Eruption Processes Associated with the 2005-06 Volcanic Episode at the East Pacific Rise ISS

智力优点：该项目涉及对从北纬9 46 '和9 56'之间的东太平洋海隆（EPR）获得的数据集进行分析，其中包括：在一个新的火山爆发地点部署了37个TowCam，拥有超过150 000张海底图像、2米/像素的DSL 120 a侧扫声纳和10米/像素的SM 2000测深仪，以及一些Alvin和Jason 2部署，提供近海底观测和样本，所有这些都将在最近爆发的一年内收集。将研究与喷发过程有关的一些问题：2005-06年爆发的规模相对于先前研究的洋中脊爆发事件的估计是多少？据保守估计，2005-06年的初步喷发量（约2200万立方米）是1991-92年该地点喷发量的4至5倍，并将其置于中到超快速扩张的洋中脊上记录的喷发的三分之一。尽管如此，我们只有有限的了解，这是否是一个典型的或大规模的EPR的这一部分的喷发。使用的火山沉积物的平面图模式作为指导，据推测，这次喷发是大的EPR的这一部分，在地方，铺在多代以前的爆发。目前的项目将调查2005-2006年喷发的熔岩输送机制，可用于推断EPR国际空间站的喷发历史。是什么控制了2005-06年火山喷发熔岩的沿着轴和横轴分布？2005-06年熔岩流的边界比以前任何莫尔火山爆发的描述都要复杂得多。据推测，流波瓣的顺序沿着脊轴直接关系到活动裂缝段的位置。一旦熔岩从AST底部的裂缝中喷发出来，穿过顶部高原的流动路径可能受到预先存在的海底地形的控制，特别是熔岩通道，它集中了流动并影响了流动的距离。离轴裂缝喷发如何符合当前关于脊轴的精细尺度分割及其与地壳中熔体的关系的范例？这一最近的EPR火山相的一个独特的方面是熔岩从一系列不连续的裂缝中喷发出来，这些裂缝位于山脊轴以东约600米处的一个狭窄的丘状特征上，该特征在北纬9 52 '-56'之间延伸。裂缝丘与脊轴的四阶不连续性相吻合，位于AST以东第一个重要的向内正断层的内侧。沿该裂隙丘和邻近的EPR轴沿着似乎有~同时代的活动。将绘制一张详细的地图，确定离轴裂缝脊的范围，并将探索模型，以解释断层、离轴裂缝丘、脊轴和轴向岩浆房之间的关系，以实现这一预测，但以前从未观察到的现象。拟议的工作将为理解预示喷发的地震和热液信号提供重要背景，以及正在进行的关于海脊顶部热液和生物过程如何对最近这一喷发事件作出反应的研究。火山喷发沉积物的详细测绘将提供一个基线，这对于解释EPR国际空间站社区正在调查的各种热液、生物、地球化学和地震过程至关重要。这项工作的结果将通过网络服务的地理信息系统数据库广泛提供，该数据库是由PI为N。EPR。该项目将部分支持MIT/WHOI联合项目研究生的博士研究。

Intellectual merit: This project involves the analysis of a dataset acquired from the East Pacific Rise (EPR) between 9 46'N and 9 56'N that will include: 37 TowCam deployments with over 150,000 seafloor images, 2 m/pixel DSL120a sidescan sonar and 10 m/pixel SM2000 bathymetry over the site of a new volcanic eruption, and a number of Alvin and Jason2 deployments that provide near-bottom observations and samples, all of which will have been collected within one year of that recent eruption. A number of questions related to eruption processes will be examined:. What is the size of the 2005-06 eruptions relative to estimates of previously studied mid-ocean ridge eruptive events? The conservatively estimated, preliminary volume of the 2005-06 eruption (~22 million cubic meters) is four to five times greater than that inferred for an eruption at that site in 1991-92, and places it among the upper one-third of documented eruptions on intermediate- to superfast-spreading mid-ocean ridges. Still, we have only a limited understanding of whether this eruption was of a typical or large size for this portion of the EPR. Using the plan-view pattern of volcanic deposits on the crestal plateau as a guide, it is hypothesized that this eruption was large for this portion of the EPR and, in places, paved over multiple generations of previous eruptions. The current project will investigate the mechanisms of lava transport for the 2005-2006 eruptions that can be used to infer eruptive histories for the EPR ISS.. What controls the along- and across-axis distribution of lava of the 2005-06 eruptions? The boundaries of the 2005-06 lava flows are considerably more complex than any previous representations of MOR eruptions. It is hypothesized that the sequence of flow lobes along the ridge axis relate directly to the location of active fissure segments. Once lava is erupted from fissures in the floor of the AST, flow paths across the crestal plateau might have been controlled by pre-existing seafloor topography, especially lava channels, which focused flow and impacted the distance to which the flows traveled.. How does the off-axis fissure eruption fit into current paradigms regarding the fine-scale segmentation of the ridge axis and its relation to melt bodies in the crust? A unique aspect of this most recent EPR volcanic phase is the eruption of lava from a discontinuous series of fissures located ~600 m east of the ridge axis on a narrow mound-like feature that extends between 9 52'-56'N. The fissure mound coincides with a fourth-order discontinuity in the ridge axis, and is located just inboard of the first significant inward facing normal fault east of the AST. It appears that there was ~coeval activity along this fissure mound and the adjacent EPR axis. A detailed map defining the extent of the off-axis fissure ridge will be constructed, and models will be explored to explain the relationship between the fault, off-axis fissure mound, ridge axis, and axial magma chamber for this predicted, but never before observed, phenomenon.Broader impacts: The proposed work will provide a critical context for understanding the seismic and hydrothermal signals that presaged the eruption, and the ongoing examination of how the ridge crest hydrothermal and biological processes respond to this most recent eruptive event. Detailed mapping of the eruption deposits will provide a baseline that will be crucial to interpreting a wide range of hydrothermal, biological, geochemical, and seismic processes being investigated by the EPR ISS community. The results of this work will be made broadly available through web-served GIS database that was created by the PI for the N. EPR. The project will partially support the PhD research of a MIT/WHOI joint program graduate student.