Synchronisation of sedimentary records using tephra: A postglacial tephrochronological model for the Chilean Lake District
Synchronisation of sedimentary records using tephra: A postglacial tephrochronological model for the Chilean Lake District
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DOI：
10.1016/j.quascirev.2016.02.015
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发表时间：
2016-04-01
影响因子：
4
通讯作者：
Moreno, Hugo
中科院分区：
文献类型：
--
作者：
Fontijn, Karen;Rawson, Harriet;Moreno, Hugo
在各种沉积环境中沉积的特征良好的Tephra层位提供了一种同步沉积档案的手段。然而，在智利南部和阿根廷，使用非洲茶作为年表工具的情况仍然普遍未得到充分利用。在这项研究中，我们通过整合陆地和湖泊的记录，建立了智利湖区(约38-42度S)的冰后年代学模型。保存在湖泊沉积物中的特弗拉沉积记录了离散事件，即使它们与原始尘埃不对应。结合陆相和湖相记录，我们获得了该地区迄今为止最完整的古地层学记录。我们提供了关键标志层的玻璃地球化学和年代学数据，可用于同步用于古环境、古气候学和古地震学目的的沉积档案。在拉伊马和卡尔布科之间的南部火山带研究区段的大多数火山至少产生了一次大爆发(4级)造成的区域标志矿床，其中一些火山的年龄估计现在有了显著提高(例如，拉伊马火山10.5ka拉伊马浮岩喷发)。其他的，包括来自普耶霍-科登·考勒的几个单位，在这里被新描述。我们还在距源头以北400公里的湖泊沉积物中发现了与柴腾火山Cha1喷发有关的Tephra。现在确定了几个清晰的标志层，这应该有助于完善各种沉积档案的年龄模型重建。我们的年代学模型表明，影响该地区的喷发活动有三个不同的阶段，早期到中期是一个相对平静的时期。将我们的年代学框架进一步向南延伸到巴塔哥尼亚，将使我们能够更详细地评估对整个冰后期爆炸性喷发的发生和规模的控制。(C)2016年提交人。由爱思唯尔有限公司出版。这是一篇在CC by License(http://creativecommons.org/licenses/by/4.0/).下的开放获取文章
Well-characterised tephra horizons deposited in various sedimentary environments provide a means of synchronising sedimentary archives. The use of tephra as a chronological tool is however still widely underutilised in southern Chile and Argentina. In this study we develop a postglacial tephrochronological model for the Chilean Lake District (ca. 38 to 42 degrees S) by integrating terrestrial and lacustrine records. Tephra deposits preserved in lake sediments record discrete events even if they do not correspond to primary fallout. By combining terrestrial with lacustrine records we obtain the most complete tephrostratigraphic record for the area to date. We present glass geochemical and chronological data for key marker horizons that may be used to synchronise sedimentary archives used for palaeoenvironmental, palaeoclimatological and palaeoseismological purposes. Most volcanoes in the studied segment of the Southern Volcanic Zone, between Llaima and Calbuco, have produced at least one regional marker deposit resulting from a large explosive eruption (magnitude >= 4), some of which now have a significantly improved age estimate (e.g., the 10.5 ka Llaima Pumice eruption from Llaima volcano). Others, including several units from Puyehue-Cordon Caulle, are newly described here. We also find tephra related to the Cha1 eruption from Chaiten volcano in lake sediments up to 400 km north from source. Several clear marker horizons are now identified that should help refine age model reconstructions for various sedimentary archives. Our chronological model suggests three distinct phases of eruptive activity impacting the area, with an early-to-mid-Holocene period of relative quiescence. Extending our tephrochronological framework further south into Patagonia will allow a more detailed evaluation of the controls on the occurrence and magnitude of explosive eruptions throughout the postglacial. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).