OSL chronology of Quaternary terraced deposits outcropping between Mt. Etna volcano and the Catania Plain (Sicily,southern Italy)     

《Physics and Chemistry of the Earth》2013

In this paper we tested the applicability of the Optically Stimulated Luminescence (OSL) technique through Single-Aliquot Regenerative-dose (SAR) protocol, on single grain quartz extracted from alluvial–coastal sediments. Five samples were collected from deposits belonging to a flight of seven orders of coastal–alluvial terraces outcropping in the area between Mt. Etna volcano and the Catania Plain (Sicily, southern Italy), at the front of the Sicilian fold and thrust system. After various performance tests, we obtained OSL ages ranging between 240 ± 12 and 80 ± 4 ka, consistent with the normal evolutionary model of a terraced sequence, moving from the highest to the lowest elevation. Obtained data allowed us to determine a mean uplift rate of 1.2 mm/year during the last 240 ka, mostly related to regional uplift processes coupled with sea-level changes. Moreover, terraces belonging to the two highest orders are folded, forming a large anticline. According to our results, the frontal thrust of the Sicilian chain was active between 236 and 197 ka ago, even though seismological and geodetic data suggest current activity to the back.  相似文献   

四川盆地南部地区新生代隆升剥露研究——低温热年代学证据   总被引：1，自引：1，他引：0       下载免费PDF全文

邓宾  刘树根  王国芝  李智武  刘顺  曹俊兴 《地球物理学报》2013,56(6):1958-1973

本文通过背斜褶皱变形与低温热年代学年龄(磷灰石和锆石(U-Th)/He、磷灰石裂变径迹)端元模型研究,约束低起伏度、低斜率地貌特征的四川盆地南部地区新生代隆升剥露过程.四川盆地南部沐川和桑木场背斜地区新生代渐新世-中新世发生了相似的快速隆升剥露过程(速率为~0.1 mm/a、现今地表剥蚀厚度1.0~2.0 km),反映出盆地克拉通基底对区域均一性快速抬升冷却过程的控制作用.川南沐川地区磷灰石(U-Th)/He年龄值为~10-28.6 Ma, 样品年龄与古深度具有明显的线性关系,揭示新生代~10-30 Ma以速率为0.12±0.02 mm/a的稳态隆升剥露过程.桑木场背斜地区磷灰石裂变径迹年龄为~36-52 Ma,古深度空间上样品AFT年龄变化不明显(~50 Ma)、且具有相似的径迹长度(~12.0 μm).磷灰石裂变径迹热演化史模拟表明桑木场地区经历三个阶段热演化过程:埋深增温阶段(~80 Ma以前)、缓慢抬升冷却阶段(80-20 Ma)和快速隆升剥露阶段(~20 Ma-现今),新生代隆升剥露速率大致分别为~0.025 mm/a和~0.1 mm/a.新生代青藏高原大规模地壳物质东向运动与四川盆地克拉通基底挤压,受板缘边界主断裂带差异性构造特征控制造就了青藏高原东缘不同的边界地貌特征.  相似文献   

塔北隆起雅克拉油气田原油成因特征   总被引：1，自引：0，他引：1  

李洪波  王铁冠  李美俊  陈金燕 《沉积学报》2012,30(6):1165-1171

针对雅克拉油气田多个含油气层位的原油,进行了一系列的地球化学测试分析,对雅克拉油气田原油的地球化学特征、成因特征进行了解剖。研究结果表明,雅克拉油气田深浅不同层位原油轻烃组成与轻烃单体烃碳同位素、类异戊二烯烷烃组成以及原油与馏分碳同位素组成具有明显的海相原油特征;深浅层原油三环萜烷、C₂₈甾烷、三芳甾烷和甲基三芳甾烷以及原油与馏分碳同位素组成皆具有典型上奥陶统来源油的特征,与寒武-下奥陶统来源油特征差异明显,暗示雅克拉油气田原油来源于上奥陶统烃源层。  相似文献   

塔里木盆地巴楚隆起北缘阿恰基底卷入构造   总被引：1，自引：0，他引：1  

杨庚  李本亮  杨海军  陈竹新  王晓波  张朝军  雷永良 《地质论评》2012,58(1):32-40

塔里木盆地巴楚隆起为第四系不整合覆盖的古隆起,在其西北缘发育NW走向的阿恰断裂、萨拉姆布拉克背斜、向斜和隐伏的乔来麦提断裂。地震剖面和钻井资料显示,阿恰断裂为倾向南的基底卷入逆冲断裂,向北逆冲,错断层位从前寒武系基底一直到中寒武统膏岩,从西向东逆冲断距减少。乔来麦提断裂则以中寒武统膏岩为滑动面,向南逆冲,并在断层端部发育萨拉姆布拉克断层扩展褶皱。这两种类型构造样式的断裂(基底卷入断裂和盖层滑脱断裂),在剖面上组成典型的楔形构造几何形态,平面上形成三角形构造。遥感影像解译指出阿恰断裂和萨拉姆布拉克向斜向北西方向延伸进入柯坪逆冲带,并在该带有相应方向的地表构造显现,与北东走向的柯坪逆冲带组成叠加构造。生长地层分析确定基底卷入构造形成于始新世—中新世,而柯坪逆冲带形成于第四纪,明显晚于巴楚隆起形成时代。  相似文献   

罗云山山前断裂带阶地调查研究及其构造意义   总被引：2，自引：1，他引：1  

孙昌斌  谢新生  许建红 《中国地震》2011,27(2):126-135

罗云山山前断裂带位于山西临汾盆地西侧,控制着盆地的西界.对罗云山山前断裂带8条冲沟的阶地测量资料的研究表明:该断裂带冲沟发育T1～T5五级阶地.T1 阶地拔沟3m左右,T2 阶地拔沟8～10m,T3 阶地拔沟20m左右,T4 阶地拔沟30m左右,T5 阶地拔沟40～50m.阶地测年数据及断错地貌调查表明:罗云山山前断裂带在晚第四纪以来有过多次活动.晚更新世中晚期以来阶地的抬升速率为0.41 mm/a,全新世以来抬升速率为0.75mm/a.罗云山山前断裂带冲沟阶地从晚更新世中晚期到全新世抬升速率有逐渐增大的趋势,反映该断裂带自晚第四纪以来构造抬升作用逐渐加强,这与临汾盆地从晚更新世晚期到全新世沉降速率也有增大的趋势比较一致.  相似文献   

The Pleistocene terrace staircase of the River Thame, central-southern England, and its significance for regional stratigraphic correlation, drainage development, and vertical crustal motions     

Rob Westaway 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(1):92-112

The Thame is one of the principal left-bank affluents of the Thames, the largest river in southern England; it joins the Upper Thames at Dorchester, ∼20 km downstream of Oxford. Its terraces include a younger group of four, which date from the late Middle Pleistocene and Late Pleistocene, are disposed subparallel to the modern river, and represent drainage within the modern catchment. At higher levels there are three older terraces, the Three Pigeons, Tiddington and Chilworth terraces, which are assigned to MIS 16, 14 and 12. With much gentler downstream gradients, these are fragmentary remnants of much more substantial fluvial deposits, indicating a much larger river that was disrupted by the Anglian (MIS 12) glaciation. This interpretation supersedes an earlier view that the glacigenic deposits in the Thame headwaters correlate with the Blackditch terrace, the highest of the younger group, which has hitherto provided an argument that the glaciation in this region occurred in MIS 10. It is suggested that the headwaters of the pre-Anglian ‘Greater Thame’ river were located near Northampton and that the Milton Sands of that area represent an upstream counterpart of the Chilworth terrace deposits. It is envisaged that this early Middle Pleistocene drainage geometry, located between the Jurassic limestone and Chalk escarpments, developed as a result of the increase in uplift rates that followed the Mid-Pleistocene Revolution (MPR). It is suggested that before this time, including during the Early Pleistocene, the modern Thame catchment and adjacent regions drained southeastward through the Chalk escarpment, but these small rivers lacked the erosional power to cut through the Chalk in pace with the faster uplift occurring in the early Middle Pleistocene, and so became diverted to the southwest, subparallel to the Chalk escarpment, to form the pre-Anglian ‘Greater Thame’ tributary of the Upper Thames. The post-MPR uplift is estimated to decrease northwestward from 90 m in the Middle Thames to 75 m near the Thame-Thames confluence and to 65 m upstream of Oxford. The post-Anglian (post-450 ka) component of uplift decreases northward from 33 m near the Thame-Thames confluence to an estimated ∼20 m in the Northampton area; the relative stability of the latter area makes feasible the proposed correlation between the Milton Sands and the pre-Anglian River Thame. Limited post-Anglian uplift in the Northampton area is also inferred from the upstream convergence of the terraces of the modern rivers Nene and Great Ouse. These observed lateral variations in vertical crustal motions reflect lateral variations in crustal properties (including heat flow, crustal thickness, and thickness of underplating at the base of the crust) that are known independently. This study thus provides, for the first time, an integrated explanation of the Pleistocene drainage development across a large region of central-southern England.  相似文献   

准噶尔盆地车排子凸起新近系“网毯式”成藏机制剖析及其对盆地油气勘探的启示   总被引：3，自引：0，他引：3  

张善文  林会喜  沈扬 《地质论评》2013,59(3):489-500

与油气通常近源聚集不同,准噶尔盆地西部车排子凸起新近系为特殊的远源成藏.其成藏的机制是什么?是否具有普遍性?如何进行勘探?本文从其充注特征和输导体系人手,剖析了成藏机制与富集特征,进而系统描述评价了准噶尔盆地宏观输导格架,预测此类油气藏的勘探潜力与有利方向.研究表明,车排子凸起新近系远源成藏是”网毯式”体系高效输导的结果,准噶尔盆地多期构造运动与”砂-泥二元结构”沉积背景促使普遍发育网毯式输导体系.网毯输导体系控制了准噶尔盆地50％以上数量的油气聚集,网毯式成藏是盆地内一种非常重要的成藏类型.毯-源关系表现为侧向或纵向直接沟通样式、断层沟通或接力样式、断层-中转层接力样式、断层-不整合接力样式等4种样式.分析毯-藏空间关系,存在毯边、毯尖、毯中削截、毯中背斜、毯中坡折、毯中断块、毯上断块、毯上岩性、毯上地层等9种毯砂油气藏与毯上相关油气藏类型.准噶尔盆地网毯式油气藏具有很大的勘探潜力,应重视并采取以网毯输导体系刻画评价为核心的研究与部署思路,大力推进此种类型油气藏的勘探.  相似文献   

车排子凸起轻质油成熟度分析与烃源层再认识   总被引：1，自引：0，他引：1  

张学军  徐兴友  彭平安 《地球化学》2013,42(2)

通过对车排子凸起南部轻质油的甲基双金刚烷和甲基菲参数分析,发现其成熟度已达等效镜质组反射率约1.3％～1.6％的高过成熟阶段.结合周边凹陷烃源岩演化特征分析,认为该区轻质油来源于侏罗系烃源岩的可能性较小,来自二叠系高过成熟烃源岩的可能性较大.该区轻质油地球化学特征与二叠系烃源岩差异较大,而与白垩系和古近系烃源岩地球化学特征相似,推断该高过成熟油气中不含生物标志化合物或生物标志化合物含量极低,其现有特征是在运移过程中受成熟度较低而生物标志化合物含量丰富的烃源岩可溶有机质浸染所致.这一认识不但对揭示研究区的油气成藏规律具有重要的理论和实践意义,也将为准噶尔南部深凹区及山前坳陷区轻质原油及天然气来源的重新认识提供合理的参考依据.  相似文献   

Constraints on the timing and regional conditions at the start of the present phase of crustal extension in western Turkey,from observations in and around the Denizli region     

《Geodinamica Acta》2013,26(3-4):209-238

The chronology of extension of the continental crust in western Turkey has been the subject of major controversies. We suggest that these difficulties have arisen in part because of past misuse of dating evidence; and in part because the assumption often made, that deposition of major terrestrial sedimentary sequences implies crustal extension to create the necessary accommodation space, is incorrect. We report evidence that the present phase of extension began in the Denizli region at ~ 7 Ma, around the start of the Messinian stage of the Late Miocene. This timing matches the estimated start of right-lateral slip on the North Anatolian Fault Zone, and corresponds to a substantial increase in the dimensions of the Aegean extensional province to roughly its present size: beforehand, between ~ 12 Ma and ~ 7 Ma, extension seems to have only occurred in the central part of this modern province. In some localities, terrestrial sedimentation that began before this start of extension continued into this extensional phase, both within and outside normal fault zones. However, in other localities within the hanging-walls of normal faults, the start of extension marked the end of sedimentation. Relationships between sedimentation and crustal extension in this region are thus not straightforward, and a simple correlation should therefore not be assumed in structural interpretations. During the time-scale of this phase of extension, the Denizli region has also experienced major vertical crustal motions that are unrelated to this extension. The northern part of this region, in the relatively arid interior of western Turkey, has uplifted by ~ 400 m since the Middle Pliocene, whereas its southern part, closer to the Mediterranean Sea and with a much wetter climate, has uplifted by ~ 1,200 m since the Early Miocene, by up to ~ 900 m since the Middle Pliocene, and by an estimated ~ 300 m since the Early Pleistocene. This regional uplift, superimposed on the local effects of active normal faulting, is interpreted as a consequence of lateral variations in rates of erosion. A reliable chronology for this phase of extension in western Turkey, in relation to changes in the geometry of motions of adjoining plates and Late Cenozoic environmental change, is now in place.  相似文献   

Constraint of Apatite T-t History on Uplift of Salient in Southern Jiyang Depression, Eastern China     

WANG Guozhi  ZHANG Shanwen  XIAO Huanqin 《《地质学报》英文版》2013,87(Z1):591-592

  相似文献