Burial and thermal history of the West Bashkirian sedimentary basins

The GALO system is applied to the numerical reconstruction of burial and thermal histories of the West Bashkirian lithosphere from the Riphean to the present. An analysis of the variation in tectonic subsidence of the basin during its development is utilized to estimate approximately the mantle heat flow variations. Our variant of basin evolution suggests that after cooling in the Early Riphean, the rather weak thermal reactivations have not led to considerable heating of the lithosphere in the study region. Surface heat flow decreased from relatively high values in the Early Riphean (60–70 mW/m² in the eastern area and 40–50 mW/m² in the western part) to present-day values of 32–40 mW/m². In spite of the relatively low temperature regime of the basin as a whole, a syn-rifting deposition of more than 10 km of limestone, shale and sandstone in the Riphean resulted in rather high temperatures (180–190 °C) at the base of present-day sedimentary blanket in the eastern area. In agreement with the observed data, computed present-day heat flow through the sediment surface increases slightly from 32 to 34 mW/m² near the west boundary of the region to 42 mW/m² near the boundary of the Ural Foldbelt, whereas the heat flow through the basement surface decreases slightly from 28–32 to 24–26 mW/m² in the same direction. The mantle heat flow is only 11.3–12.7 mW/m², which is considerable lower than mean heat flow of the Russian Platform (16–18 mW/m²) and comparable with the low heat flow of Precambrian shields.     

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.     

Stress state reconstruction and tectonic evolution of the northern slope of the Baikit anteclise,Siberian Craton,based on 3D seismic data

In this work, we consider application of an original method for determining the indicators of the tectonic stress fields in the northern Baikit anteclise based on 3D seismic data for further reconstruction of the stress state parameters when analyzing structural maps of seismic horizons and corresponded faults. The stress state parameters are determined by the orientations of the main stress axes and shape of the stress ellipsoid. To calculate the stress state parameters from data on the spatial orientations of faults and slip vectors, we used the algorithms from quasiprimary stress computation methods and cataclastic analysis, implemented in the software products FaultKinWin and StressGeol, respectively. The results of this work show that kinematic characteristics of faults regularly change toward the top of succession and that the stress state parameters are characterized by different values of the Lode–Nadai coefficient. Faults are presented as strike-slip faults with normal or reverse component of displacement. Three stages of formation of the faults are revealed: (1) partial inversion of ancient normal faults, (2) the most intense stage with the predominance of thrust and strike-slip faults at north-northeast orientation of an axis of the main compression, and (3) strike-slip faults at the west-northwest orientation of an axis of the main compression. The second and third stages are pre-Vendian in age and correlate to tectonic events that took place during the evolution of the active southwestern margin of the Siberian Craton.     

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 -     

海拉尔盆地热演化史研究

海拉尔盆地现今为中地温场,中低大地热流特征,镜质体反射率随埋深增大而逐渐增大.不同层位、不同凹陷烃源岩热演化程度不同,乌尔逊、贝尔凹陷镜质体反射率值最大,热演化程度高.应用镜质体反射率法恢复了古地温及古地温梯度.海拉尔盆地古地温高于今地温,南屯组沉积前具有较高的地温梯度,可达(4.0～5.8)×10-2℃/m.乌尔逊、贝尔凹陷古地温梯度高,生油门限浅,有利于油气的生成.而另外一些凹陷生油门限较深,不利于油气的生成.     

Qualitative and quantitative evaluation of the influence of anthropic pressure on subsidence in a sedimentary basin near Rome

This paper presents the results of analyses measuring variations in anthropic pressure and the influence of anthropic pressure on the variations in subsidence rates from 1954 to 2005 in the Tivoli-Guidonia area, located to the East of Rome, Italy. In the last 60 years, this area underwent exceptional demographic growth, as well as an increase in the quarrying and hydrothermal industries. The calculation of the increase in anthropic pressure was based on two factors: the expansion of built-up areas and the increase in quarrying. Photogrammetric techniques permitted a multi-temporal analysis of aerial photos taken in 1954, 1985, 1993, 1998 and 2005. The aim of this analysis was to estimate the increase in both urban surface area and travertine quarrying. Non-conventional techniques, such as the reconstruction of photograms using photo retouching software, allowed for the use of aerial photos from 1954. These photos were fundamental for establishing a medium-term evaluation of anthropic activity in the area. The results of the photogrammetric analysis were compared to the phases of acceleration and stabilization in subsidence phenomena, deduced from a RADAR interferometry study published by the Italian Ministry of the Environment. This comparison showed a close relationship between the rise and temporary halt of anthropic development and the rise and fall of subsidence rates. Furthermore, data on the distribution of private wells in the study area, variations in the groundwater table level and the precipitation regime were analyzed, but, although helpful in defining the geological context and considerable transformations of the territory, they were considered as qualitative data due to the lack of systematic measures or an unclear relationship to the variations in subsidence rate. Despite the difficulties involved in evaluating both the amount of anthropic pressure and the role of different human activities on environmental change, it was possible to estimate the variations in anthropic pressure and their influence on potentially dangerous geological processes.     

东濮凹陷新生代的热历史

东濮凹陷是渤海湾盆地南缘极具油气开采潜力的凹陷,本文揭示该凹陷新生代埋藏史、热史及烃源岩演化史.利用凹陷各构造单元18口井的镜质体反射率数据,恢复其埋藏史、热史.结果显示,东濮凹陷经历“一升两降”的构造沉降,并具有“马鞍型”的热演化特征.自沙四段沉积开始至沙三段,地温梯度逐渐增加,在沙三段沉积末期达到最大,为45.2℃～48℃/km.自沙二段沉积开始至今,地温梯度总体逐渐降低,仅在东营组沉积时期出现微弱回升,现今地温梯度为30℃～ 34℃/km.以埋藏史和热史为基础,结合构造及有机地球化学资料,对东濮凹陷18口井烃源岩演化史进行模拟.结果表明,烃源岩热演化受东营组沉积时期的古地温控制,3套烃源岩成熟度均在27Ma(东营组沉积时期)达到最大.     

运用磷灰石裂变径迹分析鄂尔多斯盆地周缘中新生代沉降隆升史

通过对鄂尔多斯盆地磷灰石裂变径迹资料深入分析与反演模拟,定性半定量地研究了该区相关岩石组合的地热演化史.结果表明,晚侏罗世晚白垩世早期(160～90 Ma)盆地具东升西降的特点,东部以约25 m/Ma的速率隆升,造成1500～2000 m的剥蚀量;晚白垩世末至始新世早期(90～23 Ma),盆地具整体隆升特点,盆地南部和西部隆升幅度达1500～2000 m,盆地东部表现为弹性回返,隆升缓慢,幅度小于500 m;中新世早期以来(23 Ma至今),全盆快速隆升,周边隆升速率达45～108 m/Ma,造成1000～2500 m的剥蚀量.对盆地内砂岩型铀矿年龄资料对比分析表明,后生铀成矿作用过程基本上都发生在盆缘相对快速隆升阶段.     

阿尔金山脉新生代剥露历史——前陆盆地沉积记录

新疆且末县江尕勒萨依盆地位于阿尔金山脉的北西山前,其内连续沉积了中生代一新生代地层。盆地内古新统一始新统为河流相沉积;渐新统至中新统为山麓河流相灰色砾岩和棕色砂岩;上新统为山麓洪积相砾岩夹泥岩;下更新统全为砾岩层。岩性组合特征及其砂岩碎屑、砾石组分变化规律,反映出阿尔金山脉的新生代剥蚀历史：古近纪早、中期,阿尔金山脉的地形高差小,古生界双峰式火山岩首先被剥蚀;至渐新世末一中新世早期,山脉高差加大,基底元古宇开始出露地表被剥蚀;中新世末期,山脉高差进一步加大,剥蚀速率加快;至第四纪早期西域砾岩开始沉积时,地形高差加剧,中、古元古界开始暴露被剥蚀。区域资料分析表明,阿尔金山脉在新生代具有多期次阶段性隆升的特征,存在3期次快速隆升事件：渐新世末一中新世早期、中新世晚期(大约8Ma)和第四纪早期。     

论沉积盆地构造岩相变形史研究方法及应用

基于（非）金属矿产-铀-煤-油气资源同盆共存,盆内构造岩相变形史与成藏成矿事件的耦合结构一直是科学难题。在构造岩相学填图和构造岩相变形史研究基础上,将沉积盆地构造岩相变形史划分为前盆地期、成盆期、盆地反转期、盆地构造变形改造期、盆内岩浆叠加期和盆地表生变化期6个演化期。研究发现,采用构造岩相学填图创新方法,可有效圈定沉积盆地内同生构造样式与构造组合。在火山岩区采用次火山岩侵入、火山隐爆-侵出、火山爆发-喷发等12个相系进行构造岩相填图,有助于有效圈定火山机构中心、火山热液成岩成矿中心和火山热水沉积成岩成矿中心的位置。盆-山-原转换构造岩相带是流体大规模运移和储集构造岩相带,也是（非）金属矿-铀-煤-油气资源同盆共存富集成藏成矿的有利构造岩相带;前陆盆地、山间盆地和后陆盆地具有不同的变形构造组合;构造岩相学研究和填图有助于研究沉积盆地变形期内古热储构造、冠羽状垂向热流柱构造、煤系烃（矿）源岩生排烃成藏成矿事件序列等问题。壳源岩浆、幔-壳混源岩浆、幔源岩浆在盆地岩浆叠加期,形成了相应的岩浆叠加构造样式和岩浆叠加成岩相系。在盆内岩浆底拱侵位形成的穹状不对称复式褶皱系统内,发育了强烈的岩浆-构造-岩性-热流体四重耦合结构,形成了与盆内岩浆再造-叠加成岩成矿有关的电气石热流柱构造,以底拱旋转断褶带、电气石和白云母蚀变相系为特征。与盆内岩浆-改造作用有关的富CO2型热流柱构造,表现为热启断裂组和铁锰碳酸盐矿物垂向分带,并与菱铁矿矽卡岩相→矽卡岩化大理岩相→铁锰碳酸盐化大理岩相→大理岩化结晶灰岩垂向分带相共生。     

攀西裂谷内陆盆地自由热对流应力分析及盆地沉降

康滇地区裂谷作用已得到证实,但形成这种地堑地垒的格局有多种解释,以传统的地质力学分析为主。笔者借以热力学的自由热对流原理来加以论述:攀西巨厚的火山岩体在下覆异常地幔热作用下,发生自由热对流,引起热量散失,使地壳沉降与隆起不均衡,生成地堑地垒的格局。自由对流单元的侧向迁移,使盆地形成非对称性。     

金宝屯聚煤盆地沉积环境分析

本文以金宝屯煤田为例,研究其沉积环境、聚煤规律、含煤盆地岩相序列组合和岩相的空间配置。对以后在该地区的找煤工作具有指导作用。     

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。     

南海西南部曾母盆地早中新世以来沉降史分析

采用回剥法和局部均衡模式研究曾母盆地早中新世以来的沉降史，并探讨了该盆地构造演化特征。曾母盆地自早中新世以来经历了17．5-11．6Ma、11．6-5．5Ma、5．5-3．0Ma和3．0-0Ma的4次快速沉降作用，其构造演化受控于曾母地块与南沙地块及婆罗洲地块的碰撞和盆地两侧的万安-卢帕尔断裂与廷贾走滑断裂的综合作用，可划分为南北双向挤压（晚始新世-早中新世）、走滑改造（中中新世-晚中新世）和区域沉降（上新世-第四纪）3个演化阶段。     

沉积盆地铀-油(气)共生机理

产于含油(气)盆地中的地浸砂岩型铀矿床与油(气)关系密切,在空间上常与油(气)藏呈共生关系。文章认为其成矿条件和控矿因素相似,并且具有成因联系是二者共生的主要原因。砂岩型铀矿和油(气)藏具有相似的成矿大地构造背景、岩相古地理条件、容矿地层、岩性圈闭、构造控矿条件和有机质基础;在成因上油(气)中的不同组分及其次生矿物对铀有重要的吸附和还原作用,是铀沉淀富集的重要因素之一,铀等放射性元素的存在也有利于油气的生成。由于成矿机理的差异性,砂岩型铀矿与油(气)藏属于异体共生矿床,二者的产出位置并不完全重叠,砂岩型铀矿的产出位置往往更靠近盆缘,且在油(气)储层上方,或以单一矿种产出。     

重新认识鄂尔多斯南部早奥陶世马家沟期碳酸盐台地沉积模式

地层、沉积岩组合及古地貌特征显示,鄂尔多斯盆地南部地区早奥陶世马家沟期为3个沉积单元区,即:北东部区为白云岩-蒸发盐组合;南部区为白云岩-少量蒸发盐组合;西部区以石灰岩为主。相应地北东部区以发育台内盆地-盆缘坪为主;南部区发育洼地-台坪-台地边缘-海槽;西部区则发育台地边缘-海槽。野外剖面与钻井岩心观测以及区域资料研究表明,鄂尔多斯盆地南部边缘大致在洛南瓦窑沟—西安—宝鸡一带。马家沟期研究区沉积模式总体上为:横向上"西槽、南洼、东坪、北盆",纵向上"咸-淡交替";灰岩-白云岩-蒸发岩横向上呈带状展布,纵向上则为不等厚交替沉积。     

Cenozoic development of southwestern Malay Basin: new insights from subsidence analysis and thermal history

Subsidence and thermal history analysis are carried out in order to investigate the Cenozoic basin development of the southwestern (Tenggol Arch and basinal side) part of the Malay basin. Structurally, the southwestern part consists of normal faults and horst and graben geometry. Tectonic subsidence curves show that the basinal side is more active than the Tenggol Arch due to movement along normal faults. Cenozoic development initiated with the deposition of sedimentary Units M & L (Oligocene) and the activation of the Tenggol fault on the basinal side. Several periods of accelerated and slow subsidence are observed during the Oligocene to Middle Miocene that could be associated with changes in regional stresses caused by pulsating plate movement. The Malay Basin experienced inversion throughout the Middle to Late Miocene related to mantle induced slab avalanche effect, causing relatively higher tectonic subsidence rates on the Tenggol Arch compared to the basinal side, suggesting that the Tenggol Arch is less affected by inversion than the basinal side. After a period (Late Miocene) of non-deposition, the basin was reactivated (Pliocene to recent) due to thermal relaxation with thick sedimentation. Paleo heat flows estimated utilizing a novel technique introduced in this study and present day heat flow calibrated using BHT data further supports our results, in that increase in heat flow is related to rapid tectonic subsidence. An anomalously high heat pulse affected the basin during inversion and could be the cause of meta-sediment formation whereas present heat flows, although high compared to average basins, shows decreasing trend from the inversion period.     

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。     

四川盆地中生代地热特征与前陆盆地构造、沉积作用

沉积盆地热体制与油气资源勘探有着密切的联系.基于石油钻井的Ro数据,采用古地温梯度法恢复了四川盆地钻井的最高古地温.结果显示,四川盆地西部、川东南和川东北的钻井,顶部的剥蚀量在3 700 m左右,盆地中部的剥蚀量约3 100 m.钻井古地温梯度在13.2～24.5℃/km之间,古热流在31.2～60.1 mW/m2之间...