Regional Paleosol Variability on a Dissected Alluvial/Coastal Plain: A Proposal to Develop an Empirical Paleosol-Landscape Model for Nonmarine Sequence Stratigraphy

在冲积/海岸平原上的区域古土壤变异：为非海相层序地层学和陆相盆地分析开发经验古土壤-景观模型的建议使用古土壤（古土壤）来划分大陆岩石和理解陆相沉积盆地中沉积速率的变化现在已经牢固地建立起来了。应用古地形学技术识别和对比陆地不整合面（层序边界）的早期成功，很大程度上是建立在主要从沉积盆地背景发展起来的古土壤景观模型之上的。相比之下，在相对海平面曲线下降阶段，冲积/海岸平原的古土壤变异性受到的关注相对较少。本研究将记录白垩纪（Cenomanian） Dunvegan Fm单一间隙表面古土壤的空间变异性。关于与相关山谷边缘和同时期古海岸线的距离。Dunvegan Fm。非常适合本研究，因为它在空间上很广泛，地层上也很好理解；因为同时期的浅海和岸线环境可以自信地与上倾的非海相沉积相对应；而且，由于古山谷沉积物已经被详细地绘制出来，从任何中间的古土壤到山谷边缘的距离都可以相当准确地确定。从同一时期海岸线向上延伸250多公里的样带，将在距离相邻山谷边缘不到1公里至20多公里的单个间隙取样10个古土壤。古土壤将在野外描述和分析微观形态特征，地球化学和矿物学。微形态特征将被量化，古土壤将使用土壤微形态指数进行客观比较。这些古土壤学数据将用于重建这些古土壤的土壤沉积历史，为解剖的冲积/海岸平原环境开发古土壤景观模型，并评估土壤微形态指数的价值，以客观描述和比较盆地内和盆地之间的古土壤。

Regional Paleosol Variability on a Dissected Alluvial/Coastal Plain:A Proposal to Develop an Empirical Paleosol-Landscape ModelFor Nonmarine Sequence Stratigraphy and Terrestrial Basin AnalysisPaul McCarthyEAR-0229196 The use of paleosols (fossil soils) for partitioning continental rocks and understanding changing sedimentation rates in terrestrial sedimentary basins is now firmly established. Early successes in applying paleopedological techniques to the recognition and correlation of terrestrial unconformities (sequence boundaries) have built largely upon paleosol-landscape models that were developed primarily from aggradational basin settings. In contrast, relatively little attention has been paid to paleosol variability in an alluvial/coastal plain undergoing dissection during the falling stage on the relative sea level curve. This research will document the spatial variability of paleosols across a single interfluve surface in the Cretaceous (Cenomanian) Dunvegan Fm. with respect to distance from associated valley margins and the coeval paleo-shoreline. The Dunvegan Fm. is ideally suited for this study because it is both spatially extensive and stratigraphically well understood; because coeval shallow marine and shoreline environments can be confidently correlated with nonmarine deposits updip; and because paleo-valley deposits have been mapped in detail and the distance from any interfluve paleosol to the valley margin can be fairly accurately determined. Ten paleosols will be sampled from a single interfluve at distances from less than 1 km to more than 20 km from adjacent valley margins along a transect extending more than 250 km updip from the coeval shoreline. Paleosols will be described in the field and analyzed for micromorphological features, geochemistry and mineralogy. Micromorphological features will be quantified and paleosols will be objectively compared using a soil micromorphology index. These paleopedological data will be used to reconstruct the pedosedimentary histories of these paleosols, to develop a paleosol-landscape model for dissected alluvial/coastal plain settings, and to assess the value of the soil micromorphology index for objective description and comparison of paleosols both within and between basins.