美国Bryce峡谷古新统-始新统红色层古土壤微形态特征及其指示意义

地层中的古土壤记录了古气候环境演化的重要信息,然而年代越老的地层由于受到后期持续的地质作用,使得古土壤面貌发生很大改变,增加了识别难度.美国Bryce峡谷广泛出露的古新统-始新统Claron组一直被认为是湖相石灰岩,却呈现整体氧化红色,并显示诸多古土壤特征.文章主要采用偏光显微镜和扫描电子显微镜来探究Bryce峡谷Cl...     

Ocean-continent Transition to Suprasubduction Zone Origin of the Western Yarlung Zangbo Ophiolites in SW Tibet, China: Multi-stage, Transient Evolution of the Neotethyan Oceanic Lithosphere

The ophiolites that crop out discontinuously along the~2000 km Yarlung Zangbo Suture zone(YZSZ)between the Nanga Parbat and Namche Barwa syntaxes in southern Tibet represent the remnants of Neotethyan oceanic lithosphere(Fig.1a).We have investigated the internal structure and the geochemical makeup of mafic-ultramafic rock assemblages that are exposed in the westernmost segment of the YZSZ where the suture zone architecture displays two distinct sub-belts of ophiolitic and mélange units separated by a continental Zhongba terrane(Fig.1b).These two sub-belts include the Daba–Xiugugabu in the south(Southern sub-belt,SSB)and the Dajiweng–Saga in the north(Northern sub-belt,NSB).We present new structural,geochemical,geochronological data from upper mantle peridotites and mafic dike intrusions occurring in these two sub-belts and discuss their tectonomagmatic origin.In-situ analysis of zircon grains obtained from mafic dikes within the Baer,Cuobuzha and Jianabeng massifs in the NSB,and within the Dongbo,Purang,Xiugugabu,Zhaga and Zhongba in the SSB have yielded crystallization ages ranging between130 and 122 Ma.Dike rocks in both sub-belts show N-MORB REE patterns and negative Nb,Ta and Ti anomalies,reminiscent of those documented from SSZ ophiolites.*Harzburgitic host rocks of the mafic dike intrusionsmainly display geochemical compositions of abyssal peridotites(Fig.2),with the exception of the Dajiweng harzburgites,which show the geochemical signatures of forearc peridotites(Lian et al.,2016).Extrusive rocks that are spatially associated with these peridotite massifs in both sub-belts also have varying compositional and geochemical features.Tithonian to Valanginian(150–135 Ma)basaltic rocks in the Dongbo massif have OIB-like geochemistry and 138 Ma basaltic lavas in the Purang massif have EMORB-like geochemistry(Liu et al.,2015).Tuffaceous rocks in the Dajiweng massif are140 Ma in age and show OIB-like geochemistry.We interpret these age and geochemical data to reflect a rifted continental margin origin of the extrusive rock units in both sub-belts.These data and structural observations show that the western Yarluang Zangbo ophiolites represent fragments of an Ocean-Continent Transition(OCT)peridotites altered by fluids in an initial supersubduction setting.We infer that mafic-ultramafic rock assemblages exposed in the SSB and NSB initially formed in an ocean–continent transition zone(OCTZ)during the late Jurassic,and that they were subsequently emplaced in the forearc setting of an intraoceanic subduction zone within a Neotethyan seaway during 130 to 122 Ma.The NSB and SSB are hence part of a single,S-directed nappe sheet derived from a Neotethyan seaway located north of the Zhongba terrane.     

北欧海海面高度上升减缓及其机理研究

A slowdown of sea surface height(SSH) rise occurred in the Nordic(GIN) seas around 2004.In this study,SSH satellite data and constructed steric height data for the decades before and after 2004(i.e.,May 1994 to April 2014)were used for comparative analysis.The findings indicate that the rate of slowdown of SSH rises in the GIN seas(3.0 mm/a) far exceeded that of the global mean(0.6 mm/a).In particular,the mean steric height of the GIN seas increased at a rate of 4.5 mm/a and then decreased at a slower pace.This was the main factor responsible for the stagnation of the SSH rises,while the mass factor only increased slightly.The Norwegian Sea particularly experienced the most prominent slowdown in SSH rises,mainly due to decreased warming of the 0–600 m layer.The controlling factors of this decreased warming were cessation in the increase of volume of the Atlantic inflow and stagnation of warming of the inflow.However,variations in air-sea thermal flux were not a major factor.In the recent two decades,mean halosteric components of the GIN seas decreased steadily and remained at a rate of 2 mm/a or more because of increased flow and salinity of the Atlantic inflow during the first decade,and reduction in freshwater inputs from the Arctic Ocean in the second decade.     

警戒潮位核定中建立年极值水位序列的方法研究

文章以山东省警戒潮位核定为基础,对其沿岸验潮站的实测数据情况进行分类;根据不同类别,分别采用相关分析、数值模拟等方法补充实测数据,获得年极值水位序列,并采用极值Ⅰ型方法计算重现期高潮位。在警戒潮位核定中建立年极值水位序列所使用方法的顺序是,有实测数据优先采用实测数据、没有实测数据利用相关关系、没有相关关系再使用数值模拟和调和分析的方法进行。值得注意的是,在使用相关关系建立年极值水位序列中,计算重现期高潮位时一定要满足潮汐性质相同、所受风暴潮过程相似等条件;在使用数值模拟建立年极值水位序列中,须与其全年天文潮最大值进行对比。     

中国全球化海洋战略研究

制定全球化海洋战略不仅是我国海洋强国建设的重要举措,也是服务海洋经济全方位对外开放的实际需求,更是我国海洋事业发展的必然趋势。基于价值观的演变,开展中国全球化海洋战略的战略背景分析,并探讨了全球化海洋战略的内涵;从维护国家安全、促进经济和环境可持续发展、寻求外线突破和参与全球海洋治理等方面,深入论述了全球化海洋战略对中国的战略性意义;探索了中国全球化海洋战略在四大洋整体布局框架,并讨论了其战略目标及战略手段。最后,从战略理念、法律法规、机制体制、国际合作、科技支撑与海洋文化等角度提出对策建议。     

海底边界效应对海流发电水轮机水动力性能影响研究

对30 W海流能水平轴水轮机进行叶片设计,应用FLUENT软件对水轮机的水动力性能进行数值模拟,研究了边界效应对叶片表面压力、流场、湍流强度、获能和轴向力的影响。受海底边界效应影响,海流速度沿深度呈现梯度变化,底层流速较小,中上层流速较大。边界效应导致水轮机的水动力性能呈现周期性变化,降低了水轮机的获能和轴向力。机组布置时,宜选择水流稳定且流速较大的中上层区域。     

山东文登鞠格庄金矿成矿特征及找矿方向

文登鞠格庄金矿体位于山东省牟平-乳山金成矿带外围,米山断裂东侧,是一个石英脉型金矿体。金矿体受EW向断裂构造控制,围岩为新元古代荣成序列邱家单元片麻状细粒二长花岗岩。矿石为黄铁矿化石英脉、黄铁矿化硅化绢云母化花岗质蚀变岩,矿石矿物主要为黄铁矿、方铅矿、黄铜矿、褐铁矿,金矿物主要为自然金。根据矿体地质特征和分布规律,预测(1)号金矿体深部、走向方向以及周围米山次级断裂构造内有较好的找矿前景。     

2016年青海门源MS6.4地震前的区域地壳形变特征

选取2016-01-21青海门源MS6.4强震发震区域周围200 km范围的10个连续GPS观测站和74个流动GPS观测站资料,分析研究2016年门源MS6.4地震之前的区域地壳形变特征：1）基于10余年GPS资料的速度场计算结果表明,发震区域所处的祁连-海原断裂系具有显著高于周边区域的地壳应变率和地震矩累积率。在发震区域20 km × 20 km范围内,最大和最小主应变率分别为21.5 nanostrain/a（方向NW-SE,拉张）和-46.6 nanostrain/a (方向NE-SW,挤压),地震矩累积率达17.4×1015 N·m/a。主应变挤压的主轴方向与本次地震的震源机制相一致。2）基于震前6 a连续GPS观测站坐标变化时间序列的计算结果表明,自2010年以来,发震区域的面膨胀值随时间呈“非线性”不断变小的趋势,反映出发震区域一直处于应变的挤压缩减状态,但在震前的2~3个月,面膨胀与最大剪切应变均发生了一次明显的反向趋势变化。这些震前的地壳形变异常变化,或许反映了发震区应力-应变积累在接近临界破裂状态时的非线性调整。     

倾斜摄影与近景摄影相结合的山地城市实景三维精细化重建与单体化研究

无人机倾斜摄影实景三维模型是一种能够对复杂山地环境较好感知和表达的有效手段之一。本文针对复杂山地城市开展倾斜摄影实景三维存在的问题,提出了适应于山地区域的多尺度的影像获取策略,并通过与近景摄影测量融合建模的方法,实现了对山地城市倾斜摄影实景三维模型精细化建模的目的;同时,对实景三维模型的单体化方法进行了介绍及对比分析,对后期山地城市开展倾斜摄影提供了一定的技术参考。     

黑色岩型铂族矿物中铂钯金相态ICP-MS分析方法研究

黑色岩是近年发现的铂族元素重要载体,由于其金属来源的多样性及成矿作用的复杂性,对于铂族元素在该类矿物中的分布及富集形式目前并不十分清楚,这也是造成黑色岩中铂族元素测定不稳定的主要原因。本文根据黑色岩的矿物性质及组成,将黑色岩中Pt、Pd、Au的赋存状态划分为:可交换相、有机结合相、硫化物结合相、残渣相。通过应用硫氰酸钾+氰化钠作为解吸剂,有效抑制了黑色岩中有机碳对各相态中Pt、Pd、Au的吸附,采用分离富集ICP-MS法测定了Pt、Pd、Au在各相态中的分布。结果表明:(1)各元素各相态的提取总量与该元素在样品中的总量之比分别为Pt 94.4%~101.0%,Pd 95.8%~101.0%,Au 96.7%~102.0%,说明本方法具有较好的准确性和重现性;(2)黑色岩矿物中Pt、Pd、Au的富集不仅具备亲硫性,而且与有机碳形成的地质条件、地质背景有明显的相关性,此结果为研究黑色岩中铂族元素所处的地球化学环境及其成矿规律提供了重要信息。