Marine hydrocarbon source rocks of the Upper Permian Longtan Formation and their contribution to gas accumulation in the northeastern Sichuan Basin,southwest China     

《Marine and Petroleum Geology》2014

Identification of the main hydrocarbon source rocks of the large Puguang gas field (northeastern Sichuan Basin, southwest China) has been the subject of much discussion in recent years. A key aspect has been the lack of a comprehensive understanding of the development of hydrocarbon source rocks of the Upper Permian Longtan Formation, which had been thought to contain mainly coal seams and thick carbonate layers. In this paper, based on geological data from more than ten wells and outcrops and their related mineralogy and geochemistry, we investigated the depositional environment and main factors controlling organic matter enrichment in the Longtan Formation. We propose a model which combines information on the geological environment and biological changes over time. In the model, organic matter from prolific phytoplankton blooms was deposited in quiescent platform interior sags with rising sea-levels. During the Longtan period, the area from Bazhong to Dazhou was a platform interior sag with relatively deep water and a closed environment, which was controlled by multiple factors including syngenetic fault settling, isolation of submarine uplifts and rising sea-levels leading to water column stratification. Although the bottom water was anoxic, the phytoplankton were able to bloom in the well-lit upper euphotic zone thus giving rise to a set of sapropelic black shales and marlstones containing mostly algal organic matter with minor terrestrial contributions. As a consequence, these rocks have a high hydrocarbon generation potentials and can be classified as high-quality source rocks. The area from Bazhong to Dazhou is a center of hydrocarbon generation, being the main source of reservoired paleo-oils and presently discovered as pyrobitumen in the Puguang gas field. The identification of these source rocks is very important to guide future petroleum exploration in the northeastern Sichuan Basin.  相似文献   

大兴安岭北部甲乌拉铅锌银矿床Rb-Sr同位素测年及其地质意义   总被引：11，自引：3，他引：8  

李铁刚  武广  刘军  胡姸青  张云付  罗大峰 《岩石学报》2014,30(1):257-270

甲乌拉铅锌银矿床位于内蒙古自治区满洲里市南西150km。矿床产于中蒙古-额尔古纳兴凯造山带南东缘之得尔布干断裂北西侧。本文在甲乌拉矿床选取7件闪锌矿和6件黄铁矿样品开展了Rb-Sr定年。获得闪锌矿的Rb-Sr等时线年龄为143.0±2.0Ma(MSWD=3.2),锶同位素初始值I Sr=0.71265;黄铁矿的Rb-Sr等时线年龄为142.0±3.0Ma(MSWD=5.7),锶同位素初始值ISr=0.71267;闪锌矿与黄铁矿的Rb-Sr等时线年龄为142.7±1.3Ma(MSWD=3.8),锶同位素初始值ISr=0.71266。上述定年结果表明,甲乌拉矿床形成于早白垩世初期。甲乌拉矿床硫化物的Rb和Sr含量分别介于0.1034×10-6～7.367×10-6和1.301×10-6～7.148×10-6之间,Sr同位素初始比值(87Sr/86Sr)i介于0.71238～0.71277之间,平均值为0.71264,暗示甲乌拉矿床的成矿物质主要来源于地壳。甲乌拉矿床形成于蒙古-鄂霍茨克造山过程的后碰撞阶段。  相似文献   

青藏高原东北缘柳坪新生代苦橄玄武岩地球化学及其大陆动力学意义   总被引：3，自引：2，他引：1  

赖绍聪  秦江锋  赵少伟  朱韧之 《岩石学报》2014,30(2):361-370

柳坪苦橄玄武岩出露在青藏高原东北缘特殊的构造部位,位于青藏、华北和扬子三大构造域的交接转换区域。岩石形成年龄在23~7.1Ma之间,属于新近纪火山岩。岩石SiO2介于41.72%~42.82%之间,Na2OK2O,K2O/Na2O平均0.51,为一套典型的幔源钠质碱性玄武岩类。岩石微量及稀土元素具板内火山岩特征,Th、Rb等元素呈较明显的富集状态,而岩石显著的低K2O特征(0.48%~0.90%)明显不同于青藏高原北缘新生代钾质-超钾质火山岩系列。岩石87Sr/86Sr(0.704158~0.704668)、143Nd/144Nd(0.512831~0.513352)、206Pb/204Pb(18.729871~18.779184)、207Pb/204Pb(15.591395~15.602454)和208Pb/204Pb(39.097372~39.181458)等同位素变化特征具有显著的混源属性,投影点位于EMI、EMII、BSE及PREMA等典型地幔储库的过渡部位,并可能存在HIUM地幔源的部分参与,明显不同于单一地幔源局部熔融形成的玄武岩的同位素组成特征。表明新生代期间青藏东缘西秦岭-松潘地区受青藏、扬子及华北三大构造体系域的控制,西秦岭-松潘构造结处于从下部地幔到上部陆壳物质的总体汇聚拼贴阶段,地幔具有显著的混合特征。柳坪苦橄玄武岩正是在这种特定的构造背景下,由于新生代青藏高原软流圈地幔物质向东的流动,诱发西秦岭-松潘构造结多源混合的地幔橄榄岩局部熔融而形成。  相似文献   

Genetic Analysis of Floating Enteromorpha prolifera in the Yellow Sea with AFLP Marker     

LIU Cui  ZHANG Jing  SUN Xiaoyu  LI Jian  ZHANG Xi  LIU Tao 《青岛海洋大学学报(英文版)》2011,(3):263-269

  相似文献   

稀有金属花岗岩富集成矿的烃类气体地球化学标志——以广西栗木锡多金属矿为例     

李博  徐庆鸿  陈远荣  李学彪  黎家财  柒锦捷 《地质论评》2023,69(3):987-1003

烃类气体在自然界广泛分布并具有复杂成因和来源,同时针对烃类气体的研究不应局限于石油、天然气等传统能源矿产,而需要推广到更多其他科研领域。笔者等采取苦橄岩烃类气体标准化的研究思路,以广西栗木锡多金属矿为中心,重点围绕矿区各阶段花岗岩、矿体及地表土壤开展烃类气体宏观特征和微观规律的研究工作。通过研究和对比,揭示花岗岩及矿石中烃类气体特征和变化规律,查明在成矿作用影响下烃类气体成熟度提高且通过构造裂隙向上运移,并被地表土壤吸附形成异常的事实,明确了深部隐伏矿体与土壤烃类气体异常的成因联系及空间对应关系,建立了判断稀有金属花岗岩富集成矿的烃类气体特征指标和参数,研究表明,将烃类气体特征作为判断稀有金属花岗岩富集成矿地球化学标志的思路正确且方法可行,并将对今后进一步拓展烃类气体的研究和应用领域产生积极影响。  相似文献   

利用区域宽频地震数据反演2021年5月云南漾濞M_S6.4地震震源破裂过程     

朱音杰  罗艳  赵里  田建慧 《地球物理学报》2022,(3)

本文基于有限断层模型反演方法,利用区域宽频带数据反演了2021年5月云南漾濞M_S6.4地震的震源破裂过程,结果显示:此次地震的发震断层走向为SE向,主要以右旋走滑为主.破裂主要发生在震源东南侧,最大错动量约为0.55 m,位于深度约9 km处,发生明显破裂的深度约达13 km.此次地震释放的标量地震矩为1.48×10¹⁸N·m,相当于矩震级M_W6.05.地震能量主要在前11 s释放.在深度为6~8 km处破裂速度有明显的变快,可能加剧了地表的震动.  相似文献   

Evolution of the freeze-thaw cycles in the source region of the Yellow River under the influence of climate change and its hydrological effects          下载免费PDF全文

Liang Zhu  Ming-nan Yang  Jing-tao Liu  Yu-xi Zhang  Xi Chen  Bing Zhou 《地下水科学与工程》2022,10(4):322-334

As an important water source and ecological barrier in the Yellow River Basin, the source region of the Yellow River (above the Huangheyan Hydrologic Station) presents a remarkable permafrost degradation trend due to climate change. Therefore, scientific understanding the effects of permafrost degradation on runoff variations is of great significance for the water resource and ecological protection in the Yellow River Basin. In this paper, we studied the mechanism and extent of the effect of degrading permafrost on surface flow in the source region of the Yellow River based on the monitoring data of temperature and moisture content of permafrost in 2013–2019 and the runoff data in 1960–2019. The following results have been found. From 2013 to 2019, the geotemperature of the monitoring sections at depths of 0–2.4 m increased by 0.16°C/a on average. With an increase in the thawing depth of the permafrost, the underground water storage space also increased, and the depth of water level above the frozen layer at the monitoring points decreased from above 1.2 m to 1.2–2 m. 64.7% of the average multiyear groundwater was recharged by runoff, in which meltwater from the permafrost accounted for 10.3%. Compared to 1960-1965, the runoff depth in the surface thawing period (from May to October) and the freezing period (from November to April) decreased by 1.5 mm and 1.2 mm, respectively during 1992–1997, accounting for 4.2% and 3.4% of the average annual runoff depth, respectively. Most specifically, the decrease in the runoff depth was primarily reflected in the decreased runoff from August to December. The permafrost degradation affects the runoff within a year by changing the runoff generation, concentration characteristics and the melt water quantity from permafrost, decreasing the runoff at the later stage of the permafrost thawing. However, the permafrost degradation has limited impacts on annual runoff and does not dominate the runoff changes in the source region of the Yellow River in the longterm.  相似文献   

Source constraints for the young basaltic rocks from the northernmost end of Cappadocian region,Turkey: Melting evidence from peridotite and pyroxenite source domains     

Biltan Kürkcüoğlu  M. Tekin Yürür 《Chemie der Erde / Geochemistry》2022,82(1):125838

Widespread magmatic activity developed in the Middle Miocene in the Cappadocian Region of Central Anatolia in Turkey. Despite several previous studies that focus on the geochemical features of the magmatic rocks, the source components and development of melting conditions are still a matter of debate.Recent basaltic rocks from Karaburna and Gül?ehir (1228 and 96 Ka, respectively, Dogan, 2011) are considered as a part of the Central Anatolian Volcanic Province, situated at the northernmost end of the Cappadocian Region. These lavas have similar large ion lithophile (LIL) (except Rb) and high field strength (HFS) element abundances, however, Karaburna samples are more enriched in HFS elements, and both of the rocks suites reflect HFS depletions relative to the OIB signature.Karaburna and Gül?ehir basalts have low Nb/La (0.45–0.5; 0.35–0.5), Nb/Th (2.75–4.61; 1.26–2.85) values, respectively, suggesting contributions from crustal sources, whereas Zr/Ba ratios of these samples range between 0.32–0.93 and 0.4–0.88 and imply that these rocks appear to be derived from asthenospheric sources. These incompatible element ratios can be attributed to either different geochemical processes, or are related to melting from different source component(s).The ambient mantle source of the Cappadocian region appears to be consistent with spinel peridotite, but this domain is not solely satisfactory to represent the melting conditions in the light of new elemental data. Values of Tb/Yb(N) and Zn/Fe provide new constraints suggesting the magmas were generated from the asthenosphere. Tb/Yb(N) ratio separates garnet – spinel transition Tb/Yb_(N) (>1.8) and Zn/Fe ratio displays separation between the peridotite-derived (Zn/Fe <12) and pyroxenite-derived (13?20) melts.A melting model based on REE ratios and Zn/Fe, Co/Fe, Tb/Yb(N) values indicates that basaltic rocks were not derived from a single source component (peridotite). Instead, those values suggest substantial melting contributions from a pyroxenite source domain, which has not been discussed as a source component in previous studies. Melts, from both of the source domains, with the result of asthenospheric upwelling linked to the downgoing Aegean and Cyprean slabs, are distinct from the alkaline character frequently observed as the final products of recent volcanic activity in the Cappadocian region and also explains the different trace element variations observed in such a small scale.  相似文献   

E5000型全谱直读型电弧发射光谱仪研制及其在地球化学样品分析中应用   总被引：2，自引：2，他引：0  

俞晓峰  李锐  寿淼钧  郑存江  胡勇平 《岩矿测试》2015,34(1):40-47

在地球化学样品检测工作中,Ag、B、Sn等难分析元素通常采用传统的交流电弧发射光谱法(摄谱仪),随着地球化学样品数量的增加以及对检测结果质量要求的提高,该方法操作复杂、分析过程繁琐的问题与日常大量样品分析的矛盾日益突出,多道式电弧直读发射光谱也开始在行业内应用。本文基于先进的数字光源技术和CCD全谱型光谱仪技术,改进了电弧发生系统、分光系统和检测系统,将电弧激发光源与Paschen-Runge型全谱CCD光谱仪结合,研制了一款新型的台式全谱直读型电弧发射光谱仪E5000。E5000型电弧发射光谱仪通过激光定位结合程控电极技术,自动调整电极位置,提高了采谱过程的精度控制;利用CCD全谱技术获得了激发样品的全谱信息,可轻易实现光谱信号的背景扣除和干扰校正;且无需再次测定黑度,直接获得分析结果;同时结合内标法和标准加入法,可以进一步提高复杂基体样品的分析精准度。应用研制的光谱仪对水系沉积物和土壤样品进行检测,Ag、B、Sn元素的检出限分别达到了0.01μg/g、0.65μg/g、0.16μg/g,在分析水系沉积物、土壤时检测精密度基本小于10%,优于当前的摄谱法和多道电弧直读光谱法,满足了地球化学样品检测质量要求。  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