• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Marine Geology >Distribution of methane hydrate BSRs and its implication for the prism growth in the Nankai Trough
【24h】

Distribution of methane hydrate BSRs and its implication for the prism growth in the Nankai Trough

机译：甲烷水合物BSR的分布及其对南开海槽三棱柱生长的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Detailed mapping of a bottom simulating reflector (BSR), which marks the phase transition from the methane hydrate layer above the reflector to free gas below, was conducted in the Nankai accretionary prism off Shikoku and Tokai. BSRs are widely distributed in the prism slope from the toe region to the forearc basin. BSR positions provide us with the regional heat flow variations using pressure-temperature conditions for methane hydrate stability. Estimated heat flows generally show constant values about 50 mW/m~2 shallower than the middle slope of the prism, and gradually increase seaward in the lower prism slope. Occurrences of BSRs are regarded as accumulation of free gas beneath the base of a gas hydrate stability field (BGHS) and/or concentration of methane hydrate above the BGHS. These conditions can be accomplished by updip migration of methane gas because it is unlikely that such methane concentration is completed by in situ biogenic methanogenesis within sediments including low total organic carbon. Moreover, sedimentation, uplifting, and sediment stacking by thrust faulting cause upward migration of the BGHS and migration of methane from the dissociated hydrate to new BGHS. Such recycling of methane gas may have actively occurred in accretionary prisms. In contrast, there are five regions of no BSRs: the Nankai Trough floor, prism toe, slope basin, steep slope, and deep-sea canyon. The trough floor, the prism toe and the slope basin are characterized by young sediments with low production of methane gas and sub-horizontal strata unsuitable for migration of gases and fluids. Erosion at the steep slope and the canyon causes removal of hydrated sediments and downward movement of the BGHS. BSR distribution and thermal structure estimated from BSR positions offer information about active processes occurring in accretionary prisms.
机译：在四国和东海附近的南海增生棱镜中，对底部模拟反射器（BSR）进行了详细的映射，以标记从反射器上方的甲烷水合物层到下方的游离气体的相变。 BSR广泛分布在从脚趾区域到前臂盆地的棱柱坡度中。 BSR位置使用压力温度条件为我们提供了甲烷水合物稳定性的区域热流量变化。估计的热流通常显示出比棱镜的中坡浅约50 mW / m〜2的恒定值，并在棱镜的下坡逐渐向海增加。 BSR的发生被认为是天然气水合物稳定性场（BGHS）下方游离气体的积累和/或BGHS上方甲烷水合物的浓度。这些条件可以通过向上迁移甲烷气体来实现，因为这样的甲烷浓度不可能通过包括低总有机碳在内的沉积物中的原位生物成甲烷作用来完成。此外，由于逆冲断层的沉积，隆升和沉积物堆积导致BGHS向上迁移以及甲烷从解离的水合物向新的BGHS迁移。甲烷气体的这种再循环可能已经在增生棱镜中积极发生。相比之下，有五个没有BSR的区域：南海槽底，棱形趾，斜坡盆地，陡坡和深海峡谷。槽底，棱形趾和斜坡盆地的特征是年轻的沉积物，甲烷气体的产生量低，并且水平地层不适合气体和流体的运移。陡坡和峡谷的侵蚀导致水合沉积物的去除和BGHS的向下运动。从BSR位置估算的BSR分布和热结构可提供有关在增生棱镜中发生的活动过程的信息。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号