鄂尔多斯盆地南部马家沟组成岩作用特征

通过对研究区16口钻井15条剖面数百片岩石薄片的详细鉴定,结合沉积史和区域地质特征,综合分析了主要目的层马家沟组的成岩作用类型及其特征。马家沟组储层的岩石类型主要为石灰岩和白云岩。石灰岩类型多样,主要有泥晶—微晶灰岩、微晶—亮晶颗粒灰岩及云斑灰岩等;白云岩以泥晶—微晶白云岩为主。主要的建设性成岩作用为白云石化作用和溶蚀作用;不利的成岩作用主要有重结晶、压实压溶、去白云石化、膏化等作用。在此基础上,进一步分析了鄂尔多斯盆地南部的成岩作用演化序列。     

深圳西冲湾的海蚀地貌与海滩沉积研究

利用对深圳西冲湾两个岬角之间的海蚀地貌及其海滩沉积物的野外调查资料,鉴定出三级海蚀平台,对其分别进行了高程换算,并借助于海蚀拱门和海蚀刻槽的测定,以及对典型沙层沉积剖面序列的分析和14C测年,认为：虽然西冲湾海蚀平台的岩石类型是不易被侵蚀的花岗岩,但是此处的海蚀地貌（主要是海蚀平台）以及海滩沉积物（主要是海滩岩）可以作为全新世存在高海平面的证据。此外,针对我国海岸带人口密度大,人类活动对海岸影响程度大的现况,提出了未来研究南海北部海岸新构造运动存在的问题以及其解决方案。研究成果对于认识南海北部海岸全新世的构造运动、海平面变化以及与其他地区新构造运动的对比研究都具有重要的意义。     

Comparative study of dissolution rate-determining mechanisms of limestone and dolomite

The dissolution rate-determining processes of carbonate rocks include: (1) heterogeneous reactions on rock surfaces; (2) mass transport of ions into solution from rock surfaces via diffusion; and (3) the conversion reaction of CO₂ into H⁺ and HCO ₃ ⁻ . Generally, it is the slowest of these three processes that limits the dissolution rate of carbonate rock. However, from experiment and theoretical analysis under similar conditions not only were the initial dissolution rates of dolomite lower by a factor of 3–60 than those of limestone, but also there are different dissolution rate-determining mechanisms between limestone and dolomite. For example, for limestone under the condition of CO₂ partial pressures dissolution rates increased significantly by a factor of about ten after addition of carbonic anhydrase (CA) into solution, which catalysed the conversation reaction of CO₂, whereas CA had little influence on dolomite dissolution. For dolomite, the increase of dissolution rate after addition of CA into solution appeared at Moreover, the enhancement factor of CA on dolomite dissolution rate was much lower (by a factor of about 3). In addition, when dissolution of both limestone and dolomite was determined by hydrodynamics (rotation speed or flow speed), especially under the dissolution of limestone was more sensitive to hydrodynamic change than that of dolomite. These findings are of significance in understanding the differences in karstification and relevant problems of resource and environment in dolomite and limestone areas.     

Lower Triassic δC isotope curve from shallow-marine carbonates in Japan, Panthalassa realm: Confirmation of the Tethys δC curve

δ¹³C data from Tethyan sections provide evidence of profound changes in the carbon cycle during the Lower Triassic. Sections from the Panthalassa realm were investigated to establish whether these variations are also present there. In the Jurassic accretionary wedges in Japan, exotic blocks having a Panthalassan affinity, have been incorporated. The majority of the blocks are pelagic cherts but rare shallow-water carbonates are also present. We present a δ¹³C study on the Lower Triassic of a shallow-water carbonate succession deposited on a mid-oceanic seamount and accreted to the Chichibu Belt, Japan. Two sections have been measured at Kamura, central Kyushu Island. The carbon isotope curve shows depleted values across the Permian–Triassic boundary (PTB), subsequently followed by an increase to heavier values into the Dienerian, culminating in a maximum of almost +4‰ V-PDB, before a steep drop at a stratigraphic gap. Low values are recorded in the Smithian, but rise to enriched δ¹³C values > +3.5‰ near the Smithian–Spathian boundary. The observed trend of the stable carbon isotope curve from Japanese sediments mirrors the curves derived from sections in the Tethys (e.g. Italy, Iran, Turkey, Oman and the South China Nanpanjing Basin). Our results support the interpretation of this curve as representing a global trend across the PTB and in the Lower Triassic, although some distinct features are absent around the Dienerian/Smithian boundary. Profound variations of the carbon isotope curve in the Lower Triassic are presented for the first time from a marine section outside of the Tethys. They indicate severe, global changes in the Lower Triassic carbon cycle, and the causative processes must have significantly contributed to the delayed biotic recovery after the PTB. Large amounts of carbon were shifted between carbon reservoirs, most probably between shallow- and deep-ocean waters, and/or ocean and sediment. Anoxia followed by overturn of the ocean water masses may have been the mechanism which quickly altered ecological conditions in the ocean leading to variable availability of nutrients and oxygen, and changes in isotope composition of the available carbon in the surface waters that was incorporated in the precipitated carbonate.     

西华山钨矿区复杂地层钻进的综合治理措施

总结了西华山钨矿区综合治理复杂地层的经验;着重介绍了PAA聚合物在断层破碎带、易水化碎裂岩体中的使用方法和护壁堵漏效果;提出了治理复杂地层应采取“‘辨证论治’、灵活运用”的思路方法,最大限度地降低施工成本,提高钻进效率。     

青岛崂山海岸基岩海蚀作用特征

海蚀作用会诱发各种地质灾害,为研究青岛崂山地区的海蚀作用,本研究通过野外踏勘取样、岩石手标本鉴定和偏光显微镜下薄片鉴定分析等方法,分析了岩石学和构造特征对海蚀作用的影响,并以石老人地区为例分析了海蚀地貌的特征,探讨了崂山地区的海蚀地貌分布特征及影响因素。结果表明:崂山海岸基岩为I-A型复合花岗岩。抗海蚀能力最强的是白垩系莱阳群砂岩,其次为白垩系青山群火山岩和石英二长岩,再次为碱性花岗岩,黑云二长岩最弱。断裂构造破坏岩石稳定性,促进了海蚀作用;石老人地区以流纹岩为主,在海蚀崖后退过程中,安山岩的侵入体保留下来,形成了石老人海蚀柱;崂山地区发育多种海蚀地貌,受到海浪作用、气温条件、盐类结晶以及生物作用等外部因素影响。     

广东石灰岩地区的任豆群落

本文对任豆群落的分布及生境特点，主要种群的生物不特性，其种类组成，外貌，结构，动态进行了分析，将其分为三个群落类型加以介绍，并提出开发利用与保护意义。     

中国旅游产业投资及旅游发展空间结构响应——基于2000~2015年旅游业三大核心部门数据的分析

以旅游业三大核心部门（旅游饭店、旅游景区和旅行社）的固定资产和人力资源投资为研究变量,分析了2000~2015年中国旅游产业投资演化及旅游发展空间结构的响应。研究发现,中国旅游产业投资存在与旅游发展总体协调、省域空间分布不均、年际变化多样和部门差异明显的特征;省域旅游发展响应系数的变化,反映了中国旅游产业投资的“时间磨蚀效应”和“绩效累积效应”;在“空间牵引效应”作用下,中国旅游产业投资促进了中国旅游发展空间结构特征由离散型“核式极化”向连续型“域状扩散”转变。最后,提炼了旅游发展对旅游投资空间响应的实质：以投资为驱动,依据循环积累因果机制,促进区域旅游产业可持续增长。     

The formation of beaches on shore platforms in microtidal environments

Beaches are common features of many rocky shorelines and can be considered to be constrained by the underlying geology. In mesotidal to macrotidal areas the slope of the substrate and sediment supply are the primary factors in constraining the size and development of beaches on shore platforms. In microtidal settings it is not known if these factors are wholly responsible for determining the presence of beaches on shore platforms, nor the contribution of other factors such as hydrodynamics. The microtidal coast of Victoria, Australia, is surveyed in this study in order to quantify the morphological boundary conditions that constrain beach development on semi‐horizontal shore platforms. An ample sediment supply indicates that the underlying geology is controlling the presence and absence of beaches. Where beaches occur they always overlie a rock ramp which is the steepest part of the platform. The two most important morphological constraints were platform width and height both of which significantly correlated with beach volume. An elevational threshold exists at just over +1.0 m where beaches cannot accumulate. Below this threshold, platform width appears to be the principle constraining factor in beach accumulation. An evolutionary model is inferred which suggests that dissipation of wave energy associated with platform widening plays an important role in allowing beaches to accumulate. The model suggests beaches on platforms will be particularly sensitive to sea level rise. Copyright © 2014 John Wiley & Sons, Ltd.     

Coronate echinoderms from the Ordovician of the Llanddowror area,South Wales

A large sample of coronates (over 90 specimens) from a narrow horizon in the Upper Ordovician, Sholeshook Limestone, at Talfan Farm, Llanddowror, South Wales allows assessment of variation and growth in a population of these rare Palaeozoic echinoderms. Variation is extensive and we synonymize two previously described species. This occurrence extends the stratigraphic range of Cupulocorona rugosa Donovan and Paul down to Cautleyan, Zone 2. Internal moulds reveal new morphological features, especially of the coronal canals. The flattened blade‐like and kite‐shaped portions support the idea that the coronal canals functioned in respiratory gas exchange by increasing the surface area. We suggest that internal currents flowed up the inner (adoral) canal and down the outer (aboral) canal. Quantitative estimates of flow rate suggest that a volume of coelomic fluid equivalent to the entire body cavity could be flushed through the coronal canals in 10 seconds at most. These coronates probably lived attached by a relatively long stem with a simple, conical holdfast and bent over in gentle currents. They seem to have been characteristic of relatively high‐energy environments and are not generally distributed in the Sholeshook Limestone of South Wales. Copyright © 2014 John Wiley & Sons, Ltd.