Traces of explosive eruptions in Cretaceous to Quaternary Indian Ocean sediments.

在IODP探险期间，已经钻探和采样了具有间隔层的层状沉积物，一直延伸到坎帕尼亚。钻探地点位于印度洋巽他弧火山锋以西约800公里处。巡航的目的是确定引起发震滑动的物质特性，并重建和了解印度季风环流的变化。在这个项目中，我们的目标是通过将不同地点之间广泛存在的温层与陆地喷发相关联，为整个地区建立一个海洋温层框架。因此，我们将把探险的麻风记录与ODP以前在整个印度洋钻探的海洋麻风层结合起来，特别是在尼尼特酵母脊。将利用地球化学、岩石学和火山学方法对火山泥和沉积物进行表征，定量和定性地解密其物源和喷发演替。此外，我们将执行绝对年龄定年，以改进和确认现有的年龄模型。需要稳健的年龄模型来研究巽他弧或迄今未知火山源的大火山喷发过程、震级和频率的时空变化。该研究将有助于进一步了解该地区不同火山体系的时间演化，建立该地区爆发火山活动的长时间序列。在我们的记录中，我们将确定大型的，已知的，但也是以前未知的喷发，这将使我们能够研究苏门答腊弧更新世火山中心各自的复发率，并详细说明tephra记录中的周期性。最后，我们还将研究尼科巴扇中新世至更新世的沉积记录，以发现潜在的火山作用增强事件或隐藏在背景沉积中的单一事件。特别是确定沉积物中火山物质的数量和特征，对于表征物质及其在发震和发海啸的苏门答腊辐合边缘俯冲时的作用非常重要。

During IODP Expeditions sediments with intercalated tephra layers have been drilled and sampled that reach down to the Campanian. The drill sites are located ~800 km west of the volcanic front of the Sunda arc in the Indian Ocean. The objectives of the cruises were to determine the material properties causing the seismogenic slip and to reconstruct and understand changes in Indian monsoon circulation. In this project we aim to establish a marine tephrostratigraphic framework for the entire region by correlating widespread tephra layers between the different sites and if possible, to terrestrial eruptions. Therefore we will combine the tephra records of Expeditions with marine tephra layers from previous ODP drillings from the whole Indian Ocean, and on the Ninetyeast Ridge in particular. Geochemical, petrological and volcanological approaches for tephra and sediment characterization will be used to quantitatively and qualitatively decrypt their provenance and the eruption succession. Additionally, we will perform absolute age dating to improve and confirm the existing age models. Robust age models are needed to study the temporal and spatial changes in eruption processes, magnitudes and frequencies of large volcanic eruptions from the Sunda arc, or so far unknown volcanic sources.This study will help to learn more about the temporal evolution of different volcanic systems and establish long time series of explosive volcanism in this region. Within our record we will identify large, known, but also previously unknown, eruptions, which will enable us to study the respective recurrence rates from Pleistocene volcanic centres of the Sumatran arc and to elaborate on cyclicities in the tephra record. Finally, we will also study the Miocene to Pleistocene sediment record of the Nicobar Fan to detect potential episodes of enhanced volcanism or single events hidden in the background sedimentation. Especially the determination of the amount and character of volcanic matter that is incorporated in the sediments is important to characterize the material and how it acts, when it is subducted at the seismogenic and tsunamogenic Sumatran convergent margin.