红海与加利福尼亚湾初始扩张系统的热状态差异

Contrasting thermal states of the initial spreading systems between the Red Sea and the Gulf of California

红海与加利福尼亚湾同处于由大陆裂谷向初始海底扩张的过渡阶段,但具有显著不同的构造背景与演化特征。本文基于磁异常数据,利用基于傅里叶变换和小波变换的质心法,计算得到了红海和加利福尼亚湾的居里面深度,对比发现二者热状态存在显著差异,不同方法的计算结果均显示加利福尼亚湾的居里面明显深于红海的居里面。红海扩张中心相对连续,岩浆活动较为活跃,而加利福尼亚湾扩张中心区域广泛发育了错开扩张脊的转换断层,并且扩张中心处热液活动强烈,加速了该区域的热对流和热损耗。此外,扩张速率与热状态和热液活动之间存在着明显的耦合关系。加利福尼亚湾的扩张速率是红海的两倍多,较快的扩张速率与热液活动正相关,较强的热液活动加速热损耗而加深居里面,也是引起加利福尼亚湾居里面比红海居里面深的原因之一。

Although both the Red Sea and the Gulf of California are in the transitional stage from continental rifting to initial seafloor spreading,their tectonic backgrounds and evolutionary features are vastly different.To investigate their geothermal differences,curie-point depths in the Red Sea and the Gulf of California are estimated from magnetic anomalies using the centroid method based on both Fourier and wavelet transform.Our results reveal significant differences in the thermal states between the Red Sea and the Gulf of California.Curie depths in the Gulf of California are evidently deeper than those in the Red Sea.The spreading center of the Red Sea is relatively continuous and has active magmatic activity,whereas the spreading center of the Gulf of California is staggered by extensively developed transform faults and has strong localized hydrothermal activity that accelerates the thermal convection and loss of heat in this region.In addition,the spreading rate is highly coupled with the thermal state and hydrothermal activity in the spreading center.The spreading rate in the Gulf of California more than twice that of the Red Sea,further supporting stronger hydrothermal activity and deeper Curie depths in the Gulf of California than in the Red Sea.