川西坳陷鸭子河地区基于多种古温标的钻井热史恢复

利用镜质体反射率(Ro)、磷灰石裂变径迹(AFT)和伊利石结晶度(IC指数)等古温标恢复了四川盆地川西坳陷的钻井热史,对比了不同温标最高古地温的恢复结果.研究表明,研究区晚白垩世至今总体表现为冷却及抬升剥蚀的过程,地温梯度由约26℃·km-1降低至约22℃·km-1,剥蚀量约1.3~1.9km.约80 Ma以来开始抬升剥蚀,40—2.5 Ma经历了一个热平静期,第四纪存在一定的增温,地温梯度增高约5℃·km-1.三种古地温恢复结果具有较高的一致性,相对于镜质体反射率(Ro)和磷灰石裂变径迹(AFT)等成熟古温标,伊利石结晶度作为有机质成熟度指标和沉积岩古温标的应用处于定性分析阶段,该指标的热演化模型仍需进一步探索.     

鄂西渝东方斗山-石柱褶皱带中新生代隆升剥蚀过程及构造意义

利用磷灰石与锆石(U-Th)/He年龄与磷灰石裂变径迹(AFT)、镜质组反射率(Ro)一起模拟了鄂西渝东方斗山-石柱褶皱带侏罗纪以来的构造-热演化特征.结果表明:在约130 Ma(晚侏罗世-早白垩世)研究区达到最高古地温,此后为持续抬升冷却过程.磷灰石裂变径迹与Ro表明自晚侏罗世以来不整合面剥蚀厚度可达3500m.结合...     

中上扬子地区印支期以来抬升剥蚀时限的确定

采用磷灰石裂变径迹年龄空间分布特征定性分析与径迹长度分布数据定量模拟相结合,约束了中上扬子地区的抬升剥蚀时限.江汉盆地在157～97Ma和10 Ma以来发生了两期大规模抬升剥蚀;湘鄂西-武陵地区、黔中隆起自137Ma开始持续抬升剥蚀;鄂西渝东、川东褶皱带从97 Ma开始持续抬升剥蚀;川东北和川中地区于56 Ma才开始遭受抬升剥蚀;川西-滇西地区则自23 Ma以来经历了较大规模的抬升剥蚀.印支期以来,中上扬子不同地区抬升剥蚀开始的时间存在明显差异性,总体上由东往西逐渐变晚.齐岳山断裂带以东,大规模抬升剥蚀始于中燕山期（J₃-K₁）;齐岳山断裂与华蓥山断裂带之间的川东高陡背斜带抬升剥蚀始于晚燕山期（K₂）;华蓥山断裂与龙泉山断裂之间的川中和缓褶皱带晚期抬升剥蚀始于喜马拉雅早期(E);龙泉山断裂带以西的川西凹陷晚期抬升剥蚀始于喜马拉雅晚期(N).     

南海北缘东沙隆起中生代以来的埋藏史和热史重建——来自LF35-1-1井(U-Th)/He和Ro的证据

沉积盆地埋藏史和热历史重建是了解盆地成因和油气形成条件的重要依据,而目前利用古温标手段研究珠江口盆地内东沙隆起热史和埋藏史的成果寥寥无几.本研究中,我们基于磷灰石与锆石(U-Th)/He年龄的反演结果给出了更多合理的约束条件,在此基础上对同一套镜质体反射率Ro数据进行了古热流法模拟计算,获得了钻井自中生代以来的地层温度史.反演结果显示LF35-1-1井区在早始新世-早渐新世发生了一期强烈的抬升剥蚀,地层剥蚀量为2000 m左右.拟合获得的埋藏史和热流史显示该井区在早始新世(~55Ma)经历了最高井底古热流(100 mW·m~(-2)),之后热流减小,持续至现今64.3 mW·m~(-2).最高古地温与隆升剥蚀在时间上的耦合体现了抬升事件对地温冷却的影响,但不足以排除基底热流下降因素.本次研究首次将(U-Th)/He技术用于南海北缘深水区盆地的热史研究,获得的热史结果更加符合现有的构造沉积大地构造方面的认识,展示了利用多种古温标手段进行盆地精细热史研究的良好效用.     

柴达木盆地东部晚海西-印支期剥蚀量与隆升历史--多种古温标与沉积学证据的制约

柴达木盆地东部周缘造山带内保存有较完整的晚古生代-早中生代沉积记录,但盆地内至今仍未发现二叠系-三叠系.为探讨柴东地区二叠纪-三叠纪有无沉积及隆升历史等关键地质问题,本文首先利用古温标法恢复晚海西-印支期剥蚀量,随后,通过物源分析法获得印支期柴东北缘隆升的沉积学证据.结果表明,印支运动前,柴东地区残留石炭系顶界面埋深普遍超过2500m,晚海西-印支期剥蚀量为2100~4300m,剥蚀量从南往北逐渐减小.柴东地区曾沉积了2000~3000m的二叠系-三叠系,随后被整体剥蚀.晚二叠世以来,随着古特提斯洋往北俯冲,盆地周缘开始隆升.早三叠世柴东北缘经历了一次快速隆升,先期的多套沉积地层与结晶基底被迅速剥蚀并为宗务隆南缘的隆务河群砾岩沉积提供物源.中三叠世海水往北和往东退出研究区.晚三叠世,松潘-甘孜地体强烈碰撞挤压使得东昆仑-柴达木地体下地壳显著缩短和增厚,柴东地区被整体抬升,并且形成了南高北低的古地貌格局,在古气候与水系作用下,二叠系-三叠系与部分石炭系被全部剥蚀并搬运至宗务隆、南祁连及松潘-甘孜一带.     

洛伊地区侏罗纪原型盆地形成与演化

以洛伊地区石油地震、钻井及地化资料为基础,利用镜质体反射率（Ro）进行单井剥蚀厚度恢复,应用平衡剖面恢复的早-中侏罗世古地貌呈"三凹三凸"特征,其中,中条山、熊耳山、嵩山由于隆升无早-中侏罗世沉积,在洛阳-济源、义马-宜阳、伊川形成3个沉降中心。依据盆地充填序列及沉积相带进行分析,认为研究区早-中侏罗世为山间坳陷盆地,其形成与演化受控于印支末期-燕山早期的秦岭-大别造山带陆内造山作用。     

(U-Th)/He年龄约束下的塔里木盆地早古生代构造-热演化

塔里木盆地早古生代碳酸盐岩沉积时期的热历史由于缺乏有效的古温标进行热史恢复,一直是困扰该区下古生界烃源岩演化研究的难题.磷灰石和锆石的(U-Th)/He热定年技术是近年来用于沉积盆地热史研究的新技术,可以用来揭示地层的构造抬升和热历史.本文利用塔里木盆地典型井中古生界层系的古温标来恢复古生代的热史.这些井在海西期长期隆升、遭受强烈的剥蚀、后期埋藏深度较小,因而古生界层系中的古温标可以保留原始热信息,从而反映古生代的温度状况.本文通过对这些钻井样品进行磷灰石和锆石(U-Th)/He年龄测试,并结合磷灰石裂变径迹和等效镜质体反射率等古温标,综合模拟计算了塔里木盆地不同构造单元的KQ1和T1井早古生代的构造-热演化历史.模拟结果表明,塔里木盆地塔东北和巴楚隆起区古生代热演化存在差异.巴楚隆起区T1井在寒武纪末期的古地温梯度仅为28～30℃/km,奥陶纪的地温梯度增高至30～33℃/km之间,志留-泥盆纪地温梯度为31～34℃/km;塔东北的KQ1井区奥陶纪的地温梯度可达35℃/km,志留-泥盆纪地温梯度为32～35℃/km.因此,(U-Th)/He年龄结合其他古温标综合模拟的方法可以很好地揭示沉积盆地的热历史,特别是该方法为塔里木盆地早古生代的热史恢复提供了新的途径.     

准噶尔盆地构造分区和变形样式

准噶尔盆地经历了晚海西、印支、燕山和喜马拉雅期多次构造运动的影响,多期构造变形叠加复合使盆地内构造变形复杂多样。由于各期构造运动影响的范围、应力作用方式不尽相同,因而盆地不同地区的构造变形样式、圈闭类型和分布特征各不相同。西北部构造区( 带) 发育“鱼鳞”状冲断推覆构造;东北部构造区( 带) 以雁列状展布的冲断构造为主;东、西部构造区( 带) 发育近直线状冲断构造;南部构造区(带) 发育“瓦垅”状推覆构造;中央构造区变形较弱,以隆坳变形为主,发育少量正断层和逆断层。各构造区(带) 发育了特征不同的油气圈闭     

一种基于温度历史和瞬态地温场模拟的剥露历史反演方法

根据低温热年代学数据,提取岩石从深部剥露到地表的信息,对理解诸多地质问题(如造山带演化、地表过程及其相互作用等)具有重要意义.本文提出一种基于岩石温度历史(可利用古温标、热年代计等方法制约),并考虑剥露过程对地温场扰动的剥露历史反演计算方法.基于假定的与真实数据的正反演模拟和参数敏感性分析表明:热扩散率的变化对剥蚀量计算影响不大,在常规岩石热扩散率变化范围内(20～35km2/Ma),总剥蚀量变化小于10%;传统计算方法低估了剥蚀总量,对于现今地温梯度小于20℃/km、冷却速率大于2～3℃/Ma,或现今地温梯度大于30℃/km、冷却速率大于5～10℃/Ma的地区,需要考虑热平流对剥蚀量计算的影响;匀速冷却的热历史指示剥蚀速率持续减小,而非匀速剥蚀.本文将该方法应用到龙门山南段和四川盆地,反演计算显示龙门山南段15Ma以来的剥蚀总量为8km,四川盆地中部80Ma以来剥蚀总量约为3km、东部约5km.     

川东北地区异常高压形成的地温场背景

利用四川东北地区现有的钻井测温数据及测定的岩石样品热导率数据,计算了12口钻井的大地热流值. 结果表明,川东北地区现今地温梯度为18～25 ℃/km,平均21 ℃/km,大地热流值介于41～57 mW/m2之间,平均为49 mW/m2. 在此基础上,利用镜质体反射率(Ro)资料对研究区热史进行了恢复,认为研究区在255Ma左右古热流达到最高值(62～70 mW/m2),此后热流持续降低直到现今;研究区中-新生界不整合面的剥蚀厚度最大,可达约2100 m;异常高压是在低热流的地温场背景下形成的.     

Vitrinite reflectance and consolidation characteristics of the post‐middle Miocene Forearc Basin in central and eastern Boso Peninsula,central Japan: Implications for basin subsidence

To understand the sedimentary development of the Boso Forearc Basin, central Japan, since ~ 3 Ma, we investigated paleothermal structure and consolidation trends in the central and eastern parts of the forearc basin through vitrinite reflectance measurements and consolidation tests. Vitrinite reflectance (R_m) was in the range 0.33 % to 0.61 % for the Miura Group in the central part of the forearc basin and 0.34 % to 0.41 % for the Miura and Kazusa Groups in the eastern. These values suggest a roughly uniform vitrinite reflectance for the Miura Group from the central to eastern parts. No significant vitrinite reflectance difference is observed across the ~ 3 Ma Kurotaki Unconformity in the eastern part of the basin. The consolidation yield stress (p_c) was calculated as 27.5 MPa and 32.2 MPa for the Kiyosumi and Amatsu Formations of the Miura Group in the eastern part, respectively. Both the p_c values are consistent quantitatively with represent the trend of the maximum overburden pressure estimated from the thickness and density of overlying sediments, and the difference in p_c is expected by the maximum burial depths of the strata at the sampling localities. Values of p_c in the eastern part of the basin increase with thickness of overlying sediment, showing no break across the Kurotaki Unconformity. Considering the eroded thickness of the Miura Group, the continuous trends in vitrinite reflectance and consolidation between the Miura and Kazusa Groups in the eastern part reflect the greater deposition of the eastern part of the Boso Forearc Basin since ~ 2.3 Ma.     

Vertical Delineation of Contamination in Fractured Bedrock Aquifer

The New Jersey Department of Environmental Protection's Technical Regulations require the horizontal and vertical delineation of contamination. Monitor wells screened at increasingly deeper intervals are used to delineate vertical contamination. In New Jersey, the open interval in a bedrock well cannot exceed 7.6 m. Since contamination has been found at depths as great as 91.4 m in a production well in the study area, it would be prohibitively expensive to install monitor wells with 7.6 m open holes at ever-increasing depths until no contamination was found. Isolation of discrete zones in boreholes using pneumatic packers was implemented at a site in north central New Jersey. Ground water samples were collected from selected 6.1 m sections of boreholes drilled into fractured bedrock at three locations on the property and one offsite location. The ground water samples were analyzed in a field laboratory. The analytical results were used to determine the vertical extent of gasoline-related compounds dissolved in the ground water on the property and offsite. These compounds include benzene, ethylbenzene, methyl tertiary butyl ether, toluene, and xylenes. The four boreholes were converted into bedrock monitor wells. The intake interval for each of the wells was selected through evaluation of the vertical distribution of contaminants as determined from analytical results obtained from a field laboratory located onsite. Three wells are used for the recovery of contaminated ground water. The recovered water will be treated at the onsite air-stripping unit. The fourth well is used to chemically and hydraulically monitor the progress of the ground water recovery program.     

中扬子江汉平原簰洲湾地区中、新生代构造-热演化史

本文综合运用磷灰石-锆石裂变径迹和（U-Th）/He、镜质体反射率及盆地模拟等手段,深入细致地探讨了中扬子江汉平原簰洲湾地区中、新生代构造-热史演化过程.研究结果表明,研究区中-新生代大规模构造抬升剥蚀、地层冷却事件始于早白垩世（140-130 Ma）;大规模抬升冷却过程主要发生在早白垩世中后期至晚白垩世.研究区虽然可能存在一定厚度的晚白垩世-古近纪地层沉积,总体沉积规模相对较小.综合分析认为,区内应该存在较大厚度的中侏罗统或/和上侏罗统乃至早白垩世地层的沉积;而现今残存中生代中、上侏罗统地层相对较薄,主要是由于后期持续构造抬升剥蚀造成的,估计总剥蚀厚度约4300 m左右.区内中生代地层在早白垩世达到最大古地温,而不是在古近纪沉积末期;上三叠统地层最大古地温在170~190℃之间.热史分析结果表明,区内古生代古热流相对稳定,平均热流在53.64 mW·m^-2;早侏罗世末期古热流开始降低,在早白垩世初期古热流约为48.38 mW·m^-2.     

Thermal regime transition in eastern North China and its tectonic implication

Many evidences published in recent years reveal that the thickness,chemical composition and thermal state of lithosphere in eastern North China have ex-perienced dramatic transition during the Phanero-zoic.Comparative study[1—8]of early Paleozoic dia-mond-and xenoliths-bearing kimberlites to Cenozoic mantle peridotite xenoliths-bearing alkali basalts indi-cates that the early Phanerozoic lithosphere is thick and stable to depths within the diamond stability field(180–200km)with depleted ma…     

塔里木盆地石炭-二叠纪异常热演化及其对深部构造-岩浆活动的指示

本文分析了塔里木盆地大量实测镜质体反射率(Ro)数据,显示盆地西北部石炭系与二叠系之间Ro值演化不连续,记录了石炭-二叠纪间发生的构造-热事件,是地层抬升剥蚀和高温热事件共同作用的结果.热史模拟得出盆地在石炭纪末地温梯度开始升高,至~300 Ma达到峰值,分布在4.8~5.6℃/100m之间,早二叠世迅速降低,随后进入缓慢稳定降低阶段.区域上高温热效应空间分布与塔里木大火成岩省的分布范围存在较好的相关性,但早于大规模玄武岩喷发的时间(290—288Ma),且后者热效应范围有限.因此推断这种高温异常是大规模的深部岩浆活动,即深部岩浆房相对长时间热烘烤的结果.该研究结果为塔里木盆地热演化机制及相关热效应提供了新的线索.     

辽河盆地东部凹陷现今地温场及热历史的研究

依据10口系统测温井数据和61块岩石热导率测试结果，计算了辽河盆地东部凹陷10个 高质量的大地热流数据，并在此基础上，利用镜质体反射率（Ro）资料对该区的热历史 进行了恢复. 结果表明：东部凹陷下第三系平均地温梯度为36.5℃/km，岩石平均热导率为1 .667W/(m·K)，热流密度变化于49.5～70.0mW/m2之间，平均为58.0mW/m2；东部凹陷热 流呈现古热流高现今热流低的变化特征，从沙三期到东营期，古热流值是逐渐增大的，到东 营期末达到最大值，晚第三纪至现今表现为持续冷却；构造沉降史分析显示，盆地经历了早 期的裂谷阶段（43～25Ma）和后期的热沉降阶段. 盆地现今较低的大地热流和较高的古热流 及典型的裂谷型构造沉降样式为东部凹陷的构造-热演化提供了重要认识.     

Modeling the thermal evolution of an active geothermal system

Temperature inversions at shallow to moderate depths have been observed commonly in boreholes drilled in geothermal areas. The inversions result from thermal disequilibria generated by steam and/or hydrothermal fluids invading shallow horizontal, or sub-horizontal fractures, or permeable horizons, from a deep vertical, or sub-vertical feeder-fracture.Subsurface distribution of temperatures in Momotombo geothermal area of Nicaragua, Central America, indicates that the anomaly is generated by steam and water, convecting in a narrow feeder-fracture-zone located at the western edge of the field. The north-trending zone of the feeder-fracture is bound on the west by the area of massive, impermeable andesitic rocks, and is capped by an impermeable, approximately 300 m. thick silica-cap, which seals if from the ground surface. The thermal fluids penetrate a system of horizontal, or sub-horizontal fractures, extending east of the feeder-fracture beneath the silica cap. The flow of thermal fluids eastward through the system of the horizontal, or sub-horizontal fractures is generating a plume-like geothermal anomaly, which is expressed by the temperature inversion zone pervasive in the boreholes to the east of the feeder-fracture.A time-dependant model for a semi-infinite half-space (z > 0) in contact with a hot, well stirred, isotropic fluid flowing through an aquifer overlain by a finite space of constant thickness is solved for the data collected from the Momotombo geothermal boreholes. Curve fitting between the simulated and observed temperature/depth profiles suggests that the thermo-tectonic events which caused the present-day Momotombo hydrothermal system occurred approximately 5,500 years ago, following development of vertical, or subvertical fractures along a N5°E trending faultline. Hot fluids emerging from these fractures move eastward through a system of horizontal, or sub-horizontal fractures, with a velocity of 11 to 20 m/yr.     

Mapping the thickness of sediments in the Ljubljana Moor basin (Slovenia) using microtremors

The Ljubljana Moor basin is characterized by moderate bedrock topography and thicknesses of Quaternary lacustrine and fluvial sediments ranging from 0 to 200 m. More than 65 boreholes which reached the bedrock were drilled in the area, but their distribution in the basin is very uneven and some data from the boreholes uncertain. There are also no data on S-velocity distribution within the basin, but seismic refraction measurements pointed out a rather uniform increase of P-velocity with depth, great impedance contrast with the bedrock and relatively small lateral velocity variations. The microtremor horizontal-to-vertical spectral ratio (HVSR) method was therefore applied as a complementary tool to seismic refraction survey to map the thickness of sediments. First, microtremors were measured at the locations of boreholes which reached the bedrock and the resonance frequencies determined. The inverse power relationship between the resonance frequency and the thickness of sediments was then determined from 53 data pairs. The quality of the correlation is moderate due to possible heterogeneities in sediments and possible 3D effects in some minor areas, but the obtained parameters correspond well to the values obtained in six other European basins. Secondly, a 16 km-long discontinuous seismic refraction profile was measured across the whole basin, leaving uncovered some larger segments where active seismic measurements were not possible. Microtremors were then measured at 64 locations along the same profile, using 250 m point spacing, without leaving any gaps. The frequency–thickness relationship was used to invert resonance frequencies to depths. These were first validated using the results of the seismic refraction survey, which showed good agreement, and finally used for interpolation in the segments of missing refraction data to obtain a continuous depth profile of the bedrock. The study has shown that the microtremor method can be used as a complementary tool for mapping the thickness of unconsolidated sediments also in areas characterized by moderate bedrock topography. As the input data are always to some extent uncertain, it is important to have a sufficiently large number of borehole data to establish a frequency–thickness relationship, as well as some additional independent geophysical information for its validation.