胶南地区莱阳群绒枝藻化石的发现     

张松梅  程立人  刘典涛 《吉林大学学报(地球科学版)》2001,31(3):209-212

采自山东省胶南地区莱阳群中的部分绒枝藻植物化石 :Actinoporella podolicaAlth ,Salpingoporellasp .,DissocladellacreticaOtt ,TrinocladusperplexusElliott ,其分类位置为绿藻门 ,绒枝藻目 ,绒枝藻科。莱阳盆地中生代沉积物一直被认为是陆相沉积 ,而在莱阳群地层中发现有海相成因的海相生物化石 ,对莱阳盆地形成环境应该有一个重新认识  相似文献   

长沙—澧陵—浏阳—带冷家溪群及板溪群的甚低级变质作用   总被引：13，自引：5，他引：13  

朱明新  王河锦 《岩石学报》2001,17(2):291-300

湘东长沙-澧陵-浏阳一带中晚元古宇的冷家溪群及板溪群遭受了区域甚低级变质作用.在本地区所采的＜2μm的样品中,冷家溪群伊利石结晶度的Kübler指数为0.18～0.26°△2θ,板溪群为0.21～0.28°△2θ(Kisch国际标样校正).从而可把本地区冷家溪群的区域变质划归浅变质带和近变质带上部,温度大约为280～400℃.板溪群划归近变质带上部,温度大约为250～300℃.并未普遍达到目前人们认为的绿片岩相或者是低绿片岩相.样品中冷家溪群伊利石(白云母)b0值的范围在0.8999～0.9042 nm,板溪群为0.9018～0.9042nm.由冷家溪群b0频率累积曲线图,得出本区冷家溪群处于较典型的中压区.  相似文献   

Group Strong Earthquakes and Triggering by Tidal Stress   总被引：4，自引：1，他引：4  

Zhang Guomin  Li Li  Li Kaiwu  Ma Hongsheng 《中国地震研究》2001,15(4):354-364

The results obtained using the group model of earthquakes generated in tectonic blocks are fur ther used in this paper to analyze the relationship between the Ms ≥ 7.0 events in Chinese ma inland and the modulation and triggering from the earth tides. The research shows that the Ms 7.0 events in Chinese mainland have been significantly triggered by the tidal stress, especially within the active period with group strong earthquakes. In the quiescence period of strong earthquakes, no Ms7.0 events were triggered, while within the active period, over 82.4% of strong earthquakes took place within a special moon phase, which is 36.4 % higher than the average. Therefore, the modulation and triggering of tidal stress can be used to distinguish the active periods and to forecast the time of the strong earthquakes within the active period. The relationship between the tidal triggering and the tectonic dynamic condition is investigated and the mechanism of the modulation is simulated with the group model of earthquakes generated in tectonic blocks.  相似文献   

Breakthroughs in the biodiversity, biogeography, biostratigraphy, and basin analysis of the Beaufort group     

P.J Hancox  B.S Rubidge   《Journal of African Earth Sciences》2001,33(3-4)

Over the past decade researchers working on the rocks of the Beaufort Group in the main Karoo Basin of South Africa have vastly increased our understanding of this important Permo-Triassic sequence. Many new fossil forms have been discovered, allowing for breakthroughs into the biodiversity, biogeography and biostratigraphy of the group. Taxonomic and phylogenetic advances are many and varied, and cover most of the vertebrate taxa, but with emphasis placed on the temnospondyl amphibians, archosauriforms and non-mammalian synapsids, in particular the anomodontia. Biostratigraphic breakthroughs have centered on the Middle Permian Eodicynodon and Tapinocephalus assemblage zones, the Late Permian Dicynodon Assemblage Zone, and the Triassic Lystrosaurus and Cynognathus assemblage zones. Correlation of these biozones with better dated sequences in Europe, Russia and China has allowed for many chronostratigraphic refinements, which are in turn vital for sequence stratigraphical analysis of the basin fill. Based on fossil data, both the lower (Ecca–Beaufort) and upper (Beaufort–Molteno) contacts of the group have been proved to be highly diachronous. The refined chronostratigraphic framework has also allowed for a better analysis of the basin evolution through time, particularly in terms of the correlation of external stimuli that affect basin sedimentation patterns.  相似文献   

鄂东铅锌矿床成矿中磷酸盐生物和非生物还原作用的有机地球化学研究     

胡明安  罗学常  高广立 《地球学报》1996,17(Z1):97-103

矿床产于三叠系大冶群碳酸盐岩中，有机质来自海相浮游生物和微生物。矿层中有机质发生成熟异常，已达过成熟作用早期。这得到镜质体反射率（Ro达4.6%）和矿物包裹体测温（均—温度达210℃）的证实。部分标本中有机质被微生物降解。硫同位素δ34S值大部分为正值，小部分为负值。综合研究表明在鄂东铅锌硫化物矿床的形成过程中，硫酸盐的生物和非生物还原作用，均具有十分重要的成矿意义。  相似文献   

桂北四堡群中科马提岩系及其成因类型   总被引：4，自引：0，他引：4  

唐红松  肖禧砥 《矿产与地质》1992,6(2):126-138

桂北四堡群中许多镁铁质—超镁铁质岩体,实际上是火山岩或次火山岩。有的还具有科马提岩岩流的结构分层,其堆积带上部橄榄石和辉石晶体间隙中充填有基质物质。这些基质中发育了典型的橄榄石鬣刺结构。科马提岩与其伴生玄武岩属具成因联系的同一演化系列。在微量元素及REE特征上,区内科马提岩具有较好的Ⅱ类科马提岩属性,它们系亏损地幔经较小程度部分熔融产生。  相似文献   

贺兰山群变质杂岩主期变质作用的温压环境研究   总被引：1，自引：0，他引：1  

杨家喜  胡能高 《矿物岩石》1992,12(4):12-20

分布于贺兰山脉北部的贺兰山群变质杂岩的主期变质作用达角闪麻粒岩相,其矿物组合特征与低压相系麻粒岩相似、利用共生矿物组合和矿物对的温度计、压力计估算主期变质温度740—764(?),压力460—501MPa。温度压力条件与低压相系的地热梯度线较接近,变质作用强度具面型分布的特征,与东部密云、冀东等地的麻粒岩相区相似,但变质压力明显低,压力类型也不同,应属不同构造背景下的变质产物。  相似文献   

马超营断裂以北熊耳群火山岩系是形成于弧后裂陷盆地环境的基性-酸性双峰态火山岩组合吗?——与胡德祥等同志商榷     

郭继春  姚文平  许红忠 《地球科学》1992,(4)

中元古界熊耳群火山岩分布于华北地台南缘。本文提出马超营断裂以北火山岩是以安山岩占主导地位的玄武岩—安山岩—英安岩—流纹岩组合,而不是胡德祥等人提出的基性—酸性双峰态组合,它们形成的构造环境为安第斯型火山弧。火山岩上部的粗安岩—粗面岩组合形成的构造环境为弧内盆地。  相似文献   

麻山群孔兹岩系柱晶石特征及成因研究     

姜继圣  关雅先 《矿物学报》1992,12(2):165-171

文中所涉及的柱晶石产于我国黑龙江省东部麻山群变质沉积岩系中。作者对矿物的形态、物性、化学成分、结构特征及岩石矿物共生组合进行了系统研究,并与国外同类矿物的资料进行了对比。结合对麻山群变质地质的详细研究,本文还对柱晶石的成因及地质意义进行了探讨。  相似文献   

新疆昆仑山、喀喇昆仑山中泥盆世及石炭纪一些四射珊瑚     

蔡土赐 《新疆地质》1992,(1)

昆仑山西段及喀喇昆仑山,部分四射珊瑚化石,经笔者研究计有:喀喇昆仑山楚隆帕斯坦中泥盆统落石沟组含Grypophyllum kelakunlunense(sp.nov.);昆仑山西段下石炭统他龙群产Diphyphyllum kunlunense(sp.nov.)喀喇昆仑山中石炭统含Protodurhamina kelakunlunensis(sp.nov.), Lithostrotionella sp.;昆仑山西段中、上石炭统库尔浪群含Protodurhamina kunlunensis (sp.nov.), Neokoninckophyllum sp., Kionophyllum kunlunense(sp. nov.), Paracarruthersella sp., Orygmophyllum convexum Fomitchev。  相似文献