华北地块沁水盆地下三叠统刘家沟组古地磁倾角浅化研究

对华北地块沁水盆地下三叠统刘家沟组红层样品进行系统的岩石磁学、磁组构和古地磁学研究, 并用E/I (elongation/inclination)方法对其进行磁倾角浅化的识别与校正, 获得刘家沟组红层磁倾角浅化因子f = 0.6。岩石磁学结果显示, 刘家沟组红层的主要载磁矿物是赤铁矿及磁铁矿, 其磁组构具有典型的静水沉积特征。经地层校正后, 15个采样点特征剩磁分量的平均方向为D_s=318.8°, I_s=30.9°(α₉₅= 6.9°), 对应的古地磁极为49.3°N, 5.5°E (A₉₅=6.7°), 磁倾角浅化校正后的古地磁极为53.5°N, 18.0°E。对包括本文数据在内的高质量的华北早三叠世古地磁极数据(Q≥4)进行平均, 得到校正前的古地磁极为55.3°N, 357.1°E (A₉₅=5.5°), 校正后的古地磁极为60.8°N, 13.4°E (A₉₅=5.8°)。经过古地磁倾角浅化校正, 华北地块早三叠世的古纬度有约10°的明显提高, 指示其东部早三叠世时与华南地块之间可能存在一定的纬度差, 但是该纬度差很可能并不代表华北地块东部早三叠世时与华南地块尚未对接, 而是指示华南地块下三叠统灰岩同样存在显著的磁倾角浅化现象。     

Early Pleistocene formation of the asymmetric east-west pattern of upper water structure in the equatorial Pacific Ocean

Surface-and subsurface-dwelling planktonic foraminifera from the upper 43 m of Hole A at the Ocean Drilling Program (ODP) Site 807,which was recovered from the western Pacific warm pool during ODP Leg 130,were analyzed for stable oxygen and carbon isotopes.By comparing these results with data from ODP Site 851 in the eastern equatorial Pacific,this study has reconstructed the paleoceanographic changes in upper ocean waters in the equatorial Pacific since 2.5 Ma.During the period from 1.6-1.4 Ma,the oxygen isotopes of surface and subsurface waters were found to markedly change in the western and eastern equatorial Pacific,further confirming the final formation of the well-defined asymmetric east-west (E-W) pattern at that time.This feature was similar to the zonal temperature gradient (sea surface temperature is higher in the west and lower in the east) and the asymmetric upper water structure (thermocline depth is deeper in the west and shallower in the east) in the modern equatorial Pacific.The zonal gradient change of subsurface water δ18O was greater than that of surface water δ18O,indicating that the formation of the asymmetric E-W pattern in the equatorial Pacific should be much more related to the shoaled thermocline and markedly decreased subsurface water temperature in the eastern equatorial Pacific.Moreover,since ～1.6 Ma,the carbon isotopic differences between surface and subsurface waters clearly decreased in the equatorial Pacific,and their long-term eccentricity periods changed from 400 ka to ～500 ka,reflecting the reorganization of the ocean carbon reservoir.This probably resulted from the deep water reorganization in the Southern Ocean at that time and its enhanced influence on the tropical Pacific (especially subsurface water).Our study demonstrates that the tropical ocean plays an important role in global climate change.     

汉萨同盟与中世纪西欧贸易区的形成

论述了汉萨同盟的意义,指出汉萨同盟是德意志北部城市之间形成的商业、政治联盟,在欧洲中世纪的历史上具有举足轻重的地位。汉萨同盟是日耳曼人向东扩张和殖民过程中形成的。波罗的海沿岸地区城市的兴起和商业的发展、神圣罗马帝国的衰落以及海盗的猖獗等因素是汉萨同盟形成的重要因素。汉萨同盟的形成和发展极大地促进了西、北欧地区的经济联系,改善了该地区的商贸环境,对北海、波罗的海贸易区的形成和发展乃至中世纪西欧贸易区的形成都作出了重大贡献。     

试析北宋东京南北御街街道景观

运用西方现代城市设计理念研究中国古代城市景观，是目前城市史研究领域的新动向。借鉴美国著名学者凯文·林奇《城市意象》中的观点，将北宋东京南北御街划分为北、中、南三段，对各段的界面、节点、小品及人的活动这四大景观要素分别予以分析，可以展示出北宋东京城由开放的街市制代替封闭的里坊制之后所呈现的城市面貌。     

Species of Schizotricha Allman, 1883 (Cnidaria: Hydrozoa: Halopterididae) from US Antarctic expeditions with the description of two new species

Twelve species of the genus Schizotricha Allman have been studied, two of which are new to science (Schizotricha heteromera sp. nov. and S. trinematotheca sp. nov.). The material studied was collected by several US Antarctic expeditions. Each new species is described and figured, the systematic position amongst allied species discussed and available data concerning autecology and geographical distribution given. The remaining 10 species are considered regarding diagnosis, autecology and geographical distribution. Finally, a general survey of the bathymetrical and biogeographical distribution of the known species of Schizotricha is given.     

A new genus of hemibranchiate sphaeromatid isopod crustacean from tropical Western Australia

A new genus and species of marine sphaeromatid isopod is described from the North West Shelf (Indian Ocean) tropical Western Australia. Kranosphaera haptomela gen. nov. sp. nov. (Sphaeromatinae) is distinguished from other hemibranchiate genera by the strongly rugose and deeply pitted body surfaces, projecting epistome, uniramous uropodal rami, and in the male by modified pereopod 5 which is greatly expanded and 6 which has a coupling flange on the ischium. It is known only from the vicinity of the type locality.     

New records for hermatypic corals (Anthozoa: Scleractinia) in the Gulf of California,Mexico, with an historical and biogeographical discussion

This paper reports range extensions for seven hermatypic coral species in the Gulf of California. An analysis of the distribution and fossil record of the 12 hermatypic species of the Gulf shows that the coral communities of the Gulf are the oldest ones in the eastern Pacific. Two species have been recorded in the Gulf (or nearby) since the Pliocene and several other species since the Pleistocene. The uninterrupted fossil record falsifies the hypothesis of a total extinction of reef corals in the eastern Pacific during the Pleistocene. The fossil evidence and temperature calculations support the conjecture that the Gulf of California was a refuge zone for corals and other warm-water biotas during the same epoch. Also it is suggested that some species of the genera Porites may have an Atlantic origin, contrary to the accepted idea of an exclusive Indo-Pacific origin of the eastern Pacific coral fauna.     

论阿富汗伽色尼王朝对北印度地区的影响

伽色尼王朝是突厥人于962年以阿富汗东南地区为中心建立的政权,伽色尼王朝历时225年(962—1186年)。鼎盛时期,伽色尼王朝的版图东起东北印度,西至波斯西北部,北抵花剌子模,南迄锡斯坦。伽色尼王朝对印度发起过多次远征,并确立了对北印度的统治。伽色尼突厥人的远征严重破坏了印度北部的社会生产力,使北印度人民经历了巨大的灾难。尽管如此,伽色尼王朝的远征和统治打破了北印度闭塞的状况,将北印度纳入了伊斯兰世界。     

Chaetognaths from Alvin dives in the Santa Catalina Basin (California), with description of two new Heterokrohnia species

Six species of deep-water chaetognaths have been caught near the bottom (at about 1300 m) during four dives of the submersible Alvin in the Santa Catalina Basin (California). Although few samples were taken, they are very interesting. New morphological data are presented on a supposed very well-known planktonic species (Sagitta macrocephala) and two new benthoplanktonic species of the genus Heterokrohnia are described. Details on the morphology and reproduction of the family Heterokrohniidae, and also on the bathymetric and zoogeographic distributions of Heterokrohnia species of the ‘longidentata’ group are given.