COLLABORATIVE RESEARCH: The Tectonomagmatic and Event- Stratigraphic Significance of Lower Paleozoic K-Bentonites in the Iapetus Region of N. American and NW Europe

PIs将研究巴尔托斯坎迪亚中上奥陶统地层蚀变火山灰床（k.s bentonites）的构造背景、岩浆起源和地层意义，并将这些数据与北美的类似数据进行比较。初步研究表明，勒佩特岩两侧的这些k .膨润土层具有共同的物源和共同的构造背景。如果这一迹象被证明是正确的，这些床中最广泛的将发生深刻的事件。奥陶系的地层意义，以及我们对塔科尼亚造山运动期间劳伦西亚和波罗的海板块位置的认识将大大提高。同样，巴尔托斯坎迪亚和英国境内大量的志留纪k .膨润土表明了板块运动的持续进行。从llandevery到Ludlow时期的边缘火山活动。pi将从爱沙尼亚、瑞典和挪威的岩心和露头中收集最广泛的地层样本。他们将增加这些地层的生物地层位置的现有信息，并使用大量样品和选定的斑晶的化学指纹来与北美地层进行准确的关联。这些将与trans进行比较。传统生物地层学和牙形刺对比提示的k .膨润土的大西洋地层关系。我们也会获得高。黑云母和锆石分离物的分辨率氩年龄谱和upb测年结果与生物地层学较好。这将为奥陶纪的时间尺度增加关键年龄。微量元素数据将绘制在判别图上，以解释这些地层的构造和岩浆背景。

PIs will investigate the tectonic setting, magmatic originand stratigraphic significance of altered volcanic ash beds (K.bentonites) in the Middle and Upper Ordovician strata ofBaltoscandia and to compare these data with similar data fromNorth America. Preliminary studies strongly suggest these K.bentonite beds on both sides of lapetus had a common source and acommon tectonic setting. If this indication proves correct, themost widespread of these beds will have profound event.stratigraphic implications for the Ordovician, and ourunderstanding of Laurentia and Baltica plate positions during theTaconian orogeny will be substantially improved. Similarly, theabundance of Silurian K.bentonites throughout Baltoscandia andthe UK indicates ongoing plate.margin volcanism from Llandoverythrough Ludlow time. PIs will collect samples of the mostextensive beds from cores and outcrops in Estonia, Sweden andNorway. They will add to existing information on thebiostratigraphic position of these beds and use chemicalfingerprinting of both bulk samples and selected phenocrysts tomake accurate correlations with North American beds. These willbe compared with trans.Atlantic stratigraphic relations of K.bentonites suggested by traditional biostratigraphy and bygraphic correlation using conodonts. We will also obtain high.resolution Ar age spectra and U.Pb dates from biotite and zirconseparates from biostratigraphically well.constrained K.bentonitesthat will add key ages to the Ordovician time scale. Traceelement data will be plotted on discrimination diagrams tointerpret the tectonic and magmatic settings of these beds.