强对流云新概念在积云人工增雨作业中的运用     

贾惠珍  寇书盈  孟辉  王兆宇  秦凤芝 《气象科技》2005,(Z1)

在对强对流(积云)增雨作业中,引用防雹新概念方法是利用多普勒雷达不同仰角的反射率(R)图及反射率剖面(RCS)图、径向速度剖面(VCS)图等资料,对强对流云流场特征进行定性分析,判定其主位置,通过主入流区位置和态势,确定“0”线的类型,给出增雨作业的时机和部位。用这一新概念,结合天津地区积云增雨的实际情况,在2003~2005年期间进行了应用。当流场、温度场和水凝物粒子场适当配置时,会形成大量降水粒子的集中累积,产生阵性暴雨。  相似文献   

芙蓉洞洞穴演化形成所需历史时间估算方法及其地质意义   总被引：4，自引：0，他引：4  

陈桥  雒昆利  董明星  李会杰  李树文  叶成礼  刘强 《西北地质》2005,38(4):1-7

对芙蓉洞与芙蓉江古水面高程差进行了测量，引用洞穴古老次生化学沉积物同位素地质年代资料，通过和邻区地壳相对抬升速率对比，估算出芙蓉洞洞穴演化形成所需的历史时间约为12～18万a。相对于芙蓉洞古老次生化学沉积物同位素地质年龄（16万a）来说，洞穴演化形成是一个不可忽视的过程，进一步证明了两个清晰的洞穴发育阶段的存在。对于用洞穴古老次生化学沉积物同位素地质年龄代替洞穴发育整个历史过程是需要谨慎的。通过估算方法反演所揭示的该区地壳相对抬升速率与青藏高原相对抬升速率相比，进一步证实了扬子地台和青藏高原虽然具有相同的驱动机制，但扬子地台近代隆升速率远远低于青藏高原的隆升速度。同时，笔者还对扬子地台的隆升趋势作了一定的分析，认为近代扬子地台边缘隆升速度小，中间隆升速度稍大。  相似文献   

流入型洞穴——山东沂源九天洞初步研究   总被引：1，自引：1，他引：0  

朱学稳  韩道山 《中国岩溶》2007,26(3):189-195

九天洞是一个典型的直接由外源水补给形成的流入型洞穴。洞内大片分布的石花起源于四大古水池沉积物的存在。九天洞发育于第四纪早更新世晚期至中更新世早期,经历过成洞期、残余水流(古水池)活动期(中更新世中、晚期)石花发育期(晚更新世以来)和主要滴石、流石(含浅水池)沉积期(晚更新世晚期至今)等发育阶段。今日的九天洞又是一个残余洞穴,已被完全蚀去的近流入口段的洞穴长度不小于200m,约占洞穴全长的37%。九天洞及其洞穴群的景观资源价值和科学价值,在我国北方喀斯特洞穴中占有重要的地位。   相似文献   

云南呈贡龙潭山 1 号洞堆积物的铀系年龄     

高斌  沈冠军  吉学平  程海 《中国岩溶》2007,26(4):321-325

测定了人类化石地点云南呈贡龙潭山1号洞5个次生碳酸盐样的质谱法铀系年代。其中位于含人牙化石的II 堆积层下界面不远处的L TSY- 3石笋样质谱230 Th /234U 年龄为( 305± 15) ka; 而其余4 个样品经现场地层复核,它们与堆积均缺乏明确的叠压关系,因此认为它们很可能源自洞顶或洞壁石幔。此外,还测定了该地点5个动物化石样的230 Th /234 U 年龄,其结果为60～ 80 ka,平行测定了其中3 个样品的227 Th /230 Th 年龄,二种铀系年龄均在± 1. 5σ范围内一致,从而支持了该地点骨化石样铀系年代的可信度。在没有进一步的地层和年代证据之前,暂将60～ 80 ka 作为含人牙化石的第I I层堆积的年代应是合理的。但值得指出的是,由于骨化石中铀循环模式的不确定性,与有明确层位意义的钙板相比,洞穴地点的这类材料年代结果往往偏于年轻,因此上述年代测定结果很可能也存在偏低问题。   相似文献   

The Sponge Community of a Semi-Submerged Mediterranean Cave   总被引：1，自引：0，他引：1  

Giuseppe Corriero  Lidia Scalera Liaci  Daniela Ruggiero  & Maurizio Pansini 《Marine Ecology》2000,21(1):85-96

Abstract. The sponge fauna of a semi-submerged cave from the Tremiti Archipelago (Adriatic Sea) was studied, and its distribution was analyzed in relation to abiotic (water-movement and light gradients) and biotic (algae and anthozoan substrate cover) ecological factors. Fifty-five species of sponges were recorded. The number of species and the abundance values of sponges increase in the first part of the cave, then progressively decrease, with a sharp fall at the end of the cave. The quick disappearance of algae along the light gradient allows sponges to thrive in the first portion of the cave. The subsequent, progressive decrement of sponges could be the result of food depletion phenomena due to a long persistence of the water body in this long cavity. A high water-turbulence, due to the peculiar morphology of the cave and indicated by the recorded values of water-movement, occurs at the end of the cavity and probably determines the sharp decrement of sponges in the inner portion of the cave. This turbulence may also explain the absence of typical still-water cave species and probably affects the type of development (shape, overgrowth) of the sponges in the community.  相似文献   

福建连城赖源洞穴系统研究与旅游开发探讨     

李刚  俞锦标  朱诚  吴承照 《中国岩溶》2001,20(4):253-258

连城赖源洞穴系统发育于分布面积不及2km2、厚度不足100m 的二叠系下统夹有燧石层的栖霞组灰岩中,洞穴形态不同于单一通道、树枝状通道、侧羽状通道形态特征,也与迷宫状洞穴系统以及成层状洞穴系统存在差异,是介于迷宫状和楼层状之间的类迷宫状洞穴系统。研究表明,该洞穴系统是一种处于有序动态变化的三维空间地域系统,既有空间展布形态和边界形态,又会随时间的变化而不断演化。洞穴系统水动力具有溶蚀作用、混合溶蚀作用、侵蚀作用的特征。在新构造运动影响下,经历了数次间歇性抬升,赖源洞穴最终发育为类迷宫状洞穴系统。该洞穴景观独特,有很高的旅游开发价值。   相似文献   

乐业县大石围天坑群洞穴第三纪堆积的孢粉组成特征及相关问题探讨   总被引：3，自引：2，他引：1  

刘金荣  张继淹  梁耀成  伍乃东 《中国岩溶》2004,23(3):239-246

介绍了广西乐业县大石围天坑群中蚂蜂洞、里郎洞新第三纪堆积孢粉组合特征,并由此探讨了大石围天坑四层不同高程上的洞穴的发育时代。蚂蜂洞和里郎洞新第三纪堆积是迄今广西所发现的海拔高程最高的第三纪地质剖面,其孢粉主要以被子类桤木粉属( Alnipollenites )、栎粉属( Quercoidites )、桦粉属( Betulaepollenites )、栗粉属( Cupuliteroipollenites ) , 裸子类双束松粉属( Pinuspollenites ) , 蕨类水龙骨单缝孢属( Polypodiaceaaesporites )、桫椤孢属( Cyathidites )为主,反映当时主要为亚热带温暖、阴湿的森林气候环境。根据与蚂蜂洞的相对位置,推测较之高的南东支洞、最高层洞形成时代应早于新第三纪,比之低的中洞应形成于早— 中更新世,而地下河则在全新世时期形成。   相似文献   

堤防动物洞穴的探地雷达探测研究   总被引：3，自引：0，他引：3  

王国群  何开胜 《岩土力学》2006,27(5):838-841

通过探地雷达对淮沭河大堤獾洞隐患的探测,分析了獾洞的结构特征,给出了獾洞的典型雷达图像特征,推断了测区内獾洞穴道的位置、深度和走向,为堤防獾洞隐患治理提供了资料。探测结果表明,探地雷达设备轻便,对场地要求低,易于在任意方向加密探测,对浅层地下洞穴的探测非常有效。  相似文献   

Water isotopic variability in Mallorca: a path to understanding past changes in hydroclimate          下载免费PDF全文

Oana A. Dumitru  Ferenc L. Forray  Joan J. Fornós  Vasile Ersek  Bogdan P. Onac 《水文研究》2017,31(1):104-116

This paper reports the first results on δ¹⁸O and δ²H analysis of precipitations, cave drip waters, and groundwaters from sites in Mallorca (Balearic Islands, western Mediterranean), a key region for paleoclimate studies. Understanding the isotopic variability and the sources of moisture in modern climate systems is required to develop speleothem isotope‐based climate reconstructions. The stable isotopic composition of precipitation was analysed in samples collected between March 2012 and March 2013. The values are in the range reported by GNIP Palma station. Based on these results, the local meteoric water line (LMWL) δ²H = 7.9 (±0.3) δ¹⁸O + 10.8 (±2.5) was derived, with slightly lower slope than Global Meteoric Water Line. The results help tracking two main sources of air masses affecting the study sites: rain events with the highest δ¹⁸O values (> ?5‰) originate over the Mediterranean Sea, whereas the more depleted samples (< ?8‰) are sourced in the North Atlantic region. The back trajectory analysis and deuterium excess values, ranging from 0.4 to 18.4‰, further support our findings. To assess the isotopic variation across the island, water samples from eight caves were collected. The δ¹⁸O values range between ?6.9 and ?1.6‰. With one exception (Artà), the isotopic composition of waters in caves located along the coast (Drac, Vallgornera, Cala Varques, Tancada, and Son Sant Martí) indicates Mediterranean‐sourced moisture masses. By contrast, the drip water δ¹⁸O values for inland caves (Campanet, ses Rates Pinyades) or developed under a thick (>50 m) limestone cap (Artà) exhibit more negative values. A well‐homogenized aquifer supplied by rainwaters of both origins is clearly indicated by groundwater δ¹⁸O values, which show to be within 2.4‰ of the unweighted arithmetic mean of ?7.4‰. Although limited, the isotopic data presented here constitute the baseline for future studies using speleothem δ¹⁸O records for western Mediterranean paleoclimate reconstructions. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Characteristics of Breccias and C-O-Sr-S Isotope Geochemistry of the Duocaima Pb-Zn Deposit in Tuotuohe, Qinghai Province: Implications for the Ore-forming Process     

HAO Hong  SONG Yucai  LI Liansong  JIA Zongyong  WANG Yuankui  LIU Qun 《《地质学报》英文版》2015,89(5):1568-1587

The Duocaima carbonate-hosted Pb-Zn deposit is a newly found large deposit in the southern area of Qinghai Province.In this paper, the characteristics, genesis, significance to Pb-Zn mineralization of the widely developed breccias, and the ore-forming process have been carefully studied based on geological documentation of drilling holes, microscopic observations of petrography and microstructure and some stable isotope measurements.Based on the compositions of the clast and matrix, the breccias can be classified into three types: limestone clasts cemented by marl; limestone clasts with fine-grained calcareous materials; and limestone clasts cemented by hydrothermal calcite.The mineralization in the first type of breccia is weak, whereas it is strong in the latter two types of breccias.According to the locations of occurrence and structural characteristics of the breccias along with the relationship between the breccias and mineralization, part of the limestone clasts that are cemented by marl and outcrop in the contact zone between the Wudaoliang Formation(Nw) and the underlying Jiushidaoban Formation(Pj) are attributed to synsedimentary fault-genetic breccia, whereas the last of the limestone clasts that are cemented by marl and developed in the Jiushidaoban Formation(Pj) are attributed to the breccia generated by karst cave collapse; the limestone clasts with fine-grained calcareous materials and the limestone clasts cemented by hydrothermal calcite are attributed to breccia formed by hydrothermal dissolution.The breccia formed by karst collapse had consistently evolved for a long period of time, while the breccias with other origins were formed around the period of mineralization(i.e., about or slightly later than 20–16 Ma).The breccia generated by karst cave collapse and hydrothermal dissolution are somewhat related; the formation of the breccia from karst cave collapse provided open space for the later mineralization and reaction between hydrothermal fluids and host rocks, and the subsequent strong dissolution by hydrothermal fluids transformed some of the breccia formed earlier by karst cave collapse.Meanwhile, carbonate host rocks with breccias and brecciaed mineralization can be a potential sign of Mississippi Valley Type(MVT) deposits and important indicators for regional mineral exploration.The δ13CV-PDB, δ18OVSMOW, and 87Sr/86 Sr values of hydrothermal calcite in the Duocaima deposit range from 4.3‰ to 7.1‰, 14.9‰ to 20.1‰, and 0.707494 to 0.708185, respectively; the δ13CV-PDB, δ18OV-SMOW, and 87Sr/86 Sr values of the host limestones of the Jiushidaoban Formation range from 3.6‰ to 5.3‰, 18.0‰ to 20.5‰, and 0.707372 to 0.707945, respectively.The δ13CV-PDB and 87Sr/86 Sr values of hydrothermal calcite and limestone are similar, indicating single sources of C and Sr in this deposit, with the likely source being the limestone of the Jiushidaoban Formation.The minor scattering of the δ18OV-SMOW values suggests that different O isotope fluids underwent the isotope exchange reaction.The C-O-Sr isotope characteristics indicate that the host limestones experienced a dissolution and precipitation process during mineralization, which is beneficial to improving the porosity of host rocks and promoting the precipitation of metal sulfides.The δ34SV-CDT value of the breccia-type mineralization sulfides ranges from-30.4‰ to-0.3‰; that is, the δ34SV-CDT value is negative with considerable variation, illustrating that during the breccia-type mineralization process, the bacteriogenic reduction of sulfates provided the vast majority of sulfur, whereas the thermochemical reduction of sulfates was relatively unimportant.The brecciation that occurred as a result of karst cave collapse was mainly generated by the dissolution of groundwater; however, the brecciation related to hydrothermal dissolution and mineralization processes were caused by mixing of different fluids.  相似文献