东南极格罗夫山萨哈罗夫岭漂砾暴露年龄初探

首次对格罗夫山地区漂砾的暴露年龄进行的研究表明,萨哈罗夫岭冰原岛峰的两块漂砾样品的 Be最小暴露年龄分别为1．24±0．11Ma和1．37±0．12Ma, 。A1最小暴露年龄分别为0．90 4-0．12Ma和0．44±0．04Ma。萨哈罗夫岭附近冰面上的漂砾样品的 Be和 A1最小暴露年龄分别是0．47±0．3Ma和0．44±0．04Ma。考虑到误差,萨哈罗夫岭三块漂砾的最小暴露年龄与相近高程的基岩样品的最小暴露年龄基本一致。因此,在利用原地生成宇宙成因核素测年技术对东南极内陆格罗夫山地区的冰川消涨历史进行研究时,基岩和漂砾暴露年龄所反映出的冰川演化历史是明显吻合的。     

城市地下孤石的地震波场响应特征及其在地震层析成像中的应用研究

城市浅层地质条件复杂,地下孤石是常见的地质灾害体.为降低城市地下空间开发过程中孤石造成的安全隐患,本文通过构建城市地下孤石的数值模型,分析地震波在含孤石介质中的传播特征,根据地震波的传播特征利用层析成像技术对孤石进行速度成像,并通过工程实例进行验证.研究表明:(1)地震波场的数值模拟是研究地球物理勘探的有效方法,能高效...     

江苏省连云港市东磊石海的成因

在山东半岛古冰川遗迹研究的基础上,作者又对云台山进行了实地调查。特别对东磊石海,花果山的冰碛洞群进行了认真的分析。通过大量的地质地貌资料的研究,作者认为：云台山曾被更新世期间出现的古冰川所覆盖,留下了众多的古冰川遗迹。云台山的古冰川遗迹以东磊石海和花果山的冰碛洞群为典型。连云港云台山古冰川遗迹的发现,为我国东部古冰川遗迹的研究,又增添了新的证据。     

Elevation and local refuges ensure persistence of mountain specific vegetation in the Nigerien Sahara

The inselberg structure and the local habitats of the Aïr mountains (Niger) are hypothesized to generate the coexistence of geographically isolated plant species with high conservation values. By studying the diversity and the distribution of plants on the highest peak of these mountains, we aimed to identify the respective effects of local and regional abiotic factors on isolated species. We estimated the regional effects of elevation by comparing 103 floristic quadrats with existing data in the adjacent lowlands, and we tested the effects of local abiotic variables on species distribution with ordination methods. Among the 151 species identified, 12 were recorded for the first time in Niger and 53 were not found in the adjacent lowlands, thus evidencing true mountain specificity. A five-class habitat variable separated a relatively high portion of Saharan-Mediterranean species (8%) located in volcanic gullies, and Guinean-Sudanian-Zambezian species (13%) located in granite boulders. These two habitats provided local abiotic refuges (boulders, gullies), which protected a pool of relictual species from aridity, and probably from grazers. Species persistence may thus be dependent both on regional and local abiotic variables. With probable high genetic divergence because of the surrounding desert matrix, their conservation value may be particularly high.