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

在IODP探险期间，372和375沉积物被钻取并采样至白垩纪，包括中新世至全新世的夹层层。这些钻探地点位于太平洋，位于陶波火山带（TVZ）下风约250公里处，陶波火山带是地球上最大和最活跃的硅中心之一，也靠近科罗曼德尔火山带（CVZ），这是一个研究较少的新近纪火山弧。这些中间距离较远的地点的火山遗迹清单提供了近端（<~100公里）陆地和远端（~1000公里）ODP地点之间缺失的联系，从而建立了从中新世早期到最近新西兰爆发火山活动的几乎完整的喷发历史。在之前的提案中提出的三个主要目标中，将研究其喷发产物和相关沉积物的组成，时间和遗传差异。由于疫情影响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，我们在此延迟并建议延长6个月，主要是为了确保博士的工作和论文。在该提案的前24个月，该项目重点研究了新西兰新近纪和第四纪高度爆炸性喷发的火山产物。我们使用地球化学、岩石学和火山学方法对火山和沉积物进行表征，定量和定性地解密它们的物源和喷发序列，从而实现了最初建议的目标1。我们成功地重建了两个弧系统（CVZ和TVZ）在大约13 Myrs的时间跨度内的高爆炸性火山活动的循环历史（目标2的一部分），并将进一步解决有关组成和成因差异和相似性的扩展问题，以及两个系统的复发率和周期性，首次覆盖了新近纪喷发时间序列。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，结合宏观岩相和隐岩相，将能够在扩展中对进入板块的沉积物组成进行时间和数量上的表征，与火山碎屑输入和可能的滑动块相比较。

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.