湘西北杨家坪寒武纪事件沉积

EVENT SEDIMENTS OF CAMBRIAN IN YANGJIAPING,\= NORNORTHWEST HUNAN

湘西北杨家坪处于鄂中碳酸盐台地西缘，寒武纪期间区内先后出现大洋缺氧事件、浊流事件、风暴事件等突发性灾变沉积。根据黑色岩系的岩石学特征和它产于急速海侵的层序底部，以及它在我国南方和世界性广泛分布等事实，表明它的出现是与震旦－寒武纪之交的外星撞击地球、泛大陆解体、全球性海平面突然上升有关。浊流事件和风暴事件均为强烈的地方性灾变事件，前者的产物为磷质浊积岩和钙质浊积岩，其诱发因素与风暴活动有关；

Yangjiaping,Northwestern Hunan,is situated in the west margin of Central Hubei carbonate platform.In the Cambrian,there occurred successively a series of catastrophic events in the study area,including oceanic anoxic event,turbidity event and tempest event.According to the petrological characterisitics of the black rock series and the facts that they occur on the bases of the rapid transgressional sequences and are distributed widely in South China and the whole world,the formation of the black rock series should be related to the meteorite impact,the break up of pancontinent and the eustatic sealevel abrupt rising between the Sinian and Cambrian.The turbidity events and tempest events were all strong local catastrophic events.The former resulted in phosphorous turbidites and calcareous turbidites,their induced factors were related to tempest activities;the latter resulted in near source tempestites and scoured basement autochthonous tempestites\;