Evaluation of the role of basaltic volcanism at the Cretaceous/Tertiary Boundary in Scandinavia

白垩纪/第三纪（K/T）边界争议 已经成熟到记录镶嵌图的重要性 环境和地质过程， 地球66百万年前。，尤其是在经典的欧陆式 在北美西部和经典的海洋部分， 在斯堪的纳维亚的部分。 PI的将测试的论点， 玄武质火山作用是镁蒙皂石的主要祖先 斯堪的纳维亚半岛（K/T）边界粘土单元中的粘土矿物，以及 (2)将评估玄武岩火山作用在生产铱中的作用 异常 我们报告了一个重要的新证据， Stevns Klint的K/T边界粘土单元（鱼粘土）， 主要由一种不寻常的镁蒙脱石粘土组成， 玄武质火山碎屑灰的蚀变，而不是形成 撞击产生的玻璃或喷出物。 玄武质火山碎屑 我们发现的大型半自形拉布拉多 鱼泥第三层的颗粒。 我们的初步发现还 表明玄武质火山作用发生在 在鱼粘土中沉积冲击石英之后。 矿物学、粘土矿物学、贵金属和稀土元素 镁蒙脱石的化学分析与类似的 北方古新世玄武质凝灰岩和玄武岩的分析 海地区和瑞典南部的Skane玄武岩 不确定的年龄提供了一个很好的机会，评估 在斯堪的纳维亚半岛的K/T边界玄武岩火山作用的作用。 迄今为止， 提供了一个不切实际的广泛的日期（150百万年- 80 m.y）将被修订，密切注意避免 捕虏体污染

The Cretaceous/Tertiary (K/T) boundary controversy has matured to the point where it is important to document the mosaic of environmental and geologic processes that encompassed the earth 66 m.y. ago., especially in the classic continental sections in western North America and in the classic marine sections in Scandinavia. PI's will test the contention that basaltic volcanism was a dominant progenitor of the Mg-smectite clay mineral in the (K/T) boundary clay unit in Scandinavia, and (2) will assess the role of basaltic volcanism in producing Ir anomalies. We have reported a significant new evidence that the K/T boundary clay unit at Stevns Klint (the Fish Clay), which is dominantly composed of an unusual Mg-smectite clay, is formed by alteration of basaltic pyroclastic ash as opposed to being formed from impact derived glass or ejecta. A basaltic pyroclastic origin is supported by our finding of large subhedral labradorite grains in layer III of the Fish Clay. Our initial findings also suggest that basaltic volcanism took place before, during and after the deposition of shocked quartz in the Fish Clay. Mineralogic, clay mineralogic, noble metal and rare earth element chemical analyses of the Mg-smectites compared to similar analyses of Paleocene basaltic tuffs and bentonites of the North Sea region and of the Skane basalts of southern Sweden of uncertain age provide an excellent opportunity for evaluating the role of basaltic volcanism at the K/T boundary in Scandinavia. The geographically confined Skane basalts which heretofore have provided an unrealistically wide range of dates (150 m.y - 80 m.y) will be redated, paying close attention to avoiding xenolithic contamination.