论高岭石粘土和铝土矿研究的新进展

过去我国地质界向前苏联学习,把球粘土(Ballclay)作为高岭土或耐火粘土的一个变种,使我们找矿走入误区,以致后来从美国进口球粘土。其实球粘土的结晶性质这个内在因素与高岭土或耐火粘土常不相同,则派生的性能更不一样,应成为独立的矿种,还可与国际接轨。又过去国内外学者认为高岭石高度有序为热液型的,而沉积型的为无序高岭石。但笔者等的研究,我国高岭石高度有序而规模大且均匀稳定的,应算沉积型的紫矸(古生代高岭石软质粘土),可以作流动性好的造纸涂料。又我国硬水铝石岩溶铝土矿,应属于生物有机质成矿作用的沉积型铝土矿。     

三峡地区泥灰质岩石斜坡带岩溶作用及其对工程稳定性的影响

泥灰质岩石岩溶是岩溶研究一个薄弱环节,将工程稳定性与岩溶作用相结合是岩溶地区地质灾害评价和治理所面临的新课题。三峡地区巴东组（T2b）泥灰质岩石的岩溶问题是新近发现的重大工程地质问题。由于构造破碎和河流切割引起岩石卸荷与松动,使岩石有利于水的渗入和岩溶作用。水是岩溶的溶剂,在峡谷斜坡地带,雨水是地表水和地下水的主要水源,地处亚热带的三峡地区雨水丰沛。通过对15个不同类型水样的化学成分测试和计算表明,雨水呈酸性,方解石的饱和指数（SI）低,具有强烈的溶蚀性,在地表和地下运移的过程中对泥灰质岩石产生了强烈的溶蚀作用。不同的地貌位置和构造层位具有不同的地表水和地下水状态,从而产生不同强度和不同形式的地表和地下岩溶。地质历史时期,岩溶作用使岩石发生成分和结构的一系列变化,从而导致岩石力学强度降低,岩体发生不均匀沉降、地裂缝、滑坡、崩塌、泥石流和地面塌陷。测试和计算还表明,不仅雨水及其转化成的地表水和地下水,而且江水和自来水均有一定的溶蚀性。将来,水的岩溶作用和水的诱发作用可能导致地基不均匀沉降、地裂缝、滑坡、崩塌、泥石流和地面塌陷,从而破坏工程稳定性。防治三峡地区地质灾害的关键在于防止水向地基的入渗。建议对三峡地区泥灰质岩石斜坡带岩溶进行深入研究。     

电磁波CT技术在济南地铁岩溶勘察中的应用

随着城市化进程的加速,济南城市轨道交通近年来发展迅速,地铁成为济南未来交通主要建设方向之一。作为泉城,岩溶是济南泉水补给、径流的重要通道,在济南地区普遍发育,但同时岩溶问题也是地铁施工的难点,因此,查明地铁线路下岩溶的发育程度至关重要。与南方岩溶的“大尺寸”相比,济南地区的岩溶尺寸要小得多,且多成蜂窝状、裂隙状,在空间上也无明显规律可循,这对物探工作的分辨率就提出了较高的要求。该次研究区域是地铁2号线任家庄站到腊山站沿刘长山路区间段。经初步探查,该区间段存在多处岩溶且线路地处闹区,车流量大,管线复杂。为了研究该区岩溶发育情况,该次采用电磁波CT技术对区内岩溶进行了探测,通过对区域内地质介质电磁波吸收系数差异的研究,结合钻探资料进行对比,推断出岩溶区吸收系数的取值区间;最后对推断的岩溶区进行钻探取样,验证了物探与钻探的吻合程度。该方法在岩溶勘察中取得了良好的效果,为济南地铁设计及施工提供可靠的依据。     

Investigation of a large collapse sinkhole affecting a multi-storey building by means of geophysics and the trenching technique (Zaragoza city,NE Spain)

An active sinkhole around 100 m long has been investigated in the city of Zaragoza (NE Spain). Subsidence activity on this depression, including the sudden occurrence of a collapse sinkhole 5 m across, led to the abandonment of a factory in the 1990s. At the present time, a building with 100 flats and shallow pad foundations partially built on the sinkhole, is affected by rapid differential settlement. The development of the sinkhole results from the karstification of the halite- and glauberite- bearing bedrock and the sagging and collapse of the overlying bedrock and alluvium, more than 30 m thick. GPR and electrical resistivity profiles have provided information on the distribution and geometry of the subsidence structure. The application of the trenching technique and geochronological methods (AMS and OSL dating) has allowed us to infer objective and practical data on the sinkhole including (1) Limits of the subsidence structure, (2) subsidence mechanisms, (3) cumulative subsidence (>408 cm), (4) subsidence rates on specific failure planes (>1.8 cm/year), (5) episodic displacement regime of some fault planes. The available information indicates that the progressive deformation recorded in the building will continue and might be punctuated by events of more rapid displacement. This work illustrates the practicality of the trenching technique for the study of sinkholes in mantled karst areas.     

宜万铁路野三关隧道“8.5”突水事故成因分析

2007年8月5日宜(昌)万(州)铁路野三关隧道发生了重大的岩溶突水事故.在岩溶水文地质调查的基础上,对野三关隧道所处流域两个主要岩溶洼地以NaCl为示踪剂进行了充水水源和充水途径的示踪试验.两次示踪试验结果查明水洞坪岩溶洼地是"8.5"突水事故的主要水源,茅口组灰岩中发育的周家包暗河被F18断裂切割,将暗河水导入隧道形成突水事故.稻子坪的水在隧道突水段西以渗-涌水的形式进入隧道.水洞坪示踪实验得出二叠系栖霞-茅口组岩溶含水层中的地下水流速为50 m/h.稻子坪示踪试验得到茅口组灰岩含水层中的地下水流速为45.5 m/h;大冶组灰岩含水层中的地下水流速为10.8 m/h.本示踪结果为宜万铁路野三关隧道的后期恢复施工和防渗工作提供了依据,并为岩溶地区深埋隧道的设计和施工提供了试验和分析工作的实例参考.     

Late Oligocene-Early Miocene Thrusting in Southern East Kunlun Mountains, Northern Tibetan Plateau

Southward thrusting occurred in Late Oligocene-Early Miocene in southern East Kunlun (昆仑) Mountains formed the South Kunlun thrust (SKT). Permian strata and Triassic rocks were thrusted over the Paleocene-Eocene red-beds of Fenghuoshan (风火山) Group and Oligocene brownish red conglomerate and sandstone of Yaxicuo (雅西错) Group along SKT faults, formed tectonic slices, low-angle thrust faults, multi-scaled outliers, and nappe structures in south of Middle Kunlun fault (MKF). In addition, SKT displacement or shortening is estimated to be ～(30-35) km across Dongdatan (东大滩) valley and East Wenquan (温泉) basin. 39Ar-40Ar dating of chlorite of ductile shear zone along front thrust fault indicates that SKT thrusting occurred at 26.5±2.7 Ma, and fission track dating of apatite from mylonitic granite in SKT gives the age 26±2 Ma, corresponding to initial time of rapid uplift of East Kunlun Mountains. Thrust faults and folds of SKT were covered unconformably by Late Miocene lacustrine strata, and major thrusting of SKT ended before 13.5-14.5 Ma according to regional chronological data in northern Tibetan plateau.     

青藏高原那曲地区雷电特征初步分析

通过对2002年夏季青藏高原那曲地区雷暴过程及闪电观测资料的初步分析,发现该地区雷暴电荷结构具有多样性和复杂性,地闪明显偏少. 对高原地闪的一些基本特征参量的统计分析表明,无论正地闪还是负地闪梯级先导前都具有持续时间较长的云内放电过程,地闪以单次回击为主. 与中低纬度地区相比,高原地闪中正地闪比例明显要高,为33髎;负地闪为67髎;正、负地闪回击后常常伴随短时间的连续电流.     

塔里木盆地塔北露头区的古岩溶发育模式

目前塔里木盆地海相碳酸盐岩的油气勘探已进入高峰期,为弥补钻井岩心资料不足,进一步认识井下岩溶发育规律及发育模式特征,开展塔北露头区奥陶系风化壳古岩溶缝洞系统发育特征及发育模式研究。研究表明,岩溶发育主要受控于岩性因素和不整合面,主要发育层位为一间房组地层;主要岩溶作用期为吐木休克组／一间房组沉积间断岩溶期。为井下岩溶缝洞系统的认识及岩溶地质模型的建立提供了重要理论依据。     

Indosinian Supergene Karsts in the Qaidam Basin, NW China: Evidence from Paleo-tectonics, Paleoclimates and Paleo-fluids

In the Qaidam basin,Northwest China,karstic fissures and caves are developed in many places of the Lower Carboniferous Chengqianggou Fm.and Huaitoutala Fm.and the Upper Carboniferous Keluke Fm.,in which are found typical karstic marks.Several suites of transgressive carbonate rocks formed during the Late Paleozoic epoch are preserved as reservoir properties in the Qaidam basin,with paleokarst-related cave-fractured diagenetic structures,which provided the basis for cavefractured development.Carbonate and clastic samples covering or infilling caves and fractures in Carboniferous strata were collected in the eastern Qaidam basin to focus on petrological and geochemical analyses of karst and infilling materials.Based on this study of the Caledonian diagenetic sequence,and bitumen-infilled inclusion temperature and burial history,there existed a continuous atmospheric freshwater leaching process,which played a critical role in the construction of the Carboniferous supergene paleokarsts.Investigation and survey of the tectonic setting,plate paleolatitude and river development intensity also proves that there was abundant rainfall during the Indosinian period,after which the strata undergo a shallow burial process.Because Indosinian period is earlier than the key timing of hydrocarbon-generation of the Carboniferous source rocks,this kind of karst reservoir has potential significance for oil-gas resources in this area.     

辽宁本溪晶花洞碳酸钙沉积物颜色多样性分析

辽宁本溪晶花洞发育于中奥陶统马家沟组(O2m)中厚层白云质灰岩中,洞内碳酸钙沉积物具有白色、黄色、肉红色、浅蓝色和黑褐色等多种原生色彩。在洞穴考察的基础上,通过对围岩和洞穴碳酸钙沉积物X荧光分析以及显微镜薄片鉴定,认为洞穴中白色的次生化学沉积物主要由质纯的CaCO3形成;浅蓝色、黑褐色的形成则多由沉积物含有铜、锶和锰、锌所致;而黄色、红色则为不同环境下铁、锰等变价元素所产生。