江西寻乌破火山口火山-侵入杂岩SHIRMP锆石U-Pb年龄及其地质意义

位于武夷隆起带和南岭构造带过渡部位、受NE向会昌—寻乌断裂带和EW向三南—寻乌断裂带控制的寻乌破火山口发育一套由碎斑熔岩和花岗斑岩组成的火山-侵入杂岩.SHIRMP锆石U-Pb定年结果显示,寻乌破火山口碎斑熔岩的年龄为(96.7±1.1)Ma,花岗斑岩的年龄为(97.3±0.9) Ma,根据国际地质年代表,早白垩世与晚...     

江汉盆地白垩系油气勘探潜力

江汉盆地白垩系分布范围广,全盆地均有分布,但由于其成油气地质条件和成藏条件复杂,导致勘探程度很低。本文从白垩系油源分析入手,分析油气运移方向和路径。通过成藏条件对比分析研究,优选有利区带,并深入分析其勘探潜力。     

二连盆地白北凹陷白垩系下统地震相特征

为使用地震相特征解译沉积分布规律,寻找优质储层。文章通过对地震剖面振幅、连续性、同相轴特征的研究分析,将白垩系下统地震相分为：①中弱振幅低连续性楔形充填;②中弱振幅中连续性楔形充填;③中振幅中高连续性楔形充填;④杂乱反射充填;⑤强振幅中高连续性席状充填;⑥中振幅中连续性席状充填等六种反射构型,并给出相应的识别标志、平面分布范围。分析认为中弱振幅低连续性楔形充填多发育在西部次洼周缘及南部斜坡带;中弱振幅中连续性楔形充填呈北西-南东向展布;中振幅中高连续性楔形充填由盆地边缘向内部延伸;杂乱反射充填处于紧邻断裂带下降盘一侧;强振幅中高连续性席状充填分布于凹陷湖盆中心区域;中振幅中连续性席状充填主要分布于湖盆中心区域,展布面积相对于强振幅中高连续性席状充填更大。     

A new genus and species of Cixiidae (Homoptera: Fulgoroidea) from Lower Cretaceous amber

Mundopoides aptianus gen. et sp. nov. (Homoptera: Fulgoroidea: Cixiidae) is described on the basis of a fossil of an adult female preserved in Lebanese amber of Lower Cretaceous (Aptian) age, and is compared with modern genera.     

六盘山盆地东部炭山地区下白垩统砾岩层位归属及地层对比新认识

六盘山盆地早白垩世地层称为六盘山群,由下至上划分为三桥组、和尚铺组、李洼峡组、马东山组和乃家河组,其中三桥组由紫红色砾岩组成。位于六盘山盆地东部的固原炭山剖面是六盘山盆地白垩系重点研究剖面,该剖面下白垩统六盘山群下部含有一套厚度为28.0 m的砾岩,以往一直归为三桥组,但本套砾岩的基质或填隙物为灰绿色,与三桥组的砾岩的基质或填隙物为紫红色明显不同,通过结合地震剖面地层解释和沉积演化规律研究,新确定了炭山下白垩统剖面的砾岩层位为李洼峡组边缘相,本剖面缺失六盘山群下部的三桥组、和尚铺组。     

A late Mesozoic high plateau in eastern China: Evidence from basalt vesicular paleoaltimetry

Eastern China is made of a number of large and small continental fragments throughout late Paleozoic and Mesozoic time,and is still the best natural laboratory for examining kinematic models of continent tectonics.The paleoelevation history of eastern China provides direct insight into the tectonic processes in China.Here we present basalt-vesicularity based estimates of the paleoaltimetry of the early Cretaceous basalts in northern East China,which indicate that the studied basalt units were at an elevation of more than 4 kilometers in late Mesozoic.Two vesicular basaltic rocks have been collected form bottom to top along the lava flow outcrop in eastern Inner Mongolia.After the digital precessing to the sample cross-sections,and taking advantage of the stereological conversion method to acquire the bubble size distributions,paleoelevation estimate was calculated for East China in the early Cretaceous.The results show that the elevation has been near 4700±750 m when the lava flows was cooling,implying that there were highland regions in the northern part of the East China Plateau during the early Cretaceous.Combined with other geological evidence,we conclude that there was a high plateau with elevation near 5000 m above sea level in Eastern China during the late Mesozoic.This ancient high plateau in eastern China was most likely formed by the collision of the north and south China blocks.     

First discovery and characterizations of late Cretaceous seep carbonates from Xigaze in Tibet, China

Hydrocarbon seeps,widely occurring in continental margins,have become increasingly focused owing to their close relationships with gas hydrates,strong greenhouse gas methane,and biological resources in extreme environments.Ancient hydrocarbon seeps have already been recognized from Devonian to Quaternary strata worldwide based on seep carbonates or seep-related fossil chemosynthetic assemblages.However,seep-related deposits are rarely found from ancient strata in the mainland China.Here,we report the first discovery of an ancient seep deposit,specifically late Cretaceous seep carbonates from Xigaze in Tibet,China.Xigaze seep carbonates,occurring as nodules,are enclosed in upper Cretaceous turbidite strata in Xigaze forearc basin.These carbonates are composed of authigenic carbonate(56.2% on average),clastic quartz and feldspar(27.3% on average),and clay minerals(chlorite,illite and smectite,16.5% on average).Clotted micrites,peloids and framboid pyrites are frequently observed,all of which are common in modern seep carbonates.The carbonates have negative δ13 C values varying from 27.7‰ to 4.0‰(V-PDB),suggesting that thermogenic methane is the primary carbon source.Ce/Ce* values revised by eliminating La effects show no real Ce anomaly,indicating the carbonates were primarily precipitated in a weak reducing environment.Overall,these features provide unequivocal evidences that the seafloor of Xigaze forearc basin developed hydrocarbon seeps in late Cretaceous.     

鄂尔多斯早白垩世自流水盆地沉积特征岩性分布与盆地演化

从盆地边界、盆内结构、沉积环境背景以及沉积物特征入手,探讨了盆地演化与含水岩组分布规律、含水岩组沉积相与含水性之间的关系.结果发现早白垩世时,盆地以南北向为轴、东西两翼非均衡沉降,东缓西陡,结构极不对称;盆内发育的洛河、环河华池和罗汉洞3个主要含水岩组,均受盆地构造演化和沉积相控制,其中洛河组分布最广,环河华池组以及罗汉洞组比较局限.沉积环境变化中沿盆缘以冲积扇、河流相和三角洲平原分流河道相砂砾岩和砂岩沉积为主,盆内由风成沙漠相、三角洲前缘相和湖泊相砂岩和泥岩组成.洛河组风成沙漠相含水砂岩,产状稳定、覆盖面广、岩性组分和结构成熟度高、孔渗性能好、有害可溶组分含量低,顶底板及边界隔挡岩性组合匹配合理,是自流水盆地最理想的含水层.     

New fossil ommatid (Coleoptera: Archostemata: Ommatidae) from Jehol Biota of western Liaoning, China

In this paper one new genus and one new species of fossil ommatid, Odontomma trachylaena gen. et sp. nov., is described and illustrated from the Late Jurassic or Early Cretaceous Yixian Formation of western Liaoning, China. Based on wide epipleural space of elytron with several rows of cells, the new taxa is attributed to tribe Brochocoleini of Ommatidae and compared with genus Brochocoleus. Due to the fact that most other Chinese Mesozoic ommatids are not complete, the complete preservation of the new specimens reported here enabled us to determine the characteristics of the body of these ancient ommatid. Moreover, based on the well-preserved individual of this new genus, we may suppose the affinities of the new species with extant and extinct groups.