Tephrochronostratigraphy in marine and terrestrial sediments of New Zealand: Benchmark for Miocene to Quaternary explosive volcanism

在IODP考察372和375期间，对白垩纪的沉积物进行了钻探和取样，包括从中新世到全新世的火山灰夹层。钻探地点位于太平洋，陶波火山区（TVZ）顺风约250公里处，陶波火山区是地球上最大和最频繁活动的火山活动中心之一，也靠近科罗曼德尔火山区（CVZ），这是一个很少调查的新第三纪火山弧。这些中间距离站点的火山碎屑清单提供了近端（<~100 km）陆地和非常远端（~1000 km）ODP站点之间缺失的链接，以建立从中新世早期到最近的新西兰爆发性火山活动的几乎完整的喷发历史。在三个主要目标中，在早期的提案中提出，其喷发产物和相关沉积物的成分，时间和遗传差异将被调查。由于流行病的情况阻止了我们在新西兰的实地工作，以协助海洋工作，也影响了我们的实验室工作和分析实验室访问，我们被推迟，并在这里提出延长6个月，基本上是为了确保博士的工作和论文。在本提案的头24个月，该项目的重点是新西兰沿海所有深钻地点新近纪和第四纪期间新西兰高爆炸性喷发的火山产物。我们使用地球化学，岩石学和火山学的方法火山灰和沉积物的特性，定量和定性解密其来源和喷发序列，因此实现了最初的建议的目标1。我们成功地重建了两个弧系统（CVZ和TVZ）在至少1300万年（目标2的一部分）的时间跨度内的高爆炸性火山活动的循环历史，并将在扩展中进一步解决有关成分和遗传差异和相似性的问题，以及两个系统的复发率和周期性，第一次也涵盖了新第三纪喷发时间序列。已经作为目标3的一部分获得的大块岩石沉积物地球化学，连同宏观火山岩和隐火山岩，将使在延伸的时间和定量表征的沉积物成分在传入板的火山岩输入和可能的滑动块。

During IODP Expeditions 372 and 375 sediments have been drilled and sampled down to the Cretaceous including intercalated tephra layers from the Miocene to Holocene. The drill sites are located in the Pacific, ~250 km downwind of the Taupo volcanic Zone (TVZ), one of largest and most frequently active silicic centers on earth, and also close to the Coromandel volcanic zone (CVZ) a sparsely investigated Neogene volcanic arc. The tephra inventories of these intermediate distant sites provide the missing link between the proximal (<~100 km) terrestrial and very distal (~1000 km) ODP sites to establish a nearly complete eruptive history from the early Miocene to recent for New Zealand´s explosive volcanism. Within three major goals, proposed in an earlier proposal, compositional, temporal, and genetic differences of its eruption products and associated sediments will be investigate.Since the pandemic situation prevented us from field work in New Zealand to assist the marine work and also compromised our lab work and analytical lab visits, we are delayed and propose here an extension of 6 month, basically to secure the PhD´s work and thesis. During the first 24 months of this proposal this project focused on the volcanic products from highly explosive eruptions from New Zealand during the Neogene and Quaternary in all deep drilling sites off New Zealand. We used geochemical, petrological and volcanological approaches for tephra and sediment characterization to quantitatively and qualitatively decrypt their provenance and the eruption succession and fulfilled therefore goal 1 of the initial proposal. We successfully reconstructed the cyclic history of highly explosive volcanic activity of both arc systems (CVZ and TVZ) over a time span of about at least 13 Myrs (parts of goal 2) and will further address in the extension questions regarding compositional and genetic differences and similarities, as well as recurrence rates and periodicities in both systems, covering for the first time also a Neogene eruption time series. Bulk rock sediment geochemistry, already acquired as parts of goal 3, in conjunction with macroscopic tephras and cryptotephras will enable in the extension the temporal and quantitative characterization of the sediment composition at the incoming plate in relation to the volcaniclastic input and possible slide masses.