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1.
《Sedimentary Geology》2007,193(1-4):47-58
Groups of hills on a regional Vistulian (Weichselian) deglaciation plateau (Warmia, NE Poland) are covered by till of up to a dozen metres thick. It is the same till of the main stadial of the Vistulian glaciation that outcrops in the upland. The internal parts of the hills consist of fine-grained sands. These glacial landforms are referred to as englacial kames; they result from infilling of englacial caverns with sand. The orientation of the kame fields and the form pattern within these fields coincide with the system of primary crevasses in the ice, as it was reconstructed on the basis of the orientation of postglacial crevasse forms. The origin of the englacial caverns at crossing points of crevasse surfaces in the glacier is discussed. Structural analysis (relationship with a circular lineament, local differentiation of the complete profile of the Pleistocene deposits, possibility of occurrence of faults — festoon glacitectonics) suggests that the origin of these landforms is related to movements in the substratum. 相似文献
2.
HANNA RUSZCZY&#;SKA-SZENAJCH 《Sedimentology》1981,28(5):713-722
Fossil remnants of up-turned debris-rich bands of glacial ice are recorded from three localities in the Polish Lowlands. In each case the fossil debris bands occur in proximal parts of hills built of glacitectonically disturbed sediments. The characteristics of these remnants and of the associated deposits and structures are described, and they are compared to present-day examples from Spitsbergen. 相似文献
3.
渤海湾盆地奥陶系潜山内幕油气成藏主控因素研究 总被引：6，自引：2，他引：4
本文的渤海湾盆地奥陶系潜山内幕是指有石炭系—二叠系覆盖的奥陶系潜山。潜山内幕多为单斜平行结构,储层基本为非均质"似块状结构"。古近系为主的烃源岩,通过控山断层的断面输油,形成"新生古储"的成藏模式。奥陶系潜山内幕成藏有四项主控因素,按重要程度依次为生烃灶供烃潜能、有效输烃窗口、优势输导通道以及储层裂缝发育。同时具备四项有利主控因素的潜山,油气富集规模较大。在生烃灶供烃潜能有利的前提下,其他三项主控因素之一为不利时,仍有成藏的可能,但规模一般较小。潜山内幕的储集空间以裂缝为主,裂缝的发育程度受构造和控山断层形态的影响,背斜构造、弧形断层、多向交切断层有利于裂缝的发育,而受直线型断层控制的潜山裂缝欠发育。 相似文献
4.
Edouard Ravier Jean‐François Buoncristiani Sylvain Clerc Michel Guiraud John Menzies Eric Portier 《Sedimentology》2014,61(5):1382-1410
A pit located near Ballyhorsey, 28 km south of Dublin (eastern Ireland), displays subglacially deposited glaciofluvial sediments passing upwards into proglacial subaqueous ice‐contact fan deposits. The coexistence of these two different depositional environments at the same location will help with differentiation between two very similar and easily confused glacial lithofacies. The lowermost sediments show aggrading subglacial deposits indicating a constrained accommodation space, mainly controlled by the position of an overlying ice roof during ice‐bed decoupling. These sediments are characterized by vertically stacked tills with large lenses of tabular to channelized sorted sediments. The sorted sediments consist of fine‐grained laminated facies, cross‐laminated sand and channelized gravels, and are interpreted as subglaciofluvial sediments deposited within a subglacial de‐coupled space. The subglaciofluvial sequence is characterized by glaciotectonic deformation structures within discrete beds, triggered by fluid overpressure and shear stress during episodes of ice/bed recoupling (clastic dykes and folds). The upper deposits correspond to the deposition of successive hyperpycnal flows in a proximal proglacial lake, forming a thick sedimentary wedge erosively overlying the subglacial deposits. Gravel facies and large‐scale trough bedding sand are observed within this proximal wedge, while normally graded sand beds with developed bedforms are observed further downflow. The building of the prograding ice‐contact subaqueous fan implies an unrestricted accommodation space and is associated with deformation structures related to gravity destabilization during fan spreading (normal faults). This study facilitates the recognition of subglacial/submarginal depositional environments formed, in part, during localized ice/bed coupling episodes in the sedimentary record. The sedimentary sequence exposed in Ballyhorsey permits characterization of the temporal framework of meltwater production during deglaciation, the impact on the subglacial drainage system and the consequences on the Irish Sea Ice Stream flow mechanisms. 相似文献
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6.
哀牢山浅变质岩带分布于哀牢山深大断裂与九甲-安定深大断裂之间的古生界与中生界地层中,哀牢山金矿带目前已发现的主要金矿床(点)均产于其中,金矿类型以蚀变岩型和石英脉型为主,但近年来,相继发现了一批红土型金矿.哀牢山浅变质岩带基岩的含金丰度值高,新生代以来构造活动异常强烈,而地壳抬升保持相对平稳,亚热带气候温暖潮湿,在地形平缓的山间盆地、低山、丘陵、准平原、喀斯特地貌单元中红色粘土富集,是红土型金矿成矿的有利地区.岩带南段相对于北段红土型金矿成矿条件更加有利,找矿更有远景. 相似文献
7.
西藏札达盆地及周缘高山区第四纪冰川遗迹与冰期的初步划分和对比 总被引：2，自引：1，他引：1
札达盆地及周缘高山区的第四纪冰川遗迹分布广泛,类型齐全、发育连续.特征的冰碛及冰水堆积地貌有:冰水堆积平原或冰水堆积平台、冰碛丘陵等.挤压构造遗迹有:褶皱、断裂表皮构造、压坑、压裂构造、变形砾石等.ESR年代测定结果表明,冰碛形成的最大年龄为2.33Ma.依据冰碛、冰水堆积的特征、分布和形成年代等,区域冰川发育由老到新可划分出:7次冰期、6次间冰期、1次冰缘期、1次新冰期.该区是目前所知青藏高原第四纪冰川遗迹发现最多、保存最全和发育最连续的地区,为青藏高原地区的第四纪冰川演化研究、冰期的划分和对比、古气候古环境的研究,提供了重要的实际资料和依据. 相似文献
8.
目前,针对渤海南部潜山地层结构、构造演化的研究较少.应用三维地震资料、钻井资料,系统分析了该区潜山断裂类型、地层构造类型、成因演化和动力学背景.研究表明,近南北向郯庐走滑断裂和近东西向反转断裂共同控制了研究区潜山地层分布,进而造成了研究区潜山地层的结构、构造差异.近南北向郯庐走滑断裂为调节东西两侧挤压强度差异的同印支造山期断层.郯庐走滑断裂西支以西挤压变形强度相对较弱,普遍发育古生界薄底或秃底构造,以"中生界+古生界+前寒武系"三层结构为主;以东挤压变形作用则相对较强,表现为强烈隆升,古生界剥蚀殆尽,为"中生界+前寒武系"双层结构,花状走滑构造发育.近东西向反转断层为印支期逆冲断层,燕山期伸展反转,现今断裂上升盘残存古生界,下降盘古生界剥蚀殆尽.横向挤压收缩差异是导致研究区潜山地层结构、构造差异的主要原因. 相似文献
9.
论界牌峪地区“陀状”角砾岩成因及找矿意义 总被引：6，自引：0，他引：6
湖南石门界牌峪地区存在大量的所谓“陀状”角砾岩，它们互不相连，外观圆形，有的聚集成群或者呈完全孤立的山包。角砾岩地表多为椭圆状和等轴状，与围岩多呈刺穿状接触。通过地质学、岩石学和地球化学等方面研究，认为该区“陀状”角砾岩是一种由热泉气体及部分物质在封闭还原条件下产生急剧爆发所形成的特殊的角砾岩群。它们是一种极好的容矿控矿体，具有重要的找矿意义 相似文献
10.
西藏沙拉岗锑矿控矿构造及成矿时代约束 总被引：4，自引：1，他引：3
西藏沙拉岗锑矿床位于中国北喜马拉雅地区然巴杂岩穹窿的东南部40km。该地区至少有4种矿床类型被发现:(1)金矿;(2)金锑矿;(3)锑矿;(4)铅锌(银,锑)矿。沙拉岗是该地区代表性的一个以辉锑矿为主要矿石矿物的脉状锑矿床。赋矿围岩为下白垩统甲不拉组板岩、粉砂岩、硅质岩以及辉长岩和闪长岩等侵入体。主要的矿体受控于近东西向和近南北向断裂构造。近东西向的断裂构造多为低角度浅层次的层间断裂,在成矿前和成矿后均有活动。近南北向的构造多为高角度的断裂,切割了矿区的近东西向断裂,闪长岩和辉长岩,是主要的导矿构造和成矿要素,连通了深部含矿热液和浅表近东西向断裂构造。当近东西向和近南北向的构造发生交汇,沿断裂构造分布的蚀变和矿化的规模随之扩大,往往存在较大规模的工业矿体。锆石SHRIMP U-Pb分析说明辉长岩形成于23.6Ma左右,近南北向断裂构造及其伴随的锑矿化的时间,至少要晚于23.6Ma。 相似文献
11.
Stefan Wenau Tiago M. Alves 《Boreas: An International Journal of Quaternary Research》2020,49(4):799-812
Tunnel valleys are major features of glaciated margins and they enable meltwater expulsion from underneath a thick ice cover. Their formation is related to the erosion of subglacial sediments by overpressured meltwater and direct glacial erosion. Yet, the impact of pre-existing structures on their formation and morphology remains poorly known. High-quality 3D seismic data allowed the mapping of a large tunnel valley that eroded underlying preglacial delta deposits in the southern North Sea. The valley follows the N–S strike of crestal faults related to a Zechstein salt wall. A change in downstream tunnel valley orientation towards the SE accompanies a change in the strike direction of salt-induced faults. Fault offsets indicate important activity of crestal faults during the deposition of preglacial deltaic sediments. We propose that crestal faults facilitated tunnel valley erosion by acting as high-permeability pathways and allowing subglacial meltwater to reach low-permeability sediments in the underlying Neogene deltaic sequences, ultimately resulting in meltwater overpressure build-up and tunnel valley excavation. Active faults probably also weakened the near-surface sediment to allow a more efficient erosion of the glacial substrate. This control of substrate structures on tunnel valley morphology is considered as a primary factor in subglacial drainage pattern development in the study area. 相似文献
12.
冀中坳陷斜坡带奥陶系潜山油气成藏条件分析 总被引：12，自引：1，他引：12
研究工作依据实际资料和新的地质认识,对冀中坳陷文安斜坡和杨村斜坡奥陶系潜山带的构造格局及古潜山油气藏的形成条件进行了剖析。该区发育有正向和反向正断层,奥陶系地层形成一个地垒状潜山带,上覆石炭—二叠系地层,具有新生—古生—古储—中堵的成藏条件。石炭—二叠系煤系和下第三系泥岩为供烃源;不整合面、断面及北西向断裂为供油通道。油气成藏的主力因素储层的发育明显受白云石化、岩溶和构造破裂作用的控制,喜马拉雅期的岩溶作用是由活动断层导入岩溶水而得以进行的,因此,孔隙、裂隙相对富集的岩层与活动断层的匹配是潜山储层形成的关键地质条件。潜山古风化壳并不是制约储层发育的唯一因素。对该类储层的评价应构造分析与地层分析相结合。储集条件影响了油气的富集,长期活动的大断裂控制了油气的分布。 相似文献
13.
山东乳山石英脉型金矿侧伏规律及找矿方向 总被引：5，自引：0，他引：5
山东乳山中部发育石英脉型金矿,金矿分布和产出受ＮＮＥ向及ＮＥＥ向断裂构造控制,具有棋盘格式分布规律,其中ＮＮＥ向断裂是区内金矿脉的定位构造。金矿床矿体侧伏具有同一断裂带分布的不同金矿床矿体侧伏方向两两相反,相邻断裂带中的金矿床矿体侧伏方向相同的规律。根据矿体侧伏规律指出了找矿方向。 相似文献
14.
鲁北济阳坳陷沾化凹陷东部潜山的发育及油气成藏控制因素 总被引：1，自引：0，他引：1
通过对沾化凹陷东部主要断裂发育演化的特征和主要地震测线的平衡剖面、伸展率分析,对该地区潜山发育过程及其与盆地演化的关系进行了研究,并就潜山油气成藏的控制因素进行了分析.结果表明,沾化凹陷东部潜山发育可以划分为早-中三叠世、晚三叠世、早-中侏罗世的潜山发育前期,晚侏罗世-白垩纪的潜山发育期,古近纪的潜山改造、定型期和新近纪-第四纪的潜山成藏期,断裂活动是本区潜山形成演化的主控因素.沾化凹陷东部潜山油气成藏主要受控于该区中、新生代盆地的叠合关系,中生代凸起和古近纪凹陷的叠合部位是最有利的潜山油气成藏区,中生代凸起和古近纪凸起的叠合部位不利于潜山成藏,往往形成潜山披覆背斜油气藏. 相似文献
15.
通过对沾化凹陷东部主要断裂发育演化的特征和主要地震测线的平衡剖面、伸展率分析,对该地区潜山发育过程及其与盆地演化的关系进行了研究,并就潜山油气成藏的控制因素进行了分析。结果表明,沾化凹陷东部潜山发育可以划分为早—中三叠世、晚三叠世、早—中侏罗世的潜山发育前期,晚侏罗世—白垩纪的潜山发育期,古近纪的潜山改造、定型期和新近纪—第四纪的潜山成藏期,断裂活动是本区潜山形成演化的主控因素。沾化凹陷东部潜山油气成藏主要受控于该区中、新生代盆地的叠合关系,中生代凸起和古近纪凹陷的叠合部位是最有利的潜山油气成藏区,中生代凸起和古近纪凸起的叠合部位不利于潜山成藏,往往形成潜山披覆背斜油气藏。 相似文献
16.
J. R. L. Allen 《Geological Journal》1982,17(1):31-47
On the southwest-facing slopes of a bedrock ridge lying between Cardigan Bay to the north and the Afon Teifi to the south stands a group of hills in which 30-35 m of cross-laminated and parallel-laminated sands with lenticular upward-fining gravel sequences are overlain by 10-12 m of gravel in a single foreset bed. The sediments mantle a surface of till sloping gently toward the southwest, were transported toward the southwest (across one margin of the Afon Teifi valley), and were cut by a system of densely arranged conjugate normal faults striking northwest-southeast. The lenticular gravels and fault system suggest that the deposits accumulated as a glaciofluvial outwash spread, and on top of an ice-lobe that became isolated in the Teifi valley during the downwasting of a glacier which had occupied Cardigan Bay and much of the country to the south. The large gravel foresets capping the succession are the only indication at Banc-y-Warren of the former existence of a lake, but neither a large nor deep body of water need be envisaged. 相似文献
17.
Late Pleistocene morainic sequences around Dundalk Bay, eastern Ireland, were deposited in a variety of shallow, glaciomarine environments at the margins of a grounded ice lobe. The deposits are essentially ice-proximal delta-fan and -apron sequences and are divided into two lithofacies associations. Lithofacies association 1 occurs as a series of morainal banks formed at the southern margin of the ice lobe in a body of water open to influences from the Irish Sea. The morainal banks consist mainly of diamictic muds deposited from turbid plumes and by ice-rafting with minor occurrences of turbidites, cross-bedded gravels (subaqueous outwash) and massive boulder gravels (high-density debris flows). Lithofacies association 2 was deposited in a narrow arm of the sea at the north-eastern margin of the ice lobe. The deposits consist mainly of a series of coalescing, ice-proximal Gilbert-type fan deltas which are interbedded distally with tabular and lens-shaped subaqueous deposits. The latter are mainly ice-rafted diamictons, debris-flow deposits and subaqueous sands and gravels. Both lithofacies associations are draped by diamictons formed by a combination of rain-out, debris flow and traction-current activity. At a few localities the upper parts of the sequence have been sheared by minor oscillations of the ice sheet margin. These sequences form part of an extensive belt of glaciomarine deposits which border the drumlin swarms of east-central Ireland. Lithostratigraphic variability is partially related to the arrival of large volumes of debris at the ice lobe margin when the main lowland ice sheet surged during drumlin formation. Complex depositional continua of this type lack any major erosional breaks and should not be used either as climatic proxies or for stratigraphic correlations. 相似文献
18.
RADOSLAW DOBROWOLSKI SLAWOMIR TERPILOWSKI 《Boreas: An International Journal of Quaternary Research》2006,35(2):213-221
This article describes the well-exposed landform/sediment assemblage of a Pliocene palaeouvala and Pleistocene (Saalian) ice-pushed ridge in a large quarry in Upper Cretaceous marls near Rejowiec, eastern Poland. The site provides a rare opportunity to study the development of glacial depositional and deformational processes on morphologically and structurally variable bedrock. The internal structures of both chronostratigraphic units which comprise this assemblage provide evidence of two principal stages of deformation associated with an ice advance on a karstified foreland, each stage preceded by stabilization of the ice mass. The first deformational stage was characterized by the development of imbricate structures in outwash sediments (the initial ice-pushed ridge) and listric faults at the contact between the bedrock and palaeouvala fills (caused by an increasing ice load). Shallow subglacial folding of the proximal fan deposits, and a listric thrust which limited the extent of the ice-pushed ridge under development occurred in the second deformational stage. The data assembled indicate that the formation of push moraines (in a general sense) during ice-sheet advance is controlled by the substratum undulations. Closed depressions with loose fills in the foreland of advancing ice sheets can control the deformational style, geometry and extent (both lateral and vertical) of the push moraines. 相似文献
19.
桂西地区自寒武纪至三叠纪发生了多次古侵蚀作用，已大致查明有11次沉积间断时期形成了古岩溶面，其中两次大范围的构造隆升及一次在裂谷拉张期相对持续时间较长的古水下岩溶作用，造成古生界为主的碳酸盐岩系溶蚀尤其强烈，形成大面积的古岩溶面。这些古岩溶面对微细粒浸染型金矿的控制非常明显，部分金矿床虽未直接产于古岩溶面，但其控矿断裂带多与深部古岩溶隐伏带有关系，古岩溶面起到间接控矿作用；主要金矿化的岩性有细碎屑岩、硅质岩、基性及中酸性侵入及喷出岩等，均为硅铝质岩系，而矿化最终底板均为古岩溶面下的碳酸盐岩系。金矿形成机制为：古岩溶潜山构造在后期叠加构造蚀变时，由地层淋滤出的金在古岩溶面及其影响带发生再富集而成矿。 相似文献
20.
This paper describes a complex sequence of glacigenic sediments occupying a faultbounded depression at Aberdaron Bay, western Lleyn. The sequence offers an insight into sedimentary environments during deglaciation of the Irish Sea Basin. A lower stratified diamict association (LDA) containing contorted units of fine sand/silt and displaying strong, consistent clast fabrics, is overlain by an upper diamict association (UDA) with weaker fabrics and extensive sand and gravel layers and channel fills. Certain characteristics of the sequence can be explained by a glacimarine depositional model, but there are several problems. In particular, the geometry of the sediments is difficult to explain without recourse to the melting of buried ice. An alternative model that overcomes these problems involves the decay of a terrestrial glacier containing reworked marine sediments. Supraglacial sediment flows released during decay of thinner ice covering the surrounding hills (UDA) would have rapidly buried a thick stagnant ice mass in the Aberdaron depression, facilitating slow melting and release of basal meltout till (LDA). A model is presented that accounts for the stagnation and in situ decay of a debris-rich Irish Sea glacier, and which could explain many of the deposits and landforms surrounding the Irish Sea Basin without recourse to high relative sea-levels. 相似文献