甘青二省油页岩概论及新油田之推测

(一)引言甘青二省油页岩,最初发现于甘肃永发县之炭山岭;霍世诚业已著有报告。后经中央地质调查所西北分所诸同仁在西北调查结果,续有增加,如王曰伦在永登,何春荪在华亭及隆德     

A New Basal Titanosaur (Dinosauria: Sauropoda) from the Early Cretaceous of China

A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China. The new dinosaur represents a new genus and species of Sauropoda, and is among the most basal members of Titanosauria. Its finding also suggests that titanosaurs might have originated in Asia no later than the Early Cretaceous.     

甘肃省若干地段强震地面运动特征

以甘肃、陕西等地历年来获得的强震记录,主要是汶川大震的强震记录,研究了甘肃省强震地面运动的特征以及不同场地的地震反应。注意到本地地震动具有大陆板内地震的特点,与强震记录最多的美国西部地震动有较大的差别。甘肃的场地类型大致可以分为四个区域:河西走廊、黄土地区、陇南山区和甘南高原区,强震地面运动特征各自具有其自身的特点,又和地震动的特性有密切的关系。认为有必要对汶川大震的强震记录作全面而系统的研究,进而应用到我国的地震安全性评价中去。     

天水台影区地震震相特征讨论

利用天水地震台1986～1989年的地震资料及《中国地震台站临时报告》,试算出了通道波πg、Lg1、Lg2及其速度,用最小二乘法初步求得πg、Lg1、Lg2波在本区域的走时关系式,并对πg、Lg1、Lg2波震相在该台的记录特征做了讨论。     

关于甘肃地区小震调制比异常区域面积选取问题的讨论

利用甘肃省地震台网１９８８年以来的地震目录，对计算对小震调制比的区域面积选取作了研究，发现存在一个适用的最小面积，其大小约为６个平方度。     

1125年兰州7级地震震中位置初探

通过史料考证 ,确定了 112 5年兰州 7级大震时被震毁的益机滩堡的位置 .根据史料记载的该次地震的破坏范围及实地考察结果 ,认为该次地震的震中位置可能在现今河口及八盘峡、西固、阿干镇一带 ,在这一范围内 ,黄土滑坡密集分布 .     

地震弱短临前兆信息的提取方法研究

地震短临预报是地震预报的重大难题,它有赖于好的前兆手段和数据算是方法,本提出“弱前兆信息”的观点,并研究了提取弱短临前兆信息的方法和定量指标。     

天水地区深部构造走向及区域应力场

大地电磁阻抗和倾子函数确定天水地区沉部构造主体呈北北东或近南北走向。在１６５４年天水南８级地震Ｘ区度等震级及一个邻近区域内，由ＭＴＳ资料所确定的深部构造走向基本上与等震线长轴方向相一致，而由高频ＭＴＳ资料所确定的浅部构造走向则显示了较为复杂的特征。     

甘肃地区地壳速度的非均匀分布

用天然地方震以及近震Ｐ、Ｓ波到时资料反演了甘肃７个分区的地壳结构。其速度非均匀分布表明：就垂向非均匀性而言，河西大于河东，海原、古浪两个８级大震区大于周围地区，横向非均匀性正好相反，但无论垂向还是横向非均匀性都是上地壳（大约以１９ｋｍ深度为界）大于中下地壳；青藏块体东北缘速度自ＳＳＷ向ＮＮＥ的东北角规则变化，上中地壳（约以３０ｋｍ深度为界）内沿该方向递减，下地壳及上地幔顶部递增；横向非均匀性以低速区带为主，大致沿祁连山断裂系向ＳＳＥ直到兰州附近，再沿近ＮＳ向到舟曲武都，中间与近ＥＷ向直到康乐和政的西秦岭北缘断裂低速带交接，高速区主要在嘉峪关、玉门以北，景泰附近及兰州以南等处；中强以上地震不仅在低速区带发生，而且也在高速区及其它地方发生，两个８级大震震源区速度在研究区中地壳内为最低，要注意兰州附近及张掖民乐地区可能潜在的强震危险区。     

Thermal Structure and Rheology of the Upper Mantle Derived from Mantle Xenoliths from Gansu Province, Western China

Mantle xenoliths brought up by Cenozoic volcanic rocks onto the earth‘s surface may provide direct information about the upper mantle beneath the volcanic region. This paper presents the study on mantle xenoliths collected from Haoti village, Dangchang County, Gansu Province, western China. The main purpose of the study is to gain an insight into the thermal structure and rbeology of the upper mantle beneath the region. The results show that the upper mantle of the region is composed mainly of spinel lherzolite at shallower depth (52-75km), and garnet iberzolite at greater depth (greater than 75km), instead of harzburgite and dunite as proposed by some previous studies. The upper mantle geotherm derived from the equilibrium temperatures and pressures of xenoliths from the region is lower than that of North China, and is somewhat closer to the Oceanic geotherm. The crust-mantle boundary is determined from the geotherm to be at about 52km, and the Moho seems to be the transition zone of lower crust material with spinel iberzolite. If we take 1280℃ as the temperature of the top of asthenosphere, then the fithospbere-asthenosphere boundary should be at about 120km depth. The differential stress of the upper mantle is determined by using recrystallized grain size piezometry, while the strain rate and equivalent viscosity are determined by using the high temperature flow law of peridotite. The differential stress, strain rate and viscosity profiles constructed on the basis of the obtained values indicate that asthenospberic diapir occurred in this region during the Cenozoic time, resulting in the corresponding thinning of the lithosphere. However, the scale and intensity of the diapir was significantly less than that occurring in the North China region. Moreover, numerous small-scale shear zones with localized deformation might occur in the iithospberic mantle, as evidenced by the extensive occurrence of xenoliths with tabular equigranular texture.