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Regional and global changes during Heinrich Event 1 affecting macrobenthic habitat: Ichnological evidence of sea-bottom conditions at the Galicia Interior Basin
Global and Planetary Change ( IF 3.9 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.gloplacha.2020.103227
Francisco J. Rodríguez-Tovar , Javier Dorador , Anxo Mena , Guillermo Francés

Abstract Heinrich events (HEs) are climatic changes, occurring during the Pleistocene, related to massive discharge of freshwater from the Laurentide Ice Sheet, through the Hudson Strait, recognized in the sedimentary record through distinctive layers of ice-rafted detritus (IRD), the so-called Heinrich layers (HLs). Environmental changes during HEs influence significantly in marine biota (i.e. modifications in composition and abundance of assemblages), with ecological and evolutionary consequences. This point has been only partially addressed in particular groups (e.g. microorganisms), whereas interactions with other groups remain understudied. Here, we analyse ichnological features of the Heinrich layer 1, associated to Heinrich Event 1 (HE1), from several gravity cores at the Galicia Interior Basin (NW Iberian Peninsula) to test the influence of this HE1 on environmental parameters, such as bottom and pore-water oxygenation, as well as benthic food availability, conforming the macrobenthic habitat. Freshwater input during the first phase of the HE1 caused unfavorable conditions (probably highly dysoxic to anoxic) for tracemakers, as revealed by the absence of both discrete traces and a well-developed mottled background. However, the tracemaker community was reestablished shortly after deposition of the ice-rafted detritus layer (Heinrich layer) of HE1, as reflected by the significant increase in diversity and abundance of traces (Planolites, Thalassinoides, Thalassinoides-like, Chondrites, and Zoophycos), revealing a major shift to oxic bottom and pore waters and likely benthic food. This global/general pattern, though, is affected by the regional setting and by the associated predominant sedimentation processes, leading to a variable incidence of paleoenvironmental changes associated with HE1. The ecological impact on macrobenthic biota, in term of changes in diversity and abundance of tracemakers, by HE1 soon attenuates, resulting in a negligible evolutionary impact.

中文翻译:

影响大型底栖生物栖息地的海因里希事件 1 期间的区域和全球变化:加利西亚内陆盆地海底条件的地质学证据

摘要 海因里希事件 (HEs) 是发生在更新世的气候变化,与从劳伦泰德冰盖通过哈德逊海峡大量排放淡水有关,在沉积记录中通过独特的冰筏碎屑 (IRD) 层识别,所谓的海因里希层(HL)。HE期间的环境变化对海洋生物群有显着影响(即组合的组成和丰度的改变),具有生态和进化后果。这一点仅在特定群体(例如微生物)中得到部分解决,而与其他群体的相互作用仍未得到充分研究。在这里,我们分析了与海因里希事件 1 (HE1) 相关的海因里希第 1 层的历史特征,来自加利西亚内陆盆地(伊比利亚半岛西北部)的几个重力核心,以测试此 HE1 对环境参数的影响,例如底部和孔隙水氧化,以及底栖食物可用性,符合大型底栖动物栖息地。HE1 第一阶段的淡水输入对示踪剂造成不利条件(可能是高度缺氧到缺氧),这从不连续的痕迹和发育良好的斑驳背景中可见一斑。然而,在 HE1 的冰筏碎屑层(海因里希层)沉积后不久,示踪者群落就重新建立了,这反映在痕迹的多样性和丰度(Planolites、Thalassinoides、Thalassinoides-like、Condrites 和 Zoophycos)的多样性和丰度上,揭示了向含氧底水和孔隙水以及可能的底栖食物的重大转变。然而,这种全球/一般模式受区域环境和相关主要沉积过程的影响,导致与 HE1 相关的古环境变化发生率不等。HE1 对大型底栖生物群的生态影响(就示踪剂的多样性和丰度的变化而言)很快减弱,导致进化影响可以忽略不计。
更新日期:2020-09-01
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