Burial diagenesis of carbonate rocks

碳酸盐岩的埋藏成岩作用

• 批准号: 37228-2007
• 负责人: Machel, Hans
• 金额: $ 2.91万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=361882
• 关键词: Burial; diagenesis; carbonate; rocks

Diagenesis comprises all mineralogical, physical, and chemical changes that happen to  sedimentary deposits from the time of deposition at the Earth's surface to burial at depths of about 6 - 9 km and commensurate temperatures of about 200 oC. While some diagenesis happens very close to the surface, most diagenesis occurs during burial. Certain diagenetic processes are typical for shallow (max. 1 km), intermediate (about 1 - 3 km), or deep (about 3 - 9 km) burial. Investigation of rocks from various burial depths can provide an understanding of diagenetic processes and their effects on the rocks. Such studies can be done on drill core and on outcrops of rocks that were formerly buried and then exhumed.    Most diagenetic processes are facilitated by the flow of groundwater that is contained in and passes through the pore spaces. Hence, porosity and permeability (a measure for the ease of pore water flow), flow rate and pore water salinity, are important controls on diagenesis. The main results of diagenesis are solidification of the loose sediments to rocks, and changes in mineralogy and texture, which can modify porosity and permeability dramatically. In extreme cases, a rock can have highly enhanced porosity and permeability due to extensive mineral dissolution, or it can be completely plugged up due to extensive mineral precipitation.Diagenesis is of supreme importance for human civilization. Because of the changes in porosity and permeability, diagenesis affects the ability of the rocks to carry or store groundwater (used for human consumption and irrigation in relatively shallow settings), oil and gas (commonly in deeper settings), and certain metal ores (shallow or deep settings). This research program deals with all types of diagenesis in carbonate rocks, which are either limestones (calcium carbonate) or dolostones (calcium-magnesium carbonate). It is an extension of earlier work and will focus on Devonian and Carboniferous rocks of western Canada. Rocks of similar age (more than 300 million years old) in Germany and Spain, as well as of younger age in Texas and the Caribbean, will also be studied for comparison.

成岩作用包括沉积矿床从地表沉积到埋藏在约6 - 9公里深处、相应温度约为200 ℃时发生的所有矿物学、物理和化学变化。虽然一些成岩作用发生在非常接近地表的地方，但大多数成岩作用发生在埋藏过程中。某些成岩过程是典型的浅（最大）。1公里），中等（约1 - 3公里），或深（约3 - 9公里）埋藏。对不同埋藏深度的岩石进行研究可以了解成岩过程及其对岩石的影响。这种研究可以在钻取的岩芯上进行，也可以在以前埋在地下然后又被挖掘出来的岩石的露头上进行。 大多数成岩过程是由包含在孔隙空间中并穿过孔隙空间的地下水的流动促进的。因此，孔隙度和渗透率（孔隙水流动的容易程度的量度）、流动速率和孔隙水盐度是成岩作用的重要控制因素。成岩作用的主要结果是松散沉积物固化成岩石，矿物学和结构发生变化，这可以显着改变孔隙度和渗透率。在极端情况下，岩石可能由于大量的矿物溶解而具有高度增强的孔隙度和渗透率，或者由于大量的矿物沉淀而完全堵塞。成岩作用对人类文明至关重要。由于孔隙度和渗透率的变化，成岩作用影响岩石携带或储存地下水（在相对较浅的环境中用于人类消费和灌溉），石油和天然气（通常在较深的环境中）以及某些金属矿石（浅或深环境）的能力。该研究项目涉及碳酸盐岩中的所有类型的成岩作用，包括石灰岩（碳酸钙）或白云岩（钙镁碳酸盐）。这是早期工作的延伸，将侧重于加拿大西部的泥盆纪和石炭纪岩石。德国和西班牙年龄相似（超过3亿年）的岩石，以及德克萨斯州和加勒比海地区年龄较小的岩石，也将进行比较研究。