Rare-earth elements in Luochuan loess section,Shaanxi province     

Qizhong Wen  Suhua Yu  Fuqing Sun  Yuqi Wang  Bingru Chen  Shude Tu  Jingxin Sun 《中国地球化学学报》1985,4(2):172-180

TheΣ REE in loesses of different ages in the Luochuan section shows a narrow range of variation, indicating the homogeneity of loessic materials in chemical composition. The REEs in loess are concentrated mainly in silt-sized detrital minerals. Loesses and paleosols of different ages all are relatively enriched in rare-earth elements of the Ce family, and show similar REE distribution patterns. The fractionation among various REEs in the loess is different from that in morainic, marine and lacustrine sediments, but is similar to that in sand samples from deserts in Northwest China. The ratios of Ce/Ce* and Eu/Eu* reflect that the provenance of loessic materials and their accumulating area are all in an oxidation environment with weakly basic mediums under arid or semi-arid climate.  相似文献   

QBO-like Oscillations Induced by Local Thermal Forcing     

Zhang Daizhou  Qin Yu 《大气科学进展》1995,12(2):245-254

A zonal-vertical two-dimensional equatorial model is used to study the possibility that the long period oscillation of the zonal mean flow occurring in the lower equatorial stratosphere (QBO) is caused by local thermal ac-tivities at the tropical tropopause. The model successfully reproduces QBO-like oscillations of the zonal mean flow, suggesting that the local heating or cooling at the tropical tropopause is probably the main reason of QBO’s genera-tion. The analysis of the dependence of the oscillation on the wave fencing indicates that the oscillation is not sensible to the forcing scale. The model can reproduce QBO-like oscillations with any forcing scale if the fencing period and amplitude take appropriate values, proving that the internal gravity waves generated by local thermal source take much important roles in QBO.  相似文献   

固体地球科学前沿研究的新挑战   总被引：4，自引：0，他引：4  

钱祥麟 《地学前缘》1995,2(2):183-186

在地球早期至今的几十亿年历史长河中，行星地球从过去的早期阶段到现今阶段是受整个地球系统发展的结果。借鉴地质历史演化，地球系统的过去状态特性对预测将来是非常有助的。温室效应尚不确知，因为这样一个问题难以解释，即近期１５０万年甚至整个第四纪２４０万年内冰期与间冰期相间出现，与人类释放ＣＯ＿２或消耗燃料无关。ＣＯ＿２或ＣＨ＿４叠加大气温度的变化趋势到底是什么？平流层的臭氧是否也有自身修复的功能，它自身是否也在变化？固体地球科学作为地球科学前沿，需要持续发展，应当参与全球变化研究。  相似文献   

影响蔬菜周年供应的原因及其对策     

涂悦贤 《热带地理》1995,15(2):120-127

影响蔬菜周年均衡供应的原因是多方面的，不利的天气气候影响是主要原因之一。广西以广州市为例，剖析了影响蔬菜年供应的原因，并提出缩短淡季实现周年均衡供应的对策。  相似文献   

The Principle of the Drilling by Impregnated Diamond Bits and the Classification of Rocks     

Tu Houze China University of Geosciences  Wuhan 《中国地质大学学报(英文版)》1991,(1)

Recently impregnated diamond bits have been widely applied in drilling hard and me-dium-hard formations in the world.It is quite necessary to study the fracturing mecha-nism of the impregnated diamond bit and the classification of rocks,which can realizeoptimum drilling.Using multi-parameter rotary test stand can monitor and print nineparameters.The diamond size and concentration for experiment are various and there arenearly200 types of samples,numbering over1000 pieces.The results of laboratory arethe same as those in the field.Besides,this paper expresses that the diamond concentra-tion of impregnated diamond bits effect the bonding strength of diamond imbedded in ma-trix.During drilling by impregnated diamond bits three ways are used to cool the bits.The contact area between impregnated diamond layer and flow,and the drilling flowthrough annulus carrying away heat with conduction form can be shown by equations.Itis impossible to classify the rock drillability only by using single factor.The best met  相似文献   

汉南杂岩与金成矿特征   总被引：2，自引：0，他引：2  

涂怀奎 《矿产与地质》1991,5(3):163-168,182

汉南杂岩区位于扬子地台北缘,围岩为元古界绿片岩 勉县—洋县深大断裂系统在成岩、成矿与盆地形成方面占有重要的地位.杂岩体由斜长花岗岩、二长花岗岩、钾长花岗岩、石英闪长岩和辉长辉绿岩组成.金矿化类型主要有石英脉型和蚀变岩型,与接触带、断裂带、蚀变带有关,蚀变后岩石矿物成分变化.使金重新分布,砂金分布与金源、地貌和新构造运动关系密切.  相似文献   

快速无损测定金首饰成色     

涂袁生 《华东地质学院学报》1989,12(3):57-62

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关于FD—61K型自然伽玛测井仪换算系数的定值问题     

傅祥麟  赵廷业 《铀矿地质》1989,5(3):182-187

本文讨论了FD-61K型自然伽玛测井仪的换算系数K′_0,并确认换算系数K_0应为115.6±3μR/h。  相似文献   

美国大陆地区震中图的构造解释     

马宗晋  王琦 《地质学报》1992,66(4):315-326

按照地震线的判定原则,利用美国大陆地区历史地震和现代地震的震中分布图,并结合地质和地球物理资料,画出了美国大陆地区的地震线和地震密集带,分析了美国大陆总体的和分区的地震构造格局特征,并与中国大陆的地震构造格局作了比较。结果说明,地震震中的空间分布特征反映了地壳内部活动构造的信息,大陆的地震构造格局不仅受原有构造格架和现今边界动力环境的控制,而且还可能受更高层次的全球构造动力因素的影响。  相似文献   

海南二甲多因复成金矿床时序分析与成矿模式研究   总被引：3，自引：0，他引：3       下载免费PDF全文

涂绍雄 《地质找矿论丛》1994,9(3):17-27

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