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1.
渤南洼陷沙四段膏泥岩样品中检出了高丰度孕甾烷(相对于规则甾烷),孕甾烷/规则甾烷值为0.52～7.88,平均值为3.12。这些膏泥岩样品具有指示性较强的盐湖相生物标志化合物分布特征,如较低的姥鲛烷/植烷值(Pr/Ph=0.12～0.76)、高伽马蜡烷指数(GI=0.04～1.45)、高升藿烷指数(HHI=0.03～0.22)和较高的二苯并噻吩/菲值(DBT/P多大于1),均指示了高盐度水体、强还原性和富硫沉积环境,生源输入主要为嗜盐菌和藻类等低等水生生物。根据渤南洼陷沙四段原油中检出丰富的含硫甾烷,推测渤南洼陷高丰度孕甾烷可能与含硫甾烷形成过程中的不完全硫化作用有关。通过剖面上各生物标志化合物参数随埋深的纵向变化特征发现,孕甾烷与Pr/Ph、HHI和GI值等呈现良好的相关性,它们均指示还原、高盐度以及富硫贫铁的沉积环境。 相似文献
2.
利用芳烃参数研究煤系烃源岩中重排藿烷成因 总被引：4，自引：1，他引：3
研究发现鄂尔多斯盆地部分地区上古生界煤系烃源岩存在较高丰度的17α(H)-重排藿烷和早洗脱重排藿烷,在对重排藿烷分布、组成特征及生标组成特征研究的基础上,应用芳烃参数对高丰度重排藿烷的成因进行了探讨。饱和烃生物标志物组成特征显示,高重排藿烷与陆源高等植物生源关系密切,主要在弱氧化沉积环境下演化形成。具有高-异常高丰度17α(H)-重排藿烷和早洗脱重排藿烷(C30*/C30H>0.2、C30E/C30H>0.1)的烃源岩二环+三环芳烃相对含量一般大于50%,四环、五环芳烃含量相对较低,普遍低于35%,未见芳香甾萜类,研究认为其生源主要为陆生高等植物;甲基菲指数MPI1、MPI2和甲基菲比值F1研究结果显示,Pr/Ph>1的弱氧化环境烃源岩17α(H)-重排藿烷和早洗脱重排藿烷在进入成熟阶段后开始大量形成,并随成熟度升高而增大;Pr/Ph<1还原环境下的烃源岩重排藿烷丰度相对较低,但在进入成熟阶段后仍有随成熟度升高而增大的趋势;三芴系列化合物参数表明,沉积环境的弱氧化性质对17α(H)-重排藿烷和早洗脱重排藿烷的形成有较大的影响,沼泽相沉积环境最有利于重排藿烷的形成。 相似文献
3.
通过对TZ62井原油进行热模拟实验,探讨热演化程度对原油中重排藿烷类化合物形成分布的影响及其地球化学意义。实验发现：在400～500 ℃阶段,随着热演化程度的增加,原油中高碳数微晶蜡类长链化合物热裂解和原油中的沥青质热降解作用对重排藿烷的形成具有贡献作用。在500～550 ℃对应的原油裂解高峰阶段,藿烷类化合物浓度明显降低,且17α(H)-藿烷比重排藿烷类化合物具有更快的热裂解速率。在温度为550～600 ℃阶段,较高的热演化程度对17α(H)-藿烷甲基重排作用形成重排藿烷具有贡献作用。重排藿烷参数(17α(H)-重排藿烷/17α(H)-藿烷、Ts/Tm)在400～500 ℃变化较弱,几乎不受热演化程度的影响;在500～550 ℃的原油裂解高峰阶段,逐渐增大;在550～600 ℃发生反转,逐渐减小。重排藿烷参数可作为高成熟阶段原油成熟度判识的有效参数,其有效应用范围是生油窗晚期至原油裂解高峰期。 相似文献
4.
川中侏罗系原油重排藿烷类化合物的组成及成因探讨 总被引：10，自引：1，他引：10
川中石龙场油田侏罗系湖相原油中重排藿烷类化合物异常丰富,经 GC/MS和 GC/MS/MS分析,检出 17α(H)-重排藿烷和 18α(H)-新藿烷及未知结构的早洗脱重排藿烷三个完整系列.17α(H)-重排藿烷相对含量最高,碳数分布范围为 C27、C29～ C35,分布模式与正常藿烷相似, C30化合物为主峰, C31以上化合物每个碳数有两个异构体.18α(H)-新藿烷系列含量明显低于重排藿烷,主要有 Ts和 C29Ts两个化合物,可能还存在 C30的同系物.早洗脱重排藿烷系列碳数为 C29～ C35, C31以上每个碳数有一对异构体,具有与正常藿烷和重排藿烷相似的分布特征.这些化合物的生物先质物可能是细菌藿类物质.其形成过程与氧化性且富含粘土的沉积环境性质有密切联系,高成熟度条件下有利于它们的相对富集. 相似文献
5.
鄂尔多斯盆地东北部上古生界煤系烃源岩17α(H)-重排藿烷类的分布及成因探讨 总被引：3，自引：0，他引：3
鄂尔多斯盆地东北部上古生界10个典型煤系烃源岩样品中检测出三类重排藿烷,分别为17α(H)-重排藿烷、18α(H)-新藿烷以及未知结构的早洗脱重排藿烷。烃源岩样品中藿烷类具有两种分布型式:①以C30藿烷为主峰的C27~C35(缺C28)藿烷类常规分布型式,含少量17α (H)-重排藿烷和18α(H)-新藿烷;②以富含17α(H)-重排藿烷和C30早洗脱重排藿烷为特征。含有高~异常高相对丰度17α(H)-重排藿烷的烃源岩样品,其17α(H)-重排藿烷的绝对浓度也明显较高。从烃源岩生源构成、有机质丰度及其赋存状态、成熟度以及沉积与成岩环境4个方面探讨了高丰度17α(H)-重排藿烷的成因。研究结果表明,烃源岩中高丰度的17α(H)-重排藿烷的形成与高等植物生源有一定联系、亚氧化-氧化的扇缘泥炭沼泽相是形成高~异常高丰度17α(H)-重排藿烷的有利沉积相带;而烃源岩显微组分、有机质丰度及其赋存状态以及有机质成熟度的影响尚不确定。 相似文献
6.
2-甲基藿烷:陆相湖盆中古沉积环境的分子化石 总被引：4，自引：0，他引：4
A环上带C-2或C-3位取代基的甲基藿烷常常用于反映细菌的新陈代谢过程(Summons et al．, 1999)。通过GC-MS和GC-MS-MS分析,在济阳坳陷古近系湖相沉积岩中检测到了丰富而完整的C28-C362α-甲基藿烷系列。2-甲基藿烷来源于蓝细菌体内的2β-甲基细菌藿烷多醇(Summons et al．,1999),在成岩作用中这种多羟基化合物易于结合到干酪根中,并在随后的热降解生烃过程中释放出2-甲基藿烷。2-甲基藿烷具有与藿烷类似的异构化反应,但转化速率和热力学平衡点有所变化。2-甲基藿烷的发育与古沉积环境的关系最为密切,高丰度2-甲基藿烷仅出现在浅水、低能量的碳酸盐岩沉积环境中,随着成熟度增加,2-甲基藿烷指数增大,随着湖盆水体扩大和深度增加,2-甲基藿烷指数迅速减小;在整个生烃阶段泥质岩中2-甲基藿烷都不发育。2-甲基藿烷的组成和分布形式反映了水体氧化还原条件的变化。2-甲基藿烷对于古沉积环境的恢复和古生态的重建具有重要意义,应用于陆相盆地的油气勘探则有助于更加准确地厘定有效烃源岩体。 相似文献
7.
地质体中藿烷类化合物以17αβ-藿烷系列为主,且C_(31+)升藿烷相对含量通常呈现出随碳数增加而减小的特征。本文报道了美国墨西哥湾下白垩统Aptian-Albian阶碳酸盐岩可溶有机质中异常高C_(31)-C_(32)升藿烷的检出(17α-C_(31)>C_(30))。与含正常藿烷系列的碳酸盐岩相比,该类低TOC含量碳酸盐岩中可溶有机质表现为低n-C_(17)/n-C_(21)值、5α(H),14α(H),17α(H)-C_(29)规则甾烷优势、C同位素组成偏重、高Pr/Ph和Ts/Tm值等特征。结合碳酸盐岩沉积背景和可溶有机质中甲基藿烷的分布特征,提出该类沉积有机质发育于偏氧化的近岸浅水环境,沉积环境演变导致的生源变化是促使异常高C_(31)-C_(32)升藿烷分布的主要因素,其来源可能与某种异养细菌优势有关。 相似文献
8.
9.
从华北西部和南部五个煤矿取得的石炭、二叠系腐殖煤的饱和烃馏分中,经GC和GC/MS分析,检测出了较丰富的二萜类生物标志物.根据质谱特征与卡瓦保留值,并对照文献谱图,确认其中包括五个具有贝壳松烷骨架的四环二萜烷(即ent-白叶烷、16α(H)-和16β(H)-扁枝烷、16α(H)-和16β(H)-贝壳松烷).以及一个三环的异海松烷.一个完整的四环二萜烷系列在我国华北石炭、二叠系腐殖煤中的发现在北半球很可能属首次.这些二萜类内组成在时间和空间上的差异分布,可能反映古植物群演化与分布的变化.扁枝烷和贝壳松烷的立体化学构型,可提供重要的有机成熟度信息. 相似文献
10.
热力作用对烃源岩中重排藿烷类化合物形成的作用 总被引：1，自引：1，他引：0
通过对87个采自鄂尔多斯盆地煤系烃源岩和松辽盆地湖相烃源岩样品进行的地球化学分析结果显示,热力作用对烃源岩重排藿烷组成特征的影响强烈。随成熟度的变化,来自两套沉积体系的烃源岩中重排藿烷相对丰度的分布相似,随成熟度增大17α（H）-重排藿烷和18α（H）-新藿烷相对丰度均先增大后减小,并在Ro:0.80%~0.90%（生油窗）时达峰值。不同沉积环境的烃源岩中重排藿烷的成熟度与绝对浓度的变化规律一致。在Ro:0.50%~0.70%（未熟-低熟）阶段,重排藿烷绝对浓度较大;在Ro:0.70%~0.80%（成熟）阶段,重排藿烷的绝对浓度显著降低。不同沉积环境中重排藿烷的参数随成熟度的变化规律揭示:在重排藿烷的形成过程中,热力作用的影响要强于沉积环境和生物来源。 相似文献
11.
Variations of the tree line and glaciers in the Central and Eastern Altai regions in the Holocene 总被引：1，自引：0，他引：1
Variations in the tree line position and glacier activity in the Central and Eastern Altai regions in the Holocene were reconstructed on the basis of analysis of sixty radiocarbon and eighteen dendrochronological dates. The tree line was higher than now in the Early and Middle Holocene, and the climate was warmer and, likely, more humid. Glaciers advanced in the forests 300, 1400, and 3000–6000 years ago. In the last millennium the forest decline at the upper tree limit occurred in 1206–1256, 1445–1501, and 1642–1736. 相似文献
12.
A. A. Peyve 《Geotectonics》2010,44(1):60-75
The magmatic and tectonic activity of eastern South America and the western South Atlantic shows that extension of the continental
crust is the determinant factor of magmatism. Heating of the upper mantle is a necessary condition of its manifestation. Ascending
plume material is a source of additional heat. In the Early Mesozoic, Eastern Brazil was situated above a large, ascending
and probably ramifying plume, which has supplied heat and material since the Triassic, creating favorable conditions for continental
magmatism. Magmatic activity continued, gradually waning, until the Neogene as evidence for long-term retention of heat energy
beneath the continental lithosphere after the plume ascent. It has been shown that heated mantle material can be displaced
from the continent to the ocean for a significant distance beneath the lithosphere with the formation of linear tectonomagmatic
rises of the oceanic crust. The structural elements inherited certain directions on the continent and in the ocean, beginning
from the Neoproterozoic. These directions were reactivated and continued to control the younger structural grain and magmatic
activity. In Southeastern Brazil, these were the structural units striking in the southeastern (about 120° SE) and northeastern
directions parallel to the continent-ocean boundary. In Northeastern Brazil, the W-E- and N—S-trending structural units are
predominant. All these directions are manifested in oceanic structural units (Rio Grande, Vitória-Trindadi, Fernando de Noronha,
Pernambuco rises, etc.). 相似文献
13.
Chronological analyses of correlations between certain global repeating events (mass extinctions of marine organisms, meteorite impacts, and flashes in the frequency of geomagnetic reversals) during the Phanerozoic Eon and the motion of the solar system in the Galaxy are presented for five rotationally symmetrical models for the regular Galactic gravitational field. Thirteen of sixteen mass-extinction events can be described by a repetition interval of 183±3 million years. This is in agreement with the anomalistic period (interval between two subsequent passages of the Sun through the apocenter of its Galactic orbit) in the model of Allen and Martos. The positions of the minima and maxima in Gaussian functions approximating the frequency distribution for geomagnetic reversals also agree with the times of passage of the Sun through the apocenter and pericenter, respectively, of its Galactic orbit in this model. The maximum in the distribution of the deviations of the dates of mass extinctions from the nearest dates of impacts of large, crater-forming bodies is close to zero, providing evidence that many such events are correlated. As a rule, extinctions follow impact events. The impacts of large bodies have occurred most often when the solar system passes through the Galactic plane, while mass extinctions occur more often at some distance from the Galactic plane (about 40 pc). As a rule, intervals of increases in the frequency of geomagnetic reversals coincide with dates of impacts of large bodies. At the same time, these intervals do not show a clear correlation with the dates of mass extinctions. The intensity of mass extinctions, like the energy released by impacts, is consistently higher in periods when the Sun is moving from the apocenter toward the pericenter of its orbit, than when it is moving from the pericenter toward the apocenter. Thus, there is evidence for a variety of relationships between repeating global events in the Phanerozoic and the motion of the Sun in the Galaxy. Long-period variations in the frequency of geomagnetic reversals are correlated with the orbital motion of the Sun, and increases in the frequency of geomagnetic reversals are correlated with impacts. Mass extinctions are correlated with the impacts of large bodies, whose motions may have been perturbed by clouds of interstellar material concentrated toward the Galactic plane and by the shock front associated with the Perseus spiral arm, through which the solar system passes. The velocity of the Sun relative to the spiral pattern is estimated. 相似文献
14.
我国中西部前陆盆地的特殊性和多样性及其天然气勘探 总被引：7，自引：0，他引：7
通过对我国中西部前陆盆地构造特征、大地构造背景、地球物理特征的理论研究和典型前陆盆地的详细解析,系统分析了我国中西部前陆盆地的发育特征和特殊性。强调晚二叠世以来大小不一、形态各异的多块体小型克拉通的聚合碰撞作用是导致中西部前陆盆地群形成的基本动力学过程：这些小型克拉通的多块体聚合碰撞造就了中西部前陆盆地的特殊性和多样性。同时,明确提出中西部盆地的基本特点是“两期三类前陆盆地”,即海西一印支期前陆盆地和喜山期前陆盆地,三类指海西一印支期的周缘前陆盆地和弧后前陆盆地、喜山期再生前陆盆地。根据前陆盆地的盆地结构和演化特征,又将中西部的前陆盆地划分为4种组合形式,即叠合型组合、改造型组合、早衰型组合和新生型组合。综合论述了不同时期不同类型前陆盆地构造对天然气聚集的五大控制作用。 相似文献
15.
V.A. Kashirtsev T.M. Parfenova A.K. Golovko B.L. Nikitenko I.N. Zueva O.N. Chalaya 《Russian Geology and Geophysics》2018,59(10):1380-1388
The composition and distribution of phenanthrenes (polyaromatic compounds) have been studied in chloroform extracts from dispersed organic matter (OM) of clayey, siliceous, carbonate, and terrigenous rocks of different ages and facies and from some oils of the Siberian Platform. Phenanthrenes have been analyzed by gas chromatography-mass spectrometry. High contents of 1,7,8-trimethylphenanthrene and 1,1,7,8-tetramethyl-1,2,3,4-tetrahydrophenanthrene are present in the OM of Vendian and Cambrian carbonate-shale deposits and in ancient oils of the Nepa-Botuobiya and Anabar anteclises. The OM of Permian continental deposits and oils of the Vilyui syneclise is dominated by 1-methyl-7-isopropylphenanthrene (retene). A triangular diagram for identification of the types of original OM of rocks and classification of genetically related oils has been constructed based on the assessment of phenanthrene biomarker distribution. Putative pathways of the formation of phenanthrene biomarkers are discussed. 相似文献
16.
Diamond crystallization in the Fe-Co-S-C and Fe-Ni-S-C systems and the role of sulfide-metal melts in the genesis of diamond 总被引：1，自引：0，他引：1
E. I. Zhimulev A. I. Chepurov E. F. Sinyakova V. M. Sonin A. A. Chepurov N. P. Pokhilenko 《Geochemistry International》2012,50(3):205-216
Diamond crystals 0.1–0.8 carats were synthesized in experiments conducted in a BARS split-sphere multianvil high-pressure
apparatus in the systems Fe-Co-S-C and Fe-Ni-S-C at a pressure of 5.5 GPa and temperature of 1300°C. The microtextures of
the samples and the phases accompanying diamond (carbides, graphite, monoslufide solid solution, pentlandite, and taenite)
are examined in much detail, the properties of metal-sulfide-carbon alloys are discussed, and issues related to the genesis
of sulfide inclusions in diamonds and graphite crystallization in the diamond stability field are considered. The experiments
demonstrate that diamonds can be synthesized and grow in pre-eutectic metal-sulfide melts with up to 14 wt % sulfur at relatively
low P-T parameters, which correspond to the probable temperatures and pressures of natural diamond-forming processes at depths of
approximately 150 km in the Earth’s upper mantle. 相似文献
17.
微亮晶（臼齿）碳酸盐成因及其在元古宙地球演化中的意义 总被引：14，自引：2，他引：14
本文应用多种技术方法,对微亮晶碳酸盐岩的成岩作用及其成因从宏观至微观进行了分析。根据岩石矿物学、地球化学和有机地球化学等研究证明,它是早期成岩过程中,在超高压的大气 CO_2,水平急剧下降的转折期,快速石化作用形成的具等粒结构μm级的微亮晶方解石集合体。MT 碳酸盐岩微亮晶成岩作用有两种类型:一是主要发生在海底沉积软泥中,在其底基质软泥中经差异压实作用形成褶皱肠状及复杂形的 MT 构造;二是直接在海水中或重力流搬运过程中形成的微亮晶球粒(核)。简言之,MT 碳酸盐岩石是在地球早期浅海环境下,由于微生物自养作用形成的地球化学成因产物。微亮晶碳酸盐岩是约束古大气圈和古海洋环境变化的最灵敏标志。通过详测 MT 丰度值和编制地球古大气圈 CO_2水平演化模式等,在前寒武纪发现有太古宙末期、早元古宙末期、中元古宙中期和新元古宙早-中期四个 MT 碳酸盐岩发育高峰值期,证明全球古大气圈 CO_2水平发生过四次不连续性、跳跃式下降周期,直到晚新元古宙未,全球雪球事件的发生,导致了 MT 碳酸盐岩的消失。其后,才进入显生宙的 CO_2低水平状态。MT 碳酸盐岩具有重要的油气资源远景,应予以重视。 相似文献
18.
北极地区丰富的油气资源近年来引发全世界的广泛关注。评估结果显示,北极油气资源分布不均,主要集中在俄罗斯、美国阿拉斯加、挪威、加拿大和丹麦格陵兰。不同国家和地区北极油气资源勘探开发特点不同,在新形势下可能还会发生变化。中国是油气消费大国和进口大国,俄罗斯北极地区已日渐成为中国重要油气供应地之一。综合分析几个主要北极国家北极油气开发利用现状和未来发展前景,与中国目前参与北极油气开发利用的情况,对未来中国如何参与北极油气资源开发利用提出建议,将俄罗斯作为中国北极油气开发的长期合作伙伴,与其开展项目投资、技术入股、航道建设等多个方面的合作。 相似文献
19.
Paul Tréguer 《Comptes Rendus Geoscience》2002,334(1):3-11
Silicon is a key element whose major role in the control of the cycle of carbon in the ocean has been recently revealed. This is first illustrated through the resolution of the ‘opal paradox’ in the modern Southern Ocean. Second, the ‘silica hypothesis’ explains why, during the Last Glacial Maximum, the atmospheric concentration of CO2 was about 40 % below that of the interglacial period. Increased deliveries of wind-borne silica to the surface ocean as well as of riverine inputs favoured the dominance of diatoms over coccolithophorids, resulting in a net emission decrease of CO2 by coccolithophorids from the ocean surface to the atmosphere. To cite this article: P. Tréguer, C. R. Geoscience 334 (2002) 3–11 相似文献
20.
David Thorpe 《Geoforum》1978,9(2):83-106
Geographers have devoted a considerable amount of attention to the distributive sector. In part this has arisen because this sector provides an excellent testing ground for techniques. Substantive research, despite the needs of decision makers in both the public and private sectors, has been inbalanced. It has tended to focus on shoppers' behaviour and the factors controlling supply, at least equally important, have been relatively neglected. The paper indicates the significance of these factors and demonstrates how they need to be integrated into different modelling and theoretical approaches if research is to provide really useful insights for decision makers. It outlines how the focus of geographical study has shifted from examining the distributive trades as indicators of other facts of urban systems to the examination of spatial variations which are of substantial operational significance. Such studies do, however, fit readily into a wider frame-work of a geographical environment which is continuous but partitioned, limited but expanding and organised but diversified. Fruitful research can thus adopt both a spatial and an ecological perspective. The importance of the sector in the economy is sufficient reason for such research to be conducted. 相似文献