A coupled petrological–tectonic model for sedimentary basin evolution: the influence of metamorphic reactions on basin subsidence

The lithosphere is subject to fluctuations in temperature and pressure during the formation of sedimentary basins. These fluctuations cause metamorphic reactions that change the density of the lithosphere, which, in turn, influences basin subsidence. This contribution develops a model for sedimentary basin formation to assess the importance of this coupling. The model shows that basin subsidence is significantly affected by metamorphic densification. Compared to results obtained with cruder density models, metamorphic densification accelerates subsidence in the initial post-rifting stages as garnet becomes stable over an increasing depth interval within the mantle, an effect that amplifies the crust–mantle density contrast. For models with an extraordinarily cold lithosphere, uplift is generated as a late stage of basin evolution. In general, subsidence is not smooth but occurs instead in small steps reflecting periods of accelerated/decelerated subsidence. For typical crustal thicknesses, subsidence is controlled largely by reactions in the mantle, and particularly those determining garnet stability.     

The subsidence and thermal history of the Baikit anteclise sedimentary basin

The Riphean rocks of the Baikit anteclise have been examined using pyrolysis Rock–Eval 6 to evaluate the subsidence history and erosion level. The studied Riphean rocks have the МK₃–МK₄ catagenesis grade. Based on the catagenesis of organic matter we propose a model of maximum burial before the beginning of the accumulation of Vendian deposits. Estimated calculations of subsidence and erosion have shown that the assessed catagenesis grade could be reached at a depth of 7 km, while the erosion level was approximately 5–7 km.     

沉积盆地后期改造及对油气赋存成藏的影响

中国大陆由多个块体拼接而成,结构复杂而不均一,经历了多幕次构造运动,活动性强。特殊的构造位置使得中国沉积盆地后期改造强烈而普遍,这是中国沉积盆地有别于世界其它盆地的显著特点之一。油气作为流体矿产,后期改造对油气赋存、成藏和分布具有显著的影响。后期改造是研究盆地演化、构造特征和油气资源评价不可或缺的内容。1998年召开的“改造型盆地油气勘探理论、方法及关键技术研讨会”,推动和引发了我国油气业及学术界对盆地后期改造、改造型盆地及其油气勘探诸方面的研究和关注。笔者等通过对国内外有关后期改造和改造型盆地已有研究成果的梳理和总结,综述了后期改造、改造盆地的研究进展,及其对常规油气赋存—成藏的影响、晚期成藏—定位和对非常规油气特殊影响等相关内容。     

沉积盆地后期改造及对油气赋存成藏的影响

中国大陆由多个块体拼接而成,结构复杂而不均一,经历了多幕次构造运动,活动性强。特殊的构造位置使得中国沉积盆地后期改造强烈而普遍,这是中国沉积盆地有别于世界其它盆地的显著特点之一。油气作为流体矿产,后期改造对油气赋存、成藏和分布具有显著的影响。后期改造是研究盆地演化、构造特征和油气资源评价不可或缺的内容。1998年召开的“改造型盆地油气勘探理论、方法及关键技术研讨会”,推动和引发了我国油气业及学术界对盆地后期改造、改造型盆地及其油气勘探诸方面的研究和关注。笔者等通过对国内外有关后期改造和改造型盆地已有研究成果的梳理和总结,综述了后期改造、改造盆地的研究进展,及其对常规油气赋存—成藏的影响、晚期成藏—定位和对非常规油气特殊影响等相关内容。     

连云港徐圩地面沉降BOTDR监测与评价

连云港市位于苏北沿海地区,地面沉降灾害面积较大,多地沉降速率超过20 mm/a,徐圩的沉降现状尤为严重。为了能够对徐圩地区的地面沉降进行精细化观测,文章采用BOTDR分布式光纤感测技术,对徐圩镇127 m深的钻孔地层进行了两年多的全断面精细化监测。结果表明:徐圩镇共有四个承压含水层组,I-1隔水层和I-2隔水层土体沉降量分别占总沉降量的70.29 %、24.59 %,抽水层的土体最大沉降量仅占比1.38 %。I-1隔水层和I-2隔水层的地层岩性包括淤泥质黏土（L2）、亚黏土（L3）、亚砂土夹粉砂（L4）,总厚度为44 m,由于抽水过程中隔水层向含水层失水,导致该隔水层土体固结压缩。同时,工程建设附加荷载对地面沉降的影响也不可忽视。徐圩地区现阶段的沉降仍在继续发生,但沉降速率有减小的趋势。BOTDR技术可有效获取地面沉降钻孔全断面的土层变形分布信息,为地面沉降评价提供了一种精细化的分布式监测手段。     

The role of pressure in thermocatalytic processes in the sedimentary complex of the South Caspian basin

The role of overpressures in thermochemical processes in the South Caspian basin is considered. The studies, which take the world experience into account, suggest that the South Caspian basin (mainly its deep-water part), as well as other basins with abnormally high fluid pressures, is characterized by retarded kerogen and oil cracking and reaction of clay-mineral transformation. These processes can be periodically intensified by the development of diapirs and mud volcanoes, which are centers of pulsed hydrocarbon discharge from the system. The conclusion is made that deeply buried deposits in basins with fluid overpressure are promising in terms of hydrocarbon pools.     

南秦岭古生代热水沉积盆地与热水沉积成矿

扬子地块北部被动边缘的南秦岭古生代沉积盆地中,发育一套自早古生代—中生代以来的碳酸盐岩夹细碎屑岩沉积建造,形成规模巨大独具特色的以铅锌金为主的多金属成矿带。伸展构造体制下形成的裂陷或断陷型盆地中,正常水成沉积与热水沉积同盆共存。正常水成沉积中叠加的热水沉积是一个"突发事件或灾变事件",具有特殊的物质组成和产态。通过对区内沉积成矿盆地的识别、分级,二级沉积盆地中边缘部位常发育多个三级构造热水沉积成矿盆地,它受控于沉积盆地中的同生断裂,具有沉积岩相、热水沉积岩组合、显著成矿作用及物化探异常广布的特点。三级构造热水沉积成矿盆地是矿床定位的构造空间,四级热水沉积洼地为矿体(矿层)的容纳空间。区内热水沉积岩主要为重晶石(毒重石)岩、硅质岩、钠长石岩和铁碳酸盐岩类,铅锌重晶石等矿产多产于热水沉积岩中或上盘。热水沉积形成一般由早期的热水喷发交代→主期热水喷流→晚期热水喷气演变。早期的热水喷发交代往往沿矿液喷发通道,形成网脉状、角砾状矿化;主期热水喷流主要形成多金属及热水喷流相,形成块状、条带状、层纹状矿石或热水沉积岩;晚期热水喷气主要形成浸染状矿石和热水喷气岩石。     

Evolution of sedimentary basins from the standpoint of petroleum origin and accumulation—an approach for a quantitative basin study

Generation, migration and accumulation of petroleum in a sedimentary basin is a function of geologic, hydrodynamic and thermodynamic development of the basin and the type and amount of organic matter. Temperature history not only determines rate of hydrocarbon generation, but also affects paleohydrodynamics and physical and thermal properties vs depth relationships. Therefore, paleotemperature is the most important parameter. Paleohydrodynamics together with geologic history of the basin is important in shaping secondary migration patterns and accumulation of hydrocarbons.Quantification of all the above processes is complicated. Steps in constructing a deterministic dynamic model for calculation of petroleum potential during a sedimentary basin development are stated and analyzed in this paper. The effect of paleotemperature variations on petroleum generation and on physical properties of sedimentary sequences are illustrated by numerical examples. Computer models will enable exploration geologists to make quantitative exploration predictions in sedimentary basins.     

川东北前陆盆地上三叠统沉积相及沉积演化

在对川东北前陆盆地上三叠统须家河组露头剖面野外实测和钻井等资料综合研究的基础上,对该区上三叠统须家河组层序及沉积相类型、沉积特征进行了详细的研究。结果表明:研究区内主要发育冲积扇、辫状河、曲流河、扇三角洲、辫状河三角洲、曲流河三角洲、湖泊、海相三角洲等八种主要的沉积相类型。古地理演化经历了由海相环境-海陆过渡相环境-陆相环境的转变。反映了川东北前陆盆地晚三叠世须家河期盆-山耦合过程及其沉积响应。须一段(即小塘子期)发育时期,受印支期构造运动的影响,本区大部分隆升成陆,仅在研究区北西部广元、剑阁等地发育海相三角洲相沉积。须二段发育时期,米仓山-大巴山构造山系的逆冲推覆构造作用较为强烈,川东北前陆盆地坳陷幅度加大,沉积物供给充分,沿米仓山-大巴山前缘地带主要发育辫状河三角洲沉积,而盆地西南部主要发育浅湖沉积。在须三段发育时期,米仓山-大巴山构造山系构造活动逐渐减弱,处于低幅稳定隆升状态,碎屑物供给量减少,沿米仓山-大巴山前缘地带主要发育辫状河三角洲沉积;从盆地前缘地带向中心地带则主要发育浅湖沉积。须四-须六段发育时期,米仓山-大巴山开始进入强烈逆冲推覆和构造隆升阶段,川东北前陆盆地坳陷幅度急剧加大,碎屑物供给量骤然增多,从盆地前缘地带向中心地带主要发育冲积扇-扇三角洲-辫状河三角洲、曲流河、曲流河三角洲相到浅湖相沉积。     

川西前陆盆地侏罗系沉积体系及沉积模式研究

川西前陆盆地侏罗系具有巨大的勘探开发潜力, 但对研究区沉积相研究成果却相对较少.根据岩性组合、岩石颜色、沉积构造等多种因素将川西前陆盆地侏罗系划分出冲积扇、河流、三角洲和湖泊4种沉积体系,并对各沉积亚相构成特征进行了详细的研究.川西前陆盆地侏罗系均属陆相沉积,总体上发育三级扇的沉积模式,即由盆地边缘冲积扇经河流冲积平原到三角洲再经浅湖到半深湖.通过对研究区内沉积相和沉积构造的综合研究,本区主要发育了冲积扇-河流-三角洲-湖泊的沉积模式.     

Badenian (Middle Miocene) basin development in SW Hungary: subsidence history based on quantitative paleobathymetry of foraminifera

A quantitative paleobathymetric study of Badenian foraminifera was carried out from Tekeres-1 and Tengelic-2 boreholes, north of the Mecsek Mts., SW Hungary. Paleobathymetric data, based on plankton/benthos ratio provided input for the analysis of the subsidence history. The biostratigraphic framework is mainly provided by calcareous nannoplankton (zones NN5-NN7). Changes in sedimentation rates are also considered, partly calculated from number of benthos per unit sediment, and partly estimated from the changes of lithofacies. Relative sea-level changes are calculated from changes of paleowater depth and coeval sedimentary thickness. The result is examined as the sum of accommodation space created by subsidence and eustasy. In that period of time eustatic changes were about an order of magnitude smaller than changes created by movements of the basin floor. According to our model in early Badenian (up to the half of NN5 nannozone) a very rapid transtension-related subsidence of about 500 m occurred. This was interrupted by a short period of uplift of minor magnitude at about the first third of NN5 zone; thereafter, subsidence continued and the basin floor reached its deepest position. Still within the NN5 nannozone (Early Badenian) a significant uplift occurred, terminating the life of the deep basin. The Late Badenian (NN6) is characterized by a relatively small rate of subsidence and presumably quiet tectonism. During this period bathymetric changes are thought to be controlled primarily by eustatic changes. The first uplift - only interrupting subsidence - is regarded as the result of the change of the local stress field because of convergence along the curvature of strike slip faults. The second uplift, which stopped the subsidence of the basin floor is thought to be of a regional character and is attributed to the compression generated between Tisza and Alcapa tectonic units.     

塔里木盆地北部隆起原油混合作用半定量评价

塔里木盆地北部隆起油气类型非常复杂，多期充注和储层内的混合作用极为普遍，早期充注原油遭受过生物降解作用的强烈改造，油质非常重，烃类含量和组成发生很大变化，表现为正烷烃和类异戊二烯烃完全消失，甾烷和藿烷被严重破坏，形成大量25－降藿烷，三芳甾相对富集。后期充注的正常原油油质较轻，正烷烃和类异戊二烯烃完整分布，25－降藿烷和三芳甾含量极低。两期充注原油在储层内不同的混合程度造成原油物性和分子组成复杂多变，其变化受控于混合比。根据混合油中正烷烃和25－降藿烷的绝对含量以及三芳甾的相对含量，对油藏内两期充注油的贡献进行了半定量计算，结果表明塔河油田4号构造早期充注的残留油与新近充注的正常油含量相当，塔河3号构造除沙47原油中含20％左右的早期充注油外，基本属晚期充注的产物；哈得逊油田早期充注的残留油含量在5％－15％之间，表明该油田的形成期很晚；乡3井原油中早期充注的残留油约占1／4，羊屋2井主要是晚期充注的贡献。     

Estimation of sedimentary thickness in the Godavari basin

A major portion of the southern part of the Indian subcontinent is classified as a stable continental region. However, a few segments in this region are punctuated by rifts and shear zones that are seismically active. The Godavari rift that sutures the eastern Dharwar and the Bastar cratons is one such region, prone to seismic hazard. Estimation of the sedimentary thickness in these seismically active regions assumes importance since locales of thick and soft sediments are vulnerable to destruction due to surface waves generated by earthquakes. In the present study, data from five broadband seismological stations are utilized to estimate the average sedimentary thickness of the Godavari region using the difference in travel times of the direct S and converted Sp phases from local earthquakes. The thickness of sediments varies between 0.32 and 4.32 km. Also, the site-specific response in terms of the fundamental resonance frequency and the corresponding amplifications are estimated using the well-established Nakamura technique. The predominant frequencies are in the range of 1.3–4.61 Hz, and the amplifications are higher (>1.5) for the stations inside the Godavari basin. Both the thickness and amplification values clearly indicate that the sediments tend to get thicker toward the center of the basin, in good agreement with the geological distribution of the sedimentary units.     

安徽省沉积盆地CO2地质储存适宜性评价

CO2的地质储存已成为减缓温室效应的一条有效的途径。区域的CO2地质储存适宜性评价是选址建设CO2地质储存工程的基础,而建立适当的评价指标体系与选择合理的评价方法对于CO2地质储存适宜性评价起到至关重要的作用。本次研究以安徽省内CO2减排需要为目的,根据研究区实际的地质条件,从CO2的地质储存所关联的多重因素出发,建立起包括安全性、技术性、经济性与社会环境性4个方面的评价指标体系,并引入变异系数法对评价指标确定权重与TOPSIS模型对研究区的CO2地质储存盆地适宜性进行排序。研究结果表明:阜阳盆地与合肥盆地为优先选择的CO2地质储存盆地。评价结果为安徽省初步选址CO2地质储存工程建设提供了科学依据。     

兰州—民和盆地第三纪沉积特征及环境

在野外区域地质调查的基础上 ,通过岩性、沉积构造、古流向、垂向序列、沉积体三维形态和组合及室内粒度分析、扫描电镜分析等 ,于研究区第三纪地层中识别出了三角洲相、三角洲平原相、河流相、湖泊相、冲积扇相及风成砂丘。系统地研究了盆地的垂向充填序列 ,并且就对应的环境演变进行了较详细的探讨。     

Oil and gas pools in weathering crusts on the sedimentary basin basement

Weathering crusts of the sedimentary basin basement are collectors in several regions of the world. They enclose huge reserves of oil and gas. The paper considers the geochemical, mineral, and petrophysical heterogeneities of weathering crusts that should be taken into consideration in the prospecting, exploration, and development of hydrocarbon raw material therein. Areal and linear-fissure types of weathering crust are defined. They were formed before the overlapping of basement by rocks of the sedimentary cover. Areal crusts are pervasive at the basement roof, whereas linear-fissure crusts are formed along fractures. A complete weathering crust profile includes the following zones (from the bottom to top): disintegration, leaching and hydration, hydrolysis, and final hydrolysis. Rocks of the lower two zones represent the cavernous-fissure collector, while rocks of the upper zones are impermeable. In the arches of uplifted blocks of the basement, weathering crusts are subjected to erosion during marine transgressions. In such places, the roof is composed of rocks of the lower permeable zones that often make up a single heterogeneous natural reservoir overlapped by sandy collectors of sedimentary sequences. Linear-fissure weathering crusts show zonal distribution with good filtration-capacity properties. Several large oil and gas pools have been discovered in them.     

川西龙门山前陆盆地构造沉降初步分析

研究表明,龙门山冲断带是川西前陆盆地的主要物源区,它的逆冲推覆活动直接控制着川西前陆盆地的沉积类型和沉积物供给量。晚三叠世诺利期、瑞替期和晚侏罗世早中期是川西前陆盆地构造沉降速率较高时期,反映龙门山冲断带在这些时期的逆冲推覆速率较大,是逆冲推覆作用构造抬升的强烈时期;而早侏罗世是该地区构造沉降速率相对较小时期,反映龙门山冲断带在早侏罗世的逆冲推覆抬升速率较小,是逆冲推覆作用相对平静时期。同时,估算龙门山逆冲推覆体在各个不同时期的抬升高度和抬升速率。     

Deep subsidence of the early catagenesis zones of organic matter in the sedimentary rocks of Northeastern Sakhalin shelf at high thermal regime of the basin

Doklady Earth Sciences -     

柴达木盆地西部中—新生代沉积构造演化

通过柴达木盆地西部茫崖-赛什腾山地表地质、航磁、重力、大地电磁测深和地震资料的综合分析,认为柴达木盆地夹持在昆北地块与赛什腾构造带之间,其中包括柴达木地块与祁连地块南缘2个一级构造单元和昆北地体北缘,柴达木盆地,赛什腾构造带和祁连地块南部的苏干湖盆地等4个二级构造单元。盆地的总体结构表现为东昆仑山和祁连山相向向盆地挤压对冲,盆地中部沉降的构造格局。盆地内部的构造样式以自盆地边缘至中心以此形成背斜构造为显著特征,背斜两翼多发育逆断层,构成“两断夹-隆”的构造格局。挤压应力主要来自南西方向、北东方向起阻挡作用。在两侧造山带的强烈挤压作用下,侏罗纪时期在祁连造山带南缘形成并不典型的前陆盆地,古近纪至新近纪时期则在祁连造山带与昆仑造山带之间形成双侧前陆盆地,第四纪属挤压坳陷盆地。