Distribution,Compositions and Significance of Oceanic Red Beds     

Xuan Lyu  Zhifei Liu 《地球科学进展》2017,32(12):1307-1318

Oceanic red beds are widely distributed in the global oceans and across the entire Phanerozoic period, which mostly appeared after oceanic anoxic events. They represent typical oxygen-rich sedimentary environment and play a significant role on ocean science research. Numerous studies have been carried out since the oceanic red beds were discovered. However, previous studies mainly focused on the Cretaceous oceanic red beds, and the understanding of the characteristics and scientific significance of oceanic red beds are not comprehensive. Therefore, we here summarized the global distribution characteristics and compared mineral and element compositions of various lithological oceanic red beds, including marly, clayey and cherty oceanic red beds. The main mineral and element components of oceanic red beds have no direct relationship with the color of the sediments, and mainly are affected by the regional environment and provenances. Therefore, the mineralogical and geochemical characteristics of oceanic red beds should be analyzed in combination with the regional background. The red coloration of oceanic red beds is controlled mainly by hematite, goethite and manganese-bearing calcite, which have two main mechanisms: ① Colored minerals formed in oxic conditions; ② Colored minerals formed due to low deposition rates. These two mechanisms are not completely independent, but complement one another with either dominance in most oceanic red beds. Lithological characteristics of oceanic red beds are controlled by three factors, including water depth, productivity and nutrients. Therefore, the formation of oceanic red beds should be considered with global changes and regional events. The unique origin mechanism and global distribution characteristics of long time-scale oceanic red beds can be used to indicate sedimentary paleoenvironment, paleo-oceanic current, and paleoclimate change. In addition, hydrothermal or magmatic activities on the ocean floor could also produce red-color deposits that are strongly different from sedimentary oceanic red beds. Based on the existing research, we also put forward the future in-depth studies on the oceanic red beds from multidisciplinary perspectives.  相似文献   

New Early Cambrian Chordates from Haikou, Kunming   总被引：8，自引：0，他引：8  

LUO Huilin  HU Shixue  CHEN Liangzhong Yunnan Institute of Geological Sciences  Baita Ro  Kunming  Yunnan 《《地质学报》英文版》2001,75(4):345-348

Two new chordates, Cathaymyrus haikouensis Luo et Hu sp. nov. and Zhongxiniscus intermedius Luo et Hu gen. et sp. nov. are studied in this paper. Both display numerous S-shaped myomeres on their trunk. C. haikouensis shows a long and slim body similar to that of Cathaymyrus diadexus Shu et al., Zhongxiniscus approaches to Myllokunmingia and Haikouichthys in the dorsal fin, but differs in the myomeres. Zhongxiniscus may be the intermediate form between Cathaymyrus and Myllokunmingia and Haikouichthys.  相似文献   

关于地震数据采集系统的高分辨率高保真问题     

董世学  刘起元 《吉林大学学报(地球科学版)》1995,(2)

地震数据采集系统的性能如何对增加辩信息量、提高分辨率和数据的高保真问题有直接影响。文章对这些问题进行了讨论，并对改进其性能、进行合理配置提出了具体措施  相似文献   

Isotopic dating of the Chengjiang Fauna-bearing horizon in Central Yunnan Province, China   总被引：1，自引：0，他引：1  

CHANG Xiangyang CHEN Liangzhong HU Shixue WANG Jianghai ZHU Bingquan 《中国地球化学学报》2007,26(4):345-349

Twenty black shale samples, which are free from the influence of weathering, were collected from the Chengjiang Fauna-bearing horizon, central Yunnan Province, yielding a Pb-Pb isochron age of 534±60 Ma. Although this age is younger than both the Rb-Sr isochron age and 40Ar-39Ar age, it should represent the lower isotopic age limit of the Chengjiang Fauna.  相似文献   

基于Web和FTP的农业气象移动短信业务平台          下载免费PDF全文

史彩霞余纬东  刘世学袁丽军 《气象科技》2007,35(B12):49-52

以Web和FTP技术为依托，建立了广西农业气象移动短信业务平台，并对农业气象短信编写、审查、上传到移动公司服务器、移动网关发送短信等相关技术进行了详细的介绍。短信业务平台系统分为3个部分：①编写农业气象信息并生成农业气象信息文件；②检查农业气象信息并更新农业气象信息文件；③上传最新农业气象信息文件。系统采用模块化程序设计4层架构，4层分别独立，提高系统的安全性、稳定性和可维护性，为开通农业气象短信业务提供一个参考模式。  相似文献   

Trace element composition of magnetite from the Xinqiao Fe–S(–Cu–Au) deposit,Tongling, Eastern China: constraints on fluid evolution and ore genesis     

Yichang Wang  Jianfeng Gao  Xiaowen Huang  Liang Qi  Chuan Lyu 《中国地球化学学报》2018,37(5):639-654

The Xinqiao deposit is one of several polymetallic deposits in the Tongling ore district. There are two types of mineralization in the Xinqiao: skarn-type and stratiform-type. The skarn-type mineralization is characterized by iron oxides such as magnetite and hematite, whereas stratiform-type mineralization is characterized by massive sulfides with small amounts of magnetite and hematite. We defined three types of ores within the stratiform-type mineralization by the mineral assemblages and ore structures. Type I ore is represented by magnetite crosscut by minor calcite veins. Type II is a network ore composed of magnetite and crosscutting pyrite. Type III is a massive ore containing calcite and hematite. Type I magnetite is characterized by highly variable trace element content, whereas Type II magnetite has consistently higher Si, Ti, V, and Nb. Type III magnetite contains more In, Sn, and As than the other two types. Fluid–rock interaction, oxygen fugacity (fO₂), and temperature (T) are the main factors controlling element variation between the different magnetite types. Type I magnetite was formed by more extensive fluid–rock interaction than the other two types at moderate fO₂ and T conditions. Type II magnetite is thought to have formed in relatively low fO₂ and high-T environments, and Type III in relatively high fO₂ and moderate-T environments. Ca?+?Al?+?Mn and Ti?+?V discrimination diagrams show that magnetite in the Xinqiao deposit is hydrothermal in origin and is possibly linked with skarn.  相似文献   

Geological and hydrogeological environment in Tianjin with potential geohazards and groundwater control during excavation     

Yong-Xia Wu  Hai-Min Lyu  Jack Shuilong Shen  Arul Arulrajah 《Environmental Earth Sciences》2018,77(10):392

This paper discusses the geological and hydrogeological features of Quaternary deposits in Tianjin as well as the geohazards related to groundwater hydrology in this region. The soft soil deposits, comprising silt, sand, silty clay and clay, are composed of four aquifer groups. In the first aquifer group, one phreatic aquifer and two confined aquifers have relationships with underground construction in the urban area. These three aquifers are separated by two aquitards and collectively form a multi-aquifer system. During geotechnical construction, potential geohazards present are related to the groundwater, which include water-in-rushing, quicksand and piping hazards. To prevent the aforementioned geohazards, dewatering is conducted; however, groundwater pumping may result in large settlements of the surrounding ground. To reduce pumping-induced settlement, the dewatering–waterproofing system has been adopted. According to the characteristics of the subsoil, excavation depth and the surrounding environment, the dewatering system can be divided into five patterns. In the first four patterns, when pumping is conducted in the excavation pit, the groundwater head in the adjacent aquifers outside the pit decreases due to the leakage effect of the aquitards located between the aquifers. In the fifth pattern, waterproof curtain has cut off the aquifers completely and dewatering in the pit cannot result in settlement around excavation pit. To avoid geohazards related to groundwater hydrology, countermeasures recommended include construction of an effective waterproof curtain, selection of a reasonable excavation dewatering pattern and withdrawal of required groundwater.  相似文献   

Clay mineral assemblages of the oceanic red beds in the northern South China Sea and their responses to the Middle Miocene Climate Transition     

He  Lei  Liu  Zhifei  Lyu  Xuan  Ma  Pengfei 《中国科学:地球科学(英文版)》2022,65(5):899-909

Science China Earth Sciences - The Middle Miocene Climate Transition (MMCT, ～14 Ma) is the largest cooling event in the Cenozoic “Coolhouse”, which significantly impacts the...  相似文献   

A glimpse into rapid freezing processes in clay with x-ray tomography     

Amato  Giorgia  Andò  Edward  Lyu  Chuangxin  Viggiani  Gioacchino  Eiksund  Gudmund Reinar 《Acta Geotechnica》2022,17(1):327-338

Acta Geotechnica - This short paper proposes time-series x-ray tomography as a valuable tool for quantifying freezing processes in a remoulded clay. As an example, three simple closed system...  相似文献   

陕北三叠纪煤田中—特高油产率煤分布规律及成因机理     

马丽  段中会  贺丹  周蕾  吕婷婷  闫和平  王锐 《中国煤炭地质》2022,(1)

以子长矿区内分布的300余组钻孔数据为基础,研究了陕北三叠纪煤田煤炭资源的物理化学性质,按照《煤中焦油含量分级》(MT/T1179—2019),划分了中油产率煤(7.0%<ω(Tar_d)<12.0%)和高油产率煤(12.0%<ω(Tar_d)<15.0%)的分布范围,预测了中—特高油产率煤的资源量。研究了矿区主采煤层3号煤层和5号煤层的煤质、沉积环境、变质程度等,认为矿区内中—特高油产率煤具一低两高的特征:镜质体反射率高(0.61%~0.83%)、变质程度低、挥发分高(35.78%~45.64%),认为成煤环境及变质程度是影响煤层富油的关键因素,研究区内5号煤层的焦油产率略高于3号煤层。  相似文献