Influence of bare soil and cultivated land use types upstream of a bank gully on soil erosion rates and energy consumption for different gully erosion zones in the dry-hot valley region,Southwest China

This study assessed temporal variation in soil erosion rates in response to energy consumption of flow (ΔE). It employed an in situ bank gully field flume experiment with upstream catchment areas with bare (BLG) or cultivated land (CLG) that drained down to bare gully headcuts. Water discharge treatments ranged from 30 to 120 L Min⁻¹. Concentrated flow discharge clearly affected bank gully soil erosion rates. Excluding minimal discharge in the CLG upstream catchment area (30 L min⁻¹), a declining power function trend (p ≤ 0.1) was observed with time in soil erosion rates for both BLG and CLG upstream catchment areas and downstream gully beds. Non-steady state soil erosion rates were observed after an abrupt collapse along the headcut slope after prolonged scouring treatments. However, as the experiment progressed, ΔE and energy consumption of flow per unit soil loss (ΔEu) exhibited a logarithmic growth trend (p < 0.1) at each BLG and CLG position. Although similar temporal trends in soil erosion and infiltration rates were observed, values clearly differed between BLG and CLG upstream catchment areas. Furthermore, Darcy–Weisbach friction factor (f) values in the CLG upstream catchment area were higher than the corresponding BLG area. In contrast to the BLG upstream catchment area, lower ΔEu and higher soil erosion rates were observed in the CLG upstream catchment area as a result of soil disturbances. This indicated that intensive land use changes accelerate soil erosion rates in upstream catchment areas of bank gullies and increase soil sediment transport to downstream gullies. Accordingly, reducing tillage disturbances and increasing vegetation cover in upstream catchment areas of bank gullies are essential in the dry-hot valley region of Southwest China.

     

珠江口盆地重要不整合界面与珠江沉积体系演化分析

以珠江口盆地区域二维地震资料、钻井资料为基础, 结合南海扩张演化历史, 重点研究了盆地内部重要不整合面、盆地演化以及对珠江沉积体系演化的控制作用, 旨在为南海北部珠江沉积体系深水油气勘探提供支持和参考。研究结果表明:珠江口盆地除基底外, 发育三个重要的不整合面, 即破裂不整合、陆坡跃迁不整合和陆坡坡度突变不整合;据此将珠江口盆地珠江沉积体系演化划分为四个阶段:裂陷期主要发育河流、湖泊相沉积;断陷陆坡期主要发育陆架边缘三角洲沉积(前积层较陡);拗陷缓陆坡期发育陆架边缘三角洲沉积(前积层较缓);拗陷陡陆坡期主要为三角洲-海底峡谷-海底扇沉积。断陷陆坡期与拗陷缓坡期陆架边缘三角洲的勘探, 应沿陆架坡折横向去勘探;而拗陷陡陆坡期三角洲-海底峡谷-海底扇, 应采取纵向勘探的思路, 垂直于陆架坡折方向寻找油气。     

西藏羌塘盆地半岛湖地区索瓦组锶同位素组成与演化

西藏羌塘盆地中生代发育广泛的海相碳酸盐地层,前人对该区地层的对比研究多局限于古生物地层学,本文尝试通过锶同位素地层学方法对上侏罗-下白垩统索瓦组地层进行全球对比。根据锶同位素地层学的基本原理,本文在对样品进行显微组构分析、阴极发光分析、Ca、Si、Sr和Mn等元素含量分析及评估其对同期海水代表性和样品溶解过程合理性的基础上,测试了羌塘盆地半岛湖地区上侏罗-下白垩统锶同位素组成,并建立了相应的演化曲线,进行了全球对比研究。结果表明,样品的锶同位素组成与前人已公布的同期海水锶同位素组成数据较为接近,其演化曲线与国际上已公布的锶同位素演化曲线有着较好的可对比性,晚侏罗-早白垩世时期全球海平面的变化和侵蚀作用的强弱是控制锶同位素演化曲线的主要因素。此外,通过对索瓦组海相碳酸盐锶同位素的研究,我们认为索瓦组的顶部可能延伸到早白垩世欧特里夫期,近而说明了羌塘盆地在早白垩世欧特里夫期还存在大规模的海相地层。     

从西南天山超高压变质带多期构造变形看天山古生代构造演化

通过对西南天山阿克雅孜和木扎尔特地区高压-超高压变质带构造几何学和岩石变形相关运动学的详细剖析,厘定出高压-超高压变质岩石及其相关围岩的构造单元。详细研究表明,研究区可划分为三个构造单元:北部单元、中部单元和南部单元。确定了每个构造单元的构造几何学特征及各个构造单元之间的相互关系。通过分析岩石变形特征和叠加关系,确定了岩石所记录多期变形的运动学特征。根据研究区的多期构造变形特点,建立了阿克雅孜和木扎尔特河地区构造演化序列。共划分出四期构造可识别的事件(E1-E4),分别代表了E1:高压-超高压岩石折返过程;E2:高压-超高压岩石造山带的早期改造过程;E3:北部构造事件对高压-超高压造山带影响;E4:走滑构造对高压-超高压造山带的叠加。沿造山带系列构造分析表明,西南天山高压-超高压带中发育的四期构造事件沿中天山北缘具有很好的一致性,各期构造事件也有一定的横向可对比性。在此基础上通过对多期变形事件的构造背景的探讨,建立了整个天山在古生代的构造拼合过程,揭示我国西部洋壳相关的深俯冲造山带形成过程和参与深俯冲作用(超)高压变质岩的变形变质历史。     

新疆萨尔托海高铝铬铁矿中异常矿物群的发现及意义

在萨尔托海高铝型铬铁矿中发现20余种矿物,包括金刚石、单质铬、自然铁和单质硅等自然元素类;碳化物碳硅石;铁镍、铁镍铬合金等金属合金;方铁矿、金红石、赤铁矿、磁铁矿、钛铁矿、石英和铬尖晶石等氧化物类;方铅矿、闪锌矿、针镍矿、赫硫镍矿和毒砂等硫化物类;镁橄榄石、顽火辉石、透辉石、蛇纹石、锆石和长石等硅酸岩类。这些超高压、强还原性和壳源矿物与俄罗斯极地乌拉尔以及西藏罗布莎铬铁矿可以对比,暗示萨尔托海高铝铬铁矿和高铬铬铁矿一样,可能存在深部地幔成矿阶段。深部地幔矿物以及浅部壳源矿物的发现,暗示萨尔托海铬铁矿的形成可能经历了深部地幔预富集和浅部再造富集成矿两个阶段。     

大兴安岭南部幸福之路组的时代及二叠—三叠系界线研究——来自凝灰岩LA-ICP-MS锆石U-Pb年龄的证据

多数研究者认为西拉木伦河—长春—延吉断裂带为华北与西伯利亚两大板块的最后缝合带,但最后拼合时间仍存在分歧,原因之一是对晚二叠世—早三叠世地层研究不足,尤其是对上二叠统与下三叠统接触关系研究更为欠缺。幸福之路组分布于大兴安岭南部,为一套以红层为主要特征的杂色碎屑岩组合,含有叶肢介、介形虫、双壳、植物及孢粉化石。笔者对采自巴林右旗幸福之路苏木幸福之路组上段的岩屑晶屑凝灰岩样品进行了LA-ICP-MS锆石U-Pb测年分析,结果为(254.3±2.6)Ma。结合已有的火山岩测年及化石资料认为,幸福之路组上段下部时代为晚二叠世,上部为早三叠世早期,大兴安岭地区上二叠统与下三叠统为连续沉积,晚二叠世晚期两大板块发生碰撞拼合,古亚洲洋消失,发生南北生物群的混生,早三叠世西伯利亚板块和华北板块碰撞结束。     

雅鲁藏布缝合带巴尔蛇绿岩边部石英菱镁岩成因

石英(滑石)菱镁岩是基性岩、超基性岩与富CO2流体反应形成的一套硅化-碳酸盐化蚀变岩,常伴生金、汞、菱镁矿、碱金属矿化而在国外备受关注,但国内相关研究较薄弱。巴尔蛇绿岩位于西藏阿里地区,石英菱镁岩主要出露在蛇绿岩体东北边界,出露厚度约20 m,近北西西向延伸数千米。本文系统研究了雅鲁藏布缝合带西段巴尔蛇绿岩边部石英菱镁岩矿物学及地球化学特征。根据尖晶石镜下特征,划分为两个阶段:一阶段石英菱镁岩中尖晶石稳定存在,二阶段石英菱镁岩中尖晶石几乎全部蚀变(代表更强程度蚀变作用)。石英菱镁岩主要地球化学组成为Si O2、Mg O及CO2,8件样品主量元素含量变化较大,Si O2/Mg O比值波动较大,反映石英菱镁岩形成为非等化学过程。蛇纹石化橄榄岩与石英菱镁岩有着相似微量元素分布规律,表明同源性,但两者仍有较明显差异:两阶段石英菱镁岩LREE都较地幔橄榄岩略富集,从地幔橄榄岩到两阶段石英菱镁岩,HREE先亏损再略富集。微量元素标准化图解中,Sr在橄榄岩与石英菱镁岩中都为正异常,其含量随蚀变强度增强而增加。此外,两阶段石英菱镁岩均无Au、Hg矿化。     

套管外补贴技术及其在惠州油田的应用分析

针对海洋油田长时间开发后出现的套管完整性问题,考虑到传统的修补措施如跨越式封隔器等无法满足后期作业对井眼尺寸的要求的现状,提出了套管外补贴技术。介绍了套管外补贴的原理及在惠州油田HZ19-3-6和HZ26-1-16井的应用情况。结果表明,修复后的套管能保持原有强度且产生永久密封,具有不“牺牲”井眼尺寸等优点。针对作业过程中出现的复杂情况进行了深入分析,对海洋油田套管完整性的修复工作具有实践和理论指导意义,同时也给水井、地热井套管的修复提供借鉴和启示。     

基于北斗(BDS)的野外安全生产平台设计与实现

野外安全生产平台是应用北斗短报文通信,实现地质勘查项目野外数据采集安全管理、数据管理和质量管理功能。据地质勘查野外作业特点,提出构建智能移动终端、生产管理助手和实时监控综合应用平台的设计方案,提高野外作业工作效率,增强野外作业安全保障。     

Paleostress Reconstruction of Micangshan Anticlinorium on the Southern Margin of the Qinling Orogenic Belts, China

Brittle structures in rock of different ages can be used to establish the tectonic evolution of an orogenic belt through paleostress calculations. Micangshan is located at the southern margin of the Qinling orogenic belt,between the SE-trending Longmenshan fold-and-thrust belt and the arcuate Dabashan thrust-and-fold belt. Structural observations revealed that the dominant structures are reverse and strike-slip faults and folds with E–W and NE–SE trends. To increase knowledge of the tectonic evolution of the Micangshan anticlinorium,faults,joints,veins,and folds were measured at more than eighty sites. On the basis of structural analysis,it emerged that the multiphase paleostress fields became established after the oblique collision between the North and South China plates. The earliest stress field with N–S compression was established during the Micangshan uplift associated with the E–W trending faults and folds. Subsequently,a N–S extension occurred when the Qinling orogenic belt collapsed. Then NW–SE compression developed,with NE trending faults and folds forming in relation to Longmenshan thrusting toward southwest on the eastern margin of the Tibetan plateau. With the development of the arcuate Dabashan orogenic belt,the compression stress orientation of the Micangshan anticlinorium altered from NE–SW to E–W.