Crustal Magmatic System Beneath the East Pacific Rise (8°20′ to 10°10′N): Implications for Tectonomagmatic Segmentation and Crustal Melt Transport at Fast‐Spreading Ridges
Crustal Magmatic System Beneath the East Pacific Rise (8°20′ to 10°10′N): Implications for Tectonomagmatic Segmentation and Crustal Melt Transport at Fast‐Spreading Ridges
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东太平洋隆起（北纬 8°20′ 至 10°10′N）下方的地壳岩浆系统：对快速扩张脊的构造岩浆分割和地壳熔体输送的影响
DOI：
10.1029/2018gc007590
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发表时间：
2018
期刊：
影响因子：
3.7
通讯作者：
J. Mutter
中科院分区：
文献类型：
--
作者：
M. Marjanović;S. Carbotte;H. Carton;M. Nedimović;J. Canales;J. Mutter
通过对沿着轴地震数据进行二维和三维条带处理，获得了东太平洋海隆（8°20′-10 ° 10 ′N）下中地壳岩浆系统的详细图像，并用于表征轴向地壳的性质、轴间变化以及与轴向带构造分段的关系。轴向岩浆透镜（AML）反射成像在大部分脊轴下方（平均深度1，640 ± 185 m），更深的亚AML（SAML）反射也是如此（最亮的事件在AML下方约100-800 m）。AML中的局部浅区位于海底深度为9°40′-55 MobiN和8°26′-33 MobiN的两个浅区之下。据推测，目前这两个地点下方的岩浆补充量增加，可能与附近的离轴火山链有关。主要在北纬9°20′至10°05′观测到的SAML反射，表明了一个类似于上述AML的精细分段的岩浆储层，由近水平的2至7 km长的AML段组成，通常从一个段到下一个段的反射层深度呈阶梯状变化。我们推断这些熔体与短暂的熔体不稳定区有关。在许多地方，包括地震约束最强的地方，该地区确定的山脊轴（~15-40 km）结构分段与（1）2A层平均厚度的变化一致（2）AML平均深度（<100 m）的变化;（3）上地幔间断低速带的间距变化。在每个较大的结构段内，多个AML段的~6 km的主要长度可能反映了从地壳下汇集的离散熔体储层中上升的岩浆的局部位置的间距。
Detailed images of the midcrustal magmatic system beneath the East Pacific Rise (8°20′–10°10′N) are obtained from 2‐D and 3‐D‐swath processing of along axis seismic data and are used to characterize properties of the axial crust, cross‐axis variations, and relationships with structural segmentation of the axial zone. Axial magma lens (AML) reflections are imaged beneath much of the ridge axis (mean depth 1,640 ± 185 m), as are deeper sub‐AML (SAML) reflections (brightest events ~100–800 m below AML). Local shallow regions in the AML underlie two regions of shallow seafloor depth from 9°40′–55′N and 8°26′–33′N. Enhanced magma replenishment at present beneath both sites is inferred and may be linked to nearby off‐axis volcanic chains. SAML reflections, which are observed primarily from 9°20′ to 10°05′N, indicate a finely segmented magma reservoir similar to the AML above, composed of subhorizontal, 2‐ to 7 km‐long AML segments, often with stepwise changes in reflector depth from one segment to the next. We infer that these melt bodies are related to short‐lived melt instability zones. In many locations including where seismic constraints are strongest the intermediate scale (~15–40 km) structural segmentation of the ridge axis identified in this region coincides with (1) changes in average thickness of layer 2A (by 10%–15%), (2) changes in average depth of AML (<100 m), and (3) with the spacing of punctuated low velocity zones mapped in the uppermost mantle. The ~6 km dominant length of multiple AML segments within each of the larger structural segments may reflect the spacing of local sites of ascending magma from discrete melt reservoirs pooled beneath the crust.
影响因子：
5.8
作者：
Canales, J. Pablo;Dunn, Robert A.;Sohn, Robert A.
通讯作者：
Sohn, Robert A.
影响因子：
18.3
作者：
VanderBeek, Brandon P.;Toomey, Douglas R.;Hooft, Emilie E.;Wilcock, William S.
通讯作者：
Wilcock, William S.