川西北下二叠统栖霞组微生物丘的发现及地质意义^*          下载免费PDF全文

全子婷  谭秀成  张本健  唐浩  罗冰  杨迅  张亚  肖笛  汤艳玲 《古地理学报》2021,23(6):1110-1124

通过野外露头与钻井剖面的室内外分析,确认在四川盆地西北部(川西北)下二叠统栖霞组中发育有微生物丘,它们主要由凝块灰(云)岩、叠层灰(云)岩和微生物粘结颗粒灰(云)岩等组成。这些微生物碳酸盐岩发育较为典型的凝块、叠层、窗格、粘结等组构。微生物丘大小不一,实测高度一般为几十厘米至几米,宽度通常变化于几米至几十米之间,具有底平顶凸的典型丘形外貌,以发育向上变浅的沉积序列为特征,一般由丘基、丘核、丘盖3个微相组成,也可与颗粒滩共同构成微生物丘滩复合体。基于区域古地理背景和微生物丘特征的剖析,认为川西北地区栖霞期沉积环境总体受限,推测为半局限—局限台地环境,水深较浅,能量普遍不高;海平面频繁的相对升降变化和微生物丘的侧向迁移叠置,导致发育于缓坡背景下的碳酸盐岩台地极易受限,引起早期沉积物发生与丘滩发育密切相关的准同生期白云石化作用。因此,微生物丘滩复合体是栖霞组白云岩储集层发育的物质基础,台缘坡折带、台内缓坡折带和高地是栖霞组白云岩储集层发育的有利区带,这对寻找规模性层位不稳定的带状白云岩储集层具有重要的指导作用,并将大大拓展栖霞组白云岩储集层的勘探领域。  相似文献   

上扬子地区双河露头五峰组—龙马溪组下段化学层序地层分析     

王茜  黄永建  张治锋  王长红  李祥 《西北地质》2021,(1)

综合地球化学、高分辨层序地层学理论方法,利用双河露头资料及样品分析测试,采用多元统计方法优选出陆源输入强度相关元素组合Al-K-Ti-Mg-Rb-Cr-Zr、自生沉淀强度相关元素组合Ca-Mn-Ba-Co、有机质吸附及还原强度相关元素组合V-Ni-Mo-U-Cu-Zn作为化学层序地层划分指标体系,将双河露头五峰组划分为LCW四级层序,龙马溪组下段自下而上细分为MCL1-1、MCL1-2、MCL1-3、MCL1-4四级层序。陆源输入强度相关主微量元素组合总量在层序界面附近相对较高,而最大海泛面附近相对较低,具有元素总量减少-增加旋回性变化特征;而自生沉淀强度相关主量元素组合总量和微量元素组合总量、有机质吸附及还原强度相关微量元素组合总量在层序界面附近一般较低,在最大海泛面附近一般较高,具元素总量增多-减少旋回性变化特征。  相似文献   

基于多元线性回归分析的页岩气有利区评价新方法——以上扬子地区五峰组—龙马溪组海相页岩为例          下载免费PDF全文

周业鑫  赵安坤  余谦  张娣  张茜  雷子慧 《沉积与特提斯地质》2021,41(3):387-397

本文以四川盆地及其周缘五峰组-龙马溪组页岩气评价为例,总结了页岩气有利区优选的储层参数、保存参数和压力系数等参数,量化了各关键参数平面分布,运用多元线性回归分析方法计算了参数权重,通过多参数加权叠加公式建立了多元线性回归模型：有利区=-0.317+0.75×埋深+0.285×TOC+0.148×R_O+0.093×孔隙度-0.128×渗透率+0.201×脆性矿物-0.199×压力系数,并开展了定量化优选评价页岩气有利区工作。分析结果表明,各参数权重由大到小排序为：埋深、TOC、脆性矿物和压力系数、R_O、孔隙度、渗透率,代表对含气性的影响作用依次减小。经过量化优选的有利区主要集中于四川盆地内,包括威远-自贡一线、宜宾-泸州-涪陵一线和川东区域为主,盆外的昭通、金沙、道真和黔江区域为相对有利区。该预测评价结果与四川盆地页岩气勘探实际基本相符,有利区表现形式较传统综合地质方法更清晰、直观。  相似文献   

宜昌地区早志留世（Llandoverian）腕足类一新科Spinochonetidae (fam. nov.)及其意义     

曾庆銮  张淼  李志宏 《地质学报》2015,89(4):681-691

腕足类新科Spinochonetidae(fam.nov.)建立在宜昌地区志留系兰多维列统罗惹坪组下段中部(上埃隆阶)的Spinochonetes Rong,Xu et Yang(1974)和Spinolella(gen.nov.)两个属,以及一个属、种未定的分类单元的基础上。新科成员仅有从腹壳喙部伸出一根直的腹喙刺,这与Chonetoidea超科内的Strophochonetidae科以及Chonestrophiidae科众成员的铰合缘刺都是从腹壳铰合缘上伸出来的有着本质差别。另外,本文还对Spinochonetes以及它的属型种S.notata Rong,Xu et Yang(1974)进行重要图解和补充描述。与此同时,对Spinolella(gen.nov),以及S.minuta(gen.et sp.nov.)进行系统描述和对比。据目前所知,新科成员只分布于我国鄂西、黔东北、陕南和川北等地,属于上扬子台地的土族居民。因为Spinochonetidae(fam.nov.)属于腕足类独特的一个类型,演化快,贝体极小,保存精美,因此具有分类学、地层对比,以及恢复古环境等方面的重要意义。  相似文献   

A new genus of Tanyderidae (Insecta: Diptera) from Myanmar amber,Upper Cretaceous     

《Cretaceous Research》2015

A new genus and species, Similinannotanyderus lii gen. et sp. nov., is described from Myanmar amber. It differs from other genera of Tanyderidae based on special characters of wing venation and male genitalia. This new taxon broadens the diversity of Tanyderidae in the Cretaceous, and its morphological characters enhance our understanding of the development and evolution of the primitive crane flies.  相似文献   

New insights into geochemical behaviour in ancient marine carbonates (Upper Jurassic Ammonitico Rosso): Novel proxies for interpreting sea‐level dynamics and palaeoceanography          下载免费PDF全文

Rute Coimbra  Adrian Immenhauser  Federico Olóriz  Víctor Rodríguez‐Galiano  Mario Chica‐Olmo 《Sedimentology》2015,62(1):266-302

Elemental concentrations in Phanerozoic sea water are known to fluctuate both in time and space. With regard to carbonates precipitated from marine fluids, elemental concentrations in the carbonate crystal lattice are affected by a complex array of equilibrium and non‐equilibrium as well as post‐depositional alteration processes. To assess the potential of carbonate elemental chemostratigraphy, seven Upper Jurassic sections were investigated along a proximal to distal transect across the south‐east Iberian palaeomargin. The aim was to explore stratigraphic and spatial variations in calcium, strontium, magnesium, iron and manganese elemental abundances. The epicontinental geochemical record is influenced by the combination of continental runoff and a significant diagenetic overprint. In contrast, the epioceanic geochemical record agrees with reconstructed open marine sea water values, reflecting a moderate degree of syn‐depositional to early marine pore water diagenesis. Establishing a fair degree of preservation of matrix micrite, a thorough statistical approach was applied and elemental associations tested for their environmental significance. Principal component and hierarchical cluster analyses revealed a persistent relation between carbonate magnesium, iron and strontium abundances. Processes related to early diagenetic nodulation in Ammonitico Rosso facies most probably account for the incorporation of these elements in the calcium carbonate lattice. The clear decoupling of carbonate manganese abundance with respect to the remaining elements is documented and related to high sea floor spreading rates and hydrothermal activity during the Late Jurassic. The investigation of potential time‐fluctuation of geochemical patterns was approached through variogram computation. The observed temporal behaviour is most likely to be forced by relative sea‐level dynamics, reflecting Late Jurassic palaeoceanographic conditions and potential planetary interactions. The data obtained in this study highlight the utility of elemental data from carbonate matrix micrites as geochemical proxies for studying the influence of remote trigger factors.  相似文献   

Hydrocarbon generation and expulsion characteristics of Lower Permian P1f source rocks in the Fengcheng area,northwest margin,Junggar Basin,NW China: implications for tight oil accumulation potential assessment     

Tao Hu  Xiongqi Pang  Sa Yu  Xulong Wang  Hong Pang  Jigang Guo  Fujie Jiang  Weibing Shen  Qifeng Wang  Jing Xu 《Geological Journal》2016,51(6):880-900

Combined with the actual geological settings, tight oil is the oil that occurs in shale or tight reservoirs, which has permeability less than 1 mD and is interbedded with or close to shale, including tight dolomitic oil and shale oil. The Fengcheng area (FA), at the northwest margin of the Junggar Basin, northwest China, has made significant progress in the tight oil exploration of the Fengcheng (P₁f) Formation recently, which indicates that the tight oil resources have good exploration prospects. Whereas the lack of recognition of hydrocarbon generation and expulsion characteristics of Permian P₁f source rocks results in the misunderstanding of tight oil resource potential. Based on the comprehensive analysis of geological and geochemical characteristics of wells, seismic inversion, sedimentary facies, tectonic burial depth, etc., the characteristics of P₁f source rocks were investigated, and the horizontal distributions of the following aspects were predicted: the thickness of source rocks, abundance and type of organic matter. And on this basis, an improved hydrocarbon generation potential methodology together with basin simulation techniques was applied to unravel the petroleum generation and expulsion characteristics of P₁f source rocks in FA. Results show that the P₁f source rocks distribute widely (up to 2039 km²), are thick (up to 260 m), have high total organic content (TOC, ranging from 0.15 to 4 wt%), are dominated by type II kerogen and have entered into low mature–mature stage. The modeling results indicate that the source rocks reached hydrocarbon generation threshold and hydrocarbon expulsion threshold at 0.5% Ro and 0.85% Ro and the comprehensive hydrocarbon expulsion efficiency was about 46%. The amount of generation and expulsion from the P₁f source rocks was 31.85 × 10⁸ and 15.31 × 10⁸ t, respectively, with a residual amount of 16.54 × 10⁸ t within the source rocks. Volumetrically, the geological resource of shale oil is up to 15.65 × 10⁸ t. Small differences between the amounts calculated by the volumetric method compared with that by hydrocarbon generation potential methodology may be due to other oil accumulations present within interbedded sands associated with the oil shales. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Geochemical Characteristics and Geological Significance of Early Permian Baya’ertuhushuo Gabbro in South Great Xing’an Range   总被引：1，自引：0，他引：1  

LIU Jianfeng  CHI Xiaoguo  ZHAO Zhi  ZHANG Xingzhou  MA Zhihong  WANG Tiefu  HU Zhaochu 《《地质学报》英文版》2011,85(1):116-129

Field geological investigation and geochemical analysis are carried out on Baya’ertuhushuo Gabbro in South Great Xing’an Range. Field investigation reveals that the gabbro is a magmatic intrusion rather than a component of an ophiolite suite as previously thought. Zircon laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) U-Pb dating indicates the gabbro was formed in 274–275?Ma, just as the widespread volcanic rocks of Dashizhai Formation (P1d), monzogranites and miarolitic alkali-feldspar granites in the study area. The gabbro has SiO2 content between 47.23 wt% and 50.17 wt%, high MgO and FeOT contents of 6.95–11.29 wt% and 7.32–12.24wt%, respectively, and it belongs to low-K tholeiitic series in the SiO2-K2O diagram. The Chondrite-normalized rare earth element (REE) patterns and primitive mantle-normalized spider diagrams of the gabbro are similar to those of Normal Mid-Ocean Ridge Basalt (N-MORB) except for the enrichment of large ion lithophile elements (LILE), such as Rb, Ba and K. In trace element tectonic discriminative diagrams, the samples are mainly plotted in the N-MORB field, and Zircon in?situ Lu-Hf isotopic analysis also indicates the gabbro originated from depleted mantle. Through synthetic studies of the geochemical characteristics and petrogenesis of Baya’ertuhushuo gabbro, volcanic rocks of Dashizhai Formation and granitoids in the area, it is suggested that the early Permian magmatism in the Xilinhot-Xiwuqi area formed in the tectonic setting of asthenosphere upwelling, which was caused by breaking-off of the subducted Paleo-Asian Ocean slab.  相似文献   

Sumixam maximus gen. and sp. nov., a New Pennsylvanian Species of Archaeorthoptera (Neoptera; Indiana, USA)     

Olivier BéTHOUX  Christin GROSSMANN 《《地质学报》英文版》2011,85(3):515-520

A new Mazon-Creek-type fossil specimen is described as Sumixam maximus gen. and sp. nov., assigned to the taxon Archaeorthoptera Béthoux and Nel, 2002 (composed of Orthoptera and some fossil relatives): it exhibits one of the diagnostic character states of this taxon, which is the fusion of CuA (emerging from M + CuA) with CuP, or a branch of it. A more precise taxonomic assignment is out of reach. The new taxon exhibits a fusion of the anterior branch of MA with RP, and a point of divergence of MA and MP located near the point of divergence of CuA (from M + CuA), but lack a branching of CuPa. This unique combination of character states is probably derived with respect to a number of contemporaneous species. Sumixam maximus gen. and sp. nov. is most likely the closest known relative of the panorthopterans, which include all the recent Archaeorthoptera.  相似文献   

First Description of Fossil Naucoridae (Heteroptera: Nepomorpha) from Late Mesozoic of China     

ZHANG Weiting  YAO Yunzhi  REN Dong  ZHAO Yunyun 《《地质学报》英文版》2011,85(2):490-500

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