A re-examination of the evidence for a plio-pleistocene marine transgression on the Chiltern hills. I. structures and surfaces

Borehole and surface outcrop data are used to construct sub-Chalk, sub-Upper Chalk and sub-Tertiary contour maps for the Chiltern area. The results show a southwest-northeast monocline, which coincides with the change of slope at the lower boundary of the morphological bench on the Chalk dipslope that Wooldridge and Linton attributed to Plio-Pleistocene marine erosion. Younger northwest-southeast synclines coincide with the main transverse river valleys of the Chilterns. The monoclinal flexuring casts doubt on the value of the bench as evidence for a Plio-Pleistocene transgression.     

A re-examination of the evidence for a Plio-Pleistocene marine transgression on the Chiltern Hills. II. drainage patterns

The dry valley pattern of the Chiltern Hills is divided into 55 third order drainage basins which are grouped morphometrically into five groups. The character and distribution of the groups are determined mainly by the lithology of surface deposits and the structure of the underlying Chalk. No evidence has been found for different drainage patterns on the parts of the dipslope equivalent to the ‘Mio-Pliocene peneplain’ and ‘Plio-Pleistocene marine platform’ of Wooldridge and Linton (1955), nor for superimposition of drainage from covers of Plio-Pleistocene or Palaeogene sediments.     

Did marine transgression happen in Late Cretaceous period in the southeast of Songliao Basin ？——Discussion from evidence of water chemistry

Cretaceous sediment is considered to be the important oil reservoir in the Songliao Basin, which is dominated by continental fluvial and lacustrine strata. In the past decades, research on whether the marine transgression happened in the Late Cretaceous period in the southeast of the Songliao Basin is always a hotspot in China. Previous studies analyzed the marine biology and geochemistry of sediments to argue if the marine transgression had occurred. However, the geochemistry of formation water which could indicate the paleo-environment has not attracted attention. In this paper, the geochemical variations of formation water between the Chaoyanggou anticline, Changchun anticline and Binxian depression in the southeast of the Songliao Basin are analyzed, then the results by comparisons with chemical properties of sea water indicated： （1） the extensive range of pH values from 6 to 10 concerning the formation water. The ranges of TDS of the formation water are from 1 g/L to 20 g/L, which is less than the value in the seatwater; （2） the level of the element Br, which is an important trace element to indicate the marine sedimentary environment, is lower than that from the sea water. The concentrations of the trace element B fluctuate intensively, probably due to the enhancement of water-rock interaction and the enrichment of organic matter; and （3） ionic ratio of Na/Cl and Br＊ 1000/Cl in the formation water are higher than the value of 0.8575 and lower than 1.5363 in the sea water, respectively, which might be attributed to halite dissolution.     

江苏南部滆湖成因演化的初步认识

借助高速公路勘察资料及前人研究成果,分析了江苏南部滆湖地区第四纪晚更新世土层空间的展布特征。据此认为,晚更新世晚期在常州西存在北东走向的古长江汊流河谷,滆湖是连接该河谷的古河道所在地。湖区钻探水下发现宽达300m的北东走向全新世古河道,进一步说明河道淤塞是形成现今滆湖的主要成因。     

陆相盐湖层序地层学研究简述

陆相盐湖盐源复杂多样,主要有陆源、海源和地壳深部三大类。前两类主要通过蒸发成盐,气候起着关键作用,形成的陆相盐湖低水位和高水位体系域中盐岩发育,湖侵体系域中盐岩相对不发育;第三类主要通过兑卤成盐,作为深层卤水通道的深大断裂的活动期次控制了盐岩的发育,盐岩主要发育在湖侵体系域,高水位体系域次之,低水位体系域中盐岩一般不发育。     

塔里木盆地东河砂岩沉积和储层特征及综合分析

东河砂岩是一套覆盖广泛的海侵初期的沉积产物,但不是一个等时沉积体,相当于晚泥盆世晚期至早石炭世早期沉积,具体沉积时间各地有差异。东河砂岩具有海侵初期填平补齐的特征,其沉积相决定于海侵的速度、沉积物的供给和海侵前的古地貌。塔北地区受塔北古隆起的阻挡,海水在古隆起周围滞留时间较长,又有较粗粒的物源供给,其沉积产物主要是滨岸海滩沉积;塔中地区由于地形复杂,沉积类型也比较复杂,底部砾岩段为河流相沉积,而块状砂岩段和砂砾岩段为河口湾和滨岸海滩沉积,不同段在成分、分选性和粒级上有较大的差异;塔里木盆地其他低平地区主要是海侵期快速的滨岸和陆架沉积。受沉积因素影响,东河砂岩有效储层的分布具有地域性,除沉积因素外,低的地温梯度和短期的深埋藏也是优质储层发育的重要控制因素。     

华北晚古生代陆表海盆地海侵事件微观沉积特征及成煤探讨

采用沉积学、煤地质学、古生物学、地层学及地球化学等多技术手段,结合比较分析法的思路,分析了事件型海侵的特点和海侵事件沉积组合特征,研究发现:海侵事件沉积组合为区域对比性强、具沉积时间连续性与相序间断性的暴露沉积-煤层-灰岩组合,其关键沉积学特征是煤层底板的暴露沉积.海侵事件组合灰岩的古生化石个体小、破碎强烈等特征表现为高能量水体运动等环境,孢粉表现为低含量的单缝孢和裸子植物及高含量的三缝孢.地球化学分析表明暴露沉积为陆相环境,煤层中的微量元素表现为海相主要原因是由于泥炭沼泽覆于深水后受海水影响所致.海侵事件成煤与海侵过程成煤差异体现在两个方面:第一,盆地属性差异,即海侵事件成煤形成于陆表海盆地之中,而海侵过程成煤则形成于具有缓坡的边缘海盆地,第二,成煤原理存在着差异,海侵事件成煤强调的是成煤前海侵未发生前的碎屑体系废弃而发育大量泥炭沼泽且被后期突发性海侵终止,而海侵过程成煤则强调的是泥炭沼泽发育于滨海的活动碎屑体系并终止于后期的缓慢海平面上升.     

闽江河口区晚更新世以来的自然环境变化

闽江河口区处于中亚热带向南亚热带的过渡地带,自然环境演变复杂。本文着重研究其晚更新世以来的海陆变迁与气候变化,讨论其3次海进、2次高海面以及全球气候-海面变化对它的影响。     

全新世海侵与盐城市西冈古砂堤研究

西冈位于盐城市西部,是全新世海侵时代的产物,也是盐城市境内成陆最早的陆地。本文通过对全新世以来海面变化、西冈的地貌形态、沉积特征、形成条件等方面的研究,探讨全新世海侵对西冈古砂堤形成的影响以及苏中地区海岸的演变规律。     

珠江口盆地晚第四纪地层及环境初步研究

本文利用珠江口盆地四个工程钻井的古生物、古地磁、同位素及沉积物资料，对钻孔所揭露的地层进行划分，认为所钻遇的地层包括下更新统（上部）、中更新统、上更新统及全新统。依据古生物分异度及含量作出海平面变化曲线，识别出十个海侵期，利用钙质超微化石特征种的初现面和末现面资料，将本区海平面变化曲线与太平洋Ｖ＿（２８－２３９）氧同位素曲线对比，分析了本区晚第四纪以来的沉积环境和气候，认为早更新世晚期，中更新世中期，晚更新世早期及全新世本区气候温暖，沉积环境属陆架浅海环境。