Comparison of vegetation and stream sediment geochemical patterns in northeastern New South Wales   总被引：1，自引：0，他引：1  

D. R. Cohen  C. M. Silva-Santisteban  N. F. Rutherford  D. L. Garnett  H. M. Waldron 《Journal of Geochemical Exploration》1999,66(3):383

This study compares the geochemical response of stream sediments and adjacent vegetation samples, with variations in drainage catchment lithology and the occurrence of mineralisation, within a 14,000-km² block of the northeastern region of New South Wales, Australia. The area contains a range of lithologies within a Devonian–Permian accretionary complex and Mesozoic sedimentary basin, as well as a wide range of mineral deposits. Sampling was designed to confine each sub-catchment to a single lithological group (mafic and ultramafic rocks, acid intrusives, volcanics, metasedimentary and sedimentary rocks or alluvium). Leaves of over 20 genera, dominated by (Allo-)Casuarina, Eucalyptus, Acacia, Callistemon and Melaleuca, and the <250-μm fraction of the stream sediments were analysed by INAA. The uptake of most trace elements varied between genera, with Callistemon displaying the highest median As and La contents and Eucalyptus the highest Co contents. The stream sediment and vegetation geochemistry reflect both hydromorphic and mechanical dispersion within sub-catchments, with regional patterns dominant over local influences. The vegetation appears to be influenced to a greater extent by hydromorphic dispersion, as indicated by differences in the ratio of leaf to sediment Cr concentrations in sub-catchments draining serpentinites and basalts. Although most known mineral deposits in the region produced anomalies in at least one medium, there was little correlation between the trace element concentrations of the vegetation and stream sediments on a site-by-site basis. A number of Au targets were only detected on the basis of the biogeochemistry and others were only reflected in the stream sediment geochemistry. In general, vegetation displayed more extensive dispersion trains away from mineralisation than did the stream sediments. Differences in the response of the two sampling media suggest their joint use in exploration or environmental surveys to maximise the probability of detecting mineralisation.  相似文献   

应用GIS研究矿产资源潜力--以云南澜沧江流域为例   总被引：7，自引：0，他引：7  

池顺都  赵鹏大  刘粤湘 《地球科学》1999,24(5):493-497

应用地理信息系统(GIS)技术,深入地研究了云南澜沧江流域成矿的建造和构造,划分出不同级别的地质异常单元和有利成矿的断层影响带;分析了化探异常与相关矿床的耦合度和出现率;系统地总结了已有矿点资料,建立了矿产资源潜力评价空间分析模型.在上述研究基础上作出该地区有色、稀有、贵金属资源潜力图,对资源潜力作出评价.  相似文献   

Stratigraphy, Chronology, and Paleoenvironmental Reconstruction of the Quaternary Sedimentary Infilling of a Volcanic Tube in Fuerteventura, Canary Islands     

Juan J. Coello  Carolina Castillo  Esther Martín Gonzlez 《Quaternary Research》1999,52(3):360

La Cueva del Llano is a volcanic tube of Pleistocene age on Fuerteventura Island, in the Canary Islands. Part of it is infilled with sediments of external origin. These deposits are exceptional in stratigraphic complexity and thickness compared with other known tube infillings, and they comprise nine stratigraphic units deposited in five phases. In Phase I, which has not been dated, sedimentation of cinder from a nearby cone occurred. Phase II began ca. 16,830 ± 900 ¹⁴C yr B.P., whereas phase IV dates to 9280 ± 370 ¹⁴C yr B.P. The interpretation of sedimentary features shows that phases III and V correspond to a dry climate, similar to the present one, whereas the climate was much wetter during phases II and IV. This paleoclimatic sequence agrees with those suggested by the study of deposits formed in other sedimentary environments, not only in Fuerteventura but on other islands of the Canary group and the Sud-Maroc region.  相似文献   

Quaternary colluvium in west-central Anatolia: sedimentary facies and palaeoclimatic significance   总被引：4，自引：0，他引：4  

Nemec  & Kazanci 《Sedimentology》1999,46(1):139-170

The Quaternary colluvial aprons in Lake Eğirdir area, Taurus Mountains, consist of steep coalescent fans, up to 17–20 m thick and 350–450 m in plan-view radius, and the sedimentary succession comprises four lithostratigraphic divisions. The basal red–brown colluvium consists of a chaotic, bouldery fan-core rubble covered with bedded, openwork to matrix-rich gravel, whose deposition is attributed to rockfalls and cohesive debrisflows, with minor grainflows and sheetwash processes. The middle part of this division contains interbeds of early Pleistocene tephra. The overlying light-grey colluvium consists of bedded gravel with numerous palaeogullies and its deposition is attributed to waterflow, rockfalls and cohesive debrisflows. The younger, medium-grey colluvium consists of stratified pebbly sand interspersed with cobble/boulder gravel and its deposition is attributed to sheetwash processes accompanied by rockfalls and wet snowflows/slushflows. A bulk-pollen radiocarbon date indicates Late Würm age. The youngest, yellow–grey colluvium consists of bedded, mainly pebbly and openwork gravel, whose deposition is attributed to dry grainflows, rockfalls and minor cohesive debrisflows. Based on the sedimentary facies assemblages and available isotopic dates, the four colluvial divisions are correlated with the following stages of the region's climatic history: (1) the latest Pliocene to Early Pleistocene stage of warm–humid climate with pronounced phases of drier conditions; (2) the Late Pleistocene stage of colder climate, with alternating phases of higher and lower humidity; (3) the last glacial (Würm) stage of coldest climate; and (4) the Holocene stage of warm semi-arid climate. It is concluded that colluvial depositional systems bear a valuable proxy record of climatic changes and regional geoclimatic differences.  相似文献   

生物地球化学方法与金矿找矿--以新疆西准噶尔安齐成矿断裂带为例   总被引：6，自引：0，他引：6  

沈远超  杨金中  李慎之 《地质科技情报》1999,18(3):55-59

以新疆西准噶尔安齐成矿断裂带的生物地球化学测量工作为例,详细研究了生物地球化学找金法的样品选取,采集和分析过程及其影响因素,并对生物地球化学方法的实际找金效果进行了分析。实验表明,在干旱,半干旱地区,野薤、等是金的敏感载体植物,它们可以带来地下７０ｍ深处的地球化学信息,利用这些信息生物,可以有效地指导找矿。  相似文献   

高质量矿床的勘查战略   总被引：2，自引：0，他引：2  

阳正熙 《地质科技情报》1999,18(2):37-40

邮我国矿产勘查应以高质量矿床作为目标矿床的战略;认为勘查高质量矿床需要加强矿床模式的研究和ＧＩＳ技术的推广应用;确保高质量矿床战略成功实施的思路包括：（１）以高质量金矿床作为勘查目标;（２）加强对典型高质量矿床的研究,寻找同类型高质量矿床;（３）从构造环境发展演化的机理进行成矿分析,制定高质量矿床勘查战略;（４）打破地域限制,促进勘查队伍之间的竞争机制。  相似文献   

南海东北部末次冰期-全新世古海洋学   总被引：36，自引：6，他引：30  

魏国彦  李孟扬  段威武  陈超云  汪中和 《海洋地质与第四纪地质》1999,19(3):19-28

据加速器质谱仪１４Ｃ测年,ＲＣ２６－１６孔提供了南海北部近１５２００ａ来古海洋学的连续沉积记录。其古海洋学发展过程可分为３期,（１）最后冰期（１５．２～１３．３ｋａ）;（２）冰消期（１３．３～９．０ｋａ）;（３）间冰期（９．０ｋａ～现代）。末次冰期至全新世时,冬季海水表层温度由１８℃上升至２４℃,夏季则保持在２７～２９℃之间。在１１ｋａ时,冬季水温曾短暂的一度变凉（约３℃）,此可能代表区内新仙女木事件。末次冰期时,夏季与冬季温度差约为９℃,它的变化幅度较全新世的５℃要大。末次冰期时,表层水（０～５０ｍ）与次表层水（５０～１００ｍ）间碳、氧同位素递减梯度较全新世的为小。１５～１３ｋａ时大洋表层动物衍生营养含量相对较高,推测这与较强的冬季风导致较强的上升流,而造成高养分和高生物生产率有关,全新世时冬季风变弱。全新世碳酸盐补偿深度和有孔虫溶跃层较浅,５．３ｋａ时有短暂的变深,浮游有孔虫保存高峰和碳酸钙高峰值发生在１４～１２ｋａ间,相当于全球性的ＴｅｒｍｉｎａｔｉｏｎⅠ事件。  相似文献   

山东费县大井头地区金刚石原生矿找矿前景探讨   总被引：3，自引：0，他引：3       下载免费PDF全文

仲卫国  周登诗  刘继太  程晓萍  解丽华 《山东国土资源》2003,19(1):43-49

山东费县大井头地区第四系中金刚石及其指示矿物分布异常丰富 ,并且具有较高的集中度 ;该区的加里东期超基性火山碎屑岩、沉火山碎屑岩及其他一些岩石中均有金刚石和 (或 )指示矿物存在 ;该地区的铬铁矿异常属于矿致异常。研究证明该区第四系中金刚石指示矿物与当地的相关岩体关系密切 ;加里东期超基性火山碎屑岩某些特征与火山口相金伯利岩十分相似。大井头地区所处的构造位置有利于金刚石成矿 ,具有良好的找矿前景 ,值得进一步研究探索。  相似文献   

Early Cenozoic paleontological assemblages and provenance evolution of the Lishui Sag,East China Sea     

Yingzhao Zhang  Yiming Jiang  Zhenghua Liu  Shuai Li  Ning Li  Jinshui Liu  Peijun Qiao  Kai Zhong  Shuhui Chen  Thian Lai Goh 《海洋学报(英文版)》2023,42(3):113-122

The East China Sea Shelf Basin generated a series of back-arc basins with thick successions of marine- and terrestrial-facies sediments during Cenozoic. It is enriched with abundant oil and gas resources and is of great significance to the petroleum exploration undertakings. Therein, the Lishui Sag formed fan delta, fluvial delta and littoral-to-neritic facies sediments during Paleocene–Eocene, and the research on its sedimentary environment and sediment source was controversial. This study analyzed the paleontological combination characteristics, and conducted a source-to-sink comparative analysis to restore the sedimentary environment and provenance evolution of the Lishui Sag during Paleocene–Eocene based on the integration of detrital zircon U-Pb age spectra patterns with paleontological assemblages. The results indicated that Lishui Sag was dominated by littoral and neritic-facies environment during time corroborated by large abundance of foraminifera, calcareous nannofossils and dinoflagellates. Chronological analysis of detrital zircon U-Pb revealed that there were significant differences in sediment sources between the east and west area of the Lishui Sag. The western area was featured by deeper water depths in the Paleocene–Eocene, and the sediment was characterized by a single Yanshanian peak of zircon U-Pb age spectra, and mainly influenced from Yanshanian magmatic rocks of South China Coast and the surrounding paleo-uplifts. However, its eastern area partly showed Indosinian populations. In particular, the upper Eocene Wenzhou sediments were featured by increasingly plentiful Precambrian zircons in addition to the large Indosinian-Yanshanian peaks, indicating a possible impact from the Yushan Low Uplift to the east. Therefore, it is likely that the eastern Lishui Sag generated large river systems as well as deltas during time. Due to the Yuquan Movement, the Lishui Sag experienced uplifting and exhumation in the late stage of the late Eocene and was not deposited with sediments until Miocene. Featured by transitional-facies depositions of Paleocene–Eocene, the Lishui Sag thus beared significant potential for source rock and oil-gas reservoir accumulation.  相似文献   

沉积学在造山带地层中的地位和作用     

蔡雄飞  王国灿  李德威 《海洋地质前沿》2004,20(5):17-19

根据地层层序保存程度,将造山带地层分为无序地层体、断片地层体、有序地层体。本文认为造山带绝大多数地层体可进行沉积学的恢复。沉积学在造山带地层和岩相分析中具巨大作用,应更多强调构造与沉积学的紧密结合。  相似文献