羌塘盆地侏罗系展布重力反演预测及蒸发岩沉积洼陷优选评价   总被引：1，自引：0，他引：1  

文百红  李萌  刘喜方  杨辉 《地质学报》2015,89(11):1953-1961

利用露头和岩心物性的统计资料和对羌塘盆地统一改算后的1∶50万重力资料的波谱结构分析,应用匹配滤波法分离出羌塘盆地6个构造层。通过带地形的重力反演法计算了侏罗系构造层顶底界面深度及构造层厚度,预测了羌北坳陷中5个沉积洼陷和羌南坳陷中4个沉积洼陷。这9个侏罗纪洼陷分布在中央隆起带的南北两侧,羌北坳陷侏罗纪沉积岩以海陆过渡相蒸发盐岩为主,沉积体量比羌南坳陷略小。结合地面岩矿地层分析、湖水和泉水化学测试分析和卫星遥感图像解译资料综合评价认为,羌北坳陷比羌南坳陷具有更有利的蒸发岩沉积条件,初步预测羌北坳陷QB2和QB3洼陷为一级有利的含钾沉积洼陷,羌南坳陷QN1和QN2洼陷为二级有利的含钾沉积洼陷。  相似文献   

准噶尔盆地阜康凹陷侏罗系烃源岩特征与页岩气勘探潜力分析   总被引：2，自引：0，他引：2  

郑金海  向才富  王绪龙  雷德文  杨楠  阿·布力米提  张磊  张越迁  王力宏 《地质论评》2015,61(1):217-226

页岩油气正在成为中国油气勘探的重要对象之一。准噶尔盆地是中国西部最大的叠合盆地之一,盆地中是否存在页岩油气是能否打开油气勘探新局面的关键问题。本文通过对比其最大的生烃凹陷(阜康凹陷)的侏罗系烃源岩特征与Barnett页岩,来评价准噶尔盆地页岩油气的勘探潜力。阜康凹陷侏罗系烃源岩与Barnett页岩有以下相似性:①烃源岩规模稍大。阜康凹陷侏罗系主要发育八道湾组、三工河组和西山窑组三套泥质烃源岩层,累计厚度(最大950m)大于Barnett页岩;②干酪根类型相当。阜康凹陷干酪根类型在纵向上表现出一定的差异,下部八道湾组以Ⅱ型—Ⅲ型为主,中上部以Ⅲ型为主。③有机质的丰度偏小,但是存在厚层的煤。阜康凹陷有机质丰度分布符合正态分布,主要分布在1.2%~2.5%,与Barnett页岩相比略微偏小。但是从页岩气的角度来看,阜康凹陷发育多层单层厚度5m的煤层,总厚度超过50m,最大单层厚度超过20m,弥补了泥岩丰度不足的缺憾;④烃源岩已经进入中—高成熟阶段。表征烃源岩成熟度的Ro=1.6%,与Barnett页岩相当。上述对比结果表明阜康凹陷具有生成页岩油气的潜力。在此基础上,本文试图通过生烃潜力法的残留烃量评价本区页岩油气的勘探潜力,评价结果表明残留烃的规模为874.6亿吨,展示出阜康凹陷良好的页岩油气勘探潜力。  相似文献   

The youngest record of metriorhynchid crocodylomorphs,with implications for the extinction of Thalattosuchia     

《Cretaceous Research》2015

Here we describe an isolated tooth of a metriorhynchid crocodylomorph from the Hybla Formation (Aptian, Lower Cretaceous) of Rocca Chi Parra quarry (Montagna Grande, Calatafimi, Trapani Province), Sicily, Italy. The specimen shares with the Upper Jurassic taxon Plesiosuchus manselii a mediolaterally compressed conical tooth crown, noticeable lingual curvature, mesial and distal carinae with microscopic, rectangular contiguous denticles, strong distal curvature of the mesial margin, and the presence of weak 'carinal flanges' on the labial and lingual surfaces (which are preeminent at the mid-crown). This suite of morphologies is also present in an unnamed Valanginian (Lower Cretaceous) plesiosuchinan from France. However, the Sicilian tooth differs from these taxa in having more pronounced carinae, and faint apicobasally aligned enamel ridges. It also differs from P. manselii in having more extensive 'carinal flanges' on the labial surface. The specimen extends the known geological range of Metriorhynchidae and Thalattosuchia by approximately 7–8 million years. This overturns previous hypotheses of Metriorhynchidae becoming extinct early in the Early Cretaceous.  相似文献   

准噶尔盆地南缘天然气地球化学与成因研究     

孙平安  卞保力  袁云峰  张兴雅  曹剑 《地球化学》2015,44(3)

准噶尔盆地南缘地区是我国天然气勘探和研究长期关注的一个热点,天然气成因过往一直认为是以侏罗纪煤系为主,但鉴于区内尚有其他多套潜在烃源岩系,因此是否存在其他来源与成因天然气并不很清楚,限制了成藏规律认识与勘探部署。通过较系统的天然气地球化学分析,包括组分、烷烃系列碳同位素、轻烃等,结合地质地球化学背景,取得了新认识,发现研究区的天然气除了已有认识到的侏罗系成因外,还有其他2种成因类型,分别为可能的三叠系/二叠系来源高—过成熟煤型气,以及古近系来源低—中等成熟油型气,而白垩系油型气可能是因为混入量相对较低而未能显现,但理应存在。这些不同类型的天然气在地球化学特征上可以显著区分,且分布具有明显的地区规律性差异,遵循"源控论",即受控于烃源岩的分布。据此,提出研究区多种成因类型的天然气为可能的规模成藏提供了物质基础,侏罗系天然气是相对最为现实的勘探目标,霍-玛-吐背斜带是下步天然气勘探的重点目标区。这些认识还可供我国中西部前陆盆地和其他具有相似地质背景的盆地进行天然气勘探和研究时类比参考。  相似文献   

Detrital and volcanic zircon U–Pb ages from southern Mendoza (Argentina): An insight on the source regions in the northern part of the Neuquén Basin     

《Journal of South American Earth Sciences》2015

The infill of the Neuquén Basin recorded the Meso-Cenozoic geological and tectonic evolution of the southern Central Andes being an excellent site to investigate how the pattern of detrital zircon ages varies trough time. In this work we analyze the U–Pb (LA–MC–ICP–MS) zircon ages from sedimentary and volcanic rocks related to synrift and retroarc stages of the northern part of the Neuquén Basin. These data define the crystallization age of the synrift volcanism at 223 ± 2 Ma (Cerro Negro Andesite) and the maximum depositional age of the original synrift sediments at ca. 204 Ma (El Freno Formation). Two different pulses of rifting could be recognized according to the absolute ages, the oldest developed during the Norian and the younger during the Rhaetian–Sinemurian. The source regions of the El Freno Formation show that the Choiyoi magmatic province was the main source rock of sediment supply. An important amount of detrital zircons with Triassic ages was identified and interpreted as a source area related to the synrift magmatism. The maximum depositional age calculated for the Tordillo Formation in the Atuel-La Valenciana depocenter is at ca. 149 Ma; as well as in other places of the Neuquén Basin, the U–Pb ages calculated in the Late Jurassic Tordillo Formation do not agree with the absolute age of the Kimmeridgian–Tithonian boundary (ca. 152 Ma). The main source region of sediment in the Tordillo Formation was the Andean magmatic arc. Basement regions were also present with age peaks at the Carboniferous, Neoproterozoic, and Mesoproterozoic; these regions were probably located to the east in the San Rafael Block. The pattern of zircon ages summarized for the Late Jurassic Tordillo and Lagunillas formations were interpreted as a record of the magmatic activity during the Triassic and Jurassic in the southern Central Andes. A waning of the magmatism is inferred to have happened during the Triassic. The evident lack of ages observed around ca. 200 Ma suggests cessation of the synrift magmatism. The later increase in magmatic activity during the Early Jurassic is attributed to the onset of Andean subduction, with maximum peaks at ca. 191 and 179 Ma. The trough at ca. 165 Ma and the later increase in the Late Jurassic could be explained by changes in the relative convergence rate in the Andean subduction regime, or by the shift to a more mafic composition of the magmatism with minor zircon fertility.  相似文献   

Elemental geochemistry of the early Jurassic black shales in the Qiangtang Basin,eastern Tethys: constraints for palaeoenvironment conditions     

Xiugen Fu  Jian Wang  Wenbin Chen  Xinglei Feng  Dong Wang  Chunyan Song  Shengqiang Zeng 《Geological Journal》2016,51(3):443-454

The early Jurassic black shales are the most important source rocks in the Qiangtang Basin, Tibet. These black shales may provide a useful example for understanding the sedimentary conditions during the early Jurassic in the eastern Tethys. Thirty‐two black‐shale samples were collected from the Qiangtang Basin to reconstruct the depositional environments during the early Jurassic in the eastern Tethys. The palaeoclimate index Σ(Fe + Mn + Cr + Ni + V + Co)/Σ(Ca + Mg + Sr + Ba + K + Na) varies between 0.58 and 1.14, together with low Sr/Ba (0.20–0.60) and Sr/Cu (1.68–7.88) ratios, indicating a warm humid to semi‐humid climatic condition during black‐shale deposition. The early Jurassic black shales exhibit slight Ce anomalies (0.89–0.94) and Mn enrichment (EF = 1.2), suggesting a slightly oxic depositional environment. The conditions of the sedimentary water system during black‐shale deposition were apparently brackish as evidenced by middle B/Ga (3.96–5.73) and Th/U (3.96–6.51) ratios. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Analysis of geological effects on methane adsorption capacity of continental shale: a case study of the Jurassic shale in the Tarim Basin,northwestern China     

Xiaoyue Gao  Luofu Liu  Fujie Jiang  Ying Wang  Fei Xiao  Zeying Ren  Zhengyang Xiao 《Geological Journal》2016,51(6):936-948

The Jurassic shale is an important source rock for the found gas reservoirs in the Tarim Basin, northwestern China, but has never been researched for shale gas potential. The geological effects on methane adsorption capacity for the gas shale have been investigated in this paper through the geochemical, mineralogical and adsorption analyses on samples from wells and sections. The methane adsorption capacity ranges from 0.58 to 16.57 cm³/g, and the total organic carbon (TOC) content is between 0.5 and 13.5 wt%. The organic maturity measured by T_max is between 410 °C (immature) and 499 °C (overmature). The methane adsorption capacity of the Jurassic continental shale in the Tarim Basin is affected by many geological factors, including the TOC content, organic matter maturity, mineral composition, surface area and pore size distribution. The TOC content is the most significant factor with a positive effect on the adsorption capacity of the Jurassic shale, and the influence varies piecewise according to the TOC content. The TOC content contributes much more to the methane adsorption capacity of organic‐rich shale samples (TOC content > 0.7 wt%) than to the organic‐lean samples (TOC content < 0.7 wt%). The mineral composition is a secondary factor, and the abundance of clay content has a positive effect on the methane adsorption capacity despite its relatively weaker adsorption ability compared to TOC. The pore size distribution has different effects on surface area and pore volume. Mesopores and micropores provide the major surface area and are mainly derived from TOC and illite, which has a positive influence on the adsorption capacity. Mesopores and macropores offer the major pore volume and are mainly formed by illite, which is the major contributor for pore volume rather than surface area. In addition, the TOC and illite contents of the Jurassic shale in the Tarim Basin are closely related to the origin, maturity and diagenesis evolution of the shale: (1) both TOC and illite content variations are related to the different provenances and depositional environments of shale; (2) the decrease of TOC content with increasing maturity is also partly attributed to hydrocarbon generation; and (3) the increase of illite content with increasing maturity is due to illitization in the diagenesis of shale. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

A New Species of Phoenicopsis Subgenus Windwardia (Florin) Samylina (Czekanowskiales) from the Middle Jurassic of Inner Mongolia, China     

SUN Chunlin  NA Yuling  David L. DILCHER  WANG Hongshan  LI Tao  LI Yunfeng 《《地质学报》英文版》2015,89(1):55-69

A new species of Phoenicopsis subgenus Windwardia(Florin) Samylina, Phoenicopsis neimengguensis sp.nov., is recognized from the Middle Jurassic Zhaogou Formation in the Shiguai Basin, a Jurassic coal-bearing sedimentary basin in Inner Mongolia, China. Linear leaves are in bundles of six to eight and are attached on a short shoot. The leaf is amphistomatic with one or two irregular rows of longitudinally oriented stomata in each intercostal zone on the upper epidermis and three or four(occasionally six) rows of stomata in each intercostal zone on the lower epidermis. Each stomata is surrounded by four to six subsidiary cells with unevenly developed papillae. The anticlinal walls of epidermal cells are straight. Cuticular thickenings or papillae are present on the outer surface of the periclinal walls. This is the first time that Phoenicopsis subgenus Windwardia(Florin) Samylina is recognized from the Middle Jurassic of Inner Mongolia, China. The occurrence of the new species is noteworthy because it extends the geological and geographic distribution of Phoenicopsis subg. Windwardia in China and Eurasia. The discovery is significant as it increases our knowledge of Phoenicopsis subg. Windwardia by providing new data on morphological and epidermal features.  相似文献   

The Mid-Late Jurassic Kinematic Model and Mechanical Mechanism of the Ductile Shear Zones in the South Qinling Structural Belt     

Chen Peng  Shi Wei 《地球科学进展》2015,30(1):69-77

The South Qinling structural belt, as a part of the Qinling orogen, is bounded by the Shang-Dan suture to the north. Previous studies show the two regional conjugate ductile shear zones developed in the Mid-Late Jurassic epoch, e.g., Ningshan ductile shear zone characteristic of ENE-striking, sinistral shearing, Ankang ductile shear zone typical of NW-direction, dextral shearing, whose shear deformation age respectively is 169~162 Ma and 178~163 Ma respectively. The lineations collected from the two ductile shear zones suggest the maximum principal stress (σ1) is characterized by the direction of NE trending consistent with their obtuse angle bisector, which is corresponded with maximum effective moment criterion. Thus, our work suggests the blocks delimited by the conjugate ductile shear zones (e.g., ENE-striking and NW-trending) in the interior of the Qinling orogen, dominated by NE-SW compression, pinned by the Hannan-Micangshan massif, laterally extruded in the Mid-Late Jurassic time, which is featured by westward escaping in western Qinling belt and eastward in the eastern Qinling belt. This kinematical model probably marks the dominated activity of the Qinling orogen in the Mid-Late Jurassic time.  相似文献   

藏南洛扎地区侏罗、白垩纪岩相古地理特征   总被引：4，自引：0，他引：4  

夏军  钟华明  童劲松  鲁如魁 《沉积与特提斯地质》2005,25(3):8-17

藏南洛扎地区侏罗、白垩纪处于印度板块被动边缘一侧,共划分9个沉积相带、9个沉积亚相.日当组由南而北,海水由浅变深,可划分3个相带;陆热组总体处于陆棚环境;遮拉组处于陆棚-深海盆地环境,沿绒布断裂以北,发育拉张环境下的中-基性火山岩,总体沿断裂-带呈中心式喷发,其沉积背景为深水盆地相,发育放射虫硅质岩等;维美组为深水背景,在硅质岩、泥质沉积的陆棚-盆地区,有浅水物质的夹层,发育深切河谷的水道沉积物与浊流沉积物共存现象,并对下伏地层产生强烈的下切;桑秀组区内再次表现为强烈的伸展拉张,绒布断裂可能初现,沿断层发育中心式的中-基性火山喷发,出现火山爆发角砾、枕状熔岩、柱状节理发育的安山岩,并在断裂北侧形成滑塌角砾岩,而南部相对平静,沉积-套陆棚相的泥质沉积物;甲不拉组显现“一隆两坳”的地貌单元,北侧绒布断裂以北为开阔海陆棚环境,洛扎以南为闭塞潟湖环境.  相似文献