塔河油田碎屑岩油气运聚模拟及潜力区优选     

冯兴强  宋海明 《地质力学学报》2020,26(6):892-900

为了系统研究塔河油田碎屑岩油气运聚过程，针对研究区目的层的地质特征，文章采用流径和逾渗综合方法进行油气运聚模拟分析。该方法基于断裂-砂体输导格架来开展油气运聚模拟，首先通过断层的分级、分期研究，结合实际资料形成了断层开启性判别标准，进而建立断层输导格架模型；综合使用压实曲线和孔渗关系，利用相控建模技术建立砂体输导格架模型。在断裂-砂体输导格架基础上开展了油气运聚模拟，模拟结果与现有的油气藏吻合较好，表明流径与逾渗综合法是一种模拟研究区目的层油气运聚过程的有效方法。同时，利用模拟结果，明确了主要目的层的潜力区域，对研究区碎屑岩的勘探部署有重要意义和实际价值。   相似文献   

钛同位素地球化学综述     

赵新苗  唐索寒  李津  朱祥坤  王辉  李志汉  张宏福 《地学前缘》2020,27(3):68-77

随着分析技术的进步,非传统稳定同位素体系在地球化学、天体化学和生物地球化学等研究领域的应用日益广泛。钛(Ti)是一个非常重要的过渡族金属元素,在地球和其他类地球行星中广泛存在。但是由于Ti是一种难熔的、流体不活动性元素,高温地质过程中Ti同位素分馏很小。人们对Ti同位素体系的地球化学应用的关注相对其他非传统稳定同位非常有限。而近年来,随着化学纯化方案的优化以及双稀释剂方法的改进和仪器质谱性能的提高,Ti同位素组成的高精度测试已经能够实现。天然样品中Ti同位素组成的变化随之得以发现,使得学者们能够利用这一新的稳定同位素体系来解决与高温和低温地球化学相关的问题。很快Ti同位素体系地球化学研究成为当前国际地质学界的前沿研究课题和新的发展方向之一。本文首先在简要介绍Ti元素和Ti同位素体地球化学性质的基础上,介绍了Ti元素化学分离和Ti同位素分析方法。随后笔者总结了已有的不同类型球粒陨石和地球样品的质量相关Ti同位素组成研究结果,对硅酸盐地球的Ti同位素组成做了初步评估。前人对高温地质样品的Ti同位素组成研究初步探明Ti同位素在岩浆演化过程,例如部分熔融和结晶分异等重要地质过程中的分馏行为。笔者在此基础上探讨了结晶分异过程中引起Ti同位素分馏的主要控制因素,指出Ti同位素是潜在的研究岩浆演化过程的新工具。最后笔者探讨了Ti同位素地球化学未来的发展方向,以加速我国在Ti同位素地球化学方面的应用研究。  相似文献   

榍石LA-ICP-MS U-Pb定年中元素分馏的影响及校正研究     

靳梦琪  李艳广  王鹏  汪双双  黎卫亮 《岩矿测试》2020,39(2):274-284

同位素地质年代学是探索地质体时空演化及地球动力学等问题的基础学科,应用最为广泛的当属含铀副矿物的U-Pb定年技术。榍石具有相对较低的U-Pb体系封闭温度,并广泛发育于岩浆岩、各类变质岩、热液成因岩石以及少量沉积岩中,是一种理想的中高温地质事件定年矿物。利用电感耦合等离子体质谱法(ICP-MS)测定榍石U-Pb年龄时,不可避免地要解决高普通铅以及元素分馏效应对测试的影响。本文对榍石LA-ICP-MS实验过程中的元素分馏行为进行研究,采用相同基体的标准样品与未知样品对比,发现了榍石不同颗粒之间元素分馏行为不一致的现象;同时采用不同的元素分馏校正方法,分别应用于锆石、独居石和榍石进行对比研究,认为分馏行为一致的副矿物定年可以采用"指数法"和"均值法"对数据进行校正,但是对于榍石这种分馏行为不一致的副矿物,定年时只有采用"截距法"对数据进行校正才可以获得正确的年龄。进而将此结论应用于秦岭造山带老牛山地区岩浆成因榍石样品,得到的结果与锆石年龄一致,表明"截距法"可以避免分馏行为不一致导致的校正不准确的问题。本研究成果为榍石LA-ICP-MS U-Pb定年方法的完善提供了一种思路。  相似文献   

Calibration of oxygen isotope fractionation and calcite-corundum thermometry in emery at Naxos,Greece     

Rachelle B. Turnier  Yaron Katzir  Kouki Kitajima  Ian J. Orland  Michael J. Spicuzza  John W. Valley 《Journal of Metamorphic Geology》2020,38(1):53-70

Corundum (Crn), including sapphire, occurs in emery pods surrounded by marble on the island of Naxos, Greece. The emery formed from bauxite deposited in karst that was metamorphosed to 400–700°C at 20–15 Ma. Many of these rocks initially appeared well suited for refractory accessory mineral (RAM) thermometry, which uses oxygen isotope fractionation between a RAM – corundum – and a modally dominant phase with faster diffusion of oxygen – calcite (Cc) – to determine peak metamorphic temperatures. However, previous attempts at oxygen isotope thermometry were confounded by highly variable fractionations (Δ¹⁸O) measured at mm-scale and the uncertain calibration of Δ¹⁸O(Cc-Crn) versus temperature. Secondary ion mass spectrometry (SIMS) permits in situ analysis of δ¹⁸O in corundum and calcite at the 10-μm scale in adjacent grains where textures suggest peak metamorphic equilibrium was attained. SIMS analyses of adjacent mineral pairs in eight rocks yield values of Δ(Cc-Crn) that systematically decrease from 7.2 to 2.9‰ at higher metamorphic grade. Pairing these data with independent temperature estimates from mineral isograds yields an empirical calibration of 1,000 lnα(Cc-Crn) = 2.72 ± 0.3 × 10⁶/T² (T in K). The new fractionations (2.7‰ at 1,000 K) are significantly smaller than those calculated from the modified increment method (6.5‰ at 1,000 K; Zheng, Geochimica et Cosmochimica Acta, 1991, 55:2299–2307; Zheng, Mineral Mag, 1994, 58A:1000–1001), which yield unreasonably high temperatures of 630 to 1,140°C when applied to the new Naxos data. The new calibration of Δ(Cc-Crn) can be combined with published fractionations to calculate A-factors for corundum versus a range of 14 other minerals. These new fractionation factors can be used for thermometry or to constrain the genesis of corundum. A compilation of gem corundum δ¹⁸O values shows that many igneous sapphires, including important deposits of basalt-associated sapphire, are mildly elevated in δ¹⁸O relative to the calculated range in equilibrium with mantle values (4.4–5.7‰) and formed from evolved magmas.  相似文献   

钾稳定同位素研究综述     

王昆  李伟强  李石磊 《地学前缘》2020,27(3):104-122

钾稳定同位素是重要的非传统稳定同位素体系,也是近年来迅速发展的热门研究课题。对钾同位素研究历史和现状进行综述,具体包括以下内容:(1)总结了钾元素的地球化学和宇宙化学性质,包括钾在主要地质储库(地幔、地壳、海洋)中的丰度及其分配,钾在岩浆演化中的不相容大离子亲石性,常见含钾火成岩/沉积岩矿物以及钾在表生过程中的循环,也包括主要行星物质(球粒陨石、非球粒陨石、火星和灶神星陨石以及月球样品)中钾的含量、赋存状态、主要矿物,钾在太阳星云冷凝、行星积聚以及岩浆海过程中的中等挥发性质;(2)介绍了钾同位素的研究历史,从1922年Dempster利用最早的质谱仪测量钾同位素在自然界的丰度,到Taylor和Urey在1938发表的经典的钾同位素分馏实验,再到Humayun和Clayton在1995年发表的钾同位素领域的经典研究,最后到近几年的进展;(3)介绍了对钾的前处理(离子交换柱法)以及钾同位素的主要测量方法,包括早期热电离质谱仪法(TIMS),二次离子质谱仪法(SIMS)和近十几年以来高速发展的多接收电感耦合等离子体质谱仪法(MC-ICP-MS)及其不同的技术路线;(4)介绍了高精度钾同位素比值在低温地球化学和生物地球化学中的应用,包括钾同位素在地表的风化过程中、海水洋壳的反向风化作用中的分馏及其在示踪全球钾元素循环和洋壳俯冲等过程中的应用;(5)介绍了高精度钾同位素比值在高温地球化学中的应用,包括钾同位素在岩浆分异和矿物结晶过程中的分馏;(6)介绍了高精度钾同位素比值在宇宙化学中的应用,包括在太阳星云冷凝、行星凝聚、月球形成大碰撞、岩浆海、火山喷发去气过程中的分馏作用。  相似文献   

蛇纹石化和俯冲带蛇纹岩变质脱水过程中流体活动性元素的行为   总被引：1，自引：1，他引：0  

吴凯  袁洪林  吕楠  张丽鹏 《岩石学报》2020,36(1):141-153

蛇纹石是大洋岩石圈和俯冲带内水和流体活动性元素最重要的载体之一。研究蛇纹石化和蛇纹岩变质脱水过程中流体活动性元素的行为是认识俯冲带元素地球化学循环的关键。蛇纹岩是指主要由蛇纹石类矿物构成的岩石,包括利蛇纹石、纤蛇纹石和叶蛇纹石。蛇纹石化过程中会造成流体活动性元素(B、Li、As、Sb、Pb、Cs、U、Sr和Ba等)的显著富集,并且由于原岩性质、流体成分和氧逸度等条件的不同,大洋岩石圈蛇纹岩和弧前蛇纹岩的特征也略有不同。例如,弧前蛇纹岩具有相对高的As、Sb、B和相对低的U,这反映了俯冲沉积物来源流体的贡献。在俯冲带蛇纹岩的变质脱水过程中,利蛇纹石向叶蛇纹石的转变伴随着矿物内超过50%F和Cl的释放,以及一些流体活动性元素(如B和Li)的迁出;此外,蛇纹石分解形成的变质橄榄石中的流体包裹体指示,蛇纹石脱水分解所产生的流体具有高于原始地幔几个数量级的Cl、Cs、Pb、As、Sb、Ba、Rb、B、Sr、Li和U含量。由于利蛇纹石中的Fe~(3+)含量较叶蛇纹石高,这种矿物相转变过程中也伴随着俯冲通道内的一系列氧化还原过程,从而影响流体性质和新形成的叶蛇纹石的成分。蛇纹岩与岛弧岩浆在流体活动性元素富集规律上的相似性说明蛇纹岩在俯冲带元素循环中扮演着重要的角色。此外,蛇纹石矿物相转变过程中F、Cl、B等元素的释放,可能对于斑岩型金矿、蛇绿岩中的金矿和某些蛇纹岩作为赋矿围岩的硼矿的形成起到重要的作用。  相似文献   

Modelling population retention in Australia’s Northern Territory – how do current forms of migration contribute to population turnover and retention?     

James Thurmer  D. Carson  A. Taylor 《The Australian geographer》2019,50(4):435-452

ABSTRACT

In the past, population growth in Australia's Northern Territory, as in other peripheral parts of high-income countries, has been driven by internal labour migration and migration from outside of Australia. These have been contributing to the high population turnover experienced in peripheral areas. Since 2010, the Northern Territory has experienced low (and even negative) population growth, and public policy is currently focused on migration as a lever to reverse this trend. However, the extent to which the characteristics of migrants influence the potential for longer-term population growth is poorly understood. This paper uses a new method to analyse the contributions of various types of migrants to both population turnover and retention. Two major sets of findings emerge: First, the significance of separating newer in-migrants from longer-term residents when analysing migration patterns; and secondly, the contribution of age, gender, Indigenous status, international origin, wages and industry of employment to the Northern Territory's population turnover. The research suggests that current forms of migration favour people who are likely to stay for only short periods, and have high wage demands. The main policy inference is that long-term population growth will likely not eventuate unless new forms of migration can be stimulated.  相似文献   

莱州湾表层沉积物粒度和黏土矿物分布特征与运移趋势分析     

冯利  冯秀丽  宋湦  肖晓  田动会 《海洋科学》2018,42(2):1-9

运用粒度参数分析、黏土矿物含量分析、Flemming三角图示法和Gao-Collins二维的"粒度趋势分析"等方法,对采自莱州湾海域的表层沉积物样品和黏土矿物样品进行分析,了解了该研究区域的沉积环境及沉积物的运移趋势。研究区由岸向海沉积物类型大致依次为砂-粉砂质砂-砂质粉砂-粉砂-黏土质粉砂,并且研究区表层沉积物在近岸区域呈现较为明显的平行岸线的条带状特征;同时沉积物的平均粒径、分选系数、偏态、峰态等粒度参数也呈现出良好的正相关性或负相关性;研究区黏土矿物为伊利石、蒙脱石、绿泥石、高岭石,除伊利石分布大致为黄河三角洲近岸低,向研究区东北方向逐渐升高外,其余的黏土矿物都表现出了近岸高,远海低的分布特征,且主要物源为黄河物质输入。Flemming三角图研究区所有采样点大部分分布在Ⅱ区,少部分分布在Ⅲ区,说明研究区整体水动力较强;采样点在A—E区均有分布,但在C、D两区分布最多,说明研究区沉积物粒径较集中。研究区表层沉积物整体呈由岸向海输运的趋势,具体来看,黄河沉积物入海后向北、向东、向南运移,研究区内沉积物的来源是黄河输沙以及周围入海的小河流的输沙和沿岸冲刷的物质。  相似文献   

Melt migration and melt-rock reaction in the Alpine-Apennine peridotites:Insights on mantle dynamics in extending lithosphere     

Elisabetta Rampone  Giulio Borghini  Valentin Basch 《地学前缘(英文版)》2020,11(1):151-166

The compositional variability of the lithospheric mantle at extensional settings is largely caused by the reactive percolation of uprising melts in the thermal boundary layer and in lithospheric environments.The Alpine-Apennine(A-A)ophiolites are predominantly constituted by mantle peridotites and are widely thought to represent analogs of the oceanic lithosphere formed at ocean/continent transition and slow-to ultraslow-spreading settings.Structural and geochemical studies on the A-A mantle peridotites have revealed that they preserve significant compositional and isotopic heterogeneity at variable scale,reflecting a long-lived multi-stage melt migration,intrusion and melt-rock interaction history,occurred at different lithospheric depths during progressive uplift.The A-A mantle peridotites thus constitute a unique window on mantle dynamics and lithosphere-asthenosphere interactions in very slow spreading environments.In this work,we review field,microstructural and chemical-isotopic evidence on the major stages of melt percolation and melt-rock interaction recorded by the A-A peridotites and discuss their consequences in creating chemical-isotopic heterogeneities at variable scales and enhancing weakening and deformation of the extending mantle.Focus will be on three most important stages:(i)old(pre-Jurassic)pyroxenite emplacement,and the significant isotopic modification induced in the host mantle by pyroxenite-derived melts,(ii)melt-peridotite interactions during Jurassic mantle exhumation,i.e.the open-system reactive porous flow at spinel facies depths causing bulk depletion(origin of reactive harzburgites and dunites),and the shallower melt impregnation which originated plagioclase-rich peridotites and an overall mantle refertilization.We infer that migrating melts largely originated as shallow,variably depleted,melt fractions,and acquired Si-rich composition by reactive dissolution of mantle pyroxenes during upward migration.Such melt-rock reaction processes share significant similarities with those documented in modern oceanic peridotites from slow-to ultraslow-spreading environments and track the progressive exhumation of large mantle sectors at shallow depths in oceanic settings where a thicker thermal boundary layer exists,as a consequence of slow-spreading rate.  相似文献   

A natural gas hydrate-oil-gas system in the Qilian Mountain permafrost area,northeast of Qinghai-Tibet Plateau     

《China Geology》2020,3(4):511-523

Natural gas hydrate, oil and gas were all found together in the Qilian Mountain permafrost area, northeast of Qinghai-Tibet Plateau, China. They are closely associated with each other in space, but whether they are in any genetic relations are unknown yet. In this paper, a hydrocarbon gas-generation series, gas-fluid migration series and hydrocarbon gas-accumulation series are analyzed to probe the spatial, temporal and genetic relationships among natural natural gas hydrate, oil and gas. The subsequent results show that natural gas hydrate, oil and gas actually form a natural gas hydrate-oil-gas system. Based on the Middle Jurassic and the Upper Triassic hydrocarbon gas-generation series, it is divided into four major sub-systems in the study area: (1) A conventional Upper Triassic gas-bearing sub-system with peak hydrocarbon gas-generation in the late Middle Jurassic; (2) a conventional Middle Jurassic oil-bearing sub-system with low to mature hydrocarbon gas-generation in the late Middle Jurassic; (3) a natural gas hydrate sub-system with main gas source from the Upper Triassic gas-bearing sub-system and minor gas source from the Middle Jurassic oil-bearing sub-system as well as little gas source from the Middle Jurassic coal-bed gas and the microbial gas; (4) a shallower gas sub-system with microbial alteration of the main gas source from the Upper Triassic gas-bearing sub-system. This natural gas hydrate-oil-gas system and its sub-systems are not only theoretical but also practical, and thus they will play an important role in the further exploration of natural gas hydrate, oil and gas, even other energy resources in the study area.  相似文献