Fashion and phases of late Pleistocene aggradation and incision in the Alaknanda River Valley, western Himalaya, India

We study the aggradation and incision of the Alaknanda River Valley during the late Pleistocene and Holocene. The morphostratigraphy in the river valley at Deoprayag shows the active riverbed, a cut terrace, and a fill terrace. The sedimentary fabric of the fill terrace comprises four lithofacies representing 1) riverbed accretion, 2) locally derived debris fan, 3) the deposits of waning floods and 4) palaeoflood records. The sedimentation style, coupled with geochemical analysis and Optically Stimulated Luminescence (OSL) dating, indicate that this terrace formed in a drier climate and the river valley aggraded in two phases during 21–18 ka and 13–9 ka. During these periods, sediment supply was relatively higher. Incision began after 10 ka in response to a strengthened monsoon and aided by increase of the tectonic gradient. The cut terrace formed at ~ 5 ka during a phase of stable climate and tectonic quiescence. The palaeoflood records suggest wetter climate 200–300 yr ago when the floods originated in the upper catchment of the Higher Himalaya and in the relatively drier climate ~ 1.2 ka when locally derived sediments from the Lesser Himalaya dominated flood deposits. Maximum and minimum limits of bedrock incision rate at Deoprayag are 2.3 mm/a and 1.4 mm/a.     

东辛永3断块区多期构造演化物理模拟

东辛永3地区为一多油层、中高渗透复杂断块, 内部被多级断层切割复杂化, 沙河街组为其主要含油层位。在三维地震解释基础上, 针对构造形态、成因机制不明确等问题, 根据相似理论支撑, 经过材料选取、边界设定、时间确立、受力加载, 对研究区古近纪沙河街组构造演化进行构造物理模拟。模拟结果实现了研究区基本断裂特征的恢复, 验证了地震解释结果; 初期北北东、北西向伸展、后期右旋剪切及底辟上拱多期构造能够成功模拟, 明确了其成因机制, 与整体东营凹陷伸展区域应力场及郯庐断裂带转型机制相吻合。      

六盘山盆地热历史的裂变径迹证据

研究盆地的热历史将为确定生烃过程和探勘目标提供重要制约因素。磷灰石裂变径迹研究表明，六盘山盆地白垩系地层经历两次埋深加热事件。第一次在白垩经末之前达到最高古地温，第二次在晚新生代约8MaB.P.之前达到最高古地温.第一次最高古地温要高于第二次最高古地温.晚新生代六盘山盆地古地温梯度为16℃/km.从白垩纪到新生代,六盘山盆地可能发生古地温梯度降低事件.三叠纪、中侏罗统烃源岩达到或超过生油高峰温度.白垩纪乃家河组和马东山组虽然进入生油窗温度范围,但未达到生油峰温度.按照古地温资料推断,三叠纪、中侏罗统烃源岩应为六盘山盆地主要生烃源岩,晚白垩纪之前应为六盘山盆地烃源岩的主要生烃阶段.     

土壤风蚀中有关土壤性质因子的研究历史与动向

国外土壤风蚀中有关土壤性质因子的研究历史可分为四个阶段：第一,定性描述阶段;第二,定量实验研究阶段;第三,运用综合因子建立和完善“通用风蚀方程式”阶段;第四,土壤风蚀土壤亚模型和预测系统的建立和动态研究阶段。国内对土壤风蚀的研究起步较晚,对于不同土类的土壤物理化学性质对风蚀的影响尚没有作深入研究。其历史大致可分为二个阶段：第一,野外观测研究;第二,风蚀的半定量实验研究。目前正由半定量向定量化、标准化、国际化以及动态研究方向发展。     

Unpopular Archives

This article explores the “unpopular” archived life of Charles P. Daly, thirty-five-year president (1864–1899) of the New York–based American Geographical Society. This one-time highly prominent judge and civic leader popularized geography among professionals and the public alike. Daly's popular geography, along with his subsequent containment within the archives, suggests explanations for his dismissal among geographical audiences of today. It is a useful and necessary exercise to trace the neglect of Daly within histories of geography and recapture him for today's audiences, not only because of his influence on post–Civil War American geography but also because his story can shed light on how “disciplinary remembering” functions in geography.     

Tectonic thermal history and its significance on the formation of oil and gas accumulation and mineral deposit in Ordos Basin

The analyzing data on stratigraphic temperature measurement , thermal conductivity of the strata and radioactive heat production rate show that the present average geothermal gradient in the Ordos Basin is 2.93℃/100 m, and the average heat flow value is 61.78 mW/m2, which belongs to the mesothermal basin, and the value of the present geothermal gradient and heat flow in the east is higher than that in the west. The sandstone radioactive heat production rate of Zhiluo Group in Dongsheng Uranium deposits of Yimeng uplift is obviously higher in the mudstone, indicating that there exists a uranium anomaly. Based on studies of the present thermal field of the basin, the late-Mesozoic paleotemperature and paleogeothermal gradient are determined by using different kinds of paleotemperature methods. According to the anomaly of the late-Mesozoic paleotemperature gradient and magmatic event age, there was a tectonic thermal event in the early Cretaceous epoch of late-Mesozoic. This article rebuilds tectonic thermal history of different tectonic units by thermal history simulation using basin simulating software. The evolution of oil-gas and coal, and accumulation (mineralization) of mineral uranium are all controlled by the tectonic thermal history in the Ordos basin, especially by the tectonic thermal event that happened in the late Mesozoic. For both the gas source rocks of upper Paleozoic group and lower paleozoic group, the gas was largely generated in the early Cretaceous epoch of the late Mesozoic. The main petroleum generation period for Yanchang Group in Triassic system is the early Cretaceous epoch too, and the highest thermal maturity of the coal of Permo-Carboniferous, Triassic, and Jurassic reaches is the early Cretaceous epoch also. Early Cretaceous epoch is still one of the most important mineralizing periods of uranium.     

地理学史研究范式——科学地理学史与知识地理学史

当前主流地理学史研究可归结为两种互补性范式。一种是科学地理学史：① 从近现代地理学形象出发,遵循“自上而下”的叙事模式,选择性地建构切合当前地理学的历史;② 主张一元传统的科学史观,从而导致了不同传统的对立;③ 其性质是建构性的、抽象性的,造成了自然与人文的分裂;④ 强纲领的叙事模式不仅造成了“古代思想的现代解读”,且挣扎于科学分化的大潮中。另一种是在批判科学地理学史基础上兴起的知识地理学史：① 从地理实践本身出发,遵循“自下而上”的叙事模式,从地理学知识体系的底层诠释历史;② 主张多元论传统的科学史观,从而一定程度上消解了不同地理学传统之间的对立,为多样的地理学传统纳入叙事框架奠定了基础;③ 其历史的性质是实践论的或语境论的,旨在阐发不同地理学知识形态的意义;④ 表现为对称性原则的叙事纲领,大大扩展了地理学史研究的视野,为理解作为地理学与自然并社会统一的实践统一体提供了可能。科学地理学史和知识地理学史当前表现为一种批评性关系,但这并不意味着应当制造更多的二元论对立,相反,整体的方向应当是加强科学精神与人文主义的相互对话。     

1936年中山小榄5级地震考

经过实地调查和查阅有关地震历史资料 ,认为广州《越华报》关于 1936年 4月 2 3日中山小榄地震造成塌屋伤人的报道是失实的 ,该震只是一次 3级左右的有感地震 ,应从 5级地震目录中删除     

酒泉盆地群热演化史恢复及其对比研究

酒泉盆地群是由两期不同性质、不同世代盆地叠加而成的 .晚侏罗纪-早白垩世为拉张断陷盆地 ,第三纪以来为挤压坳陷盆地 .酒泉盆地群现今地温梯度及大地热流值都较低 ,地温梯度主要在 2 51- 3 0 0℃ /1 0 0m之间 ,大地热流值在 50- 57mW /m2 之间 .酒泉盆地群中生代晚期为拉张断陷 ,古地温梯度高 ,可达 3 75- 4 50℃ /1 0 0m ,新生代以来地温梯度逐渐降低 ,而花海盆地、酒西盆地石北凹陷沉降幅度小 ,古地温高于今地温 .下白垩统烃源岩热演化程度受古地温控制 .主生烃期仅有一次 ,为早白垩世晚期 .酒西盆地青西凹陷、酒东盆地营尔凹陷在新生代以来大幅度沉降 ,下白垩统烃源岩热演化程度受现今地温控制 .主生烃期有两次 ,一次为早白垩世晚期 ,另一次为晚第三纪以来 ,且以晚第三纪以来为主 .不同盆地及同一盆地不同构造单元由于构造热演化史的不同 ,主生烃期及油气勘探前景明显不同 .