寺口子组质疑及建议新建岩石地层单位   总被引：1，自引：0，他引：1  

王培玉 《地质论评》1999,45(6):571-575

本文论述了创建了于宁夏固原县三营乡的“寺口子组”的命名沿革、存在问题及新建立的岩石地层单位－－乌产寺乌珠尔组的定义、命名剖面、岩性岩相特征及生物组合、地层年代等。并建议在西北地区东部下第三系对比中不用寺口子组,或仅在宁夏暂予保留,而在甘肃、内蒙古西部采用新建的乌兰珠尔组。  相似文献   

华东地区中强地震序列特征研究   总被引：5，自引：0，他引：5  

黄耘  郑江蓉 《地震》1999,19(2):190-198

通过系统分析１９７０年以来华东地区ＭＳ５．０以上中强震序列,结合华东地区域特征,根据最大地震与次大震震级差,将地震序列划发为弧立型、接近孤立型主余型,主余型和震群型４类。用０．５、１天、２天、３天、５天和７天等几个时段的余震样本来研究序列类型的早期判断,结果较为满意,尝试用一种新的方法分析余震持续时间,认为某区域有一个地震活动背影景值,当余震衰减这到个背景值时,则余震活动基本结束,用此方法总结了华  相似文献   

Paleoenvironmental and Human Behavioral Implications of the Boegoeberg 1 Late Pleistocene Hyena Den, Northern Cape Province, South Africa     

Richard G. Klein  Kathryn Cruz-Uribe  David Halkett  Tim Hart  John E. Parkington 《Quaternary Research》1999,52(3):393

Boegoeberg 1 (BOG1) is located on the Atlantic coast of South Africa, 850 km north of Cape Town. The site is a shallow rock shelter in the side of a sand-choked gully that was emptied by diamond miners. Abundant coprolites, chewed bones, and partially digested bones implicate hyenas as the bone accumulators. The location of the site, quantity of bones, and composition of the fauna imply it was a brown hyena nursery den. The abundance of Cape fur seal bones shows that the hyenas had ready access to the coast. Radiocarbon dates place the site before 37,000 ¹⁴C yr ago, while the large average size of the black-backed jackals and the presence of extralimital ungulates imply cool, moist conditions, probably during the early part of the last glaciation (isotope stage 4 or stage 3 before 37,000 ¹⁴C yr ago) or perhaps during one of the cooler phases (isotope substages 5d or 5b) within the last interglaciation. Comparisons of the BOG1 seal bones to those from regional Middle Stone Age (MSA) and Later Stone Age (LSA) archeological sites suggest (1) that hyena and human seal accumulations can be distinguished by a tendency for vertebrae to be much more common in a hyena accumulation and (2) that hyena and LSA accumulations can be distinguished by a tendency for hyena-accumulated seals to represent a much wider range of individual seal ages. Differences in the way hyenas and people dismember, transport, and consume seal carcasses probably explain the contrast in skeletal part representation, while differences in season of occupation explain the contrast in seal age representation. Like modern brown hyenas, the BOG1 hyenas probably occupied the coast year-round, while the LSA people focused their coastal visits on the August–October interval when nine-to-eleven-month-old seals were abundant. The MSA sample from Klasies River Mouth Cave 1 resembles BOG1 in seal age composition, suggesting that unlike LSA people, MSA people obtained seals more or less throughout the year.  相似文献   

Stratigraphic evidence for an Early Aptian sea-level fluctuation: the Graua Limestone of south-eastern Ethiopia     

Alfonso Bosellini  Antonio Russo  Rolf Schroeder 《Cretaceous Research》1999,20(6):783

The occurrence of a thin band of marine limestone (Graua Limestone) within a thick succession of fluviatile sandstones in south-eastern Ethiopia is direct evidence of flooding of part of the East African craton (Horn of Africa). According to the presence of abundant orbitolinid foraminifers (Palorbitolina lenticularis Blumenbach andPraeorbitolina cormyi Schroeder), the age of the Graua Limestone can be referred to the Early Aptian. Stratigraphy and palaeogeographic reconstructions for the Early Cretaceous in the surrounding regions (Kenya, Somalia, Yemen, Socotra, Oman, Syria, Lebanon, Israel, Egypt and Libya) show that the Early Aptian transgression was of regional extent. Our data seem to confirm that this transgression was of relatively short duration. This pulse cannot be related to tectono-eustatic mechanisms, which are too slow. A short-lived event should be invoked: either a regional tectonic pulse or the desiccation of the proto-South Atlantic.  相似文献   

试论中国东部中生代成矿大爆发   总被引：143，自引：22，他引：121  

华仁民  毛景文 《矿床地质》1999,18(4):300-308

中国东部在中生代尤其是燕山期发生了大规模的金属成矿作用,形成了一批重要矿床,其成矿强度之高,密度之大,矿种之丰富,在全球中生代成圹作用中首屈一指,故可称为中生代成矿大爆发。研究表明,中国东部中生代成矿大爆发是该地区在特定地质背景下下发生岩石圈大减薄和构造格局大转折相结合,从而导致大规模壳幔相互作用和构造圈热侵蚀事件的产物。深入研究中国东部中生代成矿大爆发的背景和过程,不仅能解决矿床学学院发展中的许  相似文献   

造山带地区花岗岩类构造混杂现象研究--以清水泉地区为例     

朱云海  张克信  拜永山 《地质科技情报》1999,18(2):11-14

通过对东昆仑东段清水泉地区花岗岩类的详细野外研究,提出造山带地区岩浆岩中普遍存在构造混杂现象,并把构造混杂岩浆岩分为构造岩浆岩片和准构造岩浆岩片两类,为造山带地区侵入岩的研究提供了新思路。  相似文献   

中国东部海域大气气溶胶入海通量的研究   总被引：18，自引：2，他引：16  

刘毅  周明煜 《海洋学报》1999,21(5):38-45

根据中国东部海域气溶胶浓度及分级采样资料,计算得出黄海、东海及日本以南海域沙尘气溶胶的代表元素铝(Al)每月干沉降通量分别为42.8、18.3、5.2mg/m2;其中各海域春季的干沉降通量均占全年干沉降通量的40%以上.相应每月总沉降通量分别为54.1、29.8、10.5mg/m2.渤海、黄海、东海及日本以南海域每年沙尘气溶胶总沉降通量分别为26.4、9.3、5.1、1.8g/m2.东海污染元素总沉降通量以春季最大,夏、秋季次之,冬季最小.日本以南海域锑(Sb)元素总沉降通量的季节分布为冬季最大,夏、秋季次之,秋季最小;硒(Se)元素总沉降通量的最大值出现在夏季,其他季节分布比较均匀.  相似文献   

Annual and Seasonal Variations of the Sea Surface Heat Fluxes in the East Asian Marginal Seas     

Jungyul Na  Jangwon Seo  Heung-Jae Lie 《Journal of Oceanography》1999,55(2):257-270

Based on the twice-daily marine atmospheric variables which were derived mostly from the weather maps for 18 years period from 1978 to 1995, the surface heat flux over the East Asian marginal seas was calculated at 0.5°×0.5° grid points twice a day. The annual mean distribution of the net heat flux shows that the maximum heat loss occurs in the central part of the Yellow Sea, along the Kuroshio axis and along the west coast of the northern Japanese islands. The area off Vladivostok turned out to be a heat-losing region, however, on the average, the amount of heat loss is minimum over the study area and the estuary of the Yangtze River also appears as a region of the minimum heat loss. The seasonal variations of heat flux show that the period of heat gain is longest in the Yellow Sea, and the maximum heat gain occurs in June. The maximum heat loss occurs in January over the study area, except the Yellow Sea where the heat loss is maximum in December. The annual mean value of the net heat flux in the East/Japan Sea is −108 W/m² which is about twice the value of Hirose et al. (1996) or about 30% higher than Kato and Asai (1983). For the Yellow Sea, it is about −89 W/m² and it becomes −75 W/m² in the East China Sea. This increase in values of the net heat flux comes mostly from the turbulent fluxes which are strongly dependent on the wind speed, which fluctuates largely during the winter season. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Monthly Variations of Water Masses in the Yellow and East China Seas, November 6, 1998   总被引：4，自引：0，他引：4  

H. B. Hur  G. A. Jacobs  W. J. Teague 《Journal of Oceanography》1999,55(2):171-184

The monthly water mass variations in the Yellow Sea and the East China Sea are investigated using over 40 years of historical temperature and salinity observations via a cluster analysis that incorporates geographical distance and depth separation in addition to the temperature and salinity. Results delineate monthly variations in the major water masses and provide some insight into formation mechanisms and intermixing. The major water masses include the Kuroshio-East China Sea water (KE), the Yellow Sea surface water (YSS) and bottom cold water (YSB), mixed water (MW), and coastal water (CW). The distribution of the KE water mass reveals the intrusion pattern into the area west of Cheju. A separate mixed water type appears between the KE water mass and the Yellow Sea water masses during winter. The formation mechanism of the YSB appears to be the surface cooling and active mixing in winter. In the East China Sea, during summer, surface water is differentiated from the subsurface water while there is no differentiation during winter. In the Yellow Sea, a three layer system exists in the summer and fall (May–November) while a two layer system exists during the rest of the year. A fresh water mass generated by Yangtze River discharge (YD) is present over the northern East China Sea and the southern Yellow Sea during summer. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

东海南部黑潮区春季温盐度垂直分布类型及其逆现象成因的初步分析   总被引：3，自引：1，他引：2  

沈雪龙 《海洋学研究》1999,17(1):8-12

用１９８８～１９９６年在东海南部黑潮区共５个航次的春季水文观测资料,分析了该海区温、盐度垂直分布类型的地理分布,讨论了春季温、盐度逆转现象的形成原因。这主要是春季季风已转变为南风,在南风的驱动下,迫使表层水离岸向东向外海扩张,台湾暖流向北伸展,黑潮次表层水的向岸入侵的结果  相似文献