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1.
Throughgoing fractures play a major role in subsurface fluid flow yet the kinematics of their formation, which directly impact rock flow properties, are often difficult to establish. We investigate throughgoing fractures in the Monterey Formation of California that developed by the coalescence of pre-existing joints. At Lompoc Landing, throughgoing fractures fall into three main groups: linked, linked with aperture, and breccia zones. The segmented nature of their walls provides numerous piercing points to firmly establish the sense of displacement. Analysis of displacement vectors derived from piercing points demonstrates that the NW–SE trending throughgoing fractures, often interpreted as strike–slip faults, are in fact extensional structures in origin. We suggest that this method may be applied to throughgoing fractures that form by the same mechanism in other geologic settings. Establishing kinematics of throughgoing fractures will lead to a better understanding of their contribution to subsurface fluid flow. 相似文献
2.
Lianbo Zeng Xiaomei Tang Jiafu Qi Lei Gong Fusheng Yu Tiecheng Wang 《International Journal of Earth Sciences》2012,101(8):2183-2191
Fractures can provide valuable information for tectonic evolution. According to the data of outcrops, cores, thin sections and well logs, the tectonic fractures in the Qaidam Basin can be divided into four types: small faults (including small normal fault and small reverse fault), vertical open fracture, bedding plane slip fracture and horizontal open fracture. Our fracture observations provide new constraints on the Cenozoic tectonic evolution of the Qaidam Basin. Syn-sedimentary small normal faults in the Paleogene strata indicate the extension deformation during the Paleogene. Small reverse faults, vertical open fractures and bedding plane slip fractures occurred in the Paleogene and Neogene strata have genetic relationship. According to the burial history and homogenization temperature of fluid inclusions of gypsum and calcite filled in the vertical open fractures, it can be deduced that the vertical open fractures being formed mainly from the late Miocene Shangyoushashan Formation with age of 5.1?Ma to the end of Pliocene Shizigou Formation with age of 2.6?Ma, indicating small reverse faults, vertical open fractures and bedding plane slip fractures were simultaneously formed in the Neogene. These fractures were resulted from the compression deformation. The horizontal open fractures occurred in the Paleogene, Neogene and Quaternary strata with apertures and intensities decreasing with depth were formed by the large-scale quick uplift and denudation resulted from the strong compression deformation since the Quaternary. 相似文献
3.
Based on our detailed structural characterization, we examine possible relationships between thrust faults and strike-slip faults and thrust-cored folds and depositional units in the Silla Syncline, a 4 km wide fold composed of fine-grained mudstone, coarse sandstone and conglomerate deposits of the Cerro Toro Formation in the Magallanes foreland basin, Chilean Patagonia. The syncline is bounded on its western flank by an asymmetric anticline and on its eastern flank by a broad zone of thrust faults and associated folds, which are oriented sub-parallel to the syncline axis. Deposition of the coarse-grained units of the Silla Syncline appears to have taken place in this structurally defined trough controlled primarily by thrust fault related growth structures flanking the syncline.The syncline and surrounding area have also been deformed by two sets of strike-slip faults, one right-lateral and one left-lateral. The strike-slip and thrust faulting operated contemporaneously for much of their active periods, although it appears that thrust faulting, confined within the fine-grained units, initiated slightly earlier than strike-slip faulting. In addition, younger igneous intrusions at high angle to bedding generally localize along the strike-slip faults. The cross-cutting relationships among the intrusions, strike-slip faults, and flexural slip faults show that all these structures were active during the same period, which extends beyond mid-Miocene.These conclusions support the premise that structures in deep-water sediments are important for understanding not only the deformation of a foreland basin, but also its depositional architecture. 相似文献
4.
西藏纳当地区石炭系永珠组主要为浅变质的砂板岩组合,断层和褶皱非常发育的特征。依据岩石和构造特征可以把区内永珠组分成上、中、下三段。永珠组形成于拉张的被动大陆边缘向裂谷转换的次深海环境,并于中晚二叠世至晚三叠世期间经历了三个构造演化阶段。 相似文献
5.
本文根据岩性组合、剖面结构及与下伏地层接触关系等特征,认为贵州地区上白垩统茅台组是炎热干燥气候条件下,于燕山构造运动后未曾夷平基面上沉积的河湖相红色磨拉石建造,沉积盆地性质为山间盆地。茅台组现今的大范围零星散布,主要是喜马拉雅运动后遭受长期侵蚀剥蚀造成的。 相似文献
6.
The Chauki, Mandi, Manil colony, Changpur, Khawas and Naghal areas are situated in between the limbs of Hazara Kashmir Syntaxis (HKS). HKS is the part of Himalayan fold and thrust belt that lies in sub-Himalayan domain. Seismically, this is an active zone. Early Miocene to Recent sedimentary rocks are exposed in the area. The stratigraphic units in Kashmir basin are the cover sequence of the Indian plate. These non-marine lithostratigraphic units are molasse deposits formed by the deposition of sediments coming from north carried by the rivers originated from higher Himalayas. Murree Formation of early Miocene age is the oldest rock unit in the studied area. Siwalik Group; Chinji, Nagri, Dhok Pathan and Soan formations of early Miocene to Pliocene and Mirpur Formation of Pleistocene age is exposed. The area is structurally deformed into folds and faults. The Sarda Sarhota syncline, Mandi syncline and Fagosh anticline are major folds in the area. These folds are isoclinal to open in nature, southwest or northeast verging and thrust direction is southwest or northeast. Major reverse faults are Riasi fault and Fagosh fault. The Changpur fault is a normal fault. Primary sedimentary structures present in the area are load cast, ripups and cross bedding. The facing of beds have been marked on the basis of these sedimentary structures. 相似文献
7.
鄂尔多斯盆地东南部延长组古地震效应及其地质启迪 总被引：2，自引：0，他引：2
印支期秦岭造山活动控制和影响着鄂尔多斯盆地南缘边界性质和盆内延长组的沉积作用。通过岩芯分析,在盆地东南部延长组地层中识别出震裂缝、层内阶梯状微断层、微褶皱、液化砂岩脉、液化卷曲变形、球-枕构造、环状层理、丘-槽构造、震积角砾岩等典型的软沉积物变形构造,反映该时期研究区有受频繁且强烈地震作用事件影响的痕迹。在此基础上,对晚三叠世鄂尔多斯盆地盆山耦合作用过程及其响应的动力学机制进行了深入分析;进一步详细研究了震浊积岩这一特殊事件沉积体的形成机制与时空分布规律,并建立其沉积模式;最终讨论了该时期地震作用事件的属性特征及周期活跃性。 相似文献
8.
浙江省老虎洞组、黄龙组生物地层的研究较薄弱，尤其是笾化石带的建立不够系统，使地层的正确划分和对比存在一些问题。笔者通过精测浙江省桐庐县杨家老虎洞组、黄龙组地层剖面，系统采集了筵化石样品，经筵薄片研究。自下而上新建2个筵化石带：Profusulinella simplex带和FusulineUa bocki—Fusulina mayiensis带(二带化石归属达拉阶)。并与浙江长兴、杭州、常山地区的老虎洞组、黄龙组剖面进行了生物地层和岩石地层的划分对比。对比结果表明：Profusulinella simplex带上延至黄龙组中一下部， 相似文献
9.
湘东南印支期褶皱特征及形成机制 总被引：16，自引：2，他引：16
湘东南地区以王仙岭-坪石一线为界,分为东部隆起区和西部坳陷区,分别发育两种不同类型和成因的印支期褶皱.东部隆起区大面积出露前泥盆纪褶皱基底并发育隔槽式褶皱,由泥盆纪跳马涧组与褶皱基底间的不整合界面所显示,表明褶皱基底参与了褶皱作用;露头显示褶皱过程中盖层未沿不整合界面产生明显滑脱.基于上述事实,认为隔槽式褶皱形成于基底(厚皮式)横向收缩与压扁作用,并从理论上论证了隔槽式褶皱不可能是盖层沿基底滑脱的产物,修正了前人的薄皮式观点.西部坳陷区主要出露中泥盆世-中三叠世地层并发育类侏罗山式褶皱,褶皱具有波长小且大小不一、垂向上不协调等特征,并伴生大量走向断裂,说明褶皱受不同层位软弱层顺层滑脱作用控制,其深层机制与区域断裂逆冲活动有关. 相似文献
10.
贵州瓮安地区北斗山矿区寒武系牛蹄塘组的特征 总被引：1，自引：0，他引：1
瓮安大信北斗山矿区牛蹄塘组出露普遍,厚度较薄,明显分为2段。下段称上磷矿段,以磷质岩或磷块岩为主,沉积结构以内碎屑结构为主,内碎屑成分主要为磷质砂屑,可见黄铁矿和海绿石;岩层具有透镜状层理、水平层理、块状层理、磷质结核体等沉积构造。上段称黑色页岩段,以黑色页岩为主,沉积结构以泥质结构为主;普遍发育水平层理和较大个体的磷结核体。黑色页岩段底部普遍含镍钼钒多金属层;下部含黄铁矿纹层或结核,中部出现碳酸盐结核。对牛蹄塘组的地层特征和岩石学特征分析表明,本区牛蹄塘组为水体较深的缺氧沉积,显示为海平面上升期的海侵层,上磷矿段沉积时为动力较强的滨海至浅海陆棚相环境,黑色页岩段沉积时为水动力较弱的陆棚边缘盆地相环境,多金属层位于最大海泛面处。 相似文献
11.
滇西勐海西定地区,在大地构造上位于西南“三江”造山带南段昌宁-孟连结合带东侧的双江-澜沧俯冲增生杂岩带内。该区分布有一套晚古生代的浅变质碎屑岩系--南段组(DCn)。该套地层既显示层型面状构造型式,又发育有顺层片理、顺层掩卧褶皱、粘滞型石香肠及顺层韧性剪切带等构造形迹,具明显的分层剪切变形、横向构造置换和顺层固态流变特点,构成较典型的褶叠层构造。本文对其构造变形特征进行了系统分析与总结,结合区域构造背景研究成果认为,南段组褶叠层构造总体形成于昌宁-孟连古特提斯洋闭合后同碰撞造山收缩挤压背景下的伸展剪切机制。同时指出,南段组是经过构造改造重建而形成的构造地层单元,应称其为南段岩组;现今露头剖面所见南段岩组岩性组合及厚度只代表改造后构造地层的岩性组合特征及褶叠层的露头厚度,不能完全代表南段组原沉积地层的韵律组合及沉积地层厚度;应按构造地层单位进行划分、填图和研究。褶叠层构造作为浅变质岩区一种普遍的构造型式,是对岩石变形组合特征的客观认识,其构造型式、形成机制、形成层次以及形成时间的研究对分析造山带构造演化过程和深化大陆动力学机制的认识具有科学意义。 相似文献
12.
In the high‐grade (granulite facies) metamorphic rocks at Broken Hill the foliation is deformed by two groups of folds. Group 1 folds have an axial‐plane schistosity and a sillimanite lineation parallel to their fold axes; the foliation has been transposed into the plane of the schistosity by these folds. Group 2 folds deform the schistosity and distort the sillimanite lineation so that it now lies in a plane. Both groups of folds are developed as large folds. The retrograde schist zones are zones in which new fold structures have formed. These structures deform Group 1 and Group 2 folds and are associated with the formation of a new schistosity and strain‐slip cleavage. The interface between ore and gneiss is folded about Group 1 axial planes but about axes different from those in the foliation in the gneiss. On the basis of this, the orebody could not have been parallel to the foliation prior to the first recognizable structural and metamorphic events at Broken Hill. The orebody has been deformed by Group 2 and later structures. 相似文献
13.
Many types of hydrothermal deposits (e.g. W, Bi, Pb, Zn, Ag) are confined by faults and hidden granodiorite in the Luowei Orefield in Xidamingshan, Guangxi, China. The orebodies in the Luowei W–Bi deposit are predominantly layered and distributed along bedding in sandstones of the Cambrian Xiaoneichong Formation. The orebodies in the Lujing Pb–Zn deposit are controlled mainly by west‐south‐west (WSW)‐trending faults, and those in the Fenghuangshan Ag deposit are controlled mainly by west‐north‐west (WNW)‐trending faults, which were reverse faults during mineralization and were later reactivated as sinistral strike‐slip faults. The Luowei fault was formed postmineralization and resulted in sinistral displacement of the subsurface granodiorite and the Cambrian strata. A tectonomagmatic mineralization model of the Luowei Orefield is proposed, and the following conclusions were made. (i) Under a regional N–S compressive stress regime, WSW‐ and WNW‐trending reverse faults and N–S‐trending tensional fractures were formed. (ii) Magma intruded along the tensional fractures. Under the force of magmatic thermodynamics, mineralizing fluid migrated along bedding planes in sandstones and formed W–Bi orebodies at favorable sites. Some fluid migrated along WSW‐ and WNW‐trending faults to sites farther from the magma source, forming vein‐type Pb–Zn and Ag orebodies. (iii) After mineralization, under ~E–W compression, a NW‐trending left‐lateral slip fault was formed, cutting the subsurface granodiorite and orebodies. Concurrently, sinistral shear slip occurred on WNW‐trending ore‐controlling faults. However, the small displacement on these faults did not change the overall distributions of the rock mass and orebodies. 相似文献
14.
岔路河断陷万昌-梁家构造带万昌组沉积相和油气成藏特征 总被引：1，自引：0，他引：1
万昌构造带和梁家构造带是岔路河断陷的两个重要油气聚集带,在形成演化过程中,万昌构造带受到东南缘控盆断裂的控制,而梁家构造带受Ⅱ号断层的控制,导致了砂体的沉积相差异。岩心、测井和地震资料研究表明,浅层万昌组地层中,万昌构造带主要发育扇三角洲砂体,梁家构造带主要发育水下扇砂体,砂体的连续性和储集物性较好,尤其是离物源较近的分流河道和辫状沟道砂体的孔渗较高,深层双阳组、奢岭组、永吉组发育较好的烃源岩,控盆断裂及其衍生的一系列断层有助于油气的运移和封闭,油气成藏条件较好。 相似文献
15.
M. G. Kale Ashwin S. Pundalik R. A. Duraiswami N. R. Karmalkar 《Journal of the Geological Society of India》2016,87(2):194-204
Soft sediment deformation structures such as slump folds, clastic dyke, syn-sedimentary faults and convolute bedding are present in the coarse–fine grained yellowish buff coloured sandstone, and interbedded reddish brown fine grained sandstone and yellowish–white siltstone at the Khari River section belonging to Rudramata member of Jhuran Formation (Upper Jurassic), Kutch. These soft sediment deformation structures are confined to lower and middle parts of the section and are invariably underlain as well as overlain by undeformed beds that have restricted lateral and vertical extent and occur in close proximity of Kutch Mainland Fault, thereby suggesting that these structures were formed by seismic activity and therefore represents seismites. 相似文献
16.
《Journal of South American Earth Sciences》1999,12(1):69-85
The Pliocene Upper Onzole Formation exposed in the vicinity of Punta Gorda, near Esmeraldas, Ecuador, is composed mainly of fine-grained mud turbidites, having regular vertical sequences of sedimentary structures associated with a positive grading, and bioturbation restricted mostly to the tops of beds. The remainder of beds measured consist of volcanic ash, mud pelagite, and glauconitic silt–sand turbidites. Vertical sequential analysis of stratigraphic sections for the most part show no pronounced trends in bed thickness or grain size. Volcanic ashes are crystal–vitric tuffs occurring in four bedding styles: (A) normally-graded ashes with burrowed gradational tops and sharp wavy bases; (B) ashes that form part of a complex microstratigraphy consisting of thinly-bedded mudstone, silt–sand turbidites, tuffaceous mudstone, and ash beds; (C) less conspicuous ash laminae and ash-filled burrows; and (D) a tuffaceous bed with ash and mud swirled together in convolute layers. Ash chemistry suggests an Andean high-K calc-alkaline provenance. Facies relations, paleontologic data and regional geologic setting suggest sediment accumulation on an inner trench slope in a basin situated oceanward of the Pliocene trench–slope break. Faulting is extensive and reflects two deformational episodes, the youngest involving Holocene marine and fluvial terraces. Faults group into an older, northerly trending, listric set, and a younger, west–northwest-trending high-angle set. Fault striations of both sets suggest dominantly dip–slip motion. The faults reflect an episode of latest Pliocene through Quaternary trench-normal extension in the forearc, followed by trench-parallel extension. Both sets of faults crosscut large northeast-trending regional folds. Post-Pliocene changes in stress regime, from generally northwest–southeast compression, to east–west tension, to north–northeast–south–southwest tension probably reflect change in stress vectors that resulted from the ongoing collision of the leading edge of the South America plate with the thick oceanic crust of the Carnegie Ridge. 相似文献
17.
通过对26口井岩心观察,结合区域构造背景,在鄂尔多斯盆地富县探区三叠系延长组中识别出典型的震积岩。该区震积岩代表性沉积构造有液化砂脉、液化卷曲变形、环状层理、负载构造、球枕构造、微断层、微裂缝、震裂岩与震碎角砾岩,其中液化砂脉和液化卷曲变形是地震引起的主要软沉积变形构造。震积岩垂向序列划分为两类:一种以脆性变形为主,自下向上依次为下伏未震层,扰动层,微断层、微裂缝及震裂岩层段,液化卷曲变形层段,震碎角砾岩层段,液化砂脉层段及上覆未震层;另一种以软沉积变形为主,自下至上依次为下伏未震层,环状层段,扰动层,球枕构造及负载构造层段,液化砂脉及液化卷曲变形层,枕状层及上覆未震层。富县探区延长组中的震积岩说明在该盆地晚三叠世存在一个强地震事件活跃期;震积岩中的微裂缝、微断层、震裂岩及液化砂脉可改善储集层物性,同时震碎角砾岩和网状砂脉也是良好的储集层。 相似文献
18.
为了揭示华北北部晚侏罗世沉积盆地性质,对赤城-宣化盆地中土城子组沉积特征及盆缘构造进行了研究。通过对土城子组沉积特征研究表明,土城子组中-下部为一套河湖相沉积,上部为一套冲积扇粗碎屑沉积;土城子组砾岩成分系统统计分析显示,赤城盆地与宣化-下花园盆地具有相似岩屑岩性相旋回,反映源区具有相同或相近的蚀顶过程。研究区晚侏罗世盆地中土城子组充填特征及盆缘构造特征表明,土城子组形成于挤压构造背景,土城子组沉积时期盆地受控于盆缘逆冲断层。大地构造背景暗示,赤城-宣化盆地晚侏罗世-早白垩世期间,古太平洋板块向NW方向的俯冲作用与尚义-赤城断裂向南逆冲并伴随右旋走滑作用是土城子组沉积时期盆地格局形成的重要控制因素。 相似文献
19.
鄂尔多斯盆地延长组是我国近些年陆相页岩气的重点勘探区之一。本文从页岩的露头观测、岩石学特征、成像测井分析、地应力特征及可压裂性等方面,研究了鄂尔多斯盆地延长组泥页岩层段的裂缝发育特征,以及地应力对人工压裂诱导缝的影响。基于岩石学分析,延长组长7和长9段的泥页岩脆性矿物平均含量较高,分别为57.2%和44%。根据泥页岩露头观测和成像测井分析,长7段泥页岩发育有北东东向为主的垂直裂缝组,同时可见北北东向和南北向的垂直裂缝组。此外,压裂诱导缝的优势方位和成像测井分析结果表明,现今最大水平主应力方向为70°左右（即北东东向）。裂缝开启性分析表明,北东东向至近东西向裂缝组与现今最大水平地应力方向一致,开启性较好;而北北东裂缝组与现今最大水平地应力交角相对较大,开启性相对较差。因为现今地应力的水平应力比值（σH/σh = 1.54）相对较小,在后期人工压裂中延长组泥页岩中的诱导裂缝更倾向形成复杂的裂缝网格系统,这样会使裂缝与储层之间获得最大的接触,从而更有利于提高产能。 相似文献
20.
鄂东黄石地区下三叠统大冶组风暴沉积 总被引：1，自引：3，他引：1
鄂东黄石地区下三叠统大冶组灰岩中发育了典型的风暴沉积，风暴岩由砾屑灰岩、颗粒灰岩和泥灰岩组成，其中风暴沉积构造包括丘状交错层理、递变层理、砾屑的撕裂构造及水平层理等，不同层位具有不同的风暴沉积构造类型和组合特征。根据风暴沉积的岩石特征、构造类型、规模、组合特点，并结合沉积背景分析，风暴沉积序列可进一步分为深水远源型、过渡型和浅水近源型。大冶组一段风暴沉积具有深水远源特点，沉积环境为水体较深的外陆棚； 大冶组二段风暴沉积具有过渡型特点，沉积环境为向上变浅的内陆棚； 大冶组三、四段风暴沉积具有浅水近源特点，沉积环境为浅水陆棚至滨岸。大冶组沉积序列具有向上变浅的特点，沉积环境由深水陆棚逐渐向滨岸转变。风暴沉积的识别对重建鄂东黄石地区早三叠世古地理具有重要意义。 相似文献