COLLABORATIVE RESEARCH: Evaluation of Controls on Carbonate Platform Evolution and Architecture Through Comparative Platform Analysis: Nanpanjiang Basin, South China

了解控制碳酸盐台地寿命、构造性和层序变化的机制，对于碳酸盐台地作为古环境记录器的科学研究和油气勘探开发具有重要的基础性意义。然而，对碳酸盐岩台地内部相结构和层序地层对比的解释通常基于这样一个假设：海平面波动是主要的控制机制。我们提出了一个堪萨斯大学和威斯康星-奥什科什大学的合作项目，以评估区域和局部变量对平台结构的作用，这些变量包括海平面变化、沉降、构造活动、硅屑流入、过剩营养物质通量和碳酸盐产量。对这些控制作用的评价将通过对分布在中国南部南盘江盆地内650平方公里范围内的不同规模、不同建筑和背景的同时代三叠纪台地进行对比分析。我们之所以选择南盘江盆地，是因为我们知道没有其他地区可以对如此多样化的台地规模和地貌进行露头研究，包括陆上台地和孤立的台地。我们将通过绘制露头图来确定层序地层架构，这些露头通过台地显示连续的二维断面。同步间隔的比较将有助于区分区域和地方控制。我们将使用详细的生物地层学和磁性反转地层学来确保在控制机制的分离和解释中对同步事件进行评估。利用这些地层和年龄数据，我们将构建沉降史，以隔离局部变化，以便我们可以检查平台之间或平台内沿走向的地层同步差异的可能原因。例如，对于具有相似沉降史和海平面历史的同时代段，我们将使用相分析来评估变量，如硅屑的流入或过量营养物质对碳酸盐台地生长的中断或终止的影响，以及评估充填盆地的硅屑对进积几何的影响。最终产品将是一系列沉积模型，这些模型说明了碳酸盐平台中实际的建筑可变性，并对控制可变性的机制有了定量的了解。

9805731EnosUnderstanding the mechanisms that control longevity, architecture, and sequence variability of carbonate platforms is of fundamental 8importance in scientific studies of carbonate platforms as recorders of ancient environments and in hydrocarbon exploration and exploitation. However, interpretations of internal facies architecture and sequence-stratigraphic correlation's of carbonate platforms are commonly based on an assumption: fluctuations in sea level are the essential controlling mechanism.We propose a collaborative project between Universities of Kansas and Wisconsin-Oshkosh to evaluate the roles of both regional and local variables including sea-level changes, subsidence, tectonic activity, siliciclastic influx, excess nutrient flux, and carbonate production rates on platform architecture. Evaluation of these controls will be accomplished through a comparative analysis of coeval Triassic platforms of various scales, architectures and settings distributed over an area of 650 kn2 within the Nanpanjiang Basin of south China. We have chosen the Nanpanjiang Basin because we know of no other area that allows outcrop study of as great a diversity of platform scales and morphologies, including both landward-attached platforms and isolated platforms.We will determine sequence-stratigraphic architecture from mapping outcrops that expose continuous two-dimensional transects through the platforms. Comparison of synchronous intervals will aid in separating regional and local controls. We will use detailed biostratigraphy and magnetic-reversal stratigraphy to ensure that synchronous events are evaluated in the separation and interpretation of controlling mechanisms. With this stratigraphic and age data we will construct subsidence histories to isolate local variations so we can examine possible causes for synchronous differences in the stratigraphy between platforms or along strike within platforms. For example, for coeval intervals with similar subsidence and eustatic histories we will use facies analysis to evaluate the impact of variables such as influx of siliciclastics or excess nutrients on interruptions or termination of carbonate platform growth and to evaluate the impact of basin-filling siliciclastics on progradation geometries. The end product will be a series of depositional models that illustrate actual architectural variability in carbonate platforms and a quantitative understanding of the mechanisms that control variability.