哈尔滨市三环西桥跨江二等水准测量

详细介绍了光学测微法跨江水准测量方法、场地选择、场地布设、砚板制作、观测方法、记录格式等内容。     

两种宽频带地震计高频段性能及记录数据差异的对比研究

通过对比两种宽频带地震计FBS-3和KS-2000 的结构,认为两种地震计在检测上限附近的高频段记录数据存在差异,并以合成地震动为输入,用模型验算方法证实了这一结论.     

汶川地震中强震动相对持时的空间变化特性研究

使用70％和90％能量持时定义,计算了汶川Ms8.0大地震中获取的来自109个台站强震动加速度记录的相对持时,并以此在竖向及两个水平向上分别进行了回归统计分析,得到了地震动持时的空间变化关系,给出了适合汶川地震地震动的持时定义.对比分析了上盘和下盘2个区域持时空间变化特征,进一步计算了地震动竖向持时与两个水平向持时的比...     

Tectonic evolution of the ‘Liguride’ accretionary wedge in the Cilento area,southern Italy: A record of early Apennine geodynamics

The early stages of southern Apennine development have been unraveled by integrating the available stratigraphic record provided by synorogenic strata (of both foredeep and wedge-top basin environments) with new structural data on the Liguride accretionary wedge cropping out in the Cilento area, southern Italy. Our results indicate that the final oceanic subduction stages and early deformation of the distal part of the Apulian continental margin were controlled by dominant NW–SE shortening. Early Miocene subduction-accretion, subsequent wedge emplacement on top of the Apulian continental margin and onset of footwall imbrication involving detached Apulian continental margin carbonate successions were followed by extensional deformation of the previously ‘obducted’ accretionary wedge. Wedge thinning also enhanced the development of accommodation space, filled by the dominantly siliciclastic Cilento Group deposits. The accretionary wedge units and the unconformably overlying wedge-top basin sediments experienced renewed NW–SE shortening immediately following the deposition of the Cilento Group (reaching the early Tortonian), confirming that the preceding wedge thinning represented an episode of synorogenic extension occurring within the general framework of NW–SE convergence. The documented Early to the Late Miocene steps of southern Apennine development are clearly distinct with respect to the subsequent (late Tortonian-Quaternary) stages of fold and thrust belt evolution coeval with Tyrrhenian back-arc extension, which were characterized by NE-directed thrusting in the southern Apennines.     

亚贵拉-沙让-洞中拉矿集区中新生代岩浆岩Hf同位素特征与岩浆源区示踪

选择西藏念青唐古拉地区的工布江达-墨竹工卡县亚贵拉-沙让-洞中拉铅锌钼铜银矿集区典型的中新生代岩浆岩作为研究对象,详细研究了岩体中锆石的Hf同位素组成.亚贵拉燕山期石英斑岩(λπ35)锆石的176Hf/177Hf比值为0.282 090～0.282 480,εHf(t)为-7.750～-21.449,TDM2为1 67...     

Precession‐scale cyclicity in the fluvial lower Eocene Willwood Formation of the Bighorn Basin,Wyoming (USA)

Little is known about controls on river avulsion at geological time scales longer than 10⁴ years, primarily because it is difficult to link observed changes in alluvial architecture to well‐defined allogenic mechanisms and to disentangle allogenic from autogenic processes. Recognition of Milankovitch‐sale orbital forcing in alluvial stratigraphy would provide unprecedented age control in terrestrial deposits, and also exploit models of allogenic forcing enabling more rigorous testing of allocyclic and autocyclic controls. The Willwood Formation of the Bighorn Basin is a lower Eocene fluvial unit distinctive for its thick sequence of laterally extensive lithological cycles on a scale of 4 to 10 m. Intervals of red palaeosols that formed on overbank mudstones are related to periods of relative channel stability when gradients between channel belts and floodplains were low. The intervening drab, heterolithic intervals with weak palaeosol development are attributed to episodes of channel avulsion that occurred when channels became super‐elevated above the floodplain. In the Deer Creek Amphitheater section in the McCullough Peaks area, these overbank and avulsion deposits alternate with a dominant cycle thickness of ca 7·1 m. Using integrated stratigraphic age constraints, this cyclicity has an estimated period of ca 21·6 kyr, which is in the range of the period of precession climate cycles in the early Eocene. Previous analyses of three older and younger sections in the Bighorn Basin showed a similar 7 to 8 m spacing of red palaeosol clusters with an estimated duration close to the precession period. Intervals of floodplain stability alternating with episodes of large‐scale reorganization of the fluvial system could be entirely autogenic; however, the remarkable regularity and the match in time scales documented here indicate that these alternations were probably paced by allogenic, astronomically forced climate change.     

Disappearing ink: How pseudotachylytes are lost from the rock record

Melt-origin pseudotachylytes are the most widely accepted feature recording earthquake slip in the fault rock record. However, reports of pseudotachylytes are rare compared to the frequency and distribution of earthquakes in active faults, suggesting melting occurs only under exceptional circumstances and therefore that pseudotachylytes are rarely formed. In this paper, we document the processes whereby pseudotachylytes are overprinted, destroyed and otherwise removed from the rock record. We present examples of recrystallized, altered, and cataclastically and crystal plastically deformed pseudotachylytes from a variety of ancient faults. Based on these observations, we identify characteristics of pseudotachylytes that are resistant to change over geologic time and develop criteria to allow recognition of relict pseudotachylytes. Our results imply that pseudotachylytes are vastly under-reported due to their vulnerability to destruction and the resulting difficulty in identification. As a consequence, the significance of frictional melting is underestimated. The criteria we propose to distinguish relict pseudotachylytes can help to reconcile the observed frequency of earthquakes with the difficulty of demonstrating ancient seismic slip in the rock record.     

环嵩山地区9000～3000aB.P.聚落演替模式及其与地形的关系

不同生产方式、生产水平、社会结构与组织形态对区域环境的选择与适应使得环嵩山地区9000～3000aB.P.聚落演替模式在时间上具有差异性.表现在裴李岗时期向仰韶时期演替过程中,为放弃原来聚落的位置,转而迁移至别的区域兴建新的聚落的“迁移型”演替模式;仰韶时期向龙山时期演替过程中,为在保留原有聚落的基础上,向周边进行扩散,寻找新的区域兴建新的聚落的“扩散型”演替模式;龙山时期向夏商时期演替过程中,为在原有聚落的基础上,面积不断扩大,规模不断扩张的“膨胀型”演替模式.这种聚落演替模式的差异性与区域环境,尤其是地形条件存在联系.生产方式的转变使得仰韶先民放弃裴李岗时期的近山台地聚落,转而迁移至更适合农业生产的山前平原兴建新的聚落.社会的稳固发展与聚落数量的增长迫使龙山先民在仰韶聚落的基础上寻求环境条件较好的区域新建聚落,以缓解人口增长带来的压力.社会形态与组织方式的变化使得夏商时期聚落在龙山时期聚落的基础上,面积不断膨胀,并最终导致聚落规模等级差异特征的形成.环嵩山地区早期聚落传承模式的差异性说明不同的社会形态与发展阶段是在一定的生产水平与特定的社会组织结构基础上对不同环境选择与适应的结果.     

鄂尔多斯盆地延安地区奥陶系风化壳古地貌恢复

鄂尔多斯盆地东南部延安地区奥陶系马家沟组顶部发育风化壳岩溶储层,因古地貌代表了地层沉积和成岩作用的背景,因而在储层的形成和演化过程中具有重要意义。在区域构造背景和地层展布的基础上,综合利用残余厚度法和印模法,并结合铝土岩厚度分布和古沟槽识别结果,准确恢复出延安地区奥陶系风化壳古地貌分布格局。结果显示,延安地区西南部表现为古岩溶高地,中部大部分地区表现为古岩溶斜坡,东部属岩溶斜坡与岩溶盆地之间的过渡带。古地貌格局和古沟槽的分布影响了储层的形成、发育和天然气的富集。延安地区岩溶古高地、靠近侵蚀古沟槽的斜坡位置含气性较好,可能与大气水淋滤等因素导致的储层发育程度、物性好坏、不整合面之上盖层的封盖性等因素有关。     

Mining the ESO WFI and INT WFC archives for known Near Earth Asteroids. Mega‐Precovery software

The ESO/MPG WFI and the INT WFC wide field archives comprising 330 000 images were mined to search for serendip‐itous encounters of known Near Earth Asteroids (NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 as‐teroids (44 PHAs and 108 other NEAs) were identified using the PRECOVERY software, their astrometry being measured on 761 images and sent to the Minor Planet Centre. Both recoveries and precoveries were reported, including prolonged orbital arcs for 18 precovered objects and 10 recoveries. We analyze all new opposition data by comparing the orbits fitted before and after including our contributions. We conclude the paper presenting “Mega‐Precovery”, a new online service focused on data mining of many instrument archives simultaneously for one or a few given asteroids. A total of 28 instrument archives have been made available for mining using this tool, adding together about 2.5 million images forming the “Mega‐Archive”