...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Submersible study of an oceanic megamullion in the central North Atlantic
【24h】

Submersible study of an oceanic megamullion in the central North Atlantic

机译：对北大西洋中部海洋成群的潜水研究

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

Recently discovered megamullions on the seafloor have been interpreted to be the exhumed footwalls of long-lived detachment faults operating near the ends of spreading segments in slow spreading crust. We conducted five submersible dives on one of these features just east of the rift valley in the Mid-Atlantic Ridge at 26 degrees 35'N and obtained visual, rock sample, gravity, and heat flow data along a transect from the breakaway zone (where the fault is interpreted to have first nucleated in similar to2.0-2.2 Ma crust) westward to near the termination (similar to0.7 Ma). Our observations are consistent with the detachment fault hypothesis and show the following features. In the breakaway zone, faulted and steeply backtilted basaltic blocks suggest rotation above a deeper shear zone; the youngest normal faults in this sequence are interpreted to have evolved into the long-lived detachment fault. In younger crust the interpreted detachment surface rises as monotonously flat seafloor in a pair of broad, gently sloping domes that formed simultaneously along isochrons and are now thinly covered by sediment. The detachment surface is locally littered with basaltic debris that may have been clipped from the hanging wall. The domes coincide with a gravity high that continues along isochrons within the spreading segment. Modeling of on-bottom gravity measurements and recovery of serpentinites imply that mantle rises steeply and is exposed within similar to7 km west of the breakaway but that rocks with intermediate densities prevail farther west. Within similar to5 km. of the termination, small volcanic cones appear on the detachment surface, indicating melt input into the footwall. We interpret the megamullion to have developed during a phase of limited magmatism in the spreading segment, with mantle being exhumed by the detachment fault <0.5 m.y. after its initiation. Increasing magmatism may eventually have weakened the lithosphere and facilitated propagation of a rift that terminated slip on the detachment fault progressively between similar to1.3 m.y. and 0.7 m.y. Identifiable but low-amplitude magnetic anomalies over the megamullion indicate that it incorporates a magmatic component. We infer that much of the footwall is composed of variably serpentinized peridotite intruded by plutons and dikes. [References: 52]
机译：最近在海底发现的类金龟属被解释为是长寿命分离断层的发掘出的下盘，它们在缓慢扩散的地壳中靠近扩散段的末端运行。我们在26度35'N大西洋中脊裂谷以东的其中一个特征上进行了五次潜水潜水，并从分离区（其中的地方）沿样线获得了视觉，岩石样本，重力和热流数据断层被解释为首先向西向类似于终止点（类似于0.7 Ma）的方向形成了一个类似于2.0-2.2 Ma地壳的核。我们的观察结果与分离断层假说是一致的，并显示出以下特征。在分离区，断层和陡峭倾斜的玄武岩块提示在更深的剪切带上旋转。该序列中最年轻的正断层被解释为演化为长寿命的分离断层。在年轻的地壳中，解释的分离面在一对等时同步形成的宽阔，缓缓倾斜的穹顶中单调平坦的海底上升，现在被薄薄的沉积物覆盖。分离表面局部散布着玄武碎屑，这些杂物可能已经从吊壁上被剪断了。穹顶与重力高点重合，该重力高点在扩展段内沿等时线连续。对底部重力测量和蛇纹岩的采收率建模表明，地幔陡峭上升，并在分离区以西约7公里的范围内暴露，但中等密度的岩石在西面更占优势。内相距5公里。在终止过程中，小火山锥出现在分离面上，表明熔体输入到底盘中。我们认为该成矿层是在扩展段岩浆作用有限的阶段形成的，地幔是由＜0.5 m.y的脱离断层挖掘出来的。启动之后。岩浆作用的增加可能最终削弱了岩石圈，并促进了裂谷的传播，该裂谷终止于分离断层上的滑动，逐渐在大约1.3 m.y.之间移动。和0.7毫米可识别的但磁振幅低的磁异常表明它包含了岩浆成分。我们推断，大部分底壁是由蛇形和岩脉侵入的蛇形化橄榄岩组成的。 [参考：52]

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