Sequence Stratigraphic Signature of a Long Term Greenhouse to Ice-House Transition in Mississippian Ramp Carbonates of Appalachian and Eastern Illinois Basins

9725308 Read本提案要求资金用于研究阿巴拉契亚/东伊利诺伊盆地早密西西比期（奥塞奇- meramecian）碳酸盐斜坡的大量暴露和广泛岩心，并将其与晚密西西比期演替进行比较，以寻找该热带碳酸盐斜坡对与晚古生代全球温室到冰库转变相关的海平面上升和气候变化的长期（30年）地层响应。我们目前有来自阿巴拉契亚盆地和伊利诺斯盆地的大数据集，显示出晚古生代冈瓦纳冰期开始时相对较大的海平面波动下沉积的证据；这些将作为与旧单位比较的基础。我们建议对早、中密西西比期斜坡相进行测井和照片拼接，这些斜坡相似乎形成于斜状斜坡上和上面，具有骨状斜坡边缘和下坡岸，沟壑斜坡和低洼砂体，这些砂体是由废弃的细节海洋自我建造而成的。将逐层记录露头和岩心，以确定组成碳酸盐岩和硅屑相的垂直和横向范围、区域潮滩相的存在或不存在、风成岩、边界面类型和发育的古土壤，以及任何侵蚀切口的证据。我们将构建详细的区域剖面，以确定密西西比早期斜坡的高分辨率层序地层学。此外，我们将利用岩心、岩屑样品和电缆测井，将我们后来在阿巴拉契亚盆地进行的密西西比（Chesterian）高分辨率层序地层露头研究扩展到整个阿巴拉契亚盆地的地下。然后，我们将使用这些早至晚密西西比的数据集，通过计算机模拟我们的地层截面来评估密西西比海平面波动的幅度。在可能的情况下，将使用字段数据约束输入参数。最后，这些数据将与冈瓦纳的冰形成历史相结合，以确定这个热带斜坡对晚古生代全球气候变化的地层响应。

9725308 Read This proposal requests funds to study the large exposures and extensive cores of the Early Mississippian (Osage-Meramecian) carbonate ramp, Appalachian/eastern Illinois Basins, and compare them to Late Mississippian successions, to search for the long term (30 m.y.) stratigraphic response of this tropical carbonate ramp to eustatic and climatic changes associated with Late Paleozoic global greenhouse to icehouse transition. We presently have a large data set on the later Mississippian (Chesterian) units from both the Appalachian and Illinois Basins, which appear to show evidence of deposition under relatively large sea level fluctuations during onset of Late Paleozoic glaciation of Gondwana; these will serve as a basis of comparison with the older units. We propose to log and photo-mosaic the Early and Middle Mississippian ramp facies, which appear to have formed on and above a clinoformal ramp with skeletal ramp margin and downslope banks, a gullied slope and low-stand (?) sand bodies, that built out from an abandoned detaic-marine self. Outcrops and cores will be logged bed-by-bed, to define vertical and lateral extent of component carbonate and siliciclastic facies, presence or absence of regional tidal flat facies, eolianites, types of bounding surfaces and paleosols developed, and any evidence of erosional incision. We will construct detailed regional cross sections to define a high-resolution sequence stratigraphy for the early Mississippian ramp. Additionally, we will extend our later Mississippian (Chesterian) high resolution, sequence stratigraphic outcrop study of the Appalachian Basin, throughout the subsurface Appalachian Basin using core, sample cuttings and wireline logs. We will then use these data sets on the Early to Late Mississippian to evaluate the magnitude of Mississippian sea level fluctuations by computer simulation of our stratigraphic cross-sections. Input parameters will be constrained where possible using the field data. Finally, this data wil l be integrated with the ice-buildup history in Gondwana, to define the stratigraphic response of this tropical ramp to Late Paleozoic global climate change.