四川华蓥山地地质灾害类型及成因分析

该文全面介绍了华蓥山地区的山地地质灾害的情况及类型。重点从地质因素、水体因素、人为因素等三方面分析了华蓥山地地质灾害的成因。     

竖向荷载作用下桩筏基础可视化模型试验研究

进行了群桩基础可视化模型试验。在试验过程中对各级竖向荷载作用下群桩基础桩、土的变形采用高清晰数码相机拍摄了照片。通过对照片进行后处理分析,得到了桩、土的位移场,也对桩身轴力也进行了量测,在该基础上研究了群桩基础的变形性状和破坏模式,重点分析对比了桩间距和桩长对桩端土体沉降以及桩身侧摩阻力的影响。试验发现,桩距是影响桩土相对滑移量的主要因素,桩距越大,桩身与土的相对滑移量就越大,桩端刺入量也越大。在柔性筏基下,随桩距增加中桩的桩土相对滑移量可能会大于边桩。桩端刺入量是大桩距桩基础主要的沉降构成,以桩端刺入量为研究对象建立一套大桩距基础新的沉降计算理论,似乎值得进一步研究。桩顶向上刺入（可通过设置褥垫层、桩顶预留净空或设置可压缩垫块来实现）有利于桩间土的压密,减小桩端刺入量,甚至改变破坏模式。     

淡水中丝状绿藻对重金属Pb2+的吸附

通过淡水中绿藻门的一些丝状种类,如毛枝藻(Stigeoclonium)、刚毛藻(Cladophora)、水绵(Spirogyra)对铅的吸附实验,研究淡水藻类与铅的吸附关系及影响因素。结果表明,淡水中丝状绿藻对铅有较强的吸附能力, 当pH值和温度以及包埋藻类的量控制在一定条件下,即pH值约为4,温度为28℃左右,按照2 g藻类处理20 mL 质量浓度为100 mg/L Pb²⁺溶液原则包埋藻类,就可以使单位藻类吸附效率达到40％。     

不同成因类型煤中烷基环己烷和烷基苯的特征探讨

通过对藻煤、烛煤、腐殖煤共生煤层的分析，将不同成因类型煤中的烷基环己烷和烷基苯进行了比较。结果表明，不同成因类型煤中所含的烷基环己烷和烷基苯明显不同。各种成因类型煤中烷基环己烷和烷基苯所提供的母质信息与煤岩结果吻合。氧化环境不利于烷基环己烷和烷基苯的形成。烷基环己烷和烷基苯有时可以作为沉积环境和成熟度的标志。     

鲁中南岱崮地貌的成因及演化——以抱犊崮为例解析

鲁中南抱犊崮地区,山体陡峭挺拔,风景秀丽,以有鲁南小泰山之称的抱犊崮为代表,山体顶部主要由古生代寒武纪九龙群张夏组灰岩组成,其下分布由长清群馒头组砂岩、砂质页岩、泥质灰岩、薄层灰岩及朱砂洞组灰岩、泥质灰岩等。“崮”的成因主要是古生代寒武纪灰岩经受了强烈的地壳切割和抬升运动,并遭受长期的侵蚀、溶蚀、重力崩塌和风化剥蚀等多重地质作用而形成抱犊崮所具有的岱崮地貌,作为地质遗迹和地质地貌景观,具有重要的地学研究价值,也是潜力巨大的旅游资源。     

Cretaceous magmatic arc in Hainan and the peri-South China Sea as evidenced by geochemical fingerprinting of granitoids in the region

Mesozoic magmatic rocks occur widely in the South China Block and are generally interpreted as the manifestations of the subduction of the Paleo-Pacific oceanic lithosphere beneath Asia.Subduction-driven magmatism in southeast(SE)China continued from the Late Permian through the Late Cretaceous with an inferred lull between 125 Ma and 115 Ma that is known in the literature as the Cretaceous\"magmatic quiescence\".We report in-situ zircon U-Pb ages,Hf-O and whole-rock Sr-Nd iso-topes,and whole-rock geochemistry of Cretaceous granitoids on Hainan Island and discuss their mag-matic evolution within the framework of the Late Mesozoic geodynamics of SE China.We recognize two main stages of the emplacement of Cretaceous granitoids on Hainan,first around 120 Ma and then around 100-95 Ma,displaying high-K calc-alkaline,Ⅰ-type geochemical affinities.Granites in both age groups are enriched in LILE and LREE,but depleted in Nb,Ta,Ba,Sr,and Eu.The 120 Ma granites have zircon εHf(t)values of-2.6 to 2.3 corresponding to Hf crustal model ages,ranging from 0.79 Ga to 1.03 Ga,and δ18O values ranging from 6.9‰ to 7.7‰.Zircons from 100-95 Ma granites have εHf(t)values of-4.2 to 1.1 corresponding to Hf crustal model ages of 1.08 Ga to 1.42 Ga,and δ18O values ranging from 6.7‰ to 8.4‰.Increasing εHf(t)values of the Cretaceous Hainan granites with younger crystallization ages indicate addition of more juvenile components and reworking of crustal material into their melt evolu-tion.The εNd(t)values of the 120 Ma and 100-95 Ma granitoids range between-4.1 to-0.4 and-7.7 to-4.0,respectively.The calculated two-stage model age of the 100-95 Ma granitoids clusters between 1.25 Ga and 1.53 Ga.These isotopic data suggest that magmas of the Cretaceous granitoids were pro-duced by partial melting of Mesoproterozoic metabasaltic rocks,which make up much of the crystalline basement of the southern Cathaysia block.The geochemical and isotopic characteristics of the Cretaceous granitoids on Hainan resemble those of magmatic arcs in the Circum-Pacific orogenic belts and identical to those of nearly coeval granitoid intrusions in the continental fragments within the South China Sea basin.We interpret these Cretaceous granitoids in the Peri-South China Sea region as the remnants of a once contiguous Late Mesozoic magmatic arc system that bounded the southern margin of the entire continental Southeast Asia.Our findings do not support the existence of an episode of magmatic quies-cence in the geological record of SE China during the Aptian.