南宁市坛洛镇岩溶塌陷群成因机制分析

岩溶塌陷是岩溶区较为常见的地质灾害,对其成因机制的研究有助于针对性的进行综合防治。为了弄清2012年6月在广西南宁市坛洛镇连续发生的岩溶塌陷的成因及发育机制,在塌陷群发生地区开展了现场调查、地球物理勘探、水文地质工程地质钻探、地下水动态长期监测、岩土样测试等多项工作。结果表明,坛洛岩溶塌陷群是各种不良因素共同作用的产物。其致塌因素主要包括特殊的“水-土-岩”组合及人为活动。研究区地下水位埋深较浅,土体结构以粘性土为主,渗透系数较低且易崩解,地下岩溶极为发育。高强度的人工地下水开采活动是坛洛岩溶塌陷的诱因。深入分析其发育机理,认为塌陷群是渗流潜蚀效应、增荷失托效应和水位波动产生的气压差效应等3个力学效应综合作用下发生的,其致塌模式是重力致塌、潜蚀致塌、真空吸蚀致塌和冲爆致塌等4种模式的相互结合。根据岩溶塌陷的发生顺序推断坛洛镇岩溶塌陷群的发育过程可分为缓慢发育—塌陷诱发—塌陷集中爆发3个阶段,各阶段的主要地质营力有所不同。      

砂岩侵入体系模拟及形成机理分析

砂岩侵入体系是一种普遍的地质现象,近些年来越来越受到地学界的重视,但对其形成机理探讨较少。作者及研究团队通过设计一套室内模拟实验装置,来简化模拟3层地层结构中砂岩侵入体系的形成和演化过程。在之前模拟实验(实验变量为顶层沉积物的厚度、进水管的结构)结果的基础上,进一步考察了地形坡度对实验结果的影响,并对砂岩侵入体系的形成机理进行了分析。实验过程中,共观察到7种不同形态不同样式的管道,并对实验过程中压力变化进行了测试。对实验结果分析认为:盖层厚度越大,压力下降的速度越慢,越不利于压力的释放;随着实验的继续进行,砂岩侵入体最终会转化为砂岩喷出体并喷出地表;不稳定的地形有利于触发疏松沉积物发生变形。实验表明,超压是砂岩侵入体发生的最重要条件之一, 沉积盆地中的压实不均衡和生烃作用是可独立产生大规模超压的2种主要机制。     

内蒙古扎鲁特旗地区中侏罗统塔木兰沟组的厘定

扎鲁特旗地区发育的一套中性火山岩,前人曾将其置于二叠纪“大石寨组”、“青凤山组”,缺少古生物资料和测年数据.本次1：25万区域地质调查,在原1：20万划分的“大石寨组”、“青凤山组”的安山岩中采集了同位素测年样品,采用全岩激光⁴⁰Ar/³⁹Ar法测年,对火山岩样品进行了年代学研究,结果表明火山岩年龄为（172.7±2.0）~（165.2±1.3）Ma.鉴于这套火山岩地层岩石组合特征清楚,时代依据充分,在区域上具有一定的延展性和可填图性,故将这套火山岩地层重新厘定为中侏罗统塔木兰沟组.     

2008年盈江地震序列的震源参数和震源机制相关系数研究

基于云南数字地震台网记录的2008年盈江地震序列的数字波形资料,采用波谱分析方法和Brune震源模型,得到盈江地震序列的震源参数。利用两次地震事件的相同台站的震源谱参数（零频振幅）计算谱振幅相关系数,据此对地震的震源机制进行聚类分组,并收集和对比地震序列已知的震源机制解结果,发现每组内震源机制解P轴的相关性较好,且相关系数越大,P轴的方位角就越接近。将盈江地区划分为三个研究区,联合震源参数的应力降和聚类分组中每组的平均震源机制解结果研究地震序列发生过程中应力的释放水平和应力场方向变化特征。结果表明：不同阶段震源机制解类型的变化和转化特征一定程度上反映了孕震过程中区域应力场随时间的变化特征,并且地震震源机制解类型在时间段上的集中并向区域构造应力场方向转换的现象可能是发生强震的标志。震源机制解分组类型和对应类型的地震的应力降有一定依赖关系,震源机制解类型反映的应力场与区域应力场接近的地震应力降高,震源机制解类型反映的应力场与区域应力场差距较大的地震应力降普遍较低。     

Subcultural enterprises,brand value,and limits to financialized growth: The rise and fall of corporate surfing brands

Geographical political economy increasingly scrutinises the socio-spatial contexts for brands and branding. Less understood is the influence of subcultures – neo-tribal groups sharing passions, a leisure pursuit or practice - on enterprise formation and the pathways through which brands emerge, trading on perceived authenticity. Subcultural contexts, we argue, unleash distinctive trajectories of enterprise formation, reputation-building, value-creation, global expansion and accumulation, and ultimately destruction. Here we focus on how particular subcultural values – of authenticity, competition, risk-taking, and active participation in ‘scenes’ – interact with capitalist growth dynamics, and where over time and space such intersections bring brands unstuck. Using the case of surfing subculture and collapse of corporate surf enterprises (Quiksilver, Billabong), we theorise subcultural brand value creation and its interaction with financialized expansion, culminating in destructive contradictions. Subcultural enterprises with ‘authentic’, ‘back-of-the van’ origins convert subcultural values of credibility, localism, risk-taking, and scene participation into brand value. Trading on place-origins and subcultural authenticity, enterprises expanded in two phases. First by widening distribution using specialist ‘surf’ retailers, and second by offshoring production, public floating, and debt-financing brand acquisitions and massive retail expansion. Dictates of shareholders and investment banks spurred market saturation, and high-volume/low-quality goods. Surfing’s cherished insouciance gave way to unhinged expansionism and unmanageable debt. The subcultural authenticity that spawned brand popularity was undermined, amplifying financial risk. Disenchanted consumers who once co-created successful brands also co-destroyed them. As subcultural brands proliferate, geographical political economy must be attentive to subcultures as spawning-grounds for enterprises with accompanying limits to market growth, (dis)connections, and values.     

Geochemical characteristics of mud volcano fluids in the southern margin of the Junggar basin,NW China: implications for fluid origin and mud volcano formation mechanisms

Mud volcanoes can provide important information about the underlying strata, hydrocarbon accumulation, and recent neotectonic movements in an area. The fluids erupting from mud volcanoes provide important information about their formation and evolution. The ion concentration and the hydrogen and oxygen isotopes of the fluids that were erupted from the three mud volcano groups, Baiyanggou, Aiqigou, and Dushanzi, and nearby rivers in the southern margin of the Junggar basin, northwestern China, are studied. The concentrations of Na and Cl in mud volcano fluids are clearly elevated, displayed as the Na-Cl type. The δD and δ18O values of the fluids are similar between the Baiyanggou and Dushanzi mud volcanoes, which are mainly from ancient sedimentary pore water. However, the Aiqigou mud volcano is depleted in dissolved Cl and shows lower δ18O values with mixed sources, including deep pore and local meteoric water. Two types of mud volcanoes are proposed in this study. One type is low-energy mud volcanoes with a low volume of fluid of deep origin on the hillcrest, which display as mud pool/pie/hole. The other type is high-energy mud volcanoes having mixed fluid origin in the valley and formed in the shape of a mud cone (dome).     

Description of a juvenile titanosaurian dinosaur from the Upper Cretaceous of Brazil

We describe a juvenile specimen of a titanosaurian sauropod dinosaur consisting of two dorsal and three caudal vertebral centra, an ilium fragment, and an ischium unearthed in 1991 from Site Km 153.5 at BR-050 highway in the Serra da Galga region, municipality of Uberaba, state of Minas Gerais, Brazil. The outcrop at the site is assigned to the Serra da Galga Member of the Marília Formation (Bauru Basin: Bauru Group; Upper Cretaceous: Maastrichtian). Although the material is very incomplete, features such as strongly procoelous caudal centra suggest an affinity with the titanosaurian clade Lithostrotia. The extensive vertebral pneumaticity with deep pleurocoels and well-developed camerae supports the hypothesis that, in titanosaurs, the air sac system was already present and fully developed even at early ontogenetic stages.     

Late Cretaceous ostracod fauna from the Shenjiatun section (Songliao Basin,Northeast China): Biostratigraphic and palaeoecological implications

This work provides the first detailed taxonomic study of ostracod species from the Shenjiatun section (Nenjiang Formation, Songliao Basin, northeast China). Ten species belonging to seven genera are recognized. At the species level, this ostracod fauna shows a high degree of endemicity. The ontogeny of two species is recognized in this study, and sexual dimorphism within Daqingella arca is unequivocally recognized for the first time. The ostracod fauna suggests that this fossil-bearing sedimentary succession should be assigned to members 3–4 (Campanian) of the Nenjiang Formation (mainly Member 3) instead of representing ‘Quaternary sediments’ as previously thought. On the basis of the ostracod fauna, Member 3 of the Nenjiang Formation at Shenjiatun represents a shallow-littoral, lacustrine depositional environment that, at least in the upper part of Member 3, potentially included less stable conditions characterized by smaller, ephemeral waterbodies and increased (non-marine, oligohaline) salinities through evaporation.     

宜昌磷矿北部整装勘查项目深孔复杂地层钻探技术

宜昌磷矿北部整装勘查工程是湖北省大型磷矿资源勘查项目,由于地形复杂,工作量大,施工条件困难,钻孔深度达到1400 m,给钻探组织和施工带来更高的要求。本文就该项目的地质钻探工作进行简要总结,介绍了寒武系和震旦系地层中的钻探施工技术及应用效果。     

青海盐溶地层钻探卤水泥浆配方研制及应用

针对青海盐溶地层在钻进过程中,上部泥页岩吸水膨胀,钻孔缩径,下部钾盐矿物层溶蚀,导致盐侵、扩径以及砂砾碎屑岩层胶结差,松散易坍塌、掉块等施工难点,开展了卤水泥浆的适岩性研究。在实验室选用正交实验法和现场实际配制,优选了4组卤水泥浆配方,通过生产应用与使用普通低固相泥浆对比,平均机械钻速由1.015 m/h提高至1.195 m/h,孔径扩大率由7.83%降低至4.36%,划眼损失率由3.05%降低至1.41%,泥浆成本由731.3元/m3降低至503.8元/m3,取得了较好的效果。