Understanding the Origin of Patterned Silica Diagenetic Reaction Fronts

化学反应边界是在反应的初始化学反应物和最终产物之间形成的一层。随着反应的发展，边界通过化学混合物传播。在实验室中，已有原子(纳米)尺度的反应边界被记录下来，在沉积岩中可达米尺度。由于它们存在于化学、生物和地质系统中，它们形成的图案和图案化的反应边界以及形成它们的过程被广泛研究。化学过程在将沉积物转变为岩石和将流体从沉积物中排出方面非常重要。大多数研究涉及观察厘米级的化学界面是如何形成的--但我们已经在沉积岩中识别了千米级的图案化反应边界，并想找出它们是如何形成的。这是以前从未尝试过的。我们已经开始记录地球上迄今见过的最大规模的化学反应边界。它们形成的图案由胞状或山脊状的网络组成，面积超过10平方公里。这些细胞的高度为50-200米，直径可达2.7公里。反应前锋的发展和模式与许多其他地质现象有关，反应前锋似乎是沉积盆地演化的一个基本方面。关于图案是如何形成的，我们有三个理论，这个建议将允许我们改进IODP钻孔的确切位置，以找出我们的理论中的哪一个-如果有的话-是正确的。我们的工作可以分为两部分：1.我们将分析石油和天然气行业提供的地震反射数据集，并通过与StatoilHydro的合作，确定IODP钻孔的位置。这项研究将导致提交IODP钻探前和全面钻探建议。2.这些数据将使我们能够评估堵塞浅层天然气或碳氢化合物的风险以及斜坡不稳定的可能性。我们将对此进行全面评估，因此，我们的IODP提案不需要任何额外和昂贵的数据收集。

A chemical reaction boundary is a layer that forms between the initial chemical reactants and final products of a reaction. As the reaction develops the boundary propagates through a chemical mixture. Reaction boundaries have been documented at atomic (nanometer) scale in the laboratory upto metre-scale in sedimentary rocks. They form patterns and patterned reaction boundaries and the processes by which they form are widely studied, since they are found in chemical, biological and geological systems. Chemical processes are very important in changing sediment into rock and for driving fluids out of sediment. Most studies involve looking at how chemical boundaries form at a centimentre scale - but we have identified patterned reaction boundaries at kilometre-scale in sedimentary rocks and want to find out how they form. This has not been attempted before. We have started to document the largest scale chemical reaction boundaries yet to be seen on the globe. They form patterns which consist of cell or ridge-type networks over 10s of square kilometres. The cells are in 50-200 m in height and up to 2.7 km across. The development of the reaction fronts and the patterns are linked to a host of other geological phenomena and the reaction fronts appear to be a fundamental aspect of sedimentary basin evolution. We have three theories as to how the patterns form, this proposal would allow us to refine where exactly IODP borehole should be positioned to find out which - if any - of our theories is correct. Our work can be divided into two parts: 1. We would analyse seismic reflection datasets provided by the oil and gas industry and through a partnership with StatoilHydro we would establish where IODP boreholes should be located. This research would result in the submission of pre- and full-IODP drilling proposals. 2. The data would allow us to evaluate the risk of encoutering shallow gas or hydrocarbons as well as the chances of slope instability. We would compile a comprehensive assessment of this, therefore our IODP proposal would not require any additional and costly data collection.