Timing, Rates and History of Post-YTT (<74ka) Resurgent Uplift of Samosir Island, Toba, Sumatra

像苏门答腊岛的多巴火山这样的大火山口是地球上最具破坏性的自然事件——超级火山爆发的发生地。由于超级火山有可能造成区域破坏和全球灾难，了解这些超级火山的过程和时间尺度对于能够应对潜在的危险至关重要。虽然气候爆发是主要事件，但这些只是打断长期相对平静的例子。正是在这些“复苏”时期，超级火山在下一次喷发周期之前恢复和调整。关于超级火山在气候前后活动的关键信息在这一时期被编码，然而，尽管经过几十年的研究，人们对它的复活仍然知之甚少。这是令人担忧的，因为今天大多数危险的火山口都处于复活阶段。这个项目的目标是通过对苏门答腊岛上最近的超级火山多巴火山口的案例研究，了解大型火山口复活的时间尺度、速率、持续时间和机制。自从公元74年2500 km^3的岩浆作为年轻的多巴凝灰岩（YTT）的高潮喷发以来，有证据表明多巴火山口内发生了几次小喷发，火山口底部垂直隆起超过1 km，形成了Samosir岛。我们将通过地层对比和年龄定年来揭示火山喷发的时空格局以及隆升的速度和动力，从而解决火山高潮喷发后留下的残余岩浆是这次复兴的来源这一假设。YTT后的熔岩将使用锆石中的U-系列和(U/Th)/He年龄测定来确定喷发年龄；Samosir的隆升速度和持续时间将使用C-14年龄测年和时间控制相结合的方法进行研究，并利用Samosir上隆升的湖泊沉积物的古地磁特性进行地层对比。多巴火山相对年轻是大型火山口中一个独特的优势，预计该项目将揭示大型火山口及其岩浆系统的后气候历史和寿命的前所未有的细节，这些细节可以用来提供比目前可用的更复杂的火山口力学数值模型。此外，解决该地区地磁场先前难以解决的方面的偶然机会将吸引对多巴和这项工作的进一步关注。研究生将在国际合作框架内与美国、德国、澳大利亚和印度尼西亚的同事一起接受现代火山口科学和相关地质年代学的跨学科培训。所进行的科学研究将进一步推动在多巴建立联合国教科文组织地质公园的努力。

Large calderas like Toba, Sumatra are the sites of the most devastating natural events on Earth, supereruptions. With their potential to cause regional devastation and global disaster, understanding the processes and timescales of these supervolcanoes is crucial to being able to address potential hazards. While the climactic eruptions are the main event, these are just instances that punctuate long periods of relative calm. It is during these "resurgent" periods that supervolcanoes recover and readjust before the next eruption cycle. Critical information about the pre- and post-climactic activity of a supervolcano is encoded during this period, yet despite decades of research, resurgence remains poorly understood. This is of concern because most hazardous calderas today are in a resurgent stage. The goal of this project is to understand the timescale, rates, duration, and mechanisms that occur at large resurgent calderas through a case study of the Toba caldera, Sumatra, the Earth's most recent supervolcano.Since the climactic eruption of 2500 km^3 of magma 74 ka as the Young Toba Tuff (YTT), there is evidence of several small eruptions within the Toba caldera as well over 1 km of vertical uplift of the caldera floor to form the island of Samosir. The hypothesis that remnant magma left after the climactic eruption was the source of this resurgence will be addressed through a program of stratigraphic correlation and age dating to reveal the spatiotemporal pattern of eruptions and the rate and motivating force for the uplift. Post YTT lavas are to be dated using coupled U-series and (U/Th)/He age determinations in zircon to resolve eruption ages and the rate and duration of uplift of Samosir are to be investigated using a combination of C-14 age dating and time control through stratigraphic correlation using paleomagnetic properties of uplifted lake sediments on Samosir. Toba's relative youth is a unique advantage among large calderas and it is anticipated that this project will reveal unprecedented details of the post-climatic history and longevity of a large caldera and its magmatic system that can be used to inform more sophisticated numerical models of caldera mechanics than currently available. Furthermore, the serendipitous opportunity to address previously recalcitrant aspects of the region's geomagnetic field will attract further attention to Toba and this work. Graduate students will receive interdisciplinary training in modern caldera science and associated geochronology within an international collaborative framework with colleagues in USA, Germany, Australia, and Indonesia. The science conducted will give further impetus to efforts to develop a UNESCO Geopark at Toba.