陈传康的学术生命路径和学术树   总被引：2，自引：0，他引：2  

吴必虎 《地理学报》2001,56(5):622-630

通过扩展传统的生命路径 ( life path)概念、并建立学术树 ( discipline tree)概念 ,研究已故当代中国著名地理学家、旅游学家陈传康教授的学术史。在统计了陈传康教授全部 1 2 1 2种次的学术著述的基础上 ,首先在时间纬度上建立了学术生命路径曲线、系统式和时序式生命路径表 ,用以统计分析陈传康教授的学术论著种次的分布情况和变迁过程 ,一方面反映出著作量随中国当代历史的脉动而出现的起伏变化 ,另一方面通过观察时间轴上这些著述的学科点的分布变化 ,不仅体现 2 0世纪 5 0年代～ 90年代陈传康学术偏好的转徙 ,也反映出 5 0年间中国地理学整体的变化轨迹。利用学术树的概念 ,统计分析陈传康一生构筑的个人学术体系 ,最终勾勒出其一生经营的学术群落的整体景观。  相似文献   

Holocene lake-level fluctuations and beach-ridge development along the northern shore of Lake Michigan, USA     

William H. Petty  Paul A. Delcourt  Hazel R. Delcourt 《Journal of Paleolimnology》1996,15(2):147-169

Geomorphology of a beach-ridge complex and adjacent lake basins along the northern shore of Lake Michigan records fluctuations in the level of Lake Michigan for the last 8000 to 10 000 ¹⁴C yr B.P. (radiocarbon years Before Present). A storm berm at 204.7–206 m (671.6–675.9 ft) exposed in a sandpit provides evidence of a pre-Chippewa Low lake level that is correlated with dropping water levels of Glacial Lake Algonquin (c. 10 300–10 100 ¹⁴C yr B.P.). Radiocarbon dates from organic material exposed in a river cutbank and basal sediments from Elbow Lake, Mackinac Co., Michigan, indicate a maximum age of a highstand of Lake Michigan at 6900 ¹⁴C yr B.P., which reached as high as 196.7 m (645 ft), during the early-Nipissing transgression of Lake Michigan. Basal radiocarbon dates from beach swales and a second lake site (Beaverhouse Lake, Mackinac Co.) provide geomorphic evidence for a subsequent highstand which reached 192.6 m (632 ft) at 5390±70 ¹⁴C yr B.P.Basal radiocarbon dates from a transect of sediment cores, along with tree-ring data, and General Land Office Surveyor notes of a shipwreck, c. A.D. 1846, reveal a late-Holocene rate for isostatic rebound of 22.6 cm/100 radiocarbon years (0.74 ft/100 radiocarbon years) for the northern shore of Lake Michigan, relative to the Lake Michigan-Lake Huron outlet at Port Huron, Michigan. Changes in sediment stratigraphy, inter-ridge distance, and sediment accumulation rates document a mid- to late-Holocene retreat of the shoreline due to isostatic rebound. This regression sequence was punctuated by brief, periodic highstands, resulting in progressive development over the past 5400 ¹⁴C yr of 75 pairs of dune ridges and swales each formed over an interval of approximately 72 years. Times of lake-level fluctuation were identified at 3900, 3200, and 1000 ¹⁴C yr B.P. based on changes in inter-ridge spacing, shifts in the course of Millecoquins River, and reorientation of beach-ridge lineation. Soil type, dune development, and selected pollen data provide supporting evidence for this chronology. Late-Holocene beach-ridge development and lake-level fluctuations are related to a retreat of the dominant Pacific airmass and the convergence of the Arctic and Tropical airmasses resulting in predominantly meridional rather than zonal air flow across the Great Lakes region.This is the 13th in a series of papers published in this special AMQUA issue. These papers were presented at the 1994 meeting of the American Quaternary Association held 19–22 June, 1994, at the University of Minnesota, Minneapolis, Minnesota, USA. Dr Linda C. K. Shane served as guest editor for these papers.  相似文献   

The late Quaternary development of three ancient tarns on southwestern Cumberland Peninsula, Baffin Island, Arctic Canada: paleolimnological evidence from diatoms and sediment chemistry     

Alexander P. Wolfe  Joachim W. Härtling 《Journal of Paleolimnology》1996,15(1):1-18

Sediment diatom and chemical analyses of cores from three poorly buffered extra-glacial lakes on the northeastern margin of the Canadian Shield (Cumberland Peninsula, Baffin Island) record interactions between aquatic and terrestrial spheres that were influenced by late Quaternary climatic conditions. Although differences exist between each of the lakes, notably with regards to the intensity of pre-Holocene catchment erosion and the timing of the onset of organic sedimentation, an underlying pattern of lake ontogeny, common to all three lakes, is identified. Although intensified watershed erosion characterized the Late Wisconsinan and Neoglacial cold periods, the lakes nonetheless remained viable ecosystems at these times. Sudden catchment stabilization during the late-glacial to earliest Holocene is associated with incipient organic sedimentation. Lake-water pH increased at this time, likely in response both longer base cation residence times as lake flushing rates decreased, and enhanced alkalinity production from sediment biogeochemical reactions. Subsequently, as the catchments remained stable during the productive early Holocene (c.9–7 ka BP), then gradually received a renewed increase of minerogenic sedimentation, the breakdown of sources of lake alkalinity resulted in natural acidification. Burial of cation-rich mineral sediments and the loss of permanent sedimentary sinks for the products of microbial reduction likely impeded within-lake alkalinity production, and catchment-derived base cations appeared ineffective in curtailing pH declines. The general nature of the Holocene development of these lakes is similar to that observed elsewhere on crystalline terrains, following deglaciation. Our data therefore suggest that catchment glaciation is not a necessary precursor for models of lake development characterized by initial base cation enrichment and subsequent gradual acidification.  相似文献   

中国桐柏大别构造带变质演化的岩石学证迹   总被引：2，自引：0，他引：2  

游振东  陈能松  张泽明 《地球学报》1996,17(Z1):16-22

桐柏大别构造带是秦岭造山带的东延部分，经历过多期次不同体制的构造运动，现今的桐柏大别山区是由一系列变质地体拼合而成，地体与地体之间为断层或韧性剪切带所围限各地体有自身变质变形史和PTt轨迹，但却有着碰撞造山带所共有的后造山抬升过程。本文揭示了随县群、红安岩群及大别杂岩中柯石英榴辉石、蓝晶铝直闪石片岩及紫苏石榴黑云母片麻岩的退变质再平衡结构特点。报道了大别山麻粒岩相变质年龄为1699Ma。各类岩石减压退变质再平衡结构，标志着后造山的隆升过程及其对桐柏大别构造带变质演化的启示。  相似文献   

世界早期历史地震史料的比较研究(待续)     

郭履灿  高建国  阎维彰 《山西地震》1992,(2)

通过对各国地震最早记载及其背景性证据的分析;用时间差分序列的双对数法,进行了地震记载资料丰富程度的探讨;研究了3700年前的全球地震活跃期;给出了公元前2221年至公元1900年105个国家(地区)的资料。  相似文献   

秦岭祁连山昆仑山构造发展史与南北中国板块的拼合   总被引：1，自引：0，他引：1  

陈家义  杨永成  霍向光  尚瑞钧 《陕西地质》1995,(2)

按秦岭祁连山昆仑山发展演化，中国大陆的形成可总结为3阶段板块拼贴“焊合”模型即：中元古代至新元古代早期，原始秦昆洋俯冲—消减，塔里木—华北古陆（北中国板块）与华南洋域新生陆壳（南中国板块）拼贴增生，形成原始中国古陆；震旦纪至志留纪，原始中国古陆裂解，秦祁海洋扩张—俯冲—消减，阿拉善—华北板块（北中国板块）与塔里木、柴达木、华南组成的联合板块（南中国板块）缝合统一，形成古中国板块，泥盆纪至三叠纪早期，古特提斯洋俯冲—消减，藏滇板块（基梅里大陆一部分）与古中国板块碰撞拼贴，滨邻古特提斯洋的中国大陆西南缘（秦祁昆地区）全面皱起，造就中国大陆轮廓；中生代以来，板内超长期继承性汇聚和滨西太平洋边缘构造带、新特提斯—喜马拉雅构造叠加、改造，造就现令中国大陆构造、地势。  相似文献   

Tectono-Sedimentary History of Southeastern Coast Region,China:a Synthesis     

Wu Chonglong Zhou Jiangyu Wang Gengfa Li ShaohuFaculty of Earth Resources  China University of Geosciencex  Wuhan Liu Pide Beijing High School  Beijing 《中国地质大学学报(英文版)》1995,(2)

According to the ideas and concepts of systems dynamic of continent structure, using previous information related to the study area, combining analyses on orogenic belt, basin and magmatic rock, the present paper synthesizes the tectono-sedimentary development of southeastern coast region, China, with special emphasis on the mountain making, basining and magmafc activity. The tectonic evolution after Late Caledonian orogeny was dominated by alternating rifting and converging, subsiding and uplifting, mountain making and basining in central and southern parts of southeastern China and the adjacent regions to the east and west. Seventeen geologic events, nine events of plate or terrain convergence , and continental crust accretion, as well as eight events of intracontinental rifting and basin faulting , are closely related to the tectonic and sedimentary evolution of the study area. The accompanied intense and frequent sedimentation , folding , faulting , magmatism and ore-forming process allowed huge coal  相似文献   

The Coupled Re—Os and Pt—Os Systematics：A Theoretical Consideration     

熊永良  翟裕生 《中国地球化学学报》1995,14(1):52-59

The ^190Pt-^186Os system should be a unique tracer for mantle processes be-cause both Pt and Os are concentrated in the mantle.The ^190Pt-^186Os system will also be a good supplement to the ^187Re-^187Os system for dating and tracing mantle pro-cesses because the ^190Pt-^186Os system is not so easily contaminated by crustal materials as the ^187Re-^187Os system.In turn,the application of the ^187Re-^187Os system to Pt-enriched materials uncontaminated by crustal materials will indirectly refine the half life of ^190Pt.The ^190Pt is refined.In the coupled ^187Re-^187Os and ^190Pt-^186Os sys-tematics,an ^186Os*/^190Pt-^187Os*/^187Re Concordia diagram similar to the ^206Pb*/^238U-^208Pb*/^232Th Concordia can be constructed.In such a Concordia diagram,a date will be obtained so long as the ^190Pt-^186Os system remains closed even if the ^187Re-^187Os sys -tem is contaminated by crustal materials.In addition ,for the coupled ^190Pt-^186Os and ^187Re-^187Os systematics,the mantle processes and the interactions between the mantle and the crust will be described by two ratios:^186Os/^188Os and ^187Os/^188Os .The coupled ^187Re-^187Os and ^190Pt-^186Os systematics will be a powerful tool in the investigation of the geodynamic history of the Earth because the ^187Re-^187Os system is sensitive to the interactions between the mantle and the crust,while the ^190Pt-^186Os system is a good tracer for mantle processes.  相似文献   

华北陆块、秦岭地块和扬子陆块构造演化的古地磁证据   总被引：15，自引：0，他引：15  

刘育燕  杨巍然  森永速男  足立泰久  米泽隆文  安川克已 《地质科技情报》1993,12(4):17-21

通过对河北井陉和湖北宜昌、兴山的39个采样点、392个样品进行的古地磁测试,以及7个采样点、71个样品中的原生剩磁以及笔者前期研究结果,系统分析了三大块体的古地磁极位置、古地磁偏角以及古纬度自寒武纪以来的变化特征,并进行了古地理复原。研究表明,三块体为不同地质构造单元,寒武纪时,华北陆块、秦岭地块以及扬子陆块自北到南顺序排列于北纬2.9°、南纬5.5°以及南纬17.0°。秦岭地块北侧和南侧分别存在一古洋盆,此时华北陆块和扬子陆块相距约1400Km左右;三块体向北漂移的过程中伴随着旋转运动;三块体开始拼合的时间为晚二叠纪至早三叠纪之间,华北陆块和秦岭地块完全拼合的时间为早三叠纪至中三叠纪之间,三块体完全拼合的时间为中三叠纪至晚白垩纪之间;晚白垩纪以后,一体化的三块体继续向北漂移,并于第四纪到达现今地理位置。  相似文献   

嘉峪关光化楼残损变形现状及抗震性能分析     

巴振宁  焦鹏  张龙  刘冰松  张翔 《震灾防御技术》2020,15(2):293-304

中国木结构建筑是我国宝贵的物质文化遗产和文化瑰宝，具有悠久的文化历史。以嘉峪关光化楼为依托，对光化楼进行实地调研，分析光化楼主要残损变形。采用ANSYS软件建立考虑光化楼残损变形的三维有限元精细模型，并进行模态分析与时程分析。研究结果表明，光化楼主要残损变形为油饰脱落、墙体剥蚀开裂、柱偏移等，极个别柱产生较大偏移；光化楼刚度相对稳定，前20阶振型自振频率均在10Hz以内；光化楼动力放大系数与层间位移角均较小，仍具有良好的抗震减震性能。  相似文献