Seismic stratigraphy of the Blue Hole (Lighthouse Reef, Belize), a late Holocene climate and storm archive
Seismic stratigraphy of the Blue Hole (Lighthouse Reef, Belize), a late Holocene climate and storm archive
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DOI：
10.1016/j.margeo.2013.07.013
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发表时间：
2013-10-01
期刊：
影响因子：
2.9
通讯作者：
Shinn, Eugene A.
中科院分区：
文献类型：
--
作者：
Gischler, Eberhard;Anselmetti, Flavio S.;Shinn, Eugene A.
在伯利兹Lighthouse Reef环礁泻湖中的一个120米深的天坑--蓝洞底部，可在约8米厚的全新世沉积物包中识别出5个地震单元。这些单位可能与继承现有的5.85米长的沉积物核心，可追溯到1385 kyrs BP。地震单元的识别是基于这样一个事实，即均匀、细粒的背景沉积物显示弱反射，而交替的背景和粗粒事件（风暴）床在地震剖面中显示强反射。沉积物的主要来源是东部和北部的边缘环礁礁和邻近的泻湖区。东北风和风暴将沉积物带入蓝洞，如沉积物厚度向东增加所示，即，蓝洞向东变浅。以前的假设更厚的全新世沉积物包在蓝洞不能得到证实。到目前为止，从蓝洞取回了近6米长的岩心，但沉积序列的基础仍有待恢复。基底沉积物的性质尚不清楚，但可以预期中全新世和可能更古老的更新世天坑沉积物。在1.385 kyr-long期间，蓝洞（n = 37）中确定的事件床数量和历史数据库中列出的气旋数量表明，只有强飓风（4类和5类）在蓝洞沉积序列中留下了事件床。在13-0.9 kyrs BP和0.8-0.5 kyrs BP期间，风暴床非常多。(C)2013爱思唯尔有限公司版权所有。
Five seismic units may be identified in the similar to 8 m thick Holocene sediment package at the bottom of the Blue Hole, a 120 m deep sinkhole located in the atoll lagoon of Lighthouse Reef, Belize. These units may be correlated with the succession of an existing 5.85-m-long sediment core that reaches back to 1385 kyrs BP. The identification of seismic units is based on the fact that uniform, fine-grained background sediments show weak reflections while alternating background and coarser-grained event (storm) beds exhibit strong reflections in the seismic profiles. The main source of sediments is the marginal atoll reef and adjacent lagoon area to the east and north. Northeasterly winds and storms transport sediment into the Blue Hole, as seen in the eastward increase in sediment thickness, i.e., the eastward shallowing of the Blue Hole. Previous assumptions of much thicker Holocene sediment packages in the Blue Hole could not be confirmed. So far, close to 6-m-long cores were retrieved from the Blue Hole but the base of the sedimentary succession remains to be recovered. The nature of the basal sediments is unknown but mid-Holocene and possibly older, Pleistocene sinkhole deposits can be expected. The number of event beds identified in the Blue Hole (n = 37) during a 1.385 kyr-long period and the number of cyclones listed in historical databases suggest that only strong hurricanes (categories 4 and 5) left event beds in the Blue Hole sedimentary succession. Storm beds are numerous during 13-0.9 kyrs BP and 0.8-0.5 kyrs BP. (C) 2013 Elsevier B.V. All rights reserved.