Timing of Hydrocarbon Fluid Emplacement in Sandstone Reservoirs in Neogene in Huizhou Sag, Southern China Sea, by Authigenic Illite ⁴⁰Ar-³⁹Ar Laser Stepwise Heating

• 责任者：Shi Hesheng (School of Ocean and Earth Science ; Tongji University ; Shanghai 200092 ; China) ; Zhu Junzhang
• 刊名：Earth Science Frontiers
• 出版年：2009
• 卷期：16(1)
• 页码：p.290-295
• 图表：2 illus., 1 table, 12 refs.
• issnNo：ISSN1005-2321
• isbnNo：CN11-3370/P

Timing of oil or gas emplacements is a new subject in isotopic geochronology and petroleum geology. The principle of the illite K-Ar age as expounded by Hamilton et al. is that the illite is often the last or one of the latest mineral cements to form prior to hydrocarbon accumulation, and since the displacement of formation water by hydrocarbons will cause silicate diagenesis to cease, K-Ar ages for illite will constrain the timing of this event and also constrain the maximum age of formation of the trap structure. In this study, the possibility of authigenic illites ⁴⁰Ar-³⁹Ar dating has been investigated. The illite samples were separated from the Tertiary sandstones in three rich oil reservoir belts within the Huizhou sag by cleaning, fractured by coolingheating cycling，Soxhletextracting with solvents of benzene and methanol and separated with centrifugal machine. Therefore, the critical emplacement of petroleum accumulation in Zhujiang Formation in Huizhou sag took place in ca 10 Ma. Later fault activity strengthened the entrance of hydrocarbon fluids into the oil systems based on the data of the fault evolvement history, petroleum system combinations and homogeneous temperatures of fluid inclusions.