沉积速率与基底蓄水层流体活动对冲绳海槽海底热流值的影响

发布时间：2018-04-17 02:11

本文选题：地热特征 + 沉积速率　；参考：《海洋地质与第四纪地质》2017年02期

【摘要】：冲绳海槽海底热流值高且离散性强、热液活动发育,这一地热特征主要表现在海槽南段与中段,其形成与沉积过程和浅层基底水热活动密切相关。首先依据居里点深度资料计算海底热流背景值,并与实测热流资料进行对比,分析了冲绳海槽的海底热流异常特征。然后选取一条与海槽扩张中心走向一致的模拟剖面,以实测地热资料为约束,利用热模拟的方法,探讨了沉积速率和基底流体活动对海底热流值的影响。最后,探讨了海槽热流特征形成机制。热模拟结果表明,如果南段与中、北段分别在中中新世和晚更新世开始拉张,在冲绳海槽的形成演化过程中,沉积速率可使海槽南段和中段的海底热流值分别降低7%~16%和4%~12%,沉积速率越大对热流值的影响也越大;在基底流体活动的影响下,海槽热流值表现出极大的离散性,下降流体使得海底热流值进一步降低,上升流体作用则相反,海槽中段的上升流体影响远远超过沉积速率影响,使得局部海底热流值提高到背景值的3倍。在局部上升流体与下降流体运移速率相同的前提下,当沉积速率25cm/ka、流体运移速率为60~66cm/a时最符合海槽南段西部的热异常形成条件;当宫古断裂及海槽中段基底蓄水层内的流体运移速率约为南段流体运移速率的4~6倍,或者蓄水层之下热流背景值约为南段背景值的2~3倍时,最符合宫古断裂带附近和海槽中段的热流异常形成条件,这可能预示着在10km深度处存在岩浆房。
[Abstract]:The Okinawa trough of the heat flow value is high and the strong discrete, hydrothermal activity and development, the geothermal features in the southern trough and middle, its formation is closely related to the deposition process and shallow basement hydrothermal activities. First according to the Curie point depth data to calculate the background value of the heat flow, and compared with the measured heat flux data and analysis of seafloor heat flow anomaly characteristics of the Okinawa trough. Then select a consistent with the trend of expansion trough simulation center section, based on the measured geothermal data as constraints, using the method of thermal simulation, discusses the influence of the deposition rate and basal fluid flow to the heat flow. Finally, discusses the characteristics of formation heat flow trough the mechanism of heat. The simulation results show that if the South and north respectively, opened in the middle Miocene and late Pleistocene, the formation and evolution of the Okinawa trough, the deposition rate to the south of the trough and middle segments The heat flow value decreased 7%~16% and 4%~12% respectively, the deposition rate increasing effect on heat value; in effect basal fluid activity, trough heat value showed great discreteness, decreased fluid makes the heat flow to further reduce the rise of fluid has the opposite effect, the effect of fluid trough middle rise far more than the deposition rate, the local heat value increased to 3 times the background value. In the local rise and fall of fluid fluid migration rate of the same premise, when the deposition rate of 25cm/ka, the rate of fluid migration is 60~66cm/a most accord with the southern trough in the abnormal heat forming condition; when 4~6 times the fluid migration rate of Miyako Island fault trough and middle basal aquifers in approximately south of fluid migration rate, or aquifer under heat background value is about 2~3 times of the background value, the most in line with the Miyako Island fault zone The conditions for the formation of heat flow anomalies in the middle section of the trough may indicate that there is a magma chamber at the depth of 10km.

【作者单位】：中国地质调查局青岛海洋地质研究所;青岛海洋科学与技术国家实验室海洋矿产资源评价与探测技术功能实验室;
【基金】：国家重点基础研究发展计划“973”项目(2013CB429701)
【分类号】：P736;P744.4

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