巢湖地区二叠系栖霞组和三叠系南陵湖组石灰岩生物标志物特征与生烃潜力——以平顶山和马家山剖面为例     

宋换新  志刚  包建平 《海相油气地质》2015,(2)

对安徽巢湖地区平顶山和马家山剖面下二叠统栖霞组和下三叠统南陵湖组进行了地层沉积特征及暗色石灰岩生烃潜力的综合分析,并对这两个层位的样品进行了饱和烃生物标志物特征研究。结果表明,两个层位的石灰岩都属于有效烃源岩,均具有一定的生烃潜力。南陵湖组石灰岩饱和烃以高丰度的长链三环萜烷、重排藿烷、重排甾烷为特征,表明其形成于偏弱氧化的沉积环境。栖霞组沉积期水体能量相对较低,受陆源物质影响明显,栖霞组石灰岩萜烷系列为常规的分布模式,但其甾烷成熟度参数明显低于平衡值,认为高的热演化程度是造成栖霞组石灰岩20S/(20S+20R)-ααα-C29甾烷值和ββ/(ββ+αα)-C29甾烷值"倒转"的主要原因。  相似文献   

长白山区二道白河流域早更新世玄武质熔岩的成因   总被引：2，自引：1，他引：1  

马晗瑞  杨清福  盘晓东  武成智  陈聪 《岩石学报》2015,31(11):3484-3494

采用岩石化学和同位素分析方法,研究了二道白河流域早更新世玄武质熔岩的成因。玄武质熔岩由钠质拉斑玄武岩和钾质粗面玄武岩、玄武质粗面安山岩组成。它们的REE分配形式比较相近,表明它们来自共同的源区。Sr、Nd、Pb同位素示踪表明,二道白河流域早更新世玄武质熔岩岩浆源区接近于似原始地幔。它们的Mg#=100Mg O/(Mg O+Fe O)低于中国东部新生代玄武岩原始岩浆的Mg#(60~68),Ni(27.76×10-6~200.6×10-6)低于原始地幔,Rb/Sr(0.05~0.09)、Ba/Rb(15.64~264)高于原始地幔,说明这些岩石不是源自原始地幔。玄武质熔岩的DI变化于42~67,具有高Ca、高Sr、Eu正异常,微量元素图解显示玄武岩保留部分熔融趋势,粗面玄武岩、玄武质粗安岩具有结晶分异趋势,岩浆上升过程中发生了不同程度的地壳混染作用。玄武质熔岩的Nb/Ta之比为14.8~15.8,与勘察加半岛深俯冲带火山类似。Nb/Ta-(Na2O-K2O)关系图解显示研究区玄武质岩浆的形成与俯冲板片的部分熔融有关。  相似文献   

Characteristics and origin of carbon isotopes of n-alkanes in crude oils from the western Pearl River Mouth Basin,South China sea     

《Marine and Petroleum Geology》2015

The quantitative characterization of carbon isotopes of n-alkanes is commonly carried out in organic geochemical studies. Possible controls on carbon isotopes include source organic matter, maturity, fractionation during oil expulsion and migration, and the mixing of different oils. In this study of the origin of crude oils in the western Pearl River Mouth Basin, the influences of all of these factors have been considered in reaching a conclusion. Carbon isotopes of n-alkanes in the crude oils, and the extracts of the two effective source rocks (the Wenchang and Enping formations) in the basin, exhibit clear differences. The Wenchang source rocks have heavy δ¹³C values that remain almost constant or become slightly heavier with increasing carbon number. The Enping source rocks have light δ¹³C values that become lighter with increasing carbon number. Two groups of oils in this area were identified based on the carbon isotopes of the n-alkanes; groupIoils are similar to extracts of the Wenchang source rocks. However, the groupIIoils are different from both the Wenchang and Enping source rocks and the carbon isotopic profiles of their n-alkanes exhibit a “V” feature with increasing carbon number. The results of artificial thermal maturation experiments indicate that, from the early stage to the peak stage of oil generation (with EasyRo between 0.64% and 1.02%), the δ¹³C values of n-alkanes in the pyrolysis oils become heavier by about 3‰ with increasing thermal maturity, but the shape of the carbon isotopic profiles are not significantly changed. Calculated δ¹³C values of n-alkanes in “mixed” artificial pyrolysis oils indicate that the mixture of oils generated from the same source rocks with different maturities could not change the carbon isotopic profile of the n-alkanes, however, a mixing of the Wenchang and Enping oils could give the “V” feature in the profiles, similar to the groupIIoils in this area. The groupIIoils appear to be mixed Wenchang and Enping oils, the latter being the dominant component in the mixture. We conclude that the source organic matter and the degree of mixing are the main factors controlling the carbon isotopic characteristics of n-alkanes in crude oils in the western Pearl River Mouth Basin.  相似文献   

考虑震源破裂过程的青海玉树地震震动图研究   总被引：4，自引：0，他引：4  

陈鲲  俞言祥  高孟潭  吕红山 《中国地震》2011,27(1):56-64

为了在缺少实时台站数据的情况下,研究震后地表地震动分布,本文尝试通过对震源做出某些约束,以提高震动图的精度.由于青海玉树地震的发震断层近似直立(倾向83°),震源破裂过程在时间和空间上呈明显的分区特征,分别考虑了地表破裂的线源发生模型和主震震级分解方法,用考虑了场地效应的震动图快速生成方法生成震动图.将两种方法生成的震动图与调查烈度比较.结果表明,基于震源破裂过程对主震震级进行分解,综合考虑各子事件生成震动图的方法,对震后的应急决策和灾情的快速评估是可行的.  相似文献   

龙潭水库诱发地震震源参数分析     

乔慧珍  张永久  任月霞  宫悦  赵敏 《四川地震》2011,(4):16-20

利用广西龙滩水库地震台网记录的数字地震波资料,用波谱分析方法计算了龙滩水库库区ML2．5—4．5级共计95个地震的震源参数。并对震源参数进行分析,结果表明：库区视应力的范围在0-3．5巴之间,2007年7月17日库区最大4．5级地震的视应力最大,为3．07巴。视应力随震级的增大呈幂函数增大趋势,两者的拟合关系为：σap...  相似文献   

Distribution of the organic matter in the channel-levees systems of the Congo mud-rich deep-sea fan (West Africa). Implication for deep offshore petroleum source rocks and global carbon cycle     

François Baudin  Jean-Robert Disnar  Philippe Martinez  Bernard Dennielou 《Marine and Petroleum Geology》2010

The quantity and the source of organic matter preserved in the Recent turbiditic channel-levees systems around 4000 m-depth off the Congo River were determined using bulk geochemical approaches (Rock-Eval, elemental and isotopic analyses) as well as molecular and optical analyses on selected samples. These mud-rich sediments contain high amount of organic matter (3% Corg on average), the origin of which is a mixture of terrestrial higher-plant debris and deeply oxidized phytoplanktonic material. Although the relative contribution of continental source versus marine source of the organic matter cannot be precisely quantified, the continental fraction appears significant (at least 70–80%) especially for such depths and distances from the coast. The organic matter distribution appears very homogeneous at different scales, from the single turbiditic event to the entire levee, and changes in accumulation rates have a little impact on the quantity and quality of preserved organic matter.  相似文献   

Advances in Glycerol Dialkyl Glycerol Tetraethers and Long-Chain Alkyl Diols in the Marine Sediments: Implications for Paleoclimatic and Paleoenvironmental Changes     

Lilei Chen  Feng Li  Jian Liu 《地球科学进展》2019,34(8):855-867

Lipid biomarkers widely dotted in marine sediments, as their distribution characteristics accurately record huge information on the metabolism of the original organisms and migration and transformation of these organic components, are often used to reconstruct the paleoclimatic and paleoenvironmental conditions. This paper reviewed the progress in the study of paleoclimatic-environmental changes during the late Quaternary using abundant core lipids Glycerol Dialkyl Glyceryl Tetraethers (GDGTs) and long-chain alkyl diols in marginal sea sediments. It is pointed out that clarifying the “source-sink” process of lipid biomarkers buried in marine sediments is a prerequisite for paleoclimatic-environmental reconstruction. It is believed that the use of multiple indicators that are less affected by early diagenesis can increase the accuracy of reconstructing paleoclimatic changes. In the large-river dominated marginal seas, the mechanism of land-sea climate coupling evolution stimulated by the paleoclimatic-environmental changes can be elucidated based on paleoclimatic records reconstructed from core lipids GDGTs and long-chain alkyl diols in marine sediments. It is hoped that this paper can provide reliable technical means and a solid theoretical basis for predicting future temperature and rainfall changes.  相似文献   

关于澜沧江正源问题   总被引：8，自引：2，他引：8  

靳长兴  周长进 《地理研究》1995,14(1):44-49

通过对澜沧江源头地区的水文、气候、地貌及河流特征等实地考察后确认,澜沧江正源应为扎阿曲,发源于青海省玉树藏族自治州杂多县阿青乡拉赛贡玛山南面的冰川末端。  相似文献   

Ground motions observed during the 15 August 2007 Pisco, Peru, earthquake     

Hernando Tavera  Isabel Bernal  Fleur O. Strasser  Maria C. Arango-Gaviria  John E. Alarcón  Julian J. Bommer 《Bulletin of Earthquake Engineering》2009,7(1):71-111

A M_w 7.9 earthquake event occurred on 15 August 2007 off the coast of central Peru, 60 km west of the city of Pisco. This event is associated with subduction processes at the interface of the Nazca and South American plates, and was characterised by a complex source mechanism involving rupture on two main asperities, with unilateral rupture propagation to the southeast. The rupture process is clearly reflected in the ground motions recorded during this event, which include two separate episodes of strong shaking. The event triggered 18 accelerographic stations; the recordings are examined in terms of their characteristics and compared to the predictions of ground-motion prediction equations for subduction environments, using the maximum-likelihood-based method of Scherbaum et al. (Bull Seismol Soc Am 94(6):2164–2185, 2004). Additionally, macroseismic observations and damage patterns are examined and discussed in the light of local construction practices, drawing on field observations gathered during the post-earthquake reconnaissance missions.  相似文献   

汶川8.0级地震前紫坪铺水库小震活动及震源参数研究   总被引：2，自引：0，他引：2  

张致伟  程万正  张永久  谢蓉华  傅莺 《中国地震》2009,25(4)

利用区域和水库地震台网记录的数字地震波资料,研究了汶川8.0级地震前的2000年1月1日～2008年5月11日紫坪铺水库区的地震活动及震源参数.结果表明:汶川8.0级地震前该区域小震活动持续,地震活动水平为M_L2～3,自2005年9月紫坪铺水库蓄水以来,特别是2008年2月地震活动明显增加,但从长期的序列来看,地震活动频次和强度仍在区域地震活动的正常起伏范围.汶川8.0级地震发生前近3个月内,中小地震的视应力差值△σ_(app)普遍大于0,计算得到的视应力总大于其拟合值.汶川8.0级地震震中位于低应力区,而相对较高的视应力差值分布在震中以东地区,局部出现视应力增加的现象.  相似文献