Mesozoic transtensional basin history of the Eastern Cordillera, Colombian Andes: Inferences from tectonic models

Backstripping analysis and forward modeling of 162 stratigraphic columns and wells of the Eastern Cordillera (EC), Llanos, and Magdalena Valley shows the Mesozoic Colombian Basin is marked by five lithosphere stretching pulses. Three stretching events are suggested during the Triassic–Jurassic, but additional biostratigraphical data are needed to identify them precisely. The spatial distribution of lithosphere stretching values suggests that small, narrow (<150 km), asymmetric graben basins were located on opposite sides of the paleo-Magdalena–La Salina fault system, which probably was active as a master transtensional or strike-slip fault system. Paleomagnetic data suggesting a significant (at least 10°) northward translation of terranes west of the Bucaramanga fault during the Early Jurassic, and the similarity between the early Mesozoic stratigraphy and tectonic setting of the Payandé terrane with the Late Permian transtensional rift of the Eastern Cordillera of Peru and Bolivia indicate that the areas were adjacent in early Mesozoic times. New geochronological, petrological, stratigraphic, and structural research is necessary to test this hypothesis, including additional paleomagnetic investigations to determine the paleolatitudinal position of the Central Cordillera and adjacent tectonic terranes during the Triassic–Jurassic. Two stretching events are suggested for the Cretaceous: Berriasian–Hauterivian (144–127 Ma) and Aptian–Albian (121–102 Ma). During the Early Cretaceous, marine facies accumulated on an extensional basin system. Shallow-marine sedimentation ended at the end of the Cretaceous due to the accretion of oceanic terranes of the Western Cordillera. In Berriasian–Hauterivian subsidence curves, isopach maps and paleomagnetic data imply a (>180 km) wide, asymmetrical, transtensional half-rift basin existed, divided by the Santander Floresta horst or high. The location of small mafic intrusions coincides with areas of thin crust (crustal stretching factors >1.4) and maximum stretching of the subcrustal lithosphere. During the Aptian–early Albian, the basin extended toward the south in the Upper Magdalena Valley. Differences between crustal and subcrustal stretching values suggest some lowermost crustal decoupling between the crust and subcrustal lithosphere or that increased thermal thinning affected the mantle lithosphere. Late Cretaceous subsidence was mainly driven by lithospheric cooling, water loading, and horizontal compressional stresses generated by collision of oceanic terranes in western Colombia. Triassic transtensional basins were narrow and increased in width during the Triassic and Jurassic. Cretaceous transtensional basins were wider than Triassic–Jurassic basins. During the Mesozoic, the strike-slip component gradually decreased at the expense of the increase of the extensional component, as suggested by paleomagnetic data and lithosphere stretching values. During the Berriasian–Hauterivian, the eastern side of the extensional basin may have developed by reactivation of an older Paleozoic rift system associated with the Guaicáramo fault system. The western side probably developed through reactivation of an earlier normal fault system developed during Triassic–Jurassic transtension. Alternatively, the eastern and western margins of the graben may have developed along older strike-slip faults, which were the boundaries of the accretion of terranes west of the Guaicáramo fault during the Late Triassic and Jurassic. The increasing width of the graben system likely was the result of progressive tensional reactivation of preexisting upper crustal weakness zones. Lateral changes in Mesozoic sediment thickness suggest the reverse or thrust faults that now define the eastern and western borders of the EC were originally normal faults with a strike-slip component that inverted during the Cenozoic Andean orogeny. Thus, the Guaicáramo, La Salina, Bitúima, Magdalena, and Boyacá originally were transtensional faults. Their oblique orientation relative to the Mesozoic magmatic arc of the Central Cordillera may be the result of oblique slip extension during the Cretaceous or inherited from the pre-Mesozoic structural grains. However, not all Mesozoic transtensional faults were inverted.     

Microstructures in the Cretaceous Bima Sandstone,Upper Benue Trough,N.E. Nigeria: Implication for hydrocarbon migration

Faulting related to movements along major fault zones in the Upper Benue Trough during Albian times, with evidence of deformation in the Cretaceous Bima Sandstone are common especially around the Kaltungo, Gombe, Zambuk and Teli lineaments. Conjugate extensional systems of deformation bands show increased siliceous cementation of the sandstones adjacent to these lineaments. During the Late Cretaceous compressional event, the deformation bands and faults in the Upper Benue Trough were reactivated, resulting into dilational opening of fractures believed to have acted as fluid conduits and/or barriers. These deformation bands which decrease in density away from the major faults are characterized with increasing porosity and permeability in the host sandstone abruptly away from the tectonic barrier. It is proposed here that the master faults of the Benue Trough, linking it with the Anambra Basin and the Niger Delta probably served as conduits for the migration of hydrocarbons into the Cretaceous reservoirs of the Upper Benue Trough and by extension into the Niger Delta.     

Structural Evolution of Chepaizi Uplift and its Control on Stratigraphic Deposition in the Western Junggar Basin,China

Geological mapping, interpreted cross sections, structural analyses and residual thickness maps were used to characterize the evolution of stress setting, structure and stratigraphic distribution of the Chepaizi Uplift, which is a NW-SE trending structure located in the Western Junggar Basin. The NS-trending faults show an important transpressional phase during the Late Permian, as demonstrated by tectonic stress field and stratigraphic thickness variations. A major compressional thrusting and strike-slip phase during the Late Jurassic created a series of NW-SE faults that originated by the large-scale uplift event in the Northern Tianshan. Faults were reactivated as thrust and dextral strike-slip faults. In addition, the angular unconformity observed between Jurassic and Cretaceous provide evidence of this tectonic event. Lots of normal faults indicate that the area records southward tilting and regional derived extensional stress that took place during the Neogene. Before that, thick Early Cenozoic strata are widely deposited. The balanced cross-section highlights the evolution of stress setting and stratigraphic distribution of the Chepaizi Uplift.     

Post-Variscan sedimentary record of the SW margin of the Bohemian massif: a review

The late-Palaeozoic to Cenozoic stratigraphic and structural record of the southwestern margin of the Bohemian massif and its extension beneath the southward adjacent Molasse basin shows that it is controlled by a system of basement-involving faults which came into evidence during Stephanian– Autunian times and which were subsequently repeatedly reactivated. Thick Permo-Carboniferous clastics accumulated in fault-bounded transtensional basins aligned with the southwestern Bohemian border zone (SWBBZ). Following late-Autunian deformation of these basins, the SWBBZ was overstepped by late-Permian to Late Jurassic platform sediments, reflecting tectonic stability. During the Early Cretaceous the SWBBZ was strongly reactivated, causing disruption and erosion of its Mesozoic sedimentary cover. Sedimentation resumed in the area of the SWBBZ during late Early and Late Cretaceous with clastic influx from the Bohemian massif reflecting gradually increasing tectonic activity along the SWBBZ. During the Late Senonian and Paleocene transpressional deformations resulted in upthrusting of major basement blocks. In the Molasse basin such structures are sealed by transgressive Late Eocene marine strata. Mio-Pliocene uplift of the Bohemian massif, involving mild reactivation of the SWBBZ, is related to the development of the volcano-tectonic Eger zone. The structural configuration of the SWBBZ is largely the result of Late Senonian–Paleocene compressional intraplate tectonics which play a major role in the structural framework of the northern Alpine and Carpathian foreland.     

湘东南印支运动变形特征研究

关于华南中三叠世晚期印支运动变形特征,一种观点强调其重要性或认为其形成了NNE向为主的上古生界盖层褶皱;另一种观点则认为印支运动强度不大,上古生界NNE向主体褶皱形成于燕山运动甚至更晚。鉴于此,本文重点对湘东南印支运动的构造线走向展开了研究,厘定其为NNE向,反映区域NWW向挤压作用。对资兴三都、宜章瑶岗仙、桂东沙田等晚三叠世—侏罗纪残留盆地进行的研究表明,早燕山构造层下伏不整合面切割了上古生界中NNE向褶皱;以NNE走向为轴将不整合面旋转至水平,恢复上古生界岩层走向及构造线方向为NNE向。不整合面之下的地层层位普遍存在沿东西方向的快速变化。以上表明湘东南印支运动构造线为NNE向而非EW向,区域挤压应力方向为NWW向而非SN向。其动力机制可能与扬子和华夏板块之间产生陆内汇聚有关。结合区域资料,认为印支运动中华南不同地区的构造背景及构造体制存在显著差异。     

小江断裂带有三纪走滑断陷盆地的充填层序特征

小江断裂是滇中走滑断裂系中的一条主干断裂，沿断裂带发育了一系列带有明显走滑特征的新生代小型断陷盆地，第三纪含煤地层主要由冲积扇－湖泊、沼泽成因地层层序构成。本在对多个断陷盆地的成因地层、充填序列、沉积体系域等剖析的基础上，讨论了走滑构造背景下断陷盆地的充填层序特征，并指出构造沉降、走滑作用和构造反转对盆地充填起作重要的作用。     

Genesis of folds in external zones: application of fault propagation fold model. Gafsa Basin example (southern central Tunisia)

The evolution of geological structures is related particularly to reactivation of preexisting fault, thus the importance of tectonic inheritance. Basing on stratigraphic and structural data in external zones leaving the example of Gafsa Basin (southern central Tunisia), we study the evolution of folds during tectonic phases. The structural and stratigraphic data prove that Gafsa Basin is subject for more than one tectonic phase where beginning by Cretaceous extension and reactivated by Atlasic compression. The combination of field results associated to that geomorphology confirms the application of “fault propagation model” as evolution mode of folds. The balanced of cross section, using numerical software Ramp E.M. 1.5.2, shows the importance of tectonic inheritance to interpret evolution of structures reliefs. The deformation increases related to reactivation of old normal fault. The most important deformation is observed in Jbal At Taghli presenting folds in the form of duplex resulted from conjugate activity of tear fault; it is the first interpretation of tear fault activity in surface in the scale of Tunisia. The application of fault propagation fold model to interpret fold genesis confirms the field data and proves the role of tectonic inheritance and reactivation of preexisting faults in the evolution of structures during different tectonic phases.     

东昆仑东段晚古生代—中生代若干不整合面特征及其对重大构造事件的响应

地层不整合接触是研究地质发展历史和鉴定地壳运动特征的重要依据。通过大范围露头尺度和填图尺度不整合面的识别,结合不同时代地层沉积体系的特征及构造变形样式的对比研究,发现东昆仑造山带东段晚古生代—中生代地层由底到顶共发育有4个不同类型的不整合面,分别是上二叠统格曲组与上石炭统浩特洛哇组之间的角度不整合面、中三叠统希里可特组与闹仓坚沟组之间的微角度不整合面、上三叠统八宝山组与下伏不同时代地层之间的角度不整合面、下侏罗统羊曲组与上三叠统八宝山组之间的平行不整合面。这几个不同时代的不整合面分别代表了东昆仑东段晚古生代—中生代地质演化时期中特定的构造事件。其中,格曲组与浩特洛哇组角度不整合关系代表东昆仑造山带南缘阿尼玛卿—布青山古特提斯洋晚二叠世开始向北俯冲的构造事件;希里可特组与闹仓坚沟组微角度不整合关系与陆(弧)陆局部差异性初始碰撞的洋陆转换构造事件密切相关;八宝山组与下伏不同时代地层角度不整合关系是东昆仑地区分布较广、意义重大的一个不整合面,代表中三叠世晚期—晚三叠世早期东昆仑地区陆(弧)陆全面碰撞的主造山构造事件,同时该期碰撞造山事件铸就了东昆仑及其周缘地区的基本构造格架。羊曲组与八宝山组之间平行不整合面则与晚三叠世晚期—早侏罗世早期陆内演化过程中地壳垂向抬升事件相关。这些不整合面的厘定及其代表的相应构造事件对于合理建立东昆仑地区晚古生代—中生代构造演化过程具有重要意义。     

“磨拉石建造”和“不整合”在地层对比中的意义——以扬子地块及其北缘晚前寒武纪地层为例

扬子地块及其北缘晚前寒武纪地层划分对比争议较大,主要是对“地层不整合”和“磨拉石建造”存在认识上的分歧,笔者据现代构造理论,对地壳变形和沉积建造的控制作用认为,地层不整合可以发育在被动大陆边缘形成初始阶段的裂谷期和裂谷期后,又可产生于造山作用过程;磨拉石建造应按构造动力学背景划分为拉张型、挤压型和剪切型三类;它们分别代表了威尔逊旋回不同阶段的产物。     

不整合分析及其在陆相盆地构造研究中的意义

讨论了3个问题,即不整合分析及其在研究陆相盆地的形成和演化中的意义;不整合分析及其与构造运动和盆地改造的关系;与不整合有关的圈闭类型。通过上述的不整合分析,可以获得以下结论：正旋回地层的超覆(或上超)是在拉张或中性构造背景中产生的,而反旋回地层的退覆和削截一不整合则是在挤压构造环境中发育的;复合递进型同构造不整合与内陆前陆盆地边缘挤压隆起的加速和减速上升有关。根据不整合面下被削截岩层的构造变形和侵蚀厚度可以推断出由构造运动所造成的盆地改造程度和与不整合有关的地层圈闭类型。     

Quaternary tectonics in a passive margin: Marajó Island,northern Brazil

Marajó Island is located in a passive continental margin that evolved from rifting associated with the opening of the Equatorial South Atlantic Ocean in the Late Jurassic/Early Cretaceous period. This study, based on remote sensing integrated with sedimentology, as well as subsurface and seismographic data available from the literature, allows discussion of the significance of tectonics during the Quaternary history of marginal basins. Results show that eastern Marajó Island contains channels with evidence of tectonic control. Mapping of straight channels defined four main groups of lineaments (i.e. NNE–SSW, NE–SW, NW–SE and E–W) that parallel main normal and strike‐slip fault zones recorded for the Amazon region. Additionally, sedimentological studies of late Quaternary and Holocene deposits indicate numerous ductile and brittle structures within stratigraphic horizons bounded by undeformed strata, related to seismogenic deformation during or shortly after sediment deposition. This conclusion is consistent with subsurface Bouguer mapping suggestive of eastern Marajó Island being still part of the Marajó graben system, where important fault reactivation is recorded up to the Quaternary. Together with the recognition of several phases of fault reactivation, these data suggest that faults developed in association with rift basins might remain active in passive margins, imposing important control on development of depositional systems. Copyright © 2007 John Wiley & Sons, Ltd.     

The paleotectonic and paleogeography reconstructions of the Tarim Basin and its adjacent areas (NW China) during the late Early and Middle Paleozoic

Tarim Basin is the large, very complex, oil-bearing basin in China, surrounded by the Tianshan–Beishan, West Kunlun and Altyn Tagh mountain belts to the north, south, and southeast, respectively. Understanding the processes and evolution of this complex superimposed basin, especially with respect to the effects of single tectonic movements, is a difficult challenge, which concerns the tectonic and dynamic interrelationships between the basin and the orogenic belts during the different stages of the Paleozoic in the Paleo-Asian and Tethyan tectonic systems and for the evaluation of the resource potentials in Tarim Basin. In this study, we focused on 3-dimensional, basin-scale structural architecture and the properties of two regional unconformities that occur within the basin and its adjacent areas. Here, we outline the structural deformations underlying the unconformity, the structural architecture styles and the distributions of the unconformity, and the stratigraphic sequence and nature of the sedimentary rocks immediately overlying the unconformity. During the late Early and Middle Paleozoic tectonic movements, disconformities developed mainly in the northern and the central parts of the basin, and angular unconformities which beneath layers were monocline and faulted-fold deformations developed in the southern, or the southern and northern parts of the basin, respectively. Before the Silurian, the Low Hotian Uplift, the NE-trending faulted-folded belts of the Tangguzibas Depression and the southern Tazhong Uplift underwent intense deformation related to SE–NW-directed tectonic compression. In addition, the NE-trending faults in the Tangguzibas Depression developed during periods of activity on the South Altyn Tagh Fault. The structural deformation, as well as the depositional facies, formed in response to the subduction and closure of the South Altun Ocean and West Kunlun–Kudi Ocean, and the resulting collisional orogeny. Prior to deposition of Upper Devonian sediments, structural deformation and erosion occurred in two marginal parts of the basin. The extent and intensity of deformation on the NE-trending faults in the Tangguzibas Depression were also reduced, whereas the NE-trending folds developed in the Manjiaer Depression. The Tabei Uplift experienced uplift and deformation. The closure of the North Altun Ocean and the eastern part of the South Tianshan Ocean with south-subduction may be the main driving forces for the tectonic activity. Extensive areas in the northern and southern margins of the basin were uplifted and denudated by orogenic activity as a prelude to the molasse basin that developed in the early Late Devonian in the northeastern and southeastern parts of the basin. The structural architecture of the unconformities reveals the geometry and dynamics of the basin–orogen system in single tectonic movements.     

藏南康马地区石炭系及其下伏变质构造地层序列

西藏康马地区位于拉轨岗日构造带南缘中部。前人对该地区的康马穹窿及周围地层进行了大量研究,但长期以来对该区石炭系及以下变质构造地层的层序及时代认识不清,致使拉轨岗日构造带前石炭纪的地质演化史成为空白。根据1∶25万江孜县幅、亚东县幅区域地质调查工作取得的地层学资料及古生物、岩石组合特征,对康马附近石炭系及其以下地层进行了重新厘定。厘定后的地层单元分别为前奥陶系郎巴群（POl）、奥陶系则果群（Oz）、下石炭统雇孜组（C₁g）。下石炭统雇孜组（C₁g）与上覆早二叠世破林浦组（P₁p）之间为伸展不整合接触,与奥陶系则果群（Oz）之间为伸展拆离断层接触,前奥陶系郎巴组（POl）与奥陶系则果群（Oz）之间为伸展不整合接触,与下伏康马岩体为伸展拆离断层接触。     

Variation of palaeostress patterns along the Oriente transform wrench corridor, Cuba: significance for Neogene–Quaternary tectonics of the Caribbean realm

In this study, we address the late Miocene to Recent tectonic evolution of the North Caribbean (Oriente) Transform Wrench Corridor in the southern Sierra Maestra mountain range, SE Cuba. The region has been affected by historical earthquakes and shows many features of brittle deformation in late Miocene to Pleistocene reef and other shallow water deposits as well as in pre-Neogene, late Cretaceous to Eocene basement rocks. These late Miocene to Quaternary rocks are faulted, fractured, and contain calcite- and karst-filled extension gashes. Type and orientation of the principal normal palaeostress vary along strike in accordance with observations of large-scale submarine structures at the south-eastern Cuban margin. Initial N–S extension is correlated with a transtensional regime associated with the fault, later reactivated by sinistral and/or dextral shear, mainly along E–W-oriented strike-slip faults. Sinistral shear predominated and recorded similar kinematics as historical earthquakes in the Santiago region. We correlate palaeostress changes with the kinematic evolution along the boundary between the North American and Caribbean plates. Three different tectonic regimes were distinguished for the Oriente transform wrench corridor (OTWC): compression from late Eocene–Oligocene, transtension from late Oligocene to Miocene (?) (D₁), and transpression from Pliocene to Present (D₂–D₄), when this fault became a transform system. Furthermore, present-day structures vary along strike of the Oriente transform wrench corridor (OTWC) on the south-eastern Cuban coast, with dominantly transpressional/compressional and strike-slip structures in the east and transtension in the west. The focal mechanisms of historical earthquakes are in agreement with the dominant ENE–WSW transpressional structures found on land.     

Structure and tectonic history of the foreland basins of southernmost South America

The common elements and differences of the neighboring Austral (Magallanes), Malvinas and South Malvinas (South Falkland) sedimentary basins are described and analyzed. The tectonic history of these basins involves Triassic to Jurassic crustal stretching, an ensuing Early Cretaceous thermal subsidence in the retroarc, followed by a Late Cretaceous–Paleogene compressional phase, and a Neogene to present-day deactivation of the fold–thrust belt dominated by wrench deformation. A concomitant Late Cretaceous onset of the foreland phase in the three basins and an integrated history during the Late Cretaceous–Cenozoic are proposed. The main lower Paleocene–lower Eocene initial foredeep depocenters were bounding the basement domain and are now deformed into the thin-skinned fold–thrust belts. A few extensional depocenters developed in the Austral and Malvinas basins during late Paleocene–early Eocene times due to a temporary extensional regime resulting from an acceleration in the separation rate between South America and Antarctica preceding the initial opening of the Drake Passage. These extensional depocenters were superimposed to the previous distal foredeep depocenter, postdating the initiation of the foredeep phase and the onset of compressional deformation. Another pervasive set of normal faults of Paleocene to Recent age that can be recognized throughout the basins are interpreted to be a consequence of flexural bending of the lithosphere, in agreement with a previous study from South Malvinas basin. Contractional deformation was replaced by transpressive kinematics during the Oligocene due to a major tectonic plate reorganization. Presently, while the South Malvinas basin is dominated by the transpressive uplift of its active margin with minor sediment supply, the westward basins undergo localized development of pull-apart depocenters and transpressional uplift of previous structures. The effective elastic thickness of the lithosphere for different sections of each basin is calculated using a dynamic finite element numerical model that simulates the lithospheric response to advancing tectonic load with active sedimentation.     

柴达木北缘达肯大坂群与滩间山群的接触关系

柴达木北缘古元古界达肯大坂群片麻岩系与上奥陶统滩间山群绿片岩系之间先存的角度不整合已经受到后期滑脱构造变形的强烈改造,是一种变质岩区特有的构造接触关系——隐蔽不整合,从而明确"过渡带"片岩系实质上是一条变质滑脱带,是伸展体制下低角度正断层沿不整合面滑脱拆离的产物,其主体应划归达肯大坂群。     

渤海海域辽中南洼压扭构造带成因演化及其控藏作用

在三维地震资料详细分析解释的基础上,利用水平相干切片和不同方向地震测线对辽中南洼压扭构造带的发育特征 进行了分析,进一步结合地层发育及应力场特征对压扭构造带的成因演化进行了研究,在此基础上探讨了其对油气成藏的 控制作用。结果表明：辽中南洼压扭构造带的形成演化受控于NNE向展布的辽中1号和中央走滑断裂,两条断裂主要表现 为伸展-走滑性质,平面上表现为弯曲的“S”形,且构成左阶排列。辽中南洼的古近纪早期的伸展沉降与后期走滑断裂派 生的挤压应力是压扭构造带形成演化的主要控制因素,古近纪孔店-沙三期辽中南洼伸展沉降,沙三末期的构造变革使得 压扭构造带开始形成,古近纪晚期（Ed） 辽中1号和中央走滑断裂表现为强烈的右旋走滑,两条断裂的左阶排列以及中央 走滑断裂的“S”形弯曲在压扭构造带派生出构造挤压应力。此后,古近纪末期东营运动以及新近纪末期渤海运动的构造挤 压对其进行了改造,压扭构造带下凹上凸,古近系东营组和新近系地层弯曲上拱。压扭构造带成藏条件优越,作为主要封 堵断层的中央走滑断裂“S”形外凸增压部位断裂带紧闭、封堵能力强,有利于形成大中型油气藏。     

东天山博格达地区石炭系构造-地层划分及成盆背景分析

东天山博格达地区经历了古生代长期俯冲增生与中—新生代多期陆内变形改造作用,但对于博格达山石炭纪构造属性与演化阶段等问题始终存在争议,制约了对北疆晚古生代构造格局的认识。利用博格达山露头及其两侧盆地钻井、地震资料,运用盆地构造分析思路与方法从盆-山尺度开展了石炭系地层格架及岩浆活动特征综合对比研究,划分博格达地区石炭系构造-地层单元并分析石炭纪构造背景。研究结果显示:博格达山相邻的准噶尔盆地和吐哈盆地发育下石炭统与下伏地层(C₁/AnC)不整合,而上、下石炭统之间(C₂/C₁)、二叠系与上石炭统(P/C₂)不整合在博格达山及相邻盆地普遍存在,由此将博格达地区石炭系划分为下石炭统和上石炭统2个主要构造层,揭示研究区经历了两个主要的构造演化阶段。进一步结合构造变形演化、盆地构造沉降特征及构造环境分析结果,认为博格达山石炭纪为俯冲相关伸展背景下的弧后盆地,经历了早、晚石炭世两阶段伸展裂陷作用,并在裂陷晚期均明显遭受了周缘块体碰撞拼贴事件的影响。     

黔西南普安铅锌矿区盆地尺度构造

贵州省普安铅锌矿区位于华南褶皱带西北缘的黔西南坳陷,矿体主要赋存在石炭系的白云质灰岩和白云岩中,构造控矿特征显著.NW-SE走向的二维地震剖面横穿了铅锌矿区,清晰地揭示了矿区的地层和NE向构造格架.从浅层的泥盆系至深层的新元古界,共标定了3个反射层和3个反射单元,据两个重要角度不整合面,矿区呈现为双层基底、单层盖层的"...