塔里木盆地西南缘中生代沉积古环境恢复

对塔里木盆地西南缘中生代沉积相和沉积环境的研究,不仅可以了解晚三叠世—晚白垩世塔里木板块南缘活动大陆边缘的历次碰撞事件,也为研究新生代中亚地区强烈的陆内变形活动提供了重要信息。本文利用野外地质调查结果和地球物理资料,在沉积相和地震相分析基础上,重建中生代沉积体系和沉积环境。结果表明:塔里木盆地西南缘中生界的原始分布受晚三叠世弧后前陆冲带冲断作用和造山后伸展作用形成的古地形控制。早侏罗世发育了一系列独立分割的小断陷,以巨厚的冲积扇、辫状河三角洲沉积为特征,其受控于NWW—SEE走向的正断层,而非NW—SE走向的古塔拉斯-费尔干纳右旋走滑断裂;早侏罗世晚期—中侏罗世广泛发育滨浅湖和河流-沼泽相沉积,可能存在一个连通了塔里木盆地南缘、吐拉以及柴达木盆地西缘的统一沉积坳陷;至晚侏罗世,冲积环境再次出现,发育的粗粒碎屑岩为早白垩世湖盆扩张前的产物;早白垩世,丰富的陆源碎屑在古昆仑山前形成多个相互叠置的冲积扇—扇三角洲—扇三角洲平原沉积体;晚白垩世,随着海水自西向东侵入,塔里木盆地西南缘陆相碎屑沉积向东逐渐退却,海相沉积占有优势。     

羌塘盆地查郎拉地区中生代岩相古地理初探

以实测剖面和路线地质填图剖面为基础,采用地层优势相 (亚相 )法和综合分析法首次系统地重建了羌塘盆地查郎拉地区中生代的岩相古地理。指出晚三叠世以海陆过渡相占主导地位,形成海退沉积旋回;由NE向SW依次出现三角洲相→滨岸相→滨浅海相带。中侏罗世浅海相沉积较发育,从NE向SW依次发育三角洲→台地相→浅海陆棚相带,呈NWW~SEE向展布,沉积中心应在中部偏西南侧,在J₂ q期和J₂ b期形成两次海侵高潮,总体组成两个由海侵→海退的沉积旋回。晚侏罗世海陆过渡相沉积较发育,从NE向SW依次发育三角洲相→潮坪相→台地相带,呈NW~SE向展布。白垩纪岩相古地理存在早晚差异 :早期为残留海背景下的台地边缘浅滩-局限台地相沉积,形成第三次海侵高潮;晚期全区迅速抬升,形成冲积扇~辫状河流相的磨拉石红色复陆屑沉积旋回及多物源供应格局。中生代沉积物源主要来自北部的中央隆起带,次为东部高地及西部隆起区;在沉积演化过程中,不同时代的沉积物源有所差别,且地形总体保持了北高南低、东高西低的格局。     

东海盆地新生代沉积环境

东海盆地是新生界为主的沉积盆地,根据地震和钻井资料分析,可划分为四套沉积层序:白垩统-古新统、始新统、渐新统-中新统和上新统-第四系.沉积环境经历了浅海、海陆交替相→海湾相→河湖交潜相→平原河流相→浅海(开阔海)相的发育历程.     

北祁连东部石炭纪岩相古地理

〗通过对石炭系实测剖面岩石的岩性、岩相、结构构造、粒度、古生物组合和古生态等特征的综合分析,利用石油勘探成果,研究了北祁连东部石炭纪岩相古地理。早石炭世早期,秦岭海域海水以天水—静宁古海峡为通道,向北侵入本区,形成由鄂尔多斯、阿拉善和陇西三大古陆围限的祁连海海湾沉积区,以咸化泻湖相、滨浅海相沉积为主,早石炭世晚期,海侵进一步扩大,以滨浅海相碎屑岩、碳酸盐岩沉积为主。晚石炭世海盆继续向东、向北扩展,海侵次数增多,形成了多个以碎屑岩为主夹灰岩沉积的海侵海退旋回,晚石炭世晚期太原组沉积时期,海水向东与华北海相连,成为广阔的陆表海沉积。中部地区存在近东西向分布的链岛状古隆起及水下隆起,古地形具西高东低、北高南低的特征。     

珠江口盆地—琼东南盆地深水区古近系沉积演化

珠江口—琼东南盆地深水区古近系共划分出三套沉积层序,即始新统—文昌层序,恩平—崖城层序和珠海—陵水层序。综合应用单井相、地层等厚图、地震相平面图、地震砂岩指数平面图,参考断陷盆地沉积体系发育特征,结合构造背景,综合编制了全区各个体系域的沉积相平面图。南海北部深水区始新统发育三个大型的湖泊区,东部为白云凹陷,西部为松南—宝岛凹陷和陵水—乐东凹陷,该时期表现出比较明显陆相断陷湖盆的分隔性,除了三大湖盆外,还发育5～6个小型湖泊。渐新世早期海进区域集中在琼东南盆地,海水可能从东西两个方向进入琼东南盆地,形成东西两个浅海区,中间有浅海相和剥蚀区分隔;东部白云凹陷未发育海进,保持湖泊环境;顺德—开平凹陷亦为湖泊环境,由独立的湖泊相逐渐扩大为连片湖相沉积。渐新世晚期全区发生海进,但海进方向存在差异,东部白云凹陷—顺德—开平凹陷的海水可能由东部进入,由东向西海进;西部琼东南盆地可能存在东西两个海口,海水从两地进入盆地,继承崖城期的海进方向。     

南海北部白垩纪—渐新世早期沉积环境演变及构造控制*

南海北部珠江口—琼东南盆地白垩系—下渐新统记录了华南大陆边缘从主动陆缘向被动陆缘的转换过程。基于盆地构造-地层、单井相、地震相等特征的综合分析,结合南海中南部的沉积环境和区域构造演化,探讨南海北部白垩纪—渐新世早期的沉积环境演变及构造控制背景。研究发现: (1)南海北部白垩系广泛分布,古新统分布极为有限; 始新世早-中期,琼东南盆地只在部分凹陷深部发育了小规模的滨浅湖相和扇三角洲相沉积,珠江口盆地白云凹陷以大规模发育的湖泊相为特征; 始新世晚期—渐新世早期,琼东南盆地和珠江口盆地白云凹陷都受到海侵作用的影响,以海岸平原相和滨浅海相为主。 (2)构造演变包括5期:包括白垩纪安第斯型大陆边缘的“弧—盆”体系发育期,古新世区域隆升剥蚀山间盆地发育期,始新世早-中期裂陷发育,始新世晚期—渐新世早期陆缘破裂期,渐新世晚期东部海盆稳定扩张期。最后,探讨了南海盆地中生代末/新生代初的动力学转换过程及特征。     

南海北部新生代海陆变迁与不同盆地的沉积充填响应*

新生代以来南中国海的多幕旋回运动形成了其北部陆坡性质各异、演化有别的多个陆缘沉积盆地。依据各盆地新生界发育特征、主干地震剖面及钻井资料对南海北部的相对海平面变化与沉积环境进行系统分析,采用年代地层对比的方法探讨南海北部构造演化序列与海陆变迁规律的内在联系,再现了南海北部陆缘新生代的海陆变迁过程,从而建立了南海北部陆缘裂谷盆地、走滑拉分盆地和陆内裂谷盆地的构造—沉积充填一体化模式。新生代海平面整体呈上升趋势,古近纪各盆地以陆相河流、粗粒三角洲湖相沉积为主;而新近纪主要发育滨浅海及三角洲相,呈现出明显的早陆后海的规律。靠近陆地一侧的陆内裂谷盆地北部湾盆地海侵最晚,其古近系充填厚度明显大于新近系,以发育近源扇三角洲为特色;而靠近海域一侧的走滑拉分盆地(莺歌海盆地)则以新近纪海相沉积占优势;陆缘裂谷盆地(琼东南与珠江口盆地)古近纪陆相与新近纪海相相对均衡发育,发育大型三角洲与碳酸盐岩台地。不同盆地的沉积充填特征主要受构造运动与海侵规模控制,并由此奠定了不同盆地的资源前景。     

东准噶尔造山带泥盆系沉积相及古地理环境

东准噶尔造山带纸房地区自晚志留世—泥盆纪可划分为哈甫提克山、绵脊梁、色克森巴依、塔克札勒、博格达五个构造沉积区。各个构造沉积区的沉积盆地内有各自的沉积相特征 ,且反映不同的古地理环境。晚志留世—早泥盆世早期海域自西向东逐渐扩大 ,在其加里东期地体 (微地块 )外围形成近 EW向带状海槽 ,为滨海环境 ;早泥盆世晚期—中泥盆世形成全区域性海侵 ,从滨浅海—半深海环境均存在 ,以滨浅海为主 ;晚泥盆世为多岛洋的鼎盛时期 ,属有限洋盆。自北往南为海陆过渡环境—浅海环境—半深海环境     

新疆北部石炭纪地层、岩相古地理与烃源岩

依据近几年新疆区域地质调查结果,结合新疆油田与吐哈油田最新勘探成果,通过区域构造背景和沉积充填演化特征推断石炭系沉积建造样式,理顺了新疆北疆地区石炭纪地层层序,目的是推断石炭纪烃源岩发育层段与主力生烃区范围。下石炭统有效烃源岩分布较广,主要发育于北疆西准噶尔达尔布特山前、博格达山前、准噶尔东部陆东—五彩湾地区早石炭世被动陆缘海相和海陆过渡相沉积盆地;上石炭统有效烃源岩分布相对局限,主要发育于东准噶尔克拉美丽山前石钱滩区、布尔津—吉木乃区及库普—三塘湖区海陆过渡相沉积盆地内。石炭系油气成藏严格遵循"源控论",有效生烃区决定其有效成藏范围,所伴随发育的火山岩体决定其富集程度。优选西准噶尔、东准噶尔、库普—三塘湖区、博格达山前区、布尔津—吉木乃区石炭系烃源岩发育区及其相邻构造带,作为今后石炭系油气勘探战略选区的重要领域和区带。     

重庆市晚二叠世含煤地层聚煤特征

晚二叠世初期上扬子盆地西部康滇古陆的隆升,是形成其东侧区域西高东低构造格局的首要因素,并控制了各期由陆到海沉积相带与富煤带随海侵向西超覆的抬升迁移。重庆市西部地区在龙潭期位于扬子盆地海陆过渡相区的东部,区内发育海陆过渡沉积相区-海湾潮坪沉积体系与浅海相沉积区,海湾潮坪沉积体系是本区主要聚煤场所。从层序地层分析,将二叠系上统划分为2个三级层序,其中层序1发育完整,主要煤层C25煤形成于海侵域之海侵初期,C18＋19煤形成于高位域内次级层序的海侵期。     

The structure,depositional style and accumulation characteristics of continental margin with diachronous breakup in the northern South China Sea

ABSTRACT

A typical diachronous breakup developed in the South China Sea (SCS); the breakup has been unequivocally identified, and gradually decreases in age from NE to SW. To illustrate the influence of a diachronous breakup on hydrocarbon accumulation, we used seismic profiles from CNOOC, and analysed crustal extension characteristics, sedimentary style and source rock accumulation. The main conclusions are as follows: (1) Because of the diachronous breakup in the SCS, various tectonic units developed in different positions on the northern continental margin with different degrees of extension. The Pearl River Mouth Basin (PRMB) is closer to the central sea basin of the SCS and has been affected by regional tension stress for a longer time. Tectonic units of proximal domain, necking zone, and distal margin types developed, and the crust structure thinned from the land towards the sea. The Qiongdongnan Basin (QB) is closer to the Southwest Sub-basin. There are symmetrical proximal domains on the southern and northern sides of the QB, with a necking zone in the central part. It presents as an abandoned passive continental margin. (2) The PRMB exhibited rifted cells first, followed by canyon type extensional faulting and horizontal axial transportation, and then by a longitudinal shelf-slope sedimentary style. But the QB has only rifted cells and canyon type faulting stages, no longitudinal shelf-slope sedimentary stage. The major source rocks in the northern SCS become younger from east to west, and the sedimentary facies change from lacustrine facies to marine-continental transitional facies. (3) The diachronous breakup process ultimately affecting oil and gas migration and accumulation process. The PRMB is dominated by deep-water shelf break accumulation with deep-water fan reservoir bodies. The QB is dominated by canyon type accumulation with channels.     

Differences in the Tectonic Evolution of Basins in the Central‐Southern South China Sea and their Hydrocarbon Accumulation Conditions

To reveal the causes of differences in the hydrocarbon accumulation in continental marginal basins in the centralsouthern South China Sea,we used gravity-magnetic,seismic,drilling,and outcrop data to investigate the tectonic histories of the basins and explore how these tectonic events controlled the hydrocarbon accumulation conditions in these basins.During the subduction of the Cenozoic proto-South China Sea and the expansion of the new South China Sea,the continental margin basins in the central-southern South China Sea could be classified as one of three types of epicontinental basins:southern extensional-foreland basins,western extensional-strike slip basins,and central extensional-drift basins.Because these basins have different tectonic and sedimentary histories,they also differ in their accumulated hydrocarbon resources.During the Cenozoic,the basin groups in the southern South China Sea generally progressed through three stages:faulting and subsidence from the late Eocene to the early Miocene,inversion and uplift in the middle Miocene,and subsidence since the late Miocene.Hydrocarbon source rocks with marine-continental transitional facies dominated byⅡ-Ⅲkerogen largely developed in extremely thick Miocene sedimentary series with the filling characteristics being mainly deep-water deposits in the early stage and shallow water deposits in the late stage.With well-developed sandstone and carbonate reservoirs,this stratum has a strong hydrocarbon generation potential.During the Cenozoic,the basin groups in the western South China Sea also progressed through the three developmental stages discussed previously.Hydrocarbon source rocks with lacustrine facies,marine-continental transitional facies,and terrigenous marine facies dominated byⅡ2-Ⅲkerogen largely developed in the relatively thick stratum with the filling characteristics being mainly lacustrine deposits in the early stage and marine deposits in the late stage.As a reservoir comprised of self-generated and self-stored sandstone,this unit also has a high hydrocarbon generation potential.Throughout those same three developmental stages,the basin groups in the central South China Sea generated hydrocarbon source rocks with terrigenous marine facies dominated byⅢkerogen that have developed in a stratum with medium thicknesses with the filling characteristics being mainly sandstone in the early stage and carbonate in the late stage.This reservoir,which is dominated by lower-generation and upper-storage carbonate rocks,also has a high hydrocarbon generation potential.     

Petroleum Geology in Deepwater Settings in a Passive Continental Margin of a Marginal Sea: A Case Study from the South China Sea

Deepwater oil and gas exploration has become a global hotspot in recent years and the study of the deep waters of marginal seas is an important frontier research area.The South China Sea(SCS)is a typical marginal sea that includes Paleo SCS and New SCS tectonic cycles.The latter includes continental marginal rifting,intercontinental oceanic expansion and oceanic shrinking,which controlled the evolution of basins,and the generation,migration and accumulation of hydrocarbons in the deepwater basins on the continental margin of the northern SCS.In the Paleogene,the basins rifted along the margin of the continent and were filled mainly with sediments in marine-continental transitional environments.In the Neogene–Quaternary,due to thermal subsidence,neritic-abyssal facies sediments from the passive continental margin of the SCS mainly filled the basins.The source rocks include mainly Oligocene coal-bearing deltaic and marine mudstones,which were heated by multiple events with high geothermal temperature and terrestrial heat flow,resulting in the generation of gas and oil.The faults,diapirs and sandstones controlled the migration of hydrocarbons that accumulated principally in a large canyon channel,a continental deepwater fan,and a shelf-margin delta.     

中寨矿区龙潭组层序划分方法及沉积相特征分析

依据研究区钻孔岩心观察,结合测井及面上区域资料,并通过室内测试分析和野外调查等手段,重点研究区内ZZ808井,运用层序地层学、沉积学等多学科理论。划分了研究区龙潭组层序地层,系统研究了各层序地层特征。结果显示:龙潭组发育4个层序界面,将其划分为3个三级层序,SQ_1属于海相层序,SQ_2、SQ_3属于海陆过渡相层序,六个体系域。层序地层格架的建立分析显示龙潭早期发生脉动式海侵,以慢速海侵,快速海退为特征,沉积主体为障壁砂坝-■湖,沉积相呈北东—南西向展布,主要发育碳酸盐台地相、■湖-潮坪相和障壁沙坝相,含煤厚度自北东—南西逐渐减薄;龙潭晚期为区域性海退过程,发育三角洲相,三角洲成为沉积主体,煤层主要形成于海退—海侵转折期之后。     

南黄海3.50 Ma以来海陆环境演变的元素地球化学记录

通过对南黄海西部陆架CSDP-1孔晚上新世-第四纪地层中的地球化学元素S、Sr和Ba的测试,结合该钻孔已发表的岩性、磁性地层和微体古生物等资料,综合分析发现：CSDP-1孔元素S、Sr、Ba质量分数及比值Sr/Ba在不同沉积相中的分布变化特征与研究区海陆沉积环境的变化密切相关,体现了S和Sr/Ba值的亲海相特性。S元素的高值主要出现在海相沉积环境中,对应了本区3.50 Ma以来的海侵事件,可以指示本钻孔海陆环境。Sr/Ba值在U2沉积单元（1.66~0.83 Ma）的高值与海侵无关,认为主要是物质来源改变导致的沉积矿物组成发生变化所控制,而在U1沉积单元（0.83 Ma以来）Sr/Ba值能指示海陆环境的变化,表明0.83 Ma以来海侵成为Sr/Ba值的主控因素。     

东海陆架盆地南部油气资源前景与选区

通过开展二维地震资料调查和重处理,结合钻井、重磁、海陆对比等新老资料开展联合解释认为:东海陆架盆地南部中生界具有分布广、厚度大、沉积中心位于东部,新生界则呈现东西厚中间薄,新生代构造单元中的台北凸起、观音凸起和雁荡凸起上均有中生界分布;白垩系较侏罗系分布更为广泛,侏罗系西部边界为雁荡凸起东侧,白垩系西部边界以瓯江凹陷西侧为界;中生界三口钻井分析结果发现了确凿的海相标志,证实了中生界东海陆架盆地发生多次海侵,结合围区沉积特征认为侏罗纪存在南北向和东西向的海侵,白垩纪主要体现为东西向的海侵;研究区中生界发育中下侏罗统、下白垩统两套烃源岩,新生界发育古新统、始新统、渐新统和中新统四套烃源岩,具有较好的油气资源前景。     

东北地区二叠纪沉积特征及原型盆地分析

东北地区二叠系分布广泛,沉积相类型主要为半深海相、滨浅海相、滨浅湖相和半深湖相等。早二叠世-中二叠世东北地区主要处于大陆边缘浅海沉积环境,面积大,沉积中心位于南部温都尔庙-西拉木伦河东西向条带区。晚二叠世东北地区为大型坳陷型盆地,东北地区各缝合线均已闭合,随着地壳抬升,海水退出,大部分地区为陆相沉积,局部有残留海相沉积,总体上具有从早二叠世到晚二叠世由海相向陆相逐渐转变的规律。西拉木伦河缝合带对晚古生代沉积起控制作用,在二叠纪整个缝合带由西向东逐渐拼合,直至晚二叠世,两板块拼合完成,闭合时间具有西早东晚的特点。     

中扬子晚二叠世沉积特征及古地理演化

通过剖面实测、岩相及沉积相分析,中扬子区晚二叠世主要发育碳酸盐岩开阔台地沉积、陆棚沉积及盆地沉积,吴家坪期以浅海相沉积为主,深水盆地范围较小,长兴期发育台地相及盆地相,深水盆地范围变大,研究区晚二叠世的沉积主要受南秦岭海活动控制和盆地演化影响,沉积分异在晚二叠世较发育.古地理演化表明,吴家坪期中扬子北缘为深水盆地沉积,...     

华北地台西缘晚石炭世-早二叠世早期海水进退及其与聚煤作用的关系

从古元古代至晚古生代,华北地台西缘经历了坳拉槽、槽后坳和坳陷发育阶段。笔者在大区域地层对比及详细的沉积环境分析基础上,对晚古生代海水进退与聚煤作用关系作了较深入研究。结果表明：晚石炭世晚期至早二叠世早期华北地台西缘主要为潮坪和三角洲沉积发育区,在空间上沉积环境具有东西有别南北分带的特点;西部由泻湖潮坪沉积环境逐渐过渡为河控泻湖三角洲和受潮汐影响的河控滨海三角洲沉积环境;东部为潮坪沉积环境,东侧边缘还出现近山滨海平原沉积环境。研究区在晚石炭世早期-早二叠世早期发生过4次2级海水进退,其中第三、第四次海侵全区发育。早二叠世早期初的第三次2级海侵是最大的一次。最大海侵前夕晚石炭世晚期末是大区域发育厚-巨厚煤层的最好时期。泻湖三角洲平原和陆源碎屑潮上泥炭坪及泥炭沼泽是最佳的聚煤场所。     

青藏高原古近纪—新近纪隆升与沉积盆地分布耦合

根据在高原及邻区近7年完成的1∶250000地质填图资料, 划分出青藏高原及邻区古近系-新近系残留盆地共92个.沉积范围大且序列完整的盆地分布在高原周缘和腹地.在高原的南、北和东缘, 沿区域性大断裂带分布许多走滑拉分盆地.古新世—始新世海相地层仅分布在藏南和新疆叶城地区.藏南半深海-深海沉积沿江孜-萨嘎-郭雅拉-桑麦一线分布, 其海水东浅西深, 西部为活动型, 反映新特提斯洋闭合的时间从东向西变新, 地壳抬升首先开始于东侧.晚白垩世隆起区主要分布在研究区东北部, 高原总体地貌格局为东北高, 西南低.古新世—始新世出现了腾冲-班戈、库牙克-格尔木新的隆起带, 西昆仑隆起带向东拓展, 祁连隆起带加宽, 松潘-甘孜隆起区范围向东有所萎缩.渐新世期间, 冈底斯和喜马拉雅带掘起, 昆仑-阿尔金-祁连的进一步隆起, 造成了整个高原的周缘为山系、而腹地为盆的宏观地貌格局.中-上新世期间, 冈底斯和喜马拉雅带、喀喇昆仑-西昆仑地区进一步较大幅度隆起;高原从渐新世及其以前的东高西低格局, 经历了中新世—上新世全区的不均衡隆升和拗陷, 最终在上新世末铸就了西高东低的地貌格局, 青藏做为一个统一的高原发生了重大的地貌反转事件.青藏高原新生代的隆升过程以多阶段、不均匀、非等速为特征, 具有强烈的时空差异性.