http://www.sciencedirect.com/science/article/pii/S1674987112001302

We present relative sea level （RSL） curves in Antarctica derived from glacial isostatic adjustment （GIA）predictions based on the melting scenarios of the Antarctic ice sheet since the Last Glacial Maximum （LGM）given in previous works.Simultaneously,Holocene-age RSL observations obtained at the raised beaches along the coast of Antarctica are shown to be in agreement with the GIA predictions.The differences from previously published ice-loading models regarding the spatial distribution and total mass change of the melted ice are significant.These models were also derived from GIA modelling; the variations can be attributed to the lack of geological and geographical evidence regarding the history of crustal movement due to ice sheet evolution.Next,we summarise the previously published ice load models and demonstrate the RSL curves based on combinations of different ice and earth models.The RSL curves calculated by GIA models indicate that the model dependence of both the ice and earth models is significantly large at several sites where RSL observations were obtained.In particular,GIA predictions based on the thin lithospheric thickness show the spatial distributions that are dependent on the melted ice thickness at each sites.These characteristics result from the short-wavelength deformation of the Earth.However,our predictions strongly suggest that it is possible to find the average ice model despite the use of the different models of lithospheric thickness.By sea level and crustal movement observations,we can deduce the geometry of the post-LGM ice sheets in detail and remove the GIA contribution from the crustal deformation and gravity change observed by space geodetic techniques,such as GPS and GRACE,for the estimation of the Antarctic ice mass change associated with recent global warming.     

The Fourth James K. Mitchell Lecture: The CPT in offshore soil investigations - a historic perspective

For the last 40 years, the CPT has played a key role in offshore soil investigations, mainly in connection with oil and gas development, but also for other purposes. The offshore application of CPT has been an important factor with regards to development of equipment, data processing and interpretation. Each of the following aspects are discussed in terms of historic development, present status and future challenges:

- Deployment method and equipment.

- Penetrometer design and construction.

- Data acquisition, processing and quality control.

- Standards and guidelines.

- Interpretation of results and application in foundation design.

It is shown that these developments have greatly enhanced the reliability and applicability of the use of the CPT in soil investigations and design. However, there are still important challenges to be faced in the future     

Effect of site-specific soil nonlinearities and uncertainties on ground motion intensity measures and structural demand parameters

ABSTRACT

This paper investigates the effects of site-specific uncertainties in soil strength and stiffness parameters on the commonly used ground motion intensity measures and the resulting engineering demand parameters of moment resisting frames of varying heights at a site in Los Angeles, California. Through a detailed site-specific uncertainty analysis, comparison with generic data, and an extensive parametric study, it is shown that underestimation or overestimation of the true soil uncertainties could significantly affect both the average values and variabilities of the Arias intensity and PGA, and that the uncertainty in the soil strength parameter has more profound effect on the intensity measures than the uncertainty in the soil stiffness parameter. It is also shown that depending upon the natural period of a structure, the uncertainty in both the soil strength and stiffness parameters could affect its peak floor acceleration and peak inter-story drift. Moreover, it is observed that the structure amplifies the soil uncertainty more than the seismological uncertainty.     

Natural sealed fractures in mudrocks: A case study tied to burial history from the Barnett Shale,Fort Worth Basin,Texas, USA

The Mississippian Barnett Shale (Texas, USA), consisting of organic-rich shales and limestones, hosts the largest gas fields of North America. This study examines sealed fractures from core and outcrop samples of the Barnett Shale of the Fort Worth Basin and aims to: 1) characterize the phases occurring in the fractures from samples having experienced different burial histories; 2) establish a paragenetic sequence to relate the timing of fracture origin and sealing with the burial history of the basin; and 3) contribute to the understanding of the mechanisms of fracture formation in shales, including overpressure origin.Four fracture generations were distinguished in the most deeply buried core samples by characterizing the sealing minerals petrographically and geochemically. The generations were inserted into the framework of a reconstructed burial history for the Fort Worth Basin, which allowed a time sequence for fracture development to be established. This in turn allowed inference of conditions of fracture development, and consideration of fracture mechanisms as well as the origin of the parent fluids of sealing minerals.Type 1 fractures formed during early mechanical compaction (at a few 10 s to 100 m of depth) of still not fully cemented sediments. Type 2 fractures formed during moderate burial (∼2 km), from slightly modified seawater. Their timing is consistent with overpressure generated during rapid deposition and differential compaction of Pennsylvanian lithologies during the onset of the Ouachita compressional event. Type 3 fractures formed during deep burial (>3 km) from silica-rich basinal brines possibly derived from clay diagenesis. Type 4 fractures formed at very deep burial (>4 km), from hot and ¹⁸O-rich fluids, carrying light oil (20-30 API) and record the opening of the fluid system after hydrocarbon migration.Differences are highlighted between the timing and thermal regimes under which fractures formed in Barnett lithologies from different areas of the basin, this suggesting that extrapolation of outcrop observations to subsurface must be used with due care.     

环境因子对海蜇生长发育影响的研究进展

<正>海蜇(Rhopilema esculenta Kishinouye)隶属于刺胞动物门(Cnidaria),钵水母纲(Scyphozoa),根口水母目(Rhizostomeae),根口水母科(Hizostomadae),海蜇属(Rhopilema)[1]。海蜇为进化比较保守的两胚层动物[2]。丁耕芜等[3]首次报告了海蜇的整个生活史。海蜇生活史具有刺胞动物门典型的世代交替特征,分为两个世代:水螅体世代和水母体世代。在水螅体世代整个过程中,海蜇螅状体于海底基质上营固着生活,以无性生殖     

Deforestation in the Ayeyarwady Delta and the conservation implications of an internationally-engaged Myanmar

Myanmar is a country of huge biodiversity importance that is undergoing major political change, bringing with it new international engagement. This includes access to international markets, which will likely spur investment in export-oriented agriculture, leading to increased pressures on already threatened ecosystems. This scenario is illustrated in the Ayeyarwady Delta, the country's agricultural heartland sustaining high deforestation rates. Using the Delta as a model system, we use an integrated approach to inquire about whether and how imminent agricultural reforms associated with an internationally-engaged Myanmar could introduce new actors and incentives to invest in agricultural expansion that could affect deforestation rates. We use a novel remote sensing analysis to quantify deforestation rates for the Delta from 1978 to 2011, develop business-as-usual deforestation scenarios, and contextualize those results with an analysis of contemporary policy changes within Myanmar that are expected to alter the principal drivers of land-cover change. We show that mangrove systems of Myanmar are under greater threat than previously recognized, and that agriculture has been the principle driver of deforestation on the Delta. The centrality of agriculture to the Myanmar economy indicates that emerging policies are likely to tip the scales towards agricultural expansion, agro-industrial investment and potentially greater rates of deforestation due to the introduction of well-funded investors, insufficient land tenure agreements, and low governance effectiveness. The broad national challenge is to initiate environmental governance reforms (including safeguards) in the face of significant pressures for land grabbing and opportunistic resource extraction.     

四川盆地北缘大巴山前陆构造中—新生代构造隆升史

大巴山前陆构造的抬升剥蚀与保存条件对其矿床和油气藏勘探潜力评价极为重要。应用磷灰石裂变径迹热年代学方法,通过研究大巴山前陆构造热演化史,恢复构造隆升过程,确定其中—新生代构造抬升剥蚀量,探讨大巴山前陆晚期构造隆升对矿床和油气资源的影响。结果表明:大巴山前陆构造在152Ma以前快速沉降,沉降速率平均高达150m·Ma-1,此后便长期处于隆升过程;136~152Ma时期为快速隆升阶段,隆升速率平均为56.3m·Ma-1,隆升量约为900m,是燕山运动导致秦岭造山期后的一次陆内挤压;70~136Ma时期为较缓慢隆升阶段,隆升速率平均为39.4m·Ma-1,隆升量约为2 600m,是秦岭造山晚期挤压的结果;0~70Ma时期的隆升速率为42.8m·Ma-1,持续时间较长,隆升幅度约3 000m,是喜马拉雅构造运动的结果。中生代构造隆升对本区低温热液矿体和油气保存极为不利;上新统以来(8Ma或5Ma),青藏高原快速隆升向东扩展的远程效应对大巴山前陆构造的影响不明显。     

关中盆地深部地下热水残存沉积水的同位素证据

应用环境同位素水文地球化学方法,结合区域沉积演化史,对关中盆地固市凹陷、咸阳-礼泉断阶和西安凹陷深部地下热水成因类型进行了探讨,并就残存沉积水存在的可能性,寻找氢氧同位素关系、硫氧同位素关系、碳氧同位素关系、N(87Sr)/N(86Sr)与古盐度的关系等环境同位素证据,rNa/rCl值、ρ(Cl-)/ρ(Br-)、rBr/rI值与ρ(Cl-)的关系等水文地球化学证据以及沉积演化史证据。结果表明:固市凹陷华阴地下热水的同位素、水文地球化学特征已基本符合沉积水的特征,推测其为混有古入渗水的残存沉积水;固市凹陷华阴之外的其他构造单元、咸阳—礼泉断阶和西安凹陷地下热水的同位素和水文地球化学特征部分接近沉积水的特征,部分介于古入渗水和沉积水之间;咸阳—礼泉断阶东部地下热水可能为古入渗水或残存沉积水与后期入渗水的混合;西安凹陷及咸阳—礼泉断阶西部地下热水属于现代入渗水与古入渗水的混合水。     

基于地理国情普查对开发冰雪丝绸之路旅游带的思考

黑龙江省第一次地理国情普查已全面展开,其目的是全面掌握黑龙江地理国情现状,系统掌握全省自然、人文地理要素的现状和空间分布情况。黑龙江省是资源大省,除煤、木、粮、油、机外,旅游资源也十分丰富。作为连接中原与黑龙江地区的水陆大通道,黑龙江冰雪丝绸之路比西北丝绸之路早了1000多年,且一直繁荣了几千年,存有大量的历史遗迹,但近百年来却鲜为人知。充分利用基于现代测绘地理信息技术获得的地理国情数据和信息,恢复和开辟黑龙江冰雪丝绸之路旅游带,对弘扬黑龙江历史文化,宣传黑龙江意义重大,功在当代,利在后世。