Long‐term landscape evolution in the Darwin region and its implications for the origin of landsurfaces in the north of the Northern Territory

The development of landsurfaces in the north of the Northern Territory has traditionally been attributed to successive episodes of uplift, erosion and weathering. The lower and younger two of the four landsurfaces attributed to such development, the Wave Hill and Koolpinyah surfaces, dominate the landscape in the Darwin region. Investigations of the relationship between the Cretaceous stratigraphy and the nature of deep weathering in the Darwin region show that these surfaces are structurally controlled. A bioturbated bed in the Darwin Member of the Cretaceous Bathurst Island Formation has limited the depth of weathering in this region mainly to the level of the Koolpinyah surface. A silicified horizon in the deeply weathered Cretaceous strata has controlled the level of the Koolpinyah and Wave Hill surfaces elsewhere. Furthermore, the presence of detrital laterite profiles, being the main form of evidence used for the identification of both of these surfaces, is challenged; in many localities these detrital profiles are in fact in situ, discounting the idea that these surfaces developed as a result of successive episodes of pediplanation. Similarities are drawn between the origin of these surfaces and the development of equivalent surfaces in the Daly River Basin to the south of Darwin. The practice of extrapolation between surfaces across widely separated regions of northern Australia has been previously shown to be based on tenuous grounds. The same degree of tenuity must now be placed upon such extrapolations in the north of the Northern Territory.     

福建三明万寿岩层状洞穴发育过程及其工程地质意义

万寿岩位于三明市西17 km的岩前盆地,是一座圆锥状灰岩孤峰,地理坐标26°16'13″N,117°29'37″E。孤峰上发育两层水平洞穴,上层洞穴以灵峰洞为代表,下层洞穴以船帆洞为代表,其中灵峰洞是在福建及东南沿海地区发现的第一个旧石器时代早期洞穴文化遗址,船帆洞内遗存的距今3万年左右的人工石铺地面对研究末次冰期古代人类生存环境和文化演进有重大意义。两级层状洞穴和区内的两级河流阶地显示万寿岩地区从中更新世晚期以来至少经历了4次隆升,262 ka前为第1隆升期,185~37 ka为第2隆升期,37.0~17.4 ka为第3隆升期,10.4 ka以来为第4隆升期;前两个间歇期内分别形成了灵峰洞和船帆洞。262~185 ka,灵峰洞从岩溶管道逐渐扩大增宽形成洞厅,期间灰岩的溶蚀速率为0.19 mm/a;37.0~17.5 ka,船帆洞逐步从岩溶管道形成洞厅及现状规模,期间灰岩的溶蚀速率为0.36 mm/a。区内新构造运动的特征和船帆洞以下未被探明的溶洞以及层状洞穴的发育过程表明,船帆洞存在底板坍塌的可能性。因此,对船帆洞的保护措施除现有的防止洞顶坍塌及防渗处理外,更应考虑对船帆洞现有底板保护,避免下层洞穴的岩溶作用引起底板坍塌。

     

Mafic peperite from the Gold Creek Volcanics in the Middle Proterozoic McArthur Basin,Northern Territory

Peperite is a non‐genetic term used to describe volcanic breccia in which a texture of dark blocks in a light matrix resembles a mixture of salt and pepper. In the Gold Creek Volcanics, peperite is a mixture of partly vesiculated basalt clasts in a mudstone‐sandstone matrix. It is formed by the buoyant intrusion of basaltic magma into wet unconsolidated sediment. The intruding bodies deform and quench, giving rise to discordant masses of hyaloclastic breccia, confined largely to the subsurface. These basalt masses may remain hot enough to locally superheat pore water and produce convective systems where the basalt clasts and fluidized sediment become mixed, forming the distinctive peperite.     

Daly Basin,Northern Territory: lithostratigraphic revision resolves context of incongruous Ordovician fossils

A local succession of interbedded dolostone, limestone and glauconitic sandstone in the central Daly Basin of the Northern Territory, dated as Early Ordovician, has for many years appeared incongruous in terms of lithology and age relative to mapped formations of the Cambrian Daly River Group. Geological mapping and stratigraphic drilling have now shown that this interval, recently named the Florina Formation and described here, unconformably overlies the karstified surface of the uppermost formation of the Daly River Group, the Oolloo Dolostone. It is the youngest formation of the Daly Basin succession, but due to the lengthy hiatus between it and the underlying units, it is not included within the Daly River Group. It comprises three intervals of carbonate rocks alternating with thicker intervals of siliciclastic rocks. The latter are viewed as forming under dominantly moderate energy, shallow marine conditions with sediments derived from a distant terrigenous source. The carbonate rocks were dominantly subtidal, too far offshore to receive significant amounts of terrigenous material but shallow enough to be above storm wave base. The Oolloo Dolostone is formally divided here into two members, the lower Briggs Member and the upper King Member. Both consist largely of dolostone, but the Briggs Member is typically well bedded, contains ooids and has a minor component of quartz sand. It accumulated mainly as ooid shoals seaward of tidal flats. The overlying King Member is massive to coarsely bedded with only traces of terrigenous sediment and was deposited in deeper water seaward of the Briggs Member.     

Mapping Proterozoic unconformity-related uranium deposits in the Rockhole area, Northern Territory, Australia using landsat ETM+

The Rockhole area, Northern Territory, Australia, hosts a number of Proterozoic unconformity-related uranium deposits. The geology of the area features within Paleoproterozoic rocks of the Pine Creek Orogen, near the unconformity with overlying platform cover sandstone of the Paleo- to Mesoproterozoic McArthur Basin. Landsat Enhanced Thematic Mapper plus (ETM+) data was used in the Rockhole area to assist in mapping geological structures and lithology, and to identify anomalous concentrations of ferrous minerals, the product of alteration, which can be indicators of buried uranium mineralization. Several image-processing procedures were applied to the ETM+ data to identify, isolate and enhance mineralogical information as simple and complex false color composites. ETM+ 754 shown as red green and blue respectively was the best simple image. Overall, complex images based on Principal Component Analysis proved to be the most useful products. Sandstone, shale and siltstone, the target lithologies, Koolpin Formation, the target stratigraphic unit, and bleaching pattern due to the removal of iron(II) compounds, the target alteration pattern, were confidently mapped to provide information required by the mineral emplacement model, which ultimately identified areas of likely uranium mineralization. Thus the contrasting behavior of the two principle oxidation states of uranium and iron can be utilized to map/delineate bleached alteration zones associated with economic concentrations of uranium using multispectral sensors like Landsat or better hyperspectral sensors.     

区域工程地质,环境工程地质论文综述

本次大会收入本专题论文70篇,约占大会论文1/3,反映了当今工程地质学的一个非常重要的研究主题。可将之分为下面几个方面进行讨论:地质灾害研究(29篇),区域地壳稳定性评价与地震工程地质(22篇),城市与区域环境地质研究及质量评价(16篇),近海区域工程地质调查和环境地质编图(3篇)。本文对该专题的发展方向进行了讨论。     

关于当前我国城市地质研究的认识

进入21世纪，保护和合理利用资源环境已成为我国的一个重大战略问题。城市地质以调查研究和解决与城市建设及发展有关的各种资源、环境等地质问题为其基本任务。随时代发展和国家需要，它的侧重点也有所不同。当前我国处于城市化高速发展的历史阶段，城市地质主要任务更是要强调环境问题，即城市地质着重解决城市环境岩土工程和地质灾害问题，或者说是解决城市安全特别是城市土工安全问题，为城市防灾减灾与城市生态建设和城市可持续发展服务。     

缅甸岩溶地质概况

缅甸岩溶地质研究正处于快速发展阶段,系统综合的岩溶地质资料有助于从宏观上了解缅甸岩溶情况。文章在系统收集资料的基础上,综合多种尺度地质图、水文地质图、构造图及其遥感资料,编制1∶100万缅甸岩溶地质分布图,从地质演化过程、岩性组合、气候环境等方面综合剖析岩溶作用的背景条件,以此总结缅甸岩溶分布规律和岩溶景观特征,为“全球岩溶地质”数据库提供基础支持。缅甸的岩溶分布面积达7×10⁴ km²,是东南亚岩溶分布面积第二大的国家,厚层的古生代碳酸盐岩地层、复杂的构造运动、温润多雨的气候、活跃的生物活动等均有利于岩溶作用的发生,其发育峰林、峰丛、洞穴岩溶景观,岩溶景观资源潜力巨大,具有全球最高的生物多样性,但同时也面临着生态被破坏、干旱、洪涝等地质环境问题。     

世界工程地质学的新潮流

本文论述近几年国际国内工程地质大会研究的重点主题及其变化以及最近(今年8月在日本东京)召开的29届国际地质大会讨论的环境问题,从而反映了世界工程地质学研究的趋势。     

辽宁省大窑湾某建筑场地岩溶发育特征及工程地质条件评价

辽宁省大窑湾地区某建筑场地内基岩为可溶性中等~强的碳酸盐岩,岩体裂隙发育,在海水入侵、潜水与岩溶裂隙水等共同作用下,岩溶发育较强烈.本场地勘察揭露溶洞的见洞率70.27%.溶洞多发育于地表下20~30 m之间,其次为30~40 m.本文根据揭露溶洞的大小将溶洞分成大型溶洞(洞高≥4 m)、中偏大型溶洞(2 m≤洞高<4 m)、中型溶洞(0.5 m≤洞高<2 m)和小型溶洞(洞高<0.5 m)等四类,分析表明本场地内溶洞以中型溶洞为主,其次为小型溶洞和中偏大型溶洞,岩溶的发育和分布对场地工程地质条件影响较大.本文围绕场地岩溶发育这一主要工程地质问题,从岩溶发育的地质背景、形成条件、分布特点等方面对场地内的岩溶发育特征进行了分析研究,认为本场地属于岩溶中等~强发育的复杂的岩溶红粘土地基,需采取CFG桩、振冲碎石桩复合地基或采用桩基等措施对地基进行处理,以保证工程安全.     

城市地质学基础理论探讨

城市地质有近百年的研究历史,学科研究取得了很大的进展,但是总体上看,学科性质存在较多的争论,城市地质学基础理论难于满足现代城市管理的需求,无法为城市高质量发展提供系统完整的地学解决方案。本文系统梳理了国内外城市地质的发展历程和研究进展,进一步明确了城市地质学的学科性质,运用系统理论提出城市地质系统的概念,并基于这一概念,清晰地界定了城市地质学的研究对象,阐述了现代城市地质学的研究内容和技术框架,为今后形成完善的城市地质学理论体系提供研究基础。     

构造地质与工程地质的基本关系

构造地质学是研究各种地质构造及其成生演化的基础地质学 ,工程地质学主要是应用地质学理论尤其是构造地质学理论解决人类工程建设活动中与构造现象和构造活动有密切关系的地质问题的应用地质学。二者的研究目的虽然不同 ,但所研究的主要对象是相同的 ,即都是地质构造 ,所研究的又都是地球变化过程中的构造变动及其各类效应。文中讨论了构造地质学与工程地质学之间的基本关系 ,主要包括地质构造对工程地质环境和工程地质条件的控制作用 ;深部构造、浅部构造以及表层构造动力学特征与区域地壳稳定性之间的关系 ;构造结构面、构造应力场与岩土体稳定性的关系 ;活动构造与工程建筑安全性的关系以及地质构造与崩滑流、地裂缝、地面沉降等地质灾害的关系等问题。     

Geological framework of the Archean and Paleoproterozoic Tanami Region, Northern Territory

The Tanami Region, a poorly exposed, mostly Paleoproterozoic province within the North Australian Craton, hosts a number of significant gold deposits in diverse settings. Rare exposures of 2,520–2,500 Ma amphibolite facies Archean gneiss and metasedimentary rocks form basement to the thick overlying metasedimentary succession of the 1,880–1,830 Ma Tanami Group. The basal unit of the Tanami Group is the Dead Bullock Formation, a fining-upward deep-water succession dominated by siltstone, carbonaceous siltstone, iron-rich siltstone and mafic sills. Carbonaceous- and iron-rich lithologies in the upper Dead Bullock Formation represent important hosts for gold mineralization. The conformably overlying Killi Killi Formation represents turbiditic sedimentary rocks that are correlated with the widespread Lander Rock beds of the Arunta Region. Sedimentation of the Tanami Group was terminated by regional deformation and greenschist to amphibolite facies metamorphism during the Tanami Event (D₁/M₁), at around 1,830 Ma. The Tanami Group is unconformably overlain by rhyolite, siliciclastic sedimentary rocks, and felsic ignimbrite of the Ware Group that were deposited at about 1,825–1,810 Ma. Subsequent ESE–WNW to SE–NW directed shortening (D₂), followed by NE–SW to E–W directed shortening (D₃), has resulted in open NE F₂- and NW F₃-trending folds in both the Tanami and Ware Groups. Voluminous granitoids, dominated by I-type, biotite granodiorite, and monzogranite were intruded in the interval 1,825–1,790 Ma and have been subdivided using geochemical criteria into the Birthday, Frederick, and Grimwade Suites. Basalt and immature sedimentary rocks of the Mount Charles Formation are restricted in extent to the Tanami mine corridor, and are interpreted to reflect a continental rift succession that was deposited around 1,800 Ma, with an early Archean sedimentary provenance. Steep S to SE dipping F₄-fold structures of Tanami and Ware Group metasedimentary rocks, many spatially associated with 1,825–1,790 Ma granitoid intrusions, indicate a period of SSE-directed regional shortening (D₄) syn-to-post the regional granitoid intrusive phase. A network of N to NW striking faults, several of which are interpreted as oblique thrusts with a component of left lateral movement, indicates a period of D₅ convergence during WSW–ENE to E–W directed shortening. The Tanami mine corridor fault system comprises a network of N, NE to ENE striking D₅ faults that merge with N to NW striking faults and probably accommodated movement between granite core domains. D₅ faulting is associated with the main phase of gold mineralization in suitable structural–lithological traps. The Paleoproterozoic basement of the Tanami Region is unconformably overlain by quartz sandstone, lithic arenite, and conglomerate of the Pargee Sandstone. Pargee Sandstone may represent syn-tectonic sedimentation related to the 1,730 Ma Strangways Orogeny, and is unconformably overlain by the late Paleoproterozoic platform cover succession of the Birrindudu Group. The Paleoproterozoic basement and cover sequences have subsequently undergone several episodes of faulting, collectively termed D₆₊. The Paleoproterozoic evolution of the Tanami Region is interpreted to have occurred in an intracratonic setting, but was fundamentally influenced by tectonic events in the adjacent Halls Creek Orogen (1,835–1,805 Ma Halls Creek Orogeny) and Arunta Region (1,815–1,800 Ma Stafford Event). The boundaries between the Tanami Region and Kimberley Region to the northwest and the Arunta Region to the southeast are transitional, and are largely defined by the presence or absence of identifiable Dead Bullock Formation.     

城市地质调查内容及其发展

随着人类城市化的进程加快 ,城市发展中越来越多的地质问题 ,需要地质调查工作解决。本文介绍了城市地质调查的内容、方法和发展过程及注意事项 ,为城市科学规划提供依据     

浅析四川成都龙泉山城市森林公园主要环境地质问题

本文在梳理前人研究成果的基础上,结合野外实地调查和样品分析数据,分析了四川成都龙泉山城市森林公园的主要环境问题。研究表明,龙泉山城市森林公园总体地质环境条件较好,其总体规划和地质环境相适宜,在建设过程中需要关注局部地区的地质灾害发育、浅层地下空间瓦斯赋存和地下水污染等环境地质问题。区内主要地质灾害发育类型为小型滑坡,其次为崩塌和不稳定斜坡,多发生于龙泉山复背斜核部及断裂带区域,建设旅游道路和游憩设施时,要加强防范。区内局部浅层地下空间瓦斯赋存,建议在园区内进行地下工程建设时,进行超前地质预报,在施工过程中要加强瓦斯浓度监测与通风,注意火源管控。区内浅层地下水类型主要为HCO₃-Ca·Mg和HCO₃-Ca型,局部地区浅层地下水因人类活动而受到污染,其中总硬度、氨氮、氯化物等超标,建议加强公园内重点规划建设区域的地下水用途管控和生态环境保护。     

第三环境工程地质问题雏论

本文首次讨论了第三环境工程地质问题。根据多年工程地质勘查中所积累的经验教训，作者深感有单独提出第三环境工程地质问题这一概念的必要。与之同时，文中也举出了大大型环境工程地质勘查中应用这一观点的成功实例。此外，作者认为，进行第三环境工程地质问题的勘查与研究的人员必须具有更中丰富的经验和广泛的知识，方能取得良好效果。     

工程地质学面临的几个困难

本文就岩土体的不连续性问题,岩体变形破坏的微观机制问题及时空问题,岩体的大变形与小变形问题,进行了讨论。     

铁路工程地质的发展趋向

本文论述了铁路选线工程地质、铁路工程地质勘察、钻探工作、铁路地质灾害、巨型铁路桥梁及长大铁路隧道等方面工程地质研究所取得的进展及进一步研究的方向。     

上海市工程地质结构特征

根据前人的研究,结合三维城市地质调查取得的阶段成果,对上海市域工程地质研究程度、工程地质层的划分及其工程地质结构特征、工程地质分区及分区评价进行了论述。     

矿山工程地质问题

本文论述了我国近年来在矿山工程地质研究中所面临的问题及进展,分5个方面进行论述:(1)采矿、选矿工业场地,(2)井巷工程;(3)尾矿处理场地;(4)露天矿边坡;(5)矿山环境工程地质。