Testing the Slab Connection: A Beryllium Isotope Tracer Study in the Trans-Mexican Volcanic Belt

“会聚板块边缘”是固体地球地球化学循环的主要界面，对宜居地球的形成和维持至关重要。在会聚的板块边缘，一个千米厚的岩石圈板块被拉到或俯冲到另一个岩石圈板块之下，该板块由地壳和最上面的地幔组成。在大约80-140公里深的地方，俯冲板块释放出富含挥发分的物质，并通过高度爆炸性的富含挥发分的火山作用将其回收回地球表面，形成成弧形排列的火山链。在人类的时间尺度上，这种单弧火山的喷发造成了致命的气候扰动(例如1815年的坦博拉)和海啸(例如1883年的喀拉喀托)。因此，了解弧火山作用如何与板材的物质转移有关仍然是地球科学研究的核心。在这类研究中，宇宙成因的同位素10Be发挥了关键作用，因为它是一种独特的地球化学示踪剂，可以明确地识别从板条材料中回收的材料。除了这项工作的重要科学影响外，这项工作还通过促进美国和墨西哥之间的国际合作来影响社会，它还支持哥伦比亚大学的学生。该项目的结果也将被纳入课程课程。最近的分析进展大大提高了弧形火山岩中10Be的探测下限，现在允许整合来自汇聚边缘的关键火山岩系列，这是以前无法研究的。在这个项目中，10Be示踪剂将通过一项在外墨西哥火山带(TMVB)的研究来进一步探索和测试。TMVB是一个主要的汇聚边缘，它以历史性的喷发而闻名，这些喷发产生了异常广泛的火山岩，具有密切的时空联系。虽然以前的地球化学研究表明，这些火山岩与板坯的物质回收有直接关系，但物质转移的关键细节(如何？多少钱？有多快？)仍然存在争议。将对中部(波波卡特佩特火山及其周围)和西部(科利马火山及其周围)的一组经过充分研究的样本进行10Be分析，以检验目前的俯冲再循环假说。总体而言，该项目将对板块俯冲和弧火山作用之间的连通性及其在调节宜居地球的长期演化和维护方面的作用提供新的限制。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

'Convergent plate margins' are major interfaces of the solid Earth geochemical cycle that are fundamental to the formation and maintenance of habitable Earth. At convergent plate margins, a kilometer-thick lithospheric plate consisting of the Earth's crust and uppermost mantle is drawn - or subducted - beneath another lithospheric plate. At around 80-140 kilometers depth, the subducted plate releases volatile-rich material and 'recycles' it back to the Earth's surface via highly explosive, volatile-rich volcanism that forms chains of volcanoes aligned in arcs. On human time scales, eruptions of such single arc volcanoes have caused deadly climate perturbations (e.g. Tambora in 1815) and tsunamis (e.g. Krakatoa in 1883). Hence, understanding how arc volcanism is related to the material transfer from slab remains at the core of geoscience research. In such studies, the cosmogenic isotope 10Be, plays a pivotal role, because it is a unique, geochemical tracer that unambiguously identifies material recycled from slab material. In addition to the important scientific impact of this work, this work impacts society by fostering international collaboration between the U.S. and Mexico, and it also supports students at Columbia. Results from this project will also be incorporated into course curricula.Recent analytical advances have much improved the detection limit of 10Be in arc volcanic rocks, now allowing for integrating critical volcanic rock series from convergent margins that could not be studied previously. In this project, the 10Be tracer will be further explored and tested through a study in the Transmexican Volcanic Belt (TMVB). The TMVB is a major convergent margin which is well-known for historic eruptions that produced an unusually broad spectrum of volcanic rocks in close temporal and spatial association. While previous geochemical studies showed that these volcanic rocks have direct bearing on the material recycling from slab, crucial details of material transfer (how? how much? how fast?) remain contested. A selected set of well-studied samples from the central (Popocatepetl volcano and surrounding) and western (Colima volcano and surrounding) TMVB will be analysed for 10Be in order to test current hypotheses of subduction recycling. Overall, the project will provide new constraints on the connectivity between slab subduction and arc volcanism and its role in regulating the longterm evolution and maintenance of habitable Earth.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.