The evolution of the Huangling uplift and its control on the accumulation and preservation of shale gas

There are plenty of Sinian and Cambrian potential shale gas resources in South China, which is characterized by high thermal evolution degrees, poor drilling performances and only occurs in local areas. Taking the principle “high to find low” is the key issue to achieving a breakthrough in older shale. China Geological Survey drilled in the periphery of the Proterozoic basement, i.e. the Huangling anticline, in the western Hubei, and Hannan paleocontinent in the southern Shanxi. It received high-quality gas-bearing shale with relatively low Ro in the in Lower Cambrian Niutitang formation and Sinian Doushantuo formation. Based on geological conditions of shale gas reservoirs in the Huangling anticline, this paper puts forward the new model named “Control over reservoirs by periphery of basement” about shale gas accumulation, suggesting that the shale deposited in a deepwater continental shelf in the periphery of the basement is characterized by shallow burial, a short burial time, stable tectonics, relatively low thermal evolution degrees, and shale gas reservoirs in a good condition. The shale of the Sinian-Cambrian strata deposited in deepwater continental shelves in the periphery of Chuanzhong paleo-uplift in Sichuan, Hannan paleocontinent in the southern Shanxi, Huangling anticline in western Hubei and Jiangnang-Xuefeng paleo-uplift in Hunan and Guizhou province have good shale gas exploration potential.     

Early Proterozoic granitoids of the Olenek complex (northern Siberian craton): petrogenesis and geodynamic setting

The paper deals with geological and geochemical studies of granitoids of the Olenek complex in the Olenek uplift of the basement of the northern Siberian craton. The age of these granitoids was earlier estimated at 2036 ± 11 Ma. The granitoids of the Olenek complex correspond in composition to high-alumina quartz diorites, granites, and leucogranites of the normal petrochemical series. According to geochemical and mineralogical characteristics, the quartz diorites can be assigned to granites of the transitional I-S type, and the granites and leucogranites, to S-type granites. The 8_Nd(T values in the granites of the Olenek complex vary from -0.2 to + 1.4, and the Nd model age is 2.4-2.5 Ga. The quartz diorite is characterized by 8_Nd(T) = + 3.0 and a Nd model age T(DM) = 2.2 Ga. The geochemical characteristics of the granites and leucogranites indicate their formation through the melting of a source of graywacke composition, whereas the quartz diorites resulted, most likely, from the mixing of granitic and basaltic melts. The fact that the granitoids of the Olenek complex intruded the folded rocks of the Eekit Formation but stay virtually undeformed massive bodies suggests that they formed at the postdeformation stage of the regional evolution after the completion of the Paleoproterozoic orogenic events. The intrusion of granitoids marks the completion of the formation of the Early Proterozoic Eekit fold belt on the western (in the recent coordinates) margin of the Birekta terrane of the Olenek superterraine and the final formation of the superterrane structure. At the next stage of magmatism (1.98-1.96 Ga), best pronounced in the uplifts of the basement of the northern Siberian craton, all terranes forming the Anabar and Olenek superterranes assembled into a single structure.     

高临界循环荷载水平下钻孔桩的抗拔性状分析

为了研究抗拔桩在循环加载过程中桩身的性状,选取杭州萧山某工地两根抗拔桩作为试桩进行循环加载试验。在抗拔桩桩身埋设钢筋应力计,测量循环加载过程中桩身应力的变化情况;在桩身预埋钢管,测量桩顶及桩端上拔量。通过对桩身应力及桩顶、桩端上拔量的分析,研究循环加载对抗拔桩承载力及上拔量的影响。综合分析抗拔桩承受循环荷载时的桩顶、桩端上拔量、桩身轴力以及桩侧摩阻力分布可知,当抗拔桩承受循环荷载时,且临界循环荷载水平较大（接近或者达到1）,抗拔桩经过2～3次循环加载后就发生破坏,其研究结果可供其他类似工程参考。     

抗拔桩变形分析与有效桩长预测

以抗拔桩变形的理论分析为基础,选择双曲线荷载传递函数对桩的极限侧阻力进行合理取值,通过迭代法得到桩身受力情况,由此预测抗拔桩的＂有效桩长＂。结合工程实例进行了计算验证,证明该方法具有实用价值和推广意义。     

山西大同口泉山隆升-挠褶构造研究

挠曲褶皱构造在山西广泛存在,大同市之西盆地边缘"口泉山断裂带"实际是一个大型挠褶构造带.以往的研究者仅把它当成几个断裂分段研究.认识和研究挠褶构造不仅能够在理论上取得进展,而且还能够指导煤矿勘探和开采,取得很好的经济效益.通过构造带上几个地方典型构造现象的研究得出,该构造带构造现象虽然复杂,但它并不是杂乱无章的,运用挠褶构造的理论上能够恢复它的原始形态以及它的发生发展的全过程.挠褶构造的形成与构造块体的隆升有关,其形成为:地幔柱隆升-地层上拱-挠褶-冲断走滑等.     

西昆仑山前晚新生代磨拉石时代及意义

西昆仑山前柯克亚剖面晚新生代沉积记录了昆仑山乃至整个青藏高原的隆升过程.古地磁研究结果显示,西昆仑山前磨拉石形成于中新世晚期-上新世早中期,反映西昆仑山-青藏高原在中新世晚期有一次快速的隆升过程.孢粉记录结合区域地质资料分析表明,柯克亚剖面上部厚层砾岩的形成时代应为上新世早中期,而整个磨拉石开始沉积的时代应更早,为中新世晚期.沉积记录和气候变化显示了青藏高原在中新世晚期发生了显著的构造隆升事件.     

Quantitative Tectonic Markers of Large Coastal Earthquakes in Fujian, Guangdong, Taiwan and Hainan——with a Discussion of Qualitative Indicators

This paper expounds the quantitative tectonic indicators and some qualitative indicators of large earthquakes in the coast areas of Fujian, Guangdong, Taiwan and Hainan. The main quantitative indicators include uplift amplitude of the Moho, Quaternary and Late Holocene coasts. The paper also gives a brief account of the research method on quantitative indicators of surface uplifted zones. Taiwan is a famous neotectonic zone and an area of large earthquakes in the world. There is only one large-earthquake area in each of Fujian, Guangdong and Hainan Provinces. Along the coast large earthquake areas there are certainly many remains of crustal activity. Among these remains, coast activity, taking the sea level as the accurate marker horizon, can determine not only the amplitude of coastal elevation and subsidence in a certain period, but also the cycle and rate of positive or negative movements.     

Distribution of Palaeozoic tectonic superimposed unconformities in the Tarim Basin,NW China: significance for the evolution of palaeogeomorphology and sedimentary response

Seismic and drilling well data were used to examine the occurrence of multiple stratigraphic unconformities in the Tarim Basin, NW China. The Early Cambrian, the Late Ordovician and the late Middle Devonian unconformities constitute three important tectonic sequence boundaries within the Palaeozoic succession. In the Tazhong, Tabei, Tadong uplifts and the southwestern Tarim palaeo‐uplift, unconformities obviously belong to superimposed unconformities. A superimposed unconformity is formed by superimposition of unconformities of multiple periods. Areas where superimposed unconformities develop are shown as composite belts of multiple tectonic unconformities, and as higher uplift areas of palaeo‐uplifts in palaeogeomorphologic units. The contact relationship of unconformities in the lower uplift areas is indicative of truncation‐overlap. A slope belt is located below the uplift areas, and the main and secondary unconformities are characterized by local onlap reflection on seismic profiles. The regional dynamics controlled the palaeotectonic setting of the Palaeozoic rocks in the Tarim Basin and the origin and evolution of the basin constrained deposition. From the Sinian to the Cambrian, the Tarim landmass and its surrounding areas belonged to an extensional tectonic setting. Since the Late Ordovician, the neighbouring north Kunlun Ocean and Altyn Ocean was transformed from a spreading ocean basin to a closed compressional setting. The maximum compression was attained in the Late Ordovician. The formation of a tectonic palaeogeomorphologic evolution succession from a cratonic margin aulacogen depression to a peripheral foreland basin in the Early Caledonian cycle controlled the deposition of platform, platform margin, and deep‐water basin. Tectonic uplift during the Late Ordovician resulted in a shallower basin which was followed by substantial erosion. Subsequently, a cratonic depression and peripheral or back‐arc foreland basin began their development in the Silurian to Early–Middle Devonian interval. In this period, the Tabei Uplift, the Northern Depression and the southern Tarim palaeo‐uplift showed obvious control on depositional systems, including onshore slope, shelf and deep‐water basin. The southern Tarim Plate was in a continuous continental compressional setting after collision, whereas the southern Tianshan Ocean began to close in the Early Ordovician and was completely closed by the Middle Devonian. At the same time, further compression from peripheral tectonic units in the eastern and southern parts of the Tarim Basin led to the expansion of palaeo‐uplift in the Late Devonian–Early Carboniferous interval, and the connection of the Tabei Uplift and Tadong Uplift, thus controlling onshore, fluvial delta, clastic coast, lagoon‐bay and shallow marine deposition. Copyright © 2015 John Wiley & Sons, Ltd.     

塔里木盆地塔北隆起奥陶系-侏罗系泥岩稀土元素地球化学特征

分析了塔里木盆地塔北隆起奥陶系、三叠系和侏罗系泥岩的稀土元素丰度。不同时代泥岩都表现出轻稀土富集、重稀土含量均一和具有Eu负异常特征;但它们∑LREE/∑HREE、LaN/YbN、(La/Yb)UCC、Eu/Eu和Ce/Ce等参数则显示这些泥岩形成时的物源和环境有差别。奥陶纪时,研究区处于相对稳定的沉积环境,物源为成熟度高的大陆上地壳;二叠纪到三叠纪构造-火山活动强烈,部分沉积物来自火山岩的风化;侏罗纪塔北隆起区则进入稳定构造沉降阶段。这一差别对认识塔里木盆地及周边造山带形成演化研究有指示意义。     

鄂尔多斯盆地渭北隆起带重磁场特征

通过对研究区已有重、磁测量资料的整理和研究,结合钻井、地质、电法及地震等成果,讨论了重磁异常分布特征,具此推断断裂构造,划分研究区的构造单元,预测油页岩有利区。研究结果表明,鄂尔多斯盆地渭北隆起地重磁场具有\