Structural evolution of the Llanos foothills, Eastern Cordillera, Colombia

The Llanos foothills are located in the frontal thrust zone of the Eastern Cordillera in Colombia in a complex environment that BP has been exploring actively since 1988. This exploration has resulted in the discovery of several fields with a variety of hydrocarbon fluids (gas condensate and volatile oil) in very tight quartz-arenites. The structural style and complexity of this fold-and-thrust belt changes along the trend from single frontal structures to an imbricate of up to five thrust sheets in a triangle zone. In highly complex environments, the seismic image quality is poor, and interpretation becomes very challenging. The structural models of the area have evolved as more data have been acquired. The initial structural model required inversion of the basin at the end of the Andean orogeny. The structural style changed to an in-sequence imbricate thrust stack with very long, trailing back limbs that return to regional elevation and finalize in a tighter structures with short back limbs. The concept of early deformation and multiple phases has been introduced. Three main phases have been distinguished: (1) an early event during the deposition of the Lower Carbonera (39–29 Ma), with incipient structures formed to create syntectonic deposition; (2) a phase of steady subsidence that increased notably at the end of the period (29–7 Ma); and (3) the latest phase (7–0 Ma), when most deformation and uplifting occurred. The migration of hydrocarbons happened simultaneously with the deformation, and its final distribution, amount, and variation in composition is related to the structural evolution of the area.     

Curved structures and interference fold patterns associated with lateral ramps in the Eastern Cordillera, Central Andes of Argentina

The conspicuous curved structures located at the eastern front of the Eastern Cordillera between 25° and 26° south latitude is coincident with the salient recognized as the El Crestón arc. Major oblique strike-slip faults associated with these strongly curved structures were interpreted as lateral ramps of an eastward displaced thrust sheet. The displacement along these oblique lateral ramps generated the local N–S stress components responsible for the complex hanging wall deformation. Accompanying each lateral ramp, there are two belts of strong oblique fault and folding: the upper Juramento River valley area and El Brete area.On both margins of the Juramento River upper valley, there is extensive map-scale evidence of complex deformation above an oblique ramp. The N–S striking folds originated during Pliocene Andean orogeny were subsequently or simultaneously folded by E–W oriented folds. The lateral ramps delimiting the thrust sheet coincident with the El Crestón arc salient are strike-slip faults emplaced in the abrupt transitions between thick strata forming the salient and thin strata outside of it. El Crestón arc is a salient related to the pre-deformational Cretaceous rift geometry, which developed over a portion of this basin (Metán depocenter) that was initially thicker. The displacement along the northern lateral ramp is sinistral, whereas it is dextral in the southern ramp. The southern end of the Eastern Cordillera of Argentina shows a particular structure reflecting a pronounced along strike variations related to the pre-deformational sedimentary thickness of the Cretaceous basin.     

Crustal velocity structure beneath the western Andes of Colombian using receiver-function inversion

Analysis of teleseismic records obtained in two broadband seismic stations of three components located on the Andean region of Colombia is presented in this work. The two stations are located at the Western Cordillera (WC), station BOL, and at the Central Cordillera (CC), station PBLA. The analysis of seismograms was performed by inversion of the receiver functions (RF) in order to obtain the crustal velocity structure beneath the receivers. The receiver function is a spectral ratio obtained from teleseismic earthquakes recorded by broadband seismic stations, which allows the calculation of the velocity structure beneath the receiver by removing source effects in the horizontal components of the seismic traces. Data stacking was performed in order to improve signal to noise ratio and then the data was inverted by using two optimization algorithms: a genetic algorithm (GA), and a simulated annealing algorithm (SA). The present work calculates the receiver functions using teleseismic earthquakes at epicentral distances (Δ) ranging between 30° and 90° and recorded at the two stations within the years 2007 and 2009.Delay times between P and PS waves converted at the Moho boundary were used to constrain the velocity structure. The receiver functions at the stations were generated from seismic events within a broad range of back azimuth. Data from gravity and magnetism were also used during the geophysical survey. The depth of the Moho boundary was found to be at 40 km in the WC beneath station BOL and at 43 km in the CC beneath station PBLA. The upper crust, with a thickness of 5 km, is characterized by a shear wave velocity of about 3.0 km s⁻¹; the shallower layers, at approximately 1.0 km, have shear wave velocities between 2.2 and 2.6 km s⁻¹, which corresponds to sediments overlying the upper crust. These observations support the hypothesis of a thickness of the crust at the root of the mountain range to be between 32 and 50 km. The calculated receiver functions were compared with artificial ones generated from the inversion of 48000 models of horizontal layers for each station using a GA and an SA that allowed a satisfactory coverage of all the sample space in order to avoid non-unique solutions. Beneath station BOL a moderate low-velocity zone (LVZ) was found, which was caused by accretionary processes of the ophiolite complex in the WC.     

Structure and tectonics of the central segment of the Eastern Cordillera of Colombia

In the Eastern Cordillera of Colombia, a new structural model constrained by field data, paleontologic determinations, and interpretations of seismic reflection profiles is proposed. The model implies 70 km of shortening, including reactivation of basement structures as inverse faults in both flanks of the chain. These faults propagated within the lower Cretaceous strata, inducing passively rooted and transported thrust sheets as the successive basement faults were reactivated. Two structural styles are identified in the western flank: (1) positive flower structures in a transpressive regime, which affected rocks older than upper Paleocene and were unconformably covered by post–late Paleocene sediments, and (2) compressive structures during the late Miocene–Recent Andean phase. Presently, WNW-ESE compression reactivates Late Paleocene structures, which locally affect Andean trends. In the western margin of the Eastern Cordillera, the Cambao thrust takes up most displacement, whereas the Bituima fault takes only a minor part. To the south, this relationship reverses, suggesting complementary behavior by the Bituima and Cambao faults, as well as a transfer zone. This suggestion explains the southward termination of the Guaduas syncline as a structure related to the Cambao fault, whereas the Bituima fault increases its displacement southward, generating the Girardot foldbelt that takes over the structural position of the Guaduas syncline.     

Kinematic variations across Eastern Cordillera at 24°S (Central Andes): Tectonic and magmatic implications

The Eastern Cordillera (Central Andes,  24°S) consists of a basement-involved thrust system, resulting from Miocene–Quaternary eastward migrating compression, separating the Puna plateau from the Santa Barbara System foreland. The inferred Tertiary strains arising from shortening in the Eastern Cordillera and Santa Barbara System are similar, higher than in the Puna. Slip data collected on the major  N–S trending faults of Eastern Cordillera show a westward progression from dip-slip (contraction) to dextral and sinistral motions. This, consistently with established tectonic models, may result from partitioning due to the oblique Mio-Quaternary underthrusting of the Brazilian Shield north of 24°S. This strain partitioning has three main implications. (1) As the dextral and sinistral shear in the Eastern Cordillera are  62% and 29% of the compressive strain respectively, the Eastern Cordillera results more strained than Santa Barbara System foreland, contrary to previous estimates. (2) The partitioning in the Eastern Cordillera may find its counterpart in that to the west of the Central Andes, giving a possible structural symmetry to the Central Andes. (3) The easternmost N–S strike-slip structures in the Eastern Cordillera coincide with the easternmost Mio-Pliocene magmatic centres in the Central Andes, at  24°S. Provided that, further to the east, the crust is partially molten, the absence of magmatic centres may be explained by the presence of pure compressive structures in this portion of the Eastern Cordillera.     

满洲里地区灵泉盆地中生代火山岩的锆石U-Pb年代学、地球化学及其地质意义

本文对满洲里地区灵泉盆地中生代火山岩进行了锆石LA-ICP-MS U-Pb年代学和岩石地球化学研究,以便对其岩石成因和区域构造演化给予制约。研究区内9个代表性火山岩中的锆石均呈自形-半自形晶,显示出典型的岩浆生长环带或条痕状吸收,结合其高的Th/U比值(0.25~7.78),暗示其岩浆成因。测年结果表明,研究区中生代火山岩可分为3期,分别以中侏罗世(约166Ma)塔木兰沟组玄武岩类、早白垩世早期(约142Ma)吉祥峰组流纹岩类和早白垩世晚期(约125Ma)上库力组流纹岩类和伊列克得组玄武岩类为代表。中侏罗世(塔木兰沟组)火山岩具有富碱、高钾和高的La/Yb、La/Nb、Hf/Sm、Nb/U和Ce/Pb比值,以及富集大离子亲石元素(LILEs)、轻稀土元素(LREEs)和亏损Nb等特征,暗示其形成应与陆壳加厚之后的岩石圈伸展作用有关;早白垩世早期(吉祥峰组)火山岩具有高硅、富碱、富K、Rb、Th及低Al、Mg、Ca、Ni、Cr、Ti等特点,类似于A型流纹岩,揭示其形成于陆内伸展环境;早白垩世晚期火山岩具双峰式组合特点,基性端元具有富碱、高钾、高度富集LILEs和LREEs,类似于钾玄质玄武岩,而酸性端元显示A型流纹岩特点,揭示该期火山岩应形成于一种与裂谷发育过程相似的强烈引张环境。结合区域中生代火山岩的空间展布特征,认为中-晚侏罗世和早白垩世早期火山岩的形成应与蒙古-鄂霍茨克缝合带的演化有关,而早白垩世晚期双峰式火山岩的形成应与太平洋板块向欧亚大陆的俯冲作用相联系。     

Evolution of the stress and strain fields in the Eastern Cordillera,Colombia

This work integrates stress data from Global Positioning System measurements and earthquake focal mechanism solutions, with new borehole breakout and natural fracture system data to better understand the complex interactions between the major tectonic plates in northwestern South America and to examine how the stress regime in the Eastern Cordillera and the Llanos foothills in Colombia has evolved through time. The dataset was used to generate an integrated stress map of the northern Andes and to propose a model for stress evolution in the Eastern Cordillera. In the Cordillera, the primary present-day maximum principal stress direction is WNW–ESE to NW–SE, and is in the direction of maximum shortening in the mountain range. There is also a secondary maximum principal stress direction that is E–W to ENE–WSW, which is associated with the northeastward “escape” of the North Andean block, relative to stable South America. In the Cupiagua hydrocarbon field, located in the Llanos foothills, the dominant NNE–SSW fractures are produced by the Panama arc–North Andes collision and range-normal compression. However, less well developed asymmetrical fractures oriented E–W to WSW–ENE and NNW–SSE are also present, and may be related to pre-folding stresses in the foreland basin of the Central Cordillera or to present-day shear associated with the northeastward “escape” of the north Andean block. Our study results suggest that an important driver for orogenic deformation and changes in the stress field at obliquely convergent subduction zone boundaries is the arrival of thickened crust, such as island arcs and aseismic ridges, at the trench.     

楚雄中生代前陆盆地的构造沉降史研究

云南楚雄盆地位于扬子陆块的西南边缘,为一典型的中生代周缘前陆盆地。盆地演化阶段明显,晚三叠世为前陆早期复理石沉积,侏罗纪则为前陆晚期磨拉石沉积。对盆地构造沉降史研究后笔者认为:①晚三叠世复理石沉积盆地构造沉降幅度巨大,沉降与沉积中心位于盆地最西部,紧邻古哀牢山造山带,沉积体呈楔形展布;②侏罗纪磨拉石沉积盆地构造沉降和沉积中心以及前缘隆起向内陆方向迁移明显;③中生代构造快速沉降的沉积体的楔形展布表明盆地具有前陆岩石圈挠曲成因特征;④盆地的高沉积速率受构造和超补偿沉积作用的共同控制。     

Geochronological, isotopic, and geochemical data from Permo-Triassic granitic gneisses and granitoids of the Colombian Central Andes

New U–Pb SHRIMP ages in zircon, Ar–Ar ages in micas and amphiboles, Nd–Sr isotopes, and major and REE geochemical analyses in granitic gneisses and granitic stocks of the Central Cordillera of Colombia indicate the presence of a collisional orogeny in Permo-Triassic times in the Northern Andes related to the construction of the Pangea supercontinent. The collision is recorded by metamorphic U–Pb SHRIMP ages in inherited zircons around 280 Ma and magmatic U–Pb SHRIMP ages in neoformed zircons around 250 Ma within syntectonic crustal granitic gneisses. Magmatic U–Pb SHRIMP and Ar–Ar Triassic ages around 228 Ma in granitic stocks indicate the presence of late tectonic magmatism related to orogenic collapse and the beginning of the breakup of the supercontinent. During this period, the Central Cordillera of Colombia would have been located between the southern United States and northern Venezuela, in the leading edge of the Gondwana supercontinent.     

中国东北地区中生代构造体制的转变:来自火山岩时空分布与岩石组合的制约

东北地区中生代经历了蒙古-鄂霍茨克构造体系向太平洋构造体系的转换,形成了不同期次火山活动。本文归纳总结了露头区与覆盖区中生代火山岩的年代学、空间分布、岩石组合以及地球化学特征,揭示了两个构造域的时空分布范围。该区火山岩锆石U-Pb年龄统计结果表明中生代存在五期火山活动:早-中侏罗世(190~160Ma)、晚侏罗世(160~145Ma)、早白垩世早期(145~120Ma)、早白垩世晚期(120~100Ma)、晚白垩世早期(100~90Ma)。早-中侏罗世火山岩分布较少,火山岩仅分布在大兴安岭西部满洲里地区和东部张广才岭以及南侧辽宁北票-朝阳地区,火山岩属于高钾钙碱性系列,为蒙古-鄂霍茨克海闭合和法拉隆板块双俯冲作用的产物。晚侏罗世东北地区火山活动明显增强,主要分布在大兴安岭地区,张广才岭以及小兴安岭也有少量分布。西部大兴安岭地区以粗面安山岩、粗面岩为主,属于同碰撞造山成因,为蒙古-鄂霍茨克海闭合造山环境产物。东部以中酸性、酸性岩为主,为法拉隆板块背离欧亚大陆,岩石圈伸展引起的壳源物质熔融产物。早白垩世早期火山活动最为强烈,火山岩主要分布在大兴安岭地区。岩性以高钾钙碱性系列的粗面玄武安山岩、粗面安山岩、安山岩、粗面岩为主,为蒙古-鄂霍茨克海闭合造山后伸展环境产物。早白垩世晚期火山岩主要分布在松辽盆地内部。火山岩以中酸性岩为主,属于中钾-高钾钙碱性系列,为伊泽奈崎板块俯冲引起的弧后拉张,软流圈上涌导致年轻地壳熔融的产物。晚白垩世早期火山岩仅分布在小兴安岭及吉林、黑龙江省东部地区。火山岩为一套玄武岩、玄武安山岩、安山岩和英安岩组合,属于中钾钙碱性系列,是伊泽奈崎-库拉板块高角度俯冲的大陆边缘岩浆活动产物。东北地区中生代不同期次火山岩记录了蒙古-鄂霍茨克构造域向太平洋构造域转换过程及其时空影响范围。     

The geological and geodynamic evolution of the eastern Black Sea basin: insights from 2-D and 3-D tectonic modelling

Subsidence mechanisms that may have controlled the evolution of the eastern Black Sea have been studied and simulated using a numerical model that integrates structural, thermal, isostatic and surface processes in both two- (2-D) and three-dimensions (3-D). The model enables the forward modelling of extensional basin evolution followed by deformation due to subsequent extensional and compressional events. Seismic data show that the eastern Black Sea has evolved via a sequence of interrelated tectonic events that began with early Tertiary rifting followed by several phases of compression, mainly confined to the edges of the basin. A large magnitude (approximately 12 km) of regional subsidence also occurred in the central basin throughout the Tertiary. Models that simulate the magnitude of observed fault controlled extension (β=1.13) do not reproduce the total depth of the basin. Similarly, the modelling of compressional deformation around the edges of the basin does little to enhance subsidence in the central basin. A modelling approach that quantifies lithosphere extension according to the amount of observed crustal thinning and thickening across the basin provides the closest match to overall subsidence. The modelling also shows that deep crustal and mantle–lithosphere processes can significantly influence the rate and magnitude of syn- to post-rift subsidence and shows that such mechanisms may have played an important role in forming the anomalously thin syn-rift and thick Miocene–Quaternary sequences observed in the basin. It is also suggested that extension of a 40–45 km thick pre-rift crust is required to generate the observed magnitude of total subsidence when considering a realistic bathymetry.     

Controls on the isotopic composition of surface water and precipitation in the Northern Andes, Colombian Eastern Cordillera

Empirical datasets provide the constraints on the variability and causes of variability in stable isotope compositions (δD or δ¹⁸O) of surface water and precipitation that are essential not only for models of modern and past climate but also for investigations of paleoelevation. This study presents stable isotope data for 76 samples from four elevation transects and three IAEA GNIP stations in the Eastern Cordillera of Colombia and the northern Andean foreland. These data are largely consistent with theories of stable isotope variability developed based on a global dataset. On a monthly basis, the precipitation-amount effect exerts the dominant control on δD_p and δ¹⁸O_p values at the IAEA GNIP stations. At the Bogotá station (2547 m), the δD_p and δ¹⁸O_p values vary seasonally, with isotopic minima correlating with maxima in precipitation-amount. Although surface water samples from Eastern Cordilleran streams and rivers fall on the Global Meteoric Water Line, samples from three of four lakes (2842–3459 m) have evaporatively elevated δD_sw and δ¹⁸O_sw values. The IAEA GNIP station data averaged over multiple years, combined with stream and river water data, define vertical lapse rates of −1.8‰ km⁻¹ for Δδ¹⁸O and −14.6‰ km⁻¹ for ΔδD, and are a close fit to a common thermodynamically based Rayleigh distillation model. Elevation uncertainties for these relationships are also evaluated. Comparison of this Colombian dataset with the elevation uncertainties generated by the thermodynamically based model shows that the model underestimates uncertainty at high Δδ¹⁸O and ΔδD values while overestimating it for low Δδ¹⁸O and ΔδD values. This study presents an independent, empirical assessment of stable isotope-based elevation uncertainties for the northern Andes based on a dataset of sufficient size to ensure statistical integrity. These vertical lapse rates and associated uncertainties form the basis for stable isotope paleoelevation studies in the northern Andes.     

The Quebradagrande Complex: A Lower Cretaceous ensialic marginal basin in the Central Cordillera of the Colombian Andes

The Quebradagrande Complex of Western Colombia consists of volcanic and Albian–Aptian sedimentary rocks of oceanic affinity and outcrops in a highly deformed zone where spatial relationships are difficult to unravel. Berriasian–Aptian sediments that display continental to shallow marine sedimentary facies and mafic and ultramafic plutonic rocks are associated with the Quebradagrande Complex. Geochemically, the basalts and andesites of the Quebradagrande Complex mostly display calc-alkaline affinities, are enriched in large-ion lithophile elements relative to high field strength elements, and thus are typical of volcanic rocks generated in supra-subduction zone mantle wedges. The Quebradagrande Complex parallels the western margin of the Colombian Andes’ Central Cordillera, forming a narrow, discontinuous strip fault-bounded on both sides by metamorphic rocks. The age of the metamorphic rocks east of the Quebradagrande Complex is well established as Neoproterozoic. However, the age of the metamorphics to the west – the Arquía Complex – is poorly constrained; they may have formed during either the Neoproterozoic or Lower Cretaceous. A Neoproterozoic age for the Arquía Complex is favored by both its close proximity to sedimentary rocks mapped as Paleozoic and its intrusion by Triassic plutons. Thus, the Quebradagrande Complex could represent an intracratonic marginal basin produced by spreading-subsidence, where the progressive thinning of the lithosphere generated gradually deeper sedimentary environments, eventually resulting in the generation of oceanic crust. This phenomenon was common in the Peruvian and Chilean Andes during the Uppermost Jurassic and Lower Cretaceous. The marginal basin was trapped during the collision of the Caribbean–Colombian Cretaceous oceanic plateau, which accreted west of the Arquía Complex in the Early Eocene. Differences in the geochemical characteristics of basalts of the oceanic plateau and those of the Quebradagrande Complex indicate these units were generated in very different tectonic settings.     

Origin of the Eastern Mediterranean basin: a reevaluation

The origin of the Eastern Mediterranean basin (EMB) by rifting along its passive margins is reevaluated. Evidence from these margins shows that this basin formed before the Middle Jurassic; where the older history is known, formation by Triassic or even Permian rifting is indicated. Off Sicily, a deep Permian basin is recorded. In Mesozoic times, Adria was located next to the EMB and moved laterally along their common boundary, but there is no clear record of rifting or significant convergence. Farther east, the Tauride block, a fragment of Africa–Arabia, separated from this continent in the Triassic. After that the Tauride block and Adria were separate units that drifted independently. The EMB originated before Pangaea disintegrated. Two scenarios are thus possible. If the configuration of Pangaea remained the same throughout its life span until the opening of the central Atlantic Ocean (configuration A), then much of the EMB is best explained as a result of separation of Adria from Africa in the Permian, but this basin was modified by later rifting. The Levant margin formed when the Tauride block was detached, but space limitations require this block to have also extended farther east. Alternatively, the original configuration (A2) of Pangaea may have changed by 500 km of left-lateral slip along the Africa–North America boundary. This implies that Adria was not located next to Africa, and most of the EMB formed by separation of the Tauride block from Africa. Adria was placed next to the EMB during the transition from the Pangaea A2 to the Pangaea A configuration in the Triassic. Both scenarios raise some problems, but these are more severe for the first one. Better constraints on the history of Pangaea are thus required to decipher the formation of the Eastern Mediterranean basin.     

The magmatic history of the Vetas-California mining district,Santander Massif,Eastern Cordillera,Colombia

The Vetas-California Mining District (VCMD), located in the central part of the Santander Massif (Colombian Eastern Cordillera), based on U–Pb dating of zircons, records the following principal tectono-magmatic events: (1) the Grenville Orogenic event and high grade metamorphism and migmatitization between ∼1240 and 957 Ma; (2) early Ordovician calc–alkalic magmatism, which was synchronous with the Caparonensis–Famatinian Orogeny (∼477 Ma); (3) middle to late Ordovician post-collisional calc–alkalic magmatism (∼466–436 Ma); (4) late Triassic to early Jurassic magmatism between ∼204 and 196 Ma, characterized by both S- and I-type calc–alkalic intrusions and; (5) a late Miocene shallowly emplaced intermediate calc–alkaline intrusions (10.9 ± 0.2 and 8.4 ± 0.2 Ma). The presence of even younger igneous rocks is possible, given the widespread magmatic–hydrothermal alteration affecting all rock units in the area.The igneous rocks from the late Triassic–early Jurassic magmatic episodes are the volumetrically most important igneous rocks in the study area and in the Colombian Eastern Cordillera. They can be divided into three groups based on their field relationships, whole rock geochemistry and geochronology. These are early leucogranites herein termed Alaskites-I (204–199 Ma), Intermediate rocks (199–198 Ma), and late leucogranites, herein referred to as Alaskites-II (198–196 Ma). This Mesozoic magmatism is reflecting subtle changes in the crustal stress in a setting above an oblique subduction of the Panthalassa plate beneath Pangea.The lower Cretaceous siliciclastic Tambor Formation has detrital zircons of the same age populations as the metamorphic and igneous rocks present in the study area, suggesting that the provenance is related to the erosion of these local rocks during the late Jurassic or early Cretaceous, implying a local supply of sediments to the local depositional basins.     

米仓山南缘中生代沉积盆地性质讨论

米仓山南缘位于四川盆地北部地区,前人认为该地区晚三叠世—白垩纪受控于米仓山造山作用形成的前陆盆地。实际上,无论是按照经典的前陆盆地概念,还是陆内前陆盆地或陆内俯冲前陆盆地等术语,米仓山南缘中生代为前陆盆地值得商榷,其一些关键的地质问题必须给以重视。主要表现在:①平面构造图显示,米仓山地区,前震旦系基底与震旦系盖层之间构成一规模较大的不完整的背斜穹隆,盖层围绕基底分布,说明不是构造推覆体;②不存在形成前陆盆地的区域应力,即该区在晚三叠世开始主要是升隆作用而非强烈的推覆挤压,研究资料表明该地区大规模的逆冲推覆作用发生在燕山期,米仓山的形成也应在该时限之内,之前米仓山为一继承性的隆起;③不具备前陆盆地的沉积格局,即晚三叠世—侏罗纪的沉积格局不是呈楔形展布。鉴于此,笔者认为前陆盆地术语不适用于米仓山南缘晚三叠世—侏罗纪沉积盆地的类型。     

Geomorphic evidence for active tectonic deformation in the coastal part of Eastern Black Sea,Eastern Pontides,Turkey

The Eastern Pontides (EP), which is the under transpressional deformation zone, is an active mountain belt that has been rising rapidly since the Cenozoic era because of the Arabian-Eurasian convergence. Morphometric studies have been performed to investigate the tectonic activity of this region and better understand the characteristics of the faults geomorphologically; the faults control the mountain fronts in the drainage basin of the EP. The results show the Hypsometric Curve (HC)-Hypsometric Integral (0.37-HI-0.67), Basin-Shaped Analysis (1.2-B_s-7), Valley-Floor-Width to Height-Ratio (0.4-V_f-1.2) and Asymmetry Factor (35-AF-81) applied to 46 drainage basins together with 9 tectonically controlled geomorphic indices (1.2-S_mf-1.5) and a Stream Length Gradient (30-S_L-120) indicate that the EP is tectonically active, and when the areas are evaluated according to S_mf and V_f analyses, the tectonic level is relatively high. According to our conceptual model for the uplifting of the EP, with respect to field studies and morphometric analysis, (i) the EP is the active deformation zone and has a “push-up” geometry in conjunction with the North Anatolian Fault; (ii) the EP is progressively uplifting at a rate of more than 0.5 mm/yr in along with the thrust faults of the Black Sea Fault (BSF) and Borjomi-Kazbegi Fault (BKF).     

胶莱盆地沉积-沉降史分析与构造演化

基于地表典型露头剖面观察、地震剖面和测井资料解释、沉降史分析,并运用叠合盆地和改造盆地的研究思路,恢复了胶莱盆地白垩纪不同演化阶段的盆地原型及其构造性质。结果表明,该盆地经历了3个显著不同的沉积-沉降阶段。早白垩世莱阳群沉积时期,盆地原型表现为两个NE至NNE向延伸的断陷槽:一个沿苴县—诸城断陷发育,另一个沿牟平—即墨构造带发育,其沉积-沉降中心分别受苏鲁造山带北缘断裂带和牟平—即墨断裂带控制;该阶段沉积-沉降速率发生显著的空间分异,最大沉积-沉降速率在断陷槽,为230～370m/Ma,沿两侧斜坡地带沉积-沉降速率减小,约60m/Ma。早白垩世青山群对应一套中基性至中酸性火山岩,在沂沭裂谷盆地中堆积了一套大盛群河湖相沉积,这个时期是典型的大陆裂谷作用阶段,胶莱盆地演化为火山盆地,盆地沉降速率为35～70m/Ma。晚白垩世盆地原型表现为受东西向断裂控制的不对称箕状断陷,由诸城凹陷、高密凹陷和莱阳凹陷组成,其构造性质属于受西侧郯庐断裂和东侧牟平—即墨断裂控制的右旋拉分盆地;该阶段沉积-沉降速率总体一致,在63～73m/Ma。最后探讨了白垩纪盆地不同伸展阶段的动力学机制。     

胶莱盆地沉积-沉降史分析与构造演化

基于地表典型露头剖面观察、地震剖面和测井资料解释、沉降史分析，并运用叠合盆地和改造盆地的研究思路，恢复了胶莱盆地白垩纪不同演化阶段的盆地原型及其构造性质。结果表明，该盆地经历了3个显著不同的沉积-沉降阶段。早白垩世莱阳群沉积时期，盆地原型表现为两个NE至NNE向延伸的断陷槽：一个沿苴县-诸城断陷发育，另一个沿牟平-即墨构造带发育．其沉积-沉降中心分别受苏鲁造山带北缘断裂带和牟平-即墨断裂带控制；该阶段沉积-沉降速率发生显著的空间分异．最大沉积-沉降速率在断陷槽，为230～370m／Ma，沿两侧斜坡地带沉积-沉降速率减小．约60m／Ma。早白垩世青山群对应一套中基性至中酸性火山岩，在沂沭裂谷盆地中堆积了一套大盛群河湖相沉积，这个时期是典型的大陆裂谷作用阶段．胶莱盆地演化为火山盆地，盆地沉降速率为35～70m／Ma。晚白垩世盆地原型表现为受东西向断裂控制的不对称箕状断陷．由诸城凹陷、高密凹陷和莱阳凹陷组成，其构造性质属于受西侧郯庐断裂和东侧牟平-即墨断裂控制的右旋拉分盆地：该阶段沉积-沉降速率总体一致，在63～73m／Ma。最后探讨了白垩纪盆地不同伸展阶段的动力学机制．     

北黄海盆地东部坳陷中生界沉积特征及演化

北黄海盆地是我国近海勘探及研究程度均较低的中新生代叠合断陷盆地, 而东部坳陷是其内最具油气勘探前景的二级构造单元。通过岩芯观察与测井相分析, 结合三维地震资料, 认为东部坳陷中生界主要发育扇三角洲、辫状河三角洲、三角洲与湖泊沉积。受构造演化阶段的制约, 不同时期具有不同的沉积演化特征。其中中侏罗世处于湖盆的初期断陷期, 半深湖-深湖亚相发育, 仅在坳陷边缘见少量小规模的扇三角洲沉积。晚侏罗世处于断陷扩展期, 整体为一个完整的湖进-湖退旋回, 早期北部缓坡发育三角洲沉积, 南部及东部陡坡见扇三角洲沉积, 中后期则由于湖平面上升, 发育暗色泥岩为主的湖泊沉积, 晚期北部缓坡见小规模三角洲前缘沉积。早白垩世处于断陷萎缩期, 垂向发育2个正旋回沉积序列, 其中旋回下部以扇三角洲、辫状河三角洲相为主, 向上渐变为滨浅湖沉积。