西南岩溶地区不同含水介质地球物理勘查技术

针对西南岩溶地区表层带岩溶水、管道型岩溶水(溶洞、暗河、管道等)、构造裂隙岩溶水等不同类型地下水赋存介质特点,通过适宜的地球物理方法使用条件以及找水特点的分析,提出不同含水介质中寻找地下水地球物理勘查要解决的地质问题、拟采用的综合物探方法,分别总结出了它们的电性参数(或曲线)的响应特征,形成了不同含水介质的地球物理勘查技术组合方案。最后通过实例验证其实用性,并对在西南岩溶地区地下水地球物理勘查工作中积累的技术经验进行了总结。      

In search of Gondwana heritage in the Outer Melanesian Arc: no pre-upper Eocene detrital zircons in Viti Levu river sands (Fiji Islands)

Volcanic arcs of the Southwest Pacific, collectively referred to as the Outer Melanesian Arc, are generally thought to result from subduction of the Pacific Plate since the Late Cretaceous. Meanwhile, it is largely accepted that eastward roll-back of the old and dense oceanic plate allowed opening of marginal basins, which isolated large blocks of the former Gondwana margin. Incidentally, some ‘intra-oceanic’ volcanic arcs may have been nucleated on small continental fragments. Detrital zircons collected from sand banks in the mid-reaches of rivers from Viti Levu Island have been analysed for U–Pb geochronology and geochemistry, in order to search for a possible ancient continental arc basement, remnants of a Late Cretaceous arc, and determine the timing and evolution of Fiji arc magmatism. In contrast with some other places of the Outer Melanesian Arc (Solomon, Vanuatu), no pre-upper Eocene zircons have been found. Thus, Gondwana-derived fragments or Late Cretaceous–Paleocene arc remnants are unlikely to form the basement of Viti Levu. Zircon geochemistry confirms the purely intra-oceanic character of volcanic-arc magmatism as well. Variations in some trace-element ratios closely reflect the evolution of Viti Levu Arc from upper Eocene inception to upper Miocene climax and finally Pliocene intra-arc rifting and abandonment.     

西南印度洋中脊63.9°E斜长石超斑状玄武岩对超慢速扩张洋脊岩浆过程的指示

人们对超慢速扩张洋中脊深部岩浆过程的了解至今仍十分模糊。我们对西南印度洋洋中脊(Southwest Indian Ridge,SWIR) 63. 9°E处采集到的斜长石超斑状玄武岩(Plagioclase Ultra-Phyric Basalt,PUB)进行了岩石学和地球化学研究。样品具有以下几个特征:斜长石斑晶的体积分数高达～25%,而橄榄石斑晶的体积分数约1%;尽管该样品中玻璃的成分与同一洋脊段玄武岩的成分基本一致,但高Fo橄榄石斑晶与玻璃基质的成分不平衡;不同类型的斜长石晶体之间存在成分差异,单个斜长石大斑晶中的An值也呈现出与正常的结晶分异过程不符的环带;斜长石斑晶中发育溶蚀、筛状等不平衡结构。因此,我们认为,斜长石超斑状玄武岩经历了多期次熔体的作用,是由通过密度分选聚集在岩浆房顶部的斜长石斑晶被之后的火山喷发带出海底形成。尽管斜长石超斑状玄武岩与同一洋脊段的非斑状玄武岩之间并不存在母熔体成分上的差别,但超斑状玄武岩的出现进一步反映了超慢速扩张洋壳岩浆活动的多样性。     

活动推覆构造区潜在震源的边界和震级上限——以1902年阿图什8(1/4)级地震构造区为例

1902年阿图什81/4级地震发生在西南天山山前推覆构造体中,逆冲推覆构造由推覆体的根部断裂、推覆体、滑脱断层和前缘逆断裂-褶皱等组成,大地震的发震断裂往往是推覆构造的根部断裂,而地震地表破裂和同震褶皱隆起则位于山前逆断层-褶皱带内。高震级的潜在震源区(MU7.5)对应于低速的天山地块和高速的塔里木地块之间的根带断裂,其长度对应于推覆体根带断裂的长度,宽度对应于根带隐伏逆冲断裂在地表的投影宽度。推覆体前缘的每个活动逆断裂-背斜对应于一个潜在震源(MU≤7.5),其长度与活动逆断裂-背斜的长度相等,宽度应覆盖活动褶皱的两翼。潜在震源的矩震级上限由W-C统计关系式确定,其中发震断裂的面积为活动褶皱的长度与隐伏断坡宽度的乘积。     

西南天山乌什北山高山峡谷地貌形成过程

地貌演化过程受大地构造及其规律的控制。本文通过对西南天山乌什北山地区滚滚铁列克河第四纪沉积和侵蚀地貌的观测,结合已发表的地层年代学研究,恢复了中更新世和全新世两期侵蚀地貌演化过程。中更新世地貌切割深度达1870 m以上,远远大于全新世50 m的地貌切割深度,认为该地区的高山峡谷地貌形成于中更新世。西南天山普遍发育的中更新世褶皱冲断构造,造成山体快速大幅隆升,是乌什北山高山峡谷地貌形成的主因。褶皱冲断构造向盆地方向扩展,导致山体向盆地方向隆升幅度减小,揭示了乌什北山地貌演化的空间规律。西南天山第四纪构造隆升过程与地貌演化之间存在密切关系。     

Review of marine recreational fisheries regulations in Argentina

The effects of recreational fishing on marine stocks and ecosystems have raised global concern in recent years. In Argentina, Southwest Atlantic, angling, netting and spearfishing of coastal bony fishes, sharks, rays and chimaeras are very popular pastime activities with more than 50 years of history. Despite the perceived traditional and economic relevance of these activities in the country, marine recreational fisheries were largely unregulated, and no official fisheries monitoring programs at the national level have been ever put in place. Except for a few particular systems for which some catch-and-effort data were collected by research institutions and non-governmental organizations, no comprehensive surveys aimed at describing the ecological, social or economic aspects of these fisheries have been made. Here, an updated review of the regulations in place for marine recreational fisheries along the Argentine coastline is presented. Of the five coastal provinces encompassing ca. 8400 km and about 20 latitude degrees (~36°S to 55°S) of coastline, only Buenos Aires province has a thorough legislation for its whole territory, which includes 15 protected areas. In the remaining provinces, the regulations for marine recreational fisheries are limited to a few protected areas (seven out of 37 coastal areas under provincial, national or shared jurisdiction). This lack of legislation encourages alleged recreational fishers to develop small-scale commercial fishing operations that are neither controlled nor monitored as such, contributing to the overexploitation of some key coastal stocks.     

巴布亚新几内亚利希尔岛拉多拉姆(Ladolam)金矿矿床地质特征及找矿标志

巴布亚新几内亚利希尔岛拉多拉姆金矿处于太平洋板块与印澳板块的板块边界部位,为西南太平洋地区最大的碱性侵入岩有关的低硫型浅成低温热液型金矿。矿床赋存在Luise火山内,成矿与更新世碱性二长闪长岩侵入体有关,该岩体形成于俯冲带环境下被流体交代的上地幔的部分熔融。矿床的矿化可分为三个阶段,在岩体侵入后形成斑岩铜矿化,并在之后逐渐过渡为浅成低温热液型金矿化。该类矿床在成矿过程和矿体的分布明显受到区域性构造、蚀变带和成矿有关角砾岩等成矿结构面的控制,在找矿标志上具有特定的物化探和地质特征,具有较好的找矿远景。     

我国西南地区岩溶水资源的基本特征及其和谐利用对策

应用岩溶学、水文地质学和水资源经济理论,以科学发展观为指导,按照经济社会可持续发展和水资源与人、生态环境、经济社会发展相和谐的理念,对我国西南地区岩溶水资源的基本特点、我国西南岩溶水资源和谐利用及其不利因素与问题进行了论述。在此基础上,提出了加强岩溶水资源勘查和有效配置、正确开发、高效利用、有效保护及统一管理为主要措施的我国西南岩溶水资源和谐利用对策。