典型岩溶包气带洞穴滴水水文过程研究——以桂林硝盐洞为例

选取桂林丫吉试验场硝盐洞为研究对象,通过示踪试验和高分辨率水文水化学监测,确定滴水补给来源,研究典型岩溶包气带洞穴滴水对降雨响应的水文过程。研究结果表明,硝盐洞XY5滴水主要受到两种径流成分补给,即集中补给的管道流和弥散流。硝盐洞上部包气带中可能存在表层岩溶带含水层,长期维持滴水流量。滴水流量、电导率和示踪剂浓度的峰值均出现在强降雨时段,表现出快速响应的管道流特征,存在降雨阈值引起硝盐洞滴水降雨响应。降雨前岩溶含水层水分条件是包气带水文响应差异的主要原因,雨季滴水对降雨响应迅速,XY5滴水对降雨响应的滞后时间为10 h;而旱季对降雨的响应滞后明显,滞后时间达9.8天,体现了土壤和表层岩溶带的调蓄作用。74.4 mm降雨量是旱季转雨季滴水响应的降雨阈值。借助于洞穴滴水的水文动态变化和示踪试验技术对于研究包气带水文过程,深入了解岩溶含水层结构及特征,揭示岩溶区降雨入渗补给机制具有重要作用。     

西南地区隧道工程条件下岩溶地下水系统变化特征分析

岩溶山区越岭长大隧道的施工不可避免地会使当地的岩溶水系统发生改变,如地下水水位的下降、地表泉点的漏失等。基于隧道工程对岩溶地下水系统边界条件、排泄状况等天然特征的影响,依据西南地区岩溶地下水系统主要特征及隧道工程特点,考虑隧道工程条件下影响岩溶地下水系统特征的主要因素,对岩溶类型(岩溶含水岩组的埋藏条件)、构造特征、补给特征、岩溶水径流方式与隧道工程特点相组合的模式下的岩溶地下水系统的变化进行特征分析,并将岩溶地下水系统的变化归纳为3种类型。据此,选择研究区金汁河地下水系统作为典型研究对象,假设3种隧道穿越方案,将不同隧道穿越方案下的岩溶地下水系统与天然岩溶地下水系统进行对比分析,归纳概述其变化特征,最后对各隧道方案下的涌水量及其涌水危险性进行初步预测及评价。     

不同植被条件下岩溶地下水δ13CDIC的差异研究——以贵州夜郎洞、天钟洞和普定岩溶水碳通量模拟试验场为例

影响石笋δ13C的因素众多,且其中一些影响机制未知,从而导致利用石笋δ13C准确重建古环境仍存在一定的困难.作为形成石笋母液的洞穴滴水,其δ13CDIC变化必然会导致石笋δ13C的变化,因而只有对影响洞穴滴水δ13CDIC的各种因素进行细致的研究才能更好地利用石笋δ13C重建古气候环境.对贵州夜郎洞、天钟洞和普定岩溶模拟试验场的研究均表明,雨季上覆植被生物量的大小以及植被类型(C3和C4)是控制岩溶地下水δ13CDIC变化的主要因素.而对于夜郎洞的研究还得出旱季先期CO2脱气作用对岩溶地下水δ13CDIC的影响较大,如夜郎洞C3植被下雨季δ13CDIC值在-10.94‰～-12.15‰之间,旱季为-3.66‰～-5.50‰,夜郎洞C3植被下滴水点雨季旱季之间差异最大达到-8.49‰,这些不仅仅是由生物量的变化而引起的,先期CO2脱气对滴水碳同位素的影响也是不可忽略的.不同于夜郎洞旱季滴水δ13CDIC,先期CO2脱气作用对天钟洞滴水δ13CDIC的影响较小,天钟洞滴水δ13CDIC总体上能够反映上覆植被发育状况,因而先期CO2脱气作用等过程对滴水δ13CDIC影响因洞穴而异,可能反映了洞穴顶部包气带不同水文地质条件的影响.     

贵州凉风洞洞穴滴水水文水化学过程分析

通过对贵州荔波凉风洞5个滴水点进行为期1年的动态监测,表明除大气降雨携带的较少物质成份外,凉风洞滴水中的物质主要来源于土壤,同时,示踪结果显示出凉风洞滴水对大气降雨的响应较快,滴水的物质组成直接源自于洞穴环境。洞穴滴水的化学组成中元素含量的变化主要由水运移过程中水-土、水-岩作用导致的方解石溶解-沉淀过程所控制,稀释作用、水来源的差异或者活塞流产生了一定的效果,但其影响较弱,表明凉风洞滴水点的次生沉积物可能记录了环境变化信息。但水在洞穴顶板内运移过程中发生的水文地球化学过程(岩石的溶解、方解石沉淀作用过程)以及洞穴滴水响应大气降雨的时间尺度、水动力过程、水流形式等因素,影响到凉风洞洞穴次生沉积物过去环境记录指标。因此,岩溶次生沉积物过去环境变化指标的解译应该有洞穴滴水水动力地球化学过程的结果作为支撑。这些过程的清晰化可以更好地为研究洞穴环境次生沉积记录的高分辨率、短时间尺度的过去变化提供依据。     

桂林硝盐洞洞穴滴水示踪及气候环境意义研究

洞穴滴水对大气降水的滞留时间的研究是准确解译洞穴沉积物气候环境代用指标的重要内容。由于研究尺度和技术手段的差异,目前对滞留时间的研究重视程度仍不够。基于此引入水文地质领域成熟的示踪方法,对桂林丫吉硝盐洞滴水对大气降水响应时间进行了连续高分辨率的研究。利用野外自动化荧光仪和荧光示踪剂,实现了滴水的自动化示踪研究,节省了人力物力且提高了分辨率。通过两次示踪试验,确定了桂林丫吉硝盐洞滴水雨季对大气降水的响应时间小于48h,一些强降雨事件,滞留时间甚至小于4h。发现滴水的温度变化可以作为高分辨率监测时大气降水形成径流的示踪剂。对于桂林丫吉硝盐洞XY5常年性滴水点,雨季日降雨强度大于16.3mm就可以形成径流,并被监测到。XY5滴水点主要存在两个水源补给,常年的基流补给和大气降水的快速补给。这些认识对洞穴滴水监测和洞穴沉积物古气候环境重建有着很好的借鉴意义。     

溶洞穴滴水元素季节变化及其气候指示意义研究—以贵州省麻黄洞为例

为揭示岩溶洞穴滴水元素季节变化特征及其对外界气候环境变化的响应关系,对贵州绥阳双河洞系支洞麻黄洞内3处滴水的Mg、Ca、Sr元素进行了为期13个月的监测。结果显示:(1)3个滴水点M1、M2和M3的水化学类型主要为HCO3·Ca型,岩溶水对于方解石与白云石等矿物的溶解处于饱和状态;(2)上覆土壤和岩层厚度逐渐增加,导致水-土-岩作用时间也随之增加;(3)Ca^2+、Mg^2+、Sr^2+浓度变化总体上呈逐级递增的特点,各离子浓度在高温多雨季节波动幅度大,低温少雨季节变化平稳;(4)Mg/Ca、Sr/Ca均表现出雨季低、旱季高的特征,反映该地区外界干湿条件的变化;(5)由模型模拟显示,3个滴水点皆以PCP/ICD作用为主,M1对降雨响应不敏感,M2滴率与离子浓度呈雨季高、旱季低的变化规律,M3位于洞穴最深、顶板最厚处,滴率与离子浓度无显著季节变化特征。结合各滴水点洞穴环境变化规律,推断M2更能准确响应外界气候环境变化。     

宜昌潮水洞岩溶间歇泉动态特征及成因

潮水洞无降雨补给时仍有规律的间歇性流出,是典型的岩溶间歇泉,其流量、水化学动态规律及形成机制缺乏系统的研究.基于长期水文气象观测和水化学测试数据,分析了潮水洞不同时期流量、水温和电导率变化特征以及潮水洞岩溶水系统的水化学特征.潮水洞为多个岩溶水子系统的连接,其动态呈现为雨期和无雨期两个不同特征,且存在多个不稳定周期的间歇出流过程.通过c(Mg2+)/c(Ca2+)比值及水文动态特征辨识出间歇出流的地下水来源为天河板组灰岩含水层,随着过程流量的不断增加,深循环地下水占比最高达97%.结合水文地质条件概化出潮水洞岩溶水系统循环模式,天河板组灰岩含水层内虹吸管道的发育是间歇性动态特征的主要成因.      

重庆市金佛山台原岩溶地下水系统结构特征分析

为了查明金佛山各洞穴之间的地下水力联系,探讨岩溶地下水系统结构特征,于2016年12月进行了多元示踪试验。将罗丹明B作为示踪剂,从药池坝附近消水洞（S01）投入,验证消水洞与北坡水源（水房泉）（S02）之间存在水力联系。结果显示,示踪剂历时曲线为多峰型,推测地下过水通道可能由单管道型演变为多管道型通道;将荧光素钠投入金佛洞地下水流动处（S05）和将罗丹明B、荧光增白剂投入羊口洞地下水流动处（S03）,利用高分辨率荧光光度计,于燕子洞（S04）在线监测。结果显示,金佛洞、羊口洞分别与燕子洞之间存在水力联系,且示踪剂历时曲线均为跳跃型,推测地下过水通道可能为发育有一定规模溶潭的多管道型。      

桂林硝盐洞滴水水文和水化学动态变化特征

为认识裸露型岩溶包气带洞穴水文水化学动态变化特征,以桂林硝盐洞滴水为例,选取桂林硝盐洞3处滴水,对滴速、电导率、pH值、Ca2+、Mg2+、Sr2+进行监测,结果显示:(1)岩溶洞穴滴水的离子浓度与温度降水关系密切,高温多雨时节岩溶作用加快,洞穴滴水中Ca2+、Mg2+含量升高,同时强降雨会导致离子浓度产生很大波动;(2)滴水化学性质受到土壤、基岩顶板厚度、滴水量等的影响,土壤层越厚,滴水中Ca2+含量越高;(3)受“慢速补给”的滴水点,其滴水量与离子浓度呈正相关性,而受“快速补给”的滴水点,其滴水量与离子浓度呈负相关性;同时接受两种方式补给的滴水点,其滴水量和离子浓度变化剧烈,且呈良好的正相关性。      

岩溶滴水中痕量磷的测定及其古环境意义

为解决因洞穴滴水中磷酸盐含量低而无法了解磷的存在形式和分布特征这一问题,借鉴经典氢氧化镁共沉淀法,开发了集分离-富集-测定于一体的共沉淀-磷钼蓝分光光度法,用于定量测定岩溶滴水中PO43-。通过4个回收实验表明,岩溶滴水中痕量磷的回收率分别是99%、102%、95%和96%,达到定量分析的要求。对湖北清江和尚洞内HS4滴点2005—2012年的滴水样品中的磷酸盐进行测定,结果表明滴水PO43- (以P计)最大浓度为12.1μg/L,最小浓度为0.1μg/L,平均值为4.55μg/L。洞穴滴水中磷的浓度呈现季节波动,总体上夏、秋季高,冬、春季低,与同期的温度和滴水速率的季节变化相一致,较好地响应了气候和环境的变化。      

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

NONMETALS DEPOSITS

正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.)     

MATHEMATICAL GEOLOGY

正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology,     

PROSPECTING EXPLORATION

正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.)     

STRUCTURAL GEOLOGY

正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se-     

STRUCTURAL GEOLOGY

正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with