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231.
青藏高原古近纪-新近纪隆升与沉积盆地分布耦合 总被引:4,自引:0,他引:4
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. 相似文献
232.
鄂尔多斯盆地北部苏里格庙含油气区上古生界层序地层研究 总被引:13,自引:6,他引:7
在区域构造变动、岩性组合、沉积相构成、测井曲线特征等研究基础上,利用层序地层学原理,对苏里格庙地区上古生界层序地层进行了研究.将在苏里格庙含油气区上古生界划分出5个层序组,并在晋祠组到石盒子组中划分出14个三级沉积层序,分别发育于陆表海、三角洲、河流3种沉积背景之下.建立层序地层格架,以体系域为单位探讨了层序地层格架内主要含气层段-层序8、9的砂体展布规律.研究表明,以体系域为单位编制的砂体等值线图,更细致地刻画了砂体的展布,砂质储集体的发育和空间展布受控于沉积环境,主要发育在低位体系域中. 相似文献
233.
济阳坳陷古近系多级控砂机制分析 总被引:1,自引:0,他引:1
济阳坳陷古近系砂体形成和分布受到多种因素的控制,主要包括:①断陷类型;②构造带类型;③坡折带类型;④体系域类型;⑤沉积相类型。在不同类型断陷中发育的沉积体系相差较大,在不同规模箕状断陷中发育的沉积体系也具有差异性。同时,断陷类型控制着构造带的发育,构造带类型又决定着坡折带的发育部位,坡折带类型则影响着湖盆沉积体系域的发育程度和分布范围,而沉积相类型对砂体的特征具有直接的控制作用。显然济阳坳陷砂岩体的形成和分布遵循“多级控砂”的特征,5种因素共同影响并逐级控制着砂岩体在断陷湖盆中的形成与分布。 相似文献
234.
Fifty‐five new SHRIMP U–Pb zircon ages from samples of northern Australian ‘basement’ and its overlying Proterozoic successions are used to refine and, in places, significantly change previous lithostratigraphic correlations. In conjunction with sequence‐stratigraphic studies, the 1800–1580 Ma rock record between Mt Isa and the Roper River is now classified into three superbasin phases—the Leichhardt, Calvert and Isa. These three major depositional episodes are separated by ~20 million years gaps. The Isa Superbasin can be further subdivided into seven supersequences each 10–15 million years in duration. Gaps in the geological record between these supersequences are variable; they approach several million years in basin‐margin positions, but are much smaller in the depocentres. Arguments based on field setting, petrography, zircon morphology, and U–Pb systematics are used to interpret these U–Pb zircon ages and in most cases to demonstrate that the ages obtained are depositional. In some instances, zircon crystals are reworked and give maximum depositional ages. These give useful provenance information as they fingerprint the source(s) of basin fill. Six new ‘Barramundi’ basement ages (around 1850 Ma) were obtained from crystalline units in the Murphy Inlier (Nicholson Granite and Cliffdale Volcanics), the Urapunga Tectonic Ridge (‘Mt Reid Volcanics’ and ‘Urapunga Granite’), and the central McArthur Basin (Scrutton Volcanics). New ages were also obtained from units assigned to the Calvert Superbasin (ca 1740–1690 Ma). SHRIMP results show that the Wollogorang Formation is not one continuous unit, but two different sequences, one deposited around 1730 Ma and a younger unit deposited around 1722 Ma. Further documentation is given of a regional 1725 Ma felsic event adjacent to the Murphy Inlier (Peters Creek Volcanics and Packsaddle Microgranite) and in the Carrara Range. A younger ca 1710 Ma felsic event is indicated in the southwestern McArthur Basin (Tanumbirini Rhyolite and overlying Nyanantu Formation). Four of the seven supersequences in the Isa Superbasin (ca 1670–1580 Ma) are reasonably well‐constrained by the new SHRIMP results: the Gun Supersequence (ca 1670–1655 Ma) by Paradise Creek Formation, Moondarra Siltstone, Breakaway Shale and Urquhart Shale ages grouped between 1668 and 1652 Ma; the Loretta Supersequence (ca 1655–1645 Ma) by results from the Lady Loretta Formation, Walford Dolomite, the upper part of the Mallapunyah Formation and the Tatoola Sandstone between ca 1653 and 1647 Ma; the River Supersequence (ca 1645–1630 Ma) by ages from the Teena Dolomite, Mt Les and Riversleigh Siltstones, and Barney Creek, Lynott, St Vidgeon and Nagi Formations clustering around 1640 Ma; and the Term Supersequence (ca 1630–1615 Ma) by ages from the Stretton Sandstone, lower Doomadgee Formation and lower part of the Lawn Hill Formation, mostly around 1630–1620 Ma. The next two younger supersequences are less well‐constrained geochronologically, but comprise the Lawn Supersequence (ca 1615–1600 Ma) with ages from the lower Balbirini Dolomite, and lower Doomadgee, Amos and middle Lawn Hill Formations, clustered around 1615–1610 Ma; and the Wide Supersequence (ca 1600–1585 Ma) with only two ages around 1590 Ma, one from the upper Balbirini Dolomite and the other from the upper Lawn Hill Formation. The Doom Supersequence (<1585 Ma) at the top of the Isa Superbasin is essentially unconstrained. The integration of high‐precision SHRIMP dating from continuously analysed stratigraphic sections, within a sequence stratigraphic context, provides an enhanced chronostratigraphic framework leading to more reliable interpretations of basin architecture and evolution. 相似文献
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238.
P. Hofmann A.Y. Huc B. Carpentier P. Schaeffer P. Albrecht B. Kelly J.R. Maxwell J.S.Sinninghe Damst J.W. de Leeuw D. Leythaeuser 《Organic Geochemistry》1993,20(8)
The lower Oligocene evaporite sequence of the Mulhouse Basin (France) contains organic matter-rich marl deposits. These marls display an overall cyclic variation of sedimentation rate, organic carbon content, hydrogen index and selected molecular parameters over a 30 m thick stratigraphic interval. The integration of all sedimentological and geochemical parameters has allowed the reconstruction and characterization of the paleoenvironment of deposition. The marls were deposited in a perennial lake that was at times connected to the sea. Two organic facies end members could be assigned to a lake stage with a marine connection and a lake stage that received dominantly continental water input. The overall stratigraphic variation in the organic matter content is interpreted to reflect the adaptation of the Oligocene flora to the changing paleoclimate and environmental conditions. 相似文献
239.
Qiao Xiufu Song Tianrui Gao Linzhi Peng Yang Li Haibing Gao Mai Song Biao Zhang Qiaoda 《《地质学报》英文版》1994,7(3):243-265
Abstract On the basis of the records of strong seismic events taking place in soft carbonate sediments, a new seismic sequence system of vibrational liquefaction is established, which consists of a series of units, such as escaped structure of micrite veins and liquefied deformation formed in the period of seismic liquefaction, land subsidence structure after liquefaction, tsunamic hummocky and turbidite produced by seismic events, This sequence is a generalization and summation of field observation in vast areas, which shows the whole process of a strong seismic event and provides an unified theoretical explanation. The pattern of the seismic sequence by vibrational liquefaction provides one of correlation standards for geologists in the field to discriminate events in carbonate sequences. Based on the pattern of seismic sequence, the authors first advance a new conception of the Palaeo - Tanlu (Tancheng - Lujiang) Zone and discuss primarily its geological significations. 相似文献
240.
Fischer图解及其在旋回层序研究中的应用──以北京西山张夏组为例 总被引:11,自引:0,他引:11
Fischer图解(又称为容纳空间图解)为人们研究沉积旋回在空间上的叠置规律、相对海平面变化、层序级次的划分以及地层层序对比等提供了一种客观实用的方法。本文较详细地讨论了该图解的绘制方法及应注意的问题。运用该图解,将北京西山下苇甸剖面张夏组划分为1个大的三级旋回层序和4个四级旋回层序,根据图解反映的相对海平面变化讨论了旋回层序与构造运动间的关系,提出华北板块晚寒武世之前的"翘翘板运动"应始于中寒武世张夏期之早期到中期。 相似文献