磷灰石U-Th/He法-&mdash|一种低温热年代计

回顾了U Th/He测年方法的发展过程 ,简要介绍了该方法测年的原理、分析流程和长α -粒子停止距离校正。然后介绍了近年来在磷灰石He扩散性研究及数值模拟方面取得的一些成果和磷灰石U Th/He热年代计在研究古地貌、岩体构造抬升、盆地热历史演化方面的应用。最后分析了U Th/He测年方法的优、缺点 ,说明这一方法既存在广阔的应用前景 ,又有待于进一步完善、提高     

越南兰龙盆地白虎油田储集层特征及成藏模式探讨

基于岩心、钻测井、三维地震和沉积相资料,对越南兰龙盆地白虎油田的碎屑岩、基岩储集层特征以及对应的两种成藏模式进行综合分析。结果表明,白虎油田发育两类岩性储集层,即碎屑岩(砂岩)、花岗岩基岩储集层,其中碎屑岩储层在兰龙盆地基底地垒构造格架下沉积,受大地构造运动、海平面变化控制,以冲积扇、扇三角洲和河流相为主,在渐新统泥岩供烃的条件下形成了具有自生自储、下生上储特征的岩性、构造油藏。花岗岩的基岩裂缝、孔洞发育,具备优势的储集空间、储层规模大,成为最主力的储集层,成因为基底演化过程中的断裂活动、热液岩熔等作用。在花岗岩基岩储层中形成了两种成藏模式：一种以花岗岩无机成因自身含烃表现出原地成藏的特征;另一种上覆渐新统泥岩为富油烃源岩,沿断层、不整合面等侧向运移至基底顶部晚期聚集成藏,最终在基底中广泛发育裂缝、缝洞型基岩油藏。     

长短时记忆神经网络在中期地震预报中的探索--以川滇地区为例

利用机器学习方法对地震活动大数据进行挖掘,识别出一些过去认识不到的异常,提高地震预测的准确性,是一个非常具有挑战性的科学问题.本文基于川滇部分地区(24°N—32°N,98°E—106°E)地震目录,采用滑动的时空窗口,选取16个反映地震时空强度分布特征的地震预测因子,建立了长短时记忆(LSTM)神经网络,对研究区域9个子区块未来一年的最大地震震级进行预测.通过设置训练集∶测试集=8∶2和训练集∶测试集=7∶3两个不同的训练测试模型,对过往发生的地震进行了回溯性预报.结果表明:训练集∶测试集=7∶3模型能够利用1970年1月至2004年9月的地震目录进行学习,成功回溯性预报2008年汶川地震;训练集∶测试集=8∶2模型利用1970年1月至2009年5月资料进行训练,回溯性预报2010—2019年间6级以上地震的R评分为0.407,回溯性7级地震预报时准确率高达92.31%.本文还探讨性给出预测意见:2022年2月前研究区西部、中部、东部、西南部存在发生5.1~5.3级地震的潜在危险性.     

用前期海温预报四川夏季气温的EOF迭代方案

应用ＥＯＦ（经验正交函数）迭代方案，考虑多时次历史资料，在全球海区海温与四川盆地气温非同步联系的基础上，以海温为预报因子进行了夏季气温的长期预报。结果表明：西太平洋高温区等关键海区海温的异常对未来四川盆地夏季气温变化有重要影响，由此建立的引入多时次海温的ＥＯＦ迭代长期温度预报方法，具有较强的预报能力     

Factors affecting the elimination of PCBs in the marine copepod Acartia tonsa

The effects of feeding, egg laying, and fecal pellet production on the elimination of polychlorinated biphenyls (PCBs) from the marine copepod Acartia tonsa were studied in a series of experiments. Copepods were exposed to ¹⁴C-labelled Aroclor 1254 and allowed to depurate in clean seawater. Copepods fed during depuration eliminated PCBs more rapidly than unfed copepods whether or not the original PCB exposure medium had contained food. Both eggs and fecal pellets contained PCBs during depuration, with the weight specific concentration of PCB in the eggs (up to 407 ppm, dry weight) exceeding four times that in the females that produced them. Female copepods eliminated PCBs twice as rapidly as males, indicating that egg production is an important route for PCB elimination.     

Paleoclimate changes during the last 100,000 yr from a record in the Brazilian Atlantic rainforest region and interhemispheric comparison

A long terrestrial record, Colônia CO-3, from the Atlantic rainforest region in Brazil (23°52′S, 46°42′20 W, 900 m a.s.l.) registrates variations in the forest expansion during the last 100,000 yr. The 780-cm depth core was analyzed at 2-cm intervals and arboreal pollen frequencies were compared to nearby speleothem stable isotope records and neighboring marine records from the tropical Atlantic. To evaluate regional versus global climate forcing, our record was compared with Greenland and Antarctic ice-core records. These comparisons suggest that changes in temperature seen in polar latitudes relate to moisture changes: e.g., to changes in the length of the dry season, in tropical and subtropical latitudes during glacial as well as interglacial times. These climatic changes result from changes in the frequency of polar air incursions to these latitudes inducing a permanent cloud cover and precipitation. This is an important result that should help define paleoclimatic features in the Southern Hemisphere for the last glaciation.     

Analyzing Accessibility Using Parcel Data: Is There Still an Access–Space Trade-Off in Long Beach,California?

This article analyzes the impact of changing housing and neighborhood characteristics on the accessibility of neighborhood businesses using Long Beach, California, as a case study. Although advocates of smart growth and New Urbanism encourage land use mixing, aggregate-level analysis can be too coarse to pick up on fine-grained aspects of urban streetscapes. This study uses assessor parcel records and a point-based business establishment data set to analyze city-wide patterns of accessibility from individual dwelling units to thirty-one types of neighborhood businesses, including grocery stores, service shops, drug stores, doctor's offices, and banks. Regression results compare parcel-level and neighborhood-level drivers of accessibility between 2006 and 2015 to gauge the aggregated effect of recent economic, demographic, and built environment changes on this aspect of urban spatial structure. Larger homes in older, multiunit buildings and higher income neighborhoods show substantial increases in accessibility to most establishment types, suggesting a trend toward both greater accessibility and larger dwelling units—despite the traditional trade-off between access and space. Although gradual increases in home and business density increased overall accessibility over this period, weaker neighborhood-level results indicate that this trend is less pronounced in high-poverty and non-white areas.     

冬季北极海冰长期变化对华北降水的可能影响

分析表明,从长期趋势来看,冬季喀拉海、巴伦支海海冰可以影响８月份海河、辽河匠降水;而冬季巴芬湾、戴维斯海峡海冰对７月黄河中上游流和水有有影响,海冰与降水变化均呈相反的变化趋势     

Paleomagnetic and palynologic analyses of Albian to Santonian strata at Bayn Shireh, Burkhant, and Khuren Dukh, eastern Gobi Desert, Mongolia

Cretaceous terrestrial sediments deposited in a series of intracratonic basins across the Gobi Desert region of southern Mongolia and northern China contain a unique and diverse vertebrate fauna. In 1996 an expedition jointly sponsored by the Mongolian Paleontological Center and the Hayashibara Museum of Natural Sciences revisited a number of famous vertebrate fossil localities in the eastern Gobi region of Mongolia and, as part of a broad geological and paleontological study, collected a series of paleomagnetic samples from measured sections at Bayn Shireh, Burkhant and Khuren Dukh, as well as from an unmeasured locality adjacent to Khuren Dukh. Expedition members also collected palynologic samples from Khuren Dukh and the adjacent locality. Paleomagnetic analysis shows that all the sites from which samples were collected display detrital remnant magnetization that is consistently normal in polarity. The measured Cretaceous magnetic directions are oriented to the east or northeast of the present day expected direction (declination 356.2°, inclination 65.2°), and they are wholly concordant with that expected for a mid-latitude Northern Hemisphere sampling locality, and with the directions for this period reported by other workers. These results, when considered in tandem with the known biostratigraphy, strongly suggest that the sedimentary deposits at all four localities in the eastern Gobi correlate to the normal polarity chron 34 (the Cretaceous Long Normal), which ranges in age from approximately 121 to 83.5 million years. Previous vertebrate, invertebrate and palynological data from Khuren Dukh suggest that the lower and middle parts of the stratigraphic interval exposed there (which have been assigned to the Shinekhudag Formation) are ‘Khukhtekian’ in age and correspond to the Aptian–Albian interval that can be broadly correlated to the older, Early Cretaceous part of the Cretaceous Long Normal, C34n. New palynologic data presented here indicate that these strata are no older than middle to late Albian. The rocks at Bayn Shireh (the Bayn Shireh Formation) have been assigned a ‘Baynshirenian’ biostratigraphic age that may range from Cenomanian to early Campanian. The magnetostratigraphy results presented here indicate that the strata at both the Bayn Shireh and Burkhant localities do not cross the Santonian/Campanian Stage boundary, however, as this is believed to lie at, or very near, the C34n/C33r reversal boundary. Thus, the Bayn Shireh Formation was most likely deposited near the end of the Cretaceous Long Normal Interval, no later than the latest Santonian.     

长时效的正压原始方程能量完全守恒(拟)谱模式

遵循误差反演补偿新计算原理,对正压原始方程传统气象全球拟谱模式方案进行了改造,构造了正压原始方程能量完全守恒全球拟增模式新计算方案,解决了正压原始方程的（非线性）计算稳定性问题和能量守恒整体性质保持问题,改进了相应正压原始方程传统气象全球拟谱模式方案的计算效能。新方案的数值试验表明：在计算实践上,新方案在解决能量守恒问题的同时,可解决（非线性）计算稳定性问题,并在一定条件下可解决非线性计算收敛性问题。进一步的比较数值试验还表明：在计算实践上,新方案具有在提高相应传统气象方案的计算精度,减少其计算量的同时,延长其计算时效,解决其中一类特定“气候漂移”问题方面的效用。本工作原理也适用于斜压原始方程情形。