块体搬运沉积构型及其对后期浊流沉积的影响——以琼东南盆地陵水凹陷L区为例

通过对琼东南盆地陵水凹陷陆坡区高分辨率三维地震资料的精细解释,在研究区发现广泛发育的块体搬运沉积体系(MTDs),表现为:①?弱振幅、低连续、杂乱或空白的地震反射特征且具有明显的侵蚀作用;②?在研究区体部和趾部区域发现大量侵蚀擦痕、逆冲推覆构造和挤压脊等内部结构;③?块体搬运沉积由于内部结构变形发育为逆冲推覆构造等,其...     

Geophysical investigations of crust-scale structural model of the Qiongdongnan Basin, Northern South China Sea

Rifting of the Qiongdongnan Basin was initiated in the Cenozoic above a pre-Cenozoic basement, which was overprinted by extensional tectonics and soon after the basin became part of the rifted passive continental margin of the South China Sea. We have integrated available grids of sedimentary horizons, wells, seismic reflection data, and the observed gravity field into the first crust-scale structural model of the Qiongdongnan Basin. Many characteristics of this model reflect the tectonostratigraphic history of the basin. The structure and isopach maps of the basin allow us to reconstruct the history of the basin comprising: (a) The sediments of central depression are about 10 km thicker than on the northern and southern sides; (b) The sediments in the western part of the basin are about 6 km thicker than that in the eastern part; (c) a dominant structural trend of gradually shifting depocentres from the Paleogene sequence (45–23.3 Ma) to the Neogene to Quaternary sequence (23.3 Ma–present) towards the west or southwest. The present-day configuration of the basin reveals that the Cenozoic sediments are thinner towards the east. By integrating several reflection seismic profiles, interval velocity and performing gravity modeling, we model the sub-sedimentary basement of the Qiongdongnan Basin. There are about 2–4 km thick high-velocity bodies horizontal extended for a about 40–70 km in the lower crust (v > 7.0 km/s) and most probably these are underplated to the lower stretched continental crust during the final rifting and early spreading phase. The crystalline continental crust spans from the weakly stretched domains (about 25 km thick) near the continental shelf to the extremely thinned domains (<2.8 km) in the central depression, representing the continental margin rifting process in the Qiongdongnan Basin. Our crust-scale structural model shows that the thinnest crystalline crust (<3 km) is found in the Changchang Sag located in the east of the basin, and the relatively thinner crystalline crust (<3.5 km) is in the Ledong Lingshui Sag in the west of the basin. The distribution of crustal extension factor β show that β in central depression is higher (>7.0), while that on northern and southern sides is lower (<3.0). This model can illuminate future numerical simulations, including the reconstruction of the evolutionary processes from the rifted basin to the passive margin and the evolution of the thermal field of the basin.     

Structural differences between the western and eastern Qiongdongnan Basin: evidence of Indochina block extrusion and South China Sea seafloor spreading

Located at the intersection between a NW-trending slip system and NE-trending rift system in the northern South China Sea, the Qiongdongnan Basin provides key clues for us to understand the proposed extrusion of the Indochina Block along with Red River Fault Zone and extensional margins. In this paper we for the first time systematically reveal the striking structural differences between the western and eastern sector of the Qiongdongnan Basin. Influenced by the NW-trending slip faults, the western Qiongdongnan Basin developed E–W-trending faults, and was subsequently inverted at 30–21 Ma. The eastern sector was dominated by faults with NE orientation before 30 Ma, and thereafter with various orientations from NE, to EW and NW during the period 30–21 Ma; rifting display composite symmetric graben instead of the composite half graben or asymmetric graben in the west. The deep and thermal structures in turn are invoked to account for such deformation differences. The lithosphere of the eastern Qiongdongnan Basin is very hot and thinned because of mantle upwelling and heating, composite symmetric grabens formed and the faults varied with the basal plate boundary. However, the Southern and Northern Uplift area and middle of the central depression is located on normal lithosphere and formed half grabens or simple grabens. The lithosphere in the western sector is transitional from very hot to normal. Eventually, the Paleogene tectonic development of the Qiongdongnan Basin may be summarized into three stages with dominating influences, the retreat of the West Pacific subduction zone (44–36 Ma), slow Indochina block extrusion together with slab-pull of the Proto-South China Sea (36–30 Ma), rapid Indochina block extrusion together with the South China Sea seafloor spreading (30–21 Ma).     

大数据时代测绘地理信息服务面临的机遇和挑战

分析了大数据时代测绘地理信息服务呈现出的新特点、新趋势,研究了大数据给测绘地理信息服务带来的机遇和挑战,提出了大数据时代测绘地理信息服务的“5v”要求,并就推进测绘地理信息服务转型升级提出建议。     

大震作用下板式楼梯框架弹塑性地震反应分析

有关大震作用下楼梯与框架共同工作方面的研究还很少,采用结构有限元软件Midas/Gen,对一个5层钢筋混凝土现浇板式楼梯框架办公楼模型进行了弹塑性分析,对模型在大震作用下的受力情况进行了详细研究.通过对楼梯和框架共同工作性能的研究,并与不考虑楼梯影响的框架的工作性能进行了对比,分析了板式楼梯框架的失效机制和受力特点,指出了楼梯与框架共同工作时的受力不利部位.结果表明:楼梯相较于框架梁柱是模型的薄弱部位;模型的失效是从楼梯发展到框架,由下层发展到上层.最后根据模型的失效机制特点提出了相应的抗震措施.     

Genetic difference of Chinese horseshoe crab (Tachypleus tridentatus) in southeast coast of China based on mitochondrial COI gene analysis

Population genetic structure and historical demography of Chinese horseshoe crab (T. tridentatus) along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit I (COI) fragment. The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities: Ninghai in Zhejiang Province, Meizhou and Zhangpu in Fujian Province, Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province. Sequence variation was relatively low with a total of seven transitions observed. In all localities, Haplotype H3 was the dominant type observed among eight haplotypes defined previously, and was at the center of radiation in Median-Joining network. The prolonged star-like network suggests a signature of population expansions. The level of diversity was low in total, with haplotype diversity (H_d) being equal to 0.765 and nucleotide diversity (π) being equal to 0.001 18, respectively. The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations. Both mismatch distribution analysis and Fu's F_s test provided consistent inference of historic population expansion. The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.     

地区间贸易流量的产业—空间模型构建与应用

通过深入剖析区域间经济联系的经济地理学理论基础,考虑到同业影响因子,重新构建引力模型,并引入空间滞后因子,利用地理加权回归方法建立了估算区域间贸易流量的产业—空间统计模型,并在中国30 个省区投入产出表的基础上,以省区间农业、化工、通信电子3 个产业贸易流量的估算为例对上述方法进行了说明。结果表明：① 空间统计模型的应用可以显著提高区域间贸易流量的估算可靠性;② 随着空间权函数中带宽的缩小,贸易流量显得更加集中。因此,带宽在一定程度上反映了地理活动的空间集聚程度,不同行业应选取不同带宽;③ 不同行业有不同的同业影响机制和贸易特征,农业输出地以中部地区为主,目的地以沿海地区为主,具有一定的同业竞争关系,而化工、通信行业的产业流动主要发生在东部地区内部,具有很强的同业合作关系。     

阳澄湖水质现状及原因探讨

阳澄湖丰水期和枯水期水质调查结果显示:TN、叶绿素、TP和CODMn丰枯期都呈从西湖区向东湖区递减趋势,且一般枯水期大于丰水期,TP反之;丰枯期水质均较差,为Ⅳ类或劣Ⅴ类,污染物主要为TN和TP;富营养化加重趋势有所缓解,但水体仍呈富营养化状态。氮磷来源分析表明:丰枯期NO₃^--N、NO₂^--N与TN以及丰水期PO₄^3--P与TP有显著正相关关系。叶绿素浓度与TN在枯水期有显著相关性,其他时期叶绿素浓度与TN、TP的相关性均不显著。阳澄湖养殖活动和底泥营养盐释放可能是导致上述变化的主要原因。     

建筑物加载过程中高精度变形监测研究

采用TM30测量机器人对图书加载过程中笔者所在院校图书馆进行变形监测,对变形观测数据进行严密平差,获取监测结果;进而根据监测结果绘制变形等值线,表达出各个方向的变形量,直观表达危险变形区域;最后获取建筑物加载过程中的变形监测规律。在图书加载初期,南北方向变形呈不稳定S型,而东西方向变形从初期开始变形趋于围绕图书加载位置。建筑物长、宽对建筑物稳定有影响,在建筑物加载位置需要增加承重及在外围采取防护措施。该研究对建筑设计有实际意义。