Age of the Socorro Magma Body: Surface Uplift History from River Terrace Correlation and Cosmochronology

Socorro岩浆体是地球上已知的最大的地壳中岩浆体之一：它是一个岩状的特征，面积约3400平方公里，约150米厚，位于新墨西哥州Socorro地区里约热内卢大裂谷中央下约19公里深。Socorro岩浆体使地表隆起，最大速率约为2.5-3毫米/年，其中心位于该岩浆体的北部。19公里深度岩浆膨胀引起的地壳弹性响应引起的地表隆起模型与InSAR干涉图吻合良好。岩浆体的年龄及其相关的地表隆起存在争议。为了解决这一争议，新墨西哥理工大学的研究小组将对阶地残留物进行初步研究，以确定地表隆起的开始年龄。他们将借助数字高程模型绘制阶地残余物的地图，并使用土壤特征（粘土和碳酸盐含量）、地貌特征（表面纹理、沙漠清漆程度、阶地内的位置）、阶地沉积物的沉积学特征（碎屑类型、沉积结构、粒度）和36Cl年龄将它们联系起来。保存完好和未改变的表面将使用36Cl宇宙成因同位素剖面定年。阶地高度的横向变化和垂直阶地间距的变化，反过来，将允许识别那些受索科罗岩浆体膨胀影响或未受影响的阶地。阶地年龄将限定Socorro岩浆体相关隆升的开始，并限制隆升和岩浆体膨胀的长期速率。索科罗岩浆体是地球上已知的最大的地壳中岩浆体之一。平地和InSAR研究表明，岩浆体以大约2.5 mm/年的速度引起地表隆起（在隆起最快的中心区）。索科罗地震异常位于岩浆体之上，是新墨西哥州上地壳地震活动性最高的地区。微震活动可能是由索科罗岩浆体上方的变形和上升的含水流体引发的。该项目旨在限制Socorro岩浆体的年龄，这与了解地壳流变学、脆性-韧性转变的演化、地壳在裂谷中的生长、裂谷过程中的岩浆成因、裂谷过程中的应力演化以及火山危险性有关。

The Socorro magma body is one of the largest known midcrustal magma bodies on Earth: it is a sill-like feature, about 3,400 square kilometers in area, about 150 meters thick, and lies at about 19 km depth under the central Rio Grande rift in the Socorro, New Mexico area The Socorro magma body causes surface uplift with a maximum rate of about 2.5-3 mm/yr centered over the northern part of the body. Models of surface uplift due to an elastic crustal response to magmatic inflation at 19 km depth agree well with InSAR interferograms. The age of the magma body and its related surface uplift are controversial. In order to resolve this controversy, the New Mexico Tech research team will carry out a pilot study of terrace remnants to determine the age of onset of surface uplift. They will map the terrace remnants with the aid of Digital Elevation Models and correlate them using soil characteristics (clay and carbonate content), geomorphic characteristics (surface textures, degree of desert varnish, location within flights of terraces), sedimentological characteristics of terrace deposits (clast types, sedimentary structures, grain size), and 36Cl ages. Well-preserved and unaltered surfaces will be dated using 36Cl cosmogenic isotope profile dating. Lateral changes in terrace elevations and vertical terrace spacing will, in turn, allow identification of those terraces affected or unaffected by Socorro magma body inflation. Terrace ages will bracket onset of Socorro magma body -related uplift and constrain long-term rates of uplift and magma-body inflation.The Socorro magma body is one of the largest known midcrustal magma bodies on Earth. Leveling and InSAR studies indicate that the magma body is causing surface uplift at rates of about 2.5 mm/yr (in the central zone of fastest uplift). The Socorro Seismic Anomaly has the highest rate of upper crustal seismicity in New Mexico and lies above the magma body. Microseismicity presumably is triggered by deformation and ascending hydrous fluids above the Socorro magma body. This project seeks to constrain the age of the Socorro magma body, which is relevant to understanding crustal rheology, evolution of the brittle-ductile transition, crustal growth in rifts, magma genesis during rifting, stress evolution during rifting, and volcanic hazard.