歌海、琼东南、珠江口及台湾西南五个沉积盆地(图1、2)。在北部湾、琼东南、珠江口及台湾西南盆地中,分别在下第三系流沙港组、陵水组、珠江组，上第三系角尾组、韩江组发现了储油气层(表1)。 相似文献
19.
THE CENOZOIC GEORECORDS IN THE NORTHWEST OF YUNNAN AND THE EVOLUTION OF QING—ZANG PLATEAU 相似文献
20.
Yu. O. Gavrilov E. V. Shchepetova E. A. Shcherbinina O. V. Golovanova R. I. Nedumov B. G. Pokrovsky 《Lithology and Mineral Resources》2017,52(6):447-466
Upper Eocene and Lower Oligocene rocks in the northeastern Caucasus were examined in the most representative Chirkei section (Sulak River basin). Sharp lithogeochemical distinctions between them were revealed. The results of the study of nannoplankton demonstrated that the Eocene/Oligocene interface occurs slightly below the boundary between the Belaya Glina and Khadum formations. The studied section revealed a series of nannoplankton bioevents facilitating its stratigraphic subdivision. It has been established that organic matter (OM) in rocks of the Khadum Formation is characterized by a relatively high degree of maturity. Probably, the material of mainly marine genesis contains a terrigenous OM admixture. Positive oxygen isotope anomaly in the upper part of the Belaya Glina Formation reflects global climate changes (cooling) near the Eocene/Oligocene interface. Limitation of the anomaly by the upper boundary of the Belaya Glina Formation is likely related to changes in water salinity variations in the Early Oligocene basin and intense early diagenetic processes in rocks therein. Lithological, geochemical, and paleoecological data suggest that the Khadum paleobasin was depleted in oxygen. Such environment was unstable with periodic intensification or attenuation. Paleoecology in the Belaya Glina basin was typical of normally aerated basins. 相似文献