杏南开发区葡Ⅰ31小层废弃河道类型及其研究意义

油田开采进入高含水期后,储层构型的精细描述对改善油田开采效果具有重大意义。废弃河道作为单一河道的边界以及识别点坝砂体的重要依据,其顶部的泥质沉积或者砂泥岩互层沉积对储层内部流体具有遮挡作用,因此正确识别废弃河道是进一步分析储层构型及挖潜油田剩余油的重要科学依据。以杏南开发区葡Ⅰ31小层为例,通过分析废弃河道在平面及剖面的沉积特征,利用砂顶相对等深图法,综合废弃河道的砂体平面分布形态和测井曲线响应特征,在葡Ⅰ31小层内识别出26处规模不等的废弃河道,宽度一般在100 m左右,其中3处突弃型废弃河道与渐弃型相比,弯曲程度更大,砂体延伸更短,沉积厚度为2~8 m不等。由于砂泥互层或泥质沉积的侧向遮挡作用,废弃河道砂体与正常河道砂体组成的半连通体导致有注无采或有采无注的注采不平衡现象,使得河道砂体顶部成为剩余油聚集的有利场所,成为进一步挖潜的重点对象。     

Basin-scale structure control of Carlin-style gold deposits in central Southwestern Guizhou,China: Insights from seismic reflection profiles and gravity data

Carlin-style gold deposits are widely distributed in Southwestern Guizhou, China. Research has dominantly focused on deposit-scale geology and structural control of mineralization. The relationship between the gold deposits and regional structures, in particular their control on the formation and distribution of those deposits is less well understood. Here we use seismic survey and gravity data to reveal the basin-scale structure control of the gold deposits in central Southwestern Guizhou. The seismic reflection profiles show strong reflection horizons including Upper Permian coal measures, and Dongwu and Guangxi unconformities. The seismic data provide important evidence of the basinal structural style and the relationship between fault-related folding and the Carlin-style gold deposits. Regional gravity data also revealed several paleo-uplifts, which appear to control the distribution of Carlin-style gold deposits.The Carlin-style gold deposits are spatially and temporally associated with fault-related folds. Based on their location, we classify the gold deposits into two types, (1) low-angle thrust-controlled deposits; and (2) high-angle reverse fault-related deposits. In the low-angle thrust-controlled deposits, main thrusts are listric, strike NW-SE and dip southwest. These thrusts detach into coal measures, tuffs and volcanic rocks and are bedding-parallel in the vicinity of the Dongwu unconformity. Gold ore bodies are found in the thrusts and characterized by cutting-layer veins near the surface and bedding-parallel veins at depth. The high-angle reverse fault-related deposits are located in the hinge of northeast-southwest-striking fault-related folds, with high-angle reverse faults near the hinge of folds crosscutting the Upper Permian coal measures, volcanic rocks and Dongwu unconformity, and then into the limestone of Middle Permian Maokou Formation. Ore bodies are bedding-parallel in anticline culminations where interlayer fracture zones in Upper Permian coal measures and volcanic rocks are generated by high-angle reverse faulting.We consider that the formation of the gold deposits is part of the tectonic evolution in the area. The two sets of NW-SE- and NE-SW-striking fault-related folds were successively formed during the closure of eastern Tethys Ocean in Late Triassic, and major gold deposits formed in the fault-related folds. The Dongwu unconformity and faults provided conduits for ore fluid flow, and the coal measures and the tuffs of Dachang Member acted as detachment layers and hosts for ore deposition.     

清溪场地区茅口组裂缝储层预测

茅口组储层以生屑灰岩储层为主,储集空间主要为溶孔、裂缝。这里运用P波振幅方位各向异性分析方法,对清溪场构造茅口组储层开展裂缝预测,搞清了裂缝发育与地层岩性以及构造发育之间的关系,明确了裂缝的走向、强度,以及密度发育部位,预测了裂缝的分布范围。实际资料应用表明,用该套方法识别裂缝—溶隙型储层是有效和可靠的,可以检测出有利的裂缝储层发育带。     

南京汤山驼子洞洞穴堆积及其意义

通过对南京汤山驼子洞洞穴堆积观察描述和样品分析测试,结合前人研究成果和汤山地区地质地貌演化的历史,讨论了驼子洞堆积的时代、堆积过程和方式,并对其蕴含的构造、地貌、气候和生物进化等古环境信息进行了合理的挖掘。初步研究表明驼子洞堆积可能是跨早更新世与中更新世早期的地层,其上部含哺乳动物化石的堆积可能反映了偏暖的气候环境。     

福建省推覆构造研究及其意义

本文主要是根据“闽西南地区推覆构造与隐伏煤田预测研究”的主要成果来写的。在概述两次研究课题取得主要成果的同时，对福建省重大基础地质有关的问题提出了新的认识。文中重点是总结了福建省推覆构造发育的特征，将推覆构造划分为两大类（逆冲推覆构造，拆离构造）和五种类型（中深层次逆冲推覆构造、浅层次逆冲推覆构造、褶皱逆冲推覆构造和拆离（滑脱）构造、褶皱拆离构造），对各类型的主要特征、分布规律、组合特征和推覆构造的发生和发展进行系统的总结，明确指出了燕山早期中深层次边冲推覆构造是福建省规模最大、对今后寻找隐伏矿产关系最密切和最重要的推覆构造，对研究我省的推覆构造具有重要意义。并结合福建省的实际，从基础地质和找矿两方面进行论述。     

湖南宝山铜铅锌多金属矿床控矿构造特征研究

宝山铜铅锌多金属矿床位于南岭成矿带中段北缘,分为中区的矽卡岩型铜钼矿、外围的热液型铅锌银矿床,具有明显的水平矿化分带性,矿体受构造控制。通过野外工作及室内综合研究认为,宝山铜铅锌多金属矿床的形成具有多期性。矽卡岩形成时期的控矿构造为F₀断层,金属硫化物形成时期的控矿构造为F₂₁与F₂₅断层。F₀、F₂₁、F₂₅断层为含矿热液运移的主要通道,倒转背斜、向斜构造则为含矿热液的富集成矿提供了良好的空间。     

Calibration of cyclic constitutive models by oscillating functions

Most structures are subjected to more cyclic loads during their life time than static loads. These cyclic action could be a result of either natural or man-made activities and may lead to soil failure. In order to understand the response of the foundation and its interaction with these complex cyclic loadings, various researchers have over the years developed different constitutive models. Although a lot of research is being carried out on these relatively new models, little or no details exist in literature about the model-based identification of the cyclic constitutive parameters which to a large extent govern the quality of the model output. This could be attributed to the difficulties and complexities of the inverse modeling of such complex phenomena. A variety of optimisation strategies are available for the solution of the sum of least-squares problems as usually done in the field of model calibration. However, for the back analysis (calibration) of the soil response to oscillatory load functions, this article gives insight into the model calibration challenges and also puts forward a method for the inverse modeling of cyclic loaded foundation response such that high-quality solutions are obtained with minimum computational effort.     

Crustal complexity in the Lachlan Orogen revealed from teleseismic receiver functions

There is an ongoing debate about the tectonic evolution of southeast Australia, particularly about the causes and nature of its accretion to a much older Precambrian core to the west. Seismic imaging of the crust can provide useful clues to address this issue. Seismic tomography imaging is a powerful tool often employed to map elastic properties of the Earth's lithosphere, but in most cases does not constrain well the depth of discontinuities such as the Mohorovi?i? (Moho). In this study, an alternative imaging technique known as receiver function (RF) has been employed for seismic stations near Canberra in the Lachlan Orogen to investigate: (i) the shear-wave-velocity profile in the crust and uppermost mantle, (ii) variations in the Moho depth beneath the Lachlan Orogen, and (iii) the nature of the transition between the crust and mantle. A number of styles of RF analyses were conducted: H-K stacking to obtain the best compressional–shear velocity (V _P /V _S) ratio and crustal thickness; nonlinear inversion for the shear-wave-velocity structure and inversion of the observed variations in RFs with back-azimuth to investigate potential dipping of the crustal layers and anisotropy. The thick crust (up to 48 km) and the mostly intermediate nature of the crust?mantle transition in the Lachlan Orogen could be due to the presence of underplating at the base of the crust, and possibly to the existing thick piles of Ordovician mafic rocks present in the mid and lower crust. Results from numerical modelling of RFs at three seismic stations (CAN, CNB and YNG) suggest that the observed variations with back-azimuth could be related to a complex structure beneath these stations with the likelihood of both a dipping Moho and crustal anisotropy. Our analysis reveals crustal thickening to the west beneath CAN station which could be due to slab convergence. The crustal thickening may also be related to the broad Macquarie volcanic arc, which is rooted to the Moho. The crustal anisotropy may arise from a strong N–S structural trend in the eastern Lachlan Orogen and to the preferred crystallographic orientation of seismically anisotropic minerals in the lower and middle crust related to the paleo-Pacific plate convergence.     

山东省灵山岛负载构造和球-枕构造研究

本文运用野外露头考察、沉积岩石学、地质统计等方法,对灵山岛的负载构造和球-枕构造进行研究。这些负载构造和球-枕构造侧向延伸好,在整个剖面上连续分布,具有多尺度、多形态、多组合等特点。形成负载构造和球-枕构造的前提条件是地层密度的倒置(上大下小),变形的根本驱动力是沉积物自身的重力。球-枕构造和负载构造的形成机制相同,只是变形程度和阶段不同。根据不对称负载构造受横向剪切力分析,证明早白垩世时该盆地存在古斜坡,并且SE高、NW低。综合考虑地震触发形成震积岩的标志特征和灵山岛的构造地质背景,认为本研究区的负载构造和球-枕构造系古地震触发形成。