Seismic survey of the Blue Hole, Belize: a pre-study for ICDP-drilling

倡导者的一项核心研究表明，位于伯利兹灯塔礁环礁泻湖125米深的更新世天坑蓝洞底部的沉积物由未受干扰的、每年分层的生物碳酸盐泥和粉砂组成，其中穿插着粗粒度的风暴床。层状剖面的平均沉积速率为2.5 mm/年，我们的6 m长的岩心跨越了过去1400年。层状沉积物的氧同位素提供了一个全新世晚期的气候代用物：一个高分辨率的<s:1> 18O时间序列追踪了中世纪暖期、小冰期和工业温度上升。碳同位素（<s:1> 13C）在岩心上部减小，显示了玛雅文化衰落和人为燃烧化石燃料的影响。风暴事件床在公元650-850年，公元1000年左右，公元1200-1300年和公元1450-1550年最常见。在过去的500年里，风暴床是罕见的。考虑到灯塔礁泻湖的平均沉积速率和全新世早期的海洋淹没，仅蓝洞的全新世海洋沉积记录就可以覆盖约8 kyr。以及每年超过20米的层状沉积物。我们计划在ICDP的框架内对该沉积物包进行取心，因此需要进行地震预研究，以验证晚第四纪沉积物的层状性质和厚度。

A core study of the proponent has revealed that sediments at the bottom of the Blue Hole, a 125 m deep Pleistocene sinkhole located in the lagoon of Lighthouse Reef Atoll, Belize, consist of undisturbed, annually layered biogenic carbonate muds and silts with intercalated coarser grained storm beds. Sedimentation-rate of layered sections is 2.5 mm/yr on average, and our 6 m long core spans the past 1400 yrs. Oxygen isotopes of laminated sediment provide a late Holocene climate proxy: a highresolution 18O time series traces the Medieval Warm Period, the Little Ice Age, and the industrial temperature rise. Carbon isotopes (13C) decrease upcore and show the impacts of the decline of the Maya culture and the anthropogenic combustion of fossil fuel. Storm event beds are most common during AD 650-850, around AD 1000, during AD 1200-1300, and AD 1450-1550. Storm beds are rare during the past 500 years BP. Given the average sedimentation rate and the early Holocene marine inundation of the Lighthouse Reef lagoon, the total Holocene marine sediment record in the Blue Hole alone can be expected to cover about 8 kyrs. and more than 20 m of annually layered sediment. We plan to core this sediment package in the framework of the ICDP, and, therefore, need to perform a seismic pre-study in order to validate the layered nature and thickness of the late Quaternary sediments.