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Late Neogene evolution of the Peruvian margin and its ecosystems: a synthesis from the Sacaco record
International Journal of Earth Sciences ( IF 1.8 ) Pub Date : 2021-03-09 , DOI: 10.1007/s00531-021-02003-1
Diana Ochoa , Rodolfo Salas-Gismondi , Thomas J. DeVries , Patrice Baby , Christian de Muizon , Alí Altamirano , Angel Barbosa-Espitia , David A. Foster , Kelly Quispe , Jorge Cardich , Dimitri Gutiérrez , Alexander Perez , Juan Valqui , Mario Urbina , Matthieu Carré

The highly productive waters of the Humboldt Current System (HCS) host a particular temperate ecosystem within the tropics, whose history is still largely unknown. The Pisco Formation, deposited during Mio-Pliocene times in the Peruvian continental margin has yielded an outstanding collection of coastal-marine fossils, providing an opportunity to understand the genesis of the HCS ecosystem. We present a comprehensive review, completed with new results, that integrates geological and paleontological data from the last 10 My, especially focusing on the southern East Pisco Basin (Sacaco area). We discuss the depositional settings of the Pisco Formation and integrate new U/Pb radiometric ages into the chronostratigraphic framework of the Sacaco sub-basin. The last preserved Pisco sediments at Sacaco were deposited ~ 4.5 Ma, while the overlying Caracoles Formation accumulated from ~ 2.7 Ma onwards. We identified a Pliocene angular unconformity encompassing 1.7 My between these formations, associated with a regional phase of uplift. Local and regional paleoenvironmental indicators suggest that shallow settings influenced by the offshore upwelling of ventilated and warm waters prevailed until the early Pliocene. We present an extensive synthesis of the late Miocene–Pleistocene vertebrate fossil record, which allows for an ecological characterization of the coastal-marine communities, an assessment of biodiversity trends, and changes in coastal-marine lineages in relation to modern HCS faunas. Our synthesis shows that: (i) typical endemic coastal Pisco vertebrates persisted up to ~ 4.5 Ma, (ii) first modern HCS toothed cetaceans appear at ~ 7–6 Ma, coinciding with a decline in genus diversity, and (iii) a vertebrate community closer to the current HCS was only reached after 2.7 Ma. The genesis of the Peruvian coastal ecosystem seems to be driven by a combination of stepwise transformations of the coastal geomorphology related to local tectonic pulses and by a global cooling trend leading to the modern oceanic circulation system.



中文翻译:

秘鲁边缘及其生态系统的新近晚期晚期演化:Sacaco记录的综合

洪堡洋流系统(HCS)的高产水域在热带地区拥有一个特定的温带生态系统,其历史仍然未知。秘鲁海岸边缘的上新世时期沉积的皮斯科组形成了大量沿海海洋化石,为了解HCS生态系统的成因提供了机会。我们提供了一个全面的综述,并以新的结果完成了该综述,其中整合了最近10 My的地质和古生物学数据,尤其是对南部东皮斯科盆地(萨卡科地区)的关注。我们讨论了皮斯科组的沉积环境,并将新的U / Pb辐射年龄整合到Sacaco盆地的年代地层学框架中。萨卡科(Sacaco)最后保存的皮斯科(Pisco)沉积物沉积至约4.5 Ma,而上层的Caracoles地层则是从〜2.7 Ma开始累积的。我们确定了这些地层之间的上新世角不整合度为1.7 My,这与隆起的区域性阶段有关。局部和区域古环境指标表明,受通风和温水的海上上升影响的浅层环境一直盛行到上新世早期。我们介绍了中新世至更新世脊椎动物化石记录的广泛综合,其可以对沿海海洋群落进行生态表征,评估生物多样性趋势以及与现代HCS动物群相关的沿海海洋世系的变化。我们的综合表明:(i)典型的地方性皮斯科沿海脊椎动物持续到〜4.5 Ma,(ii)最早的现代HCS齿鲸类鲸科动物出现在〜7-6 Ma,与此相符的是,该物种的多样性下降,并且(iii)仅在2.7 Ma之后才形成了一个与当前HCS较近的脊椎动物群落。秘鲁沿海生态系统的起源似乎是由与局部构造脉冲有关的沿海地貌的逐步转变和导致现代海洋环流系统的全球冷却趋势共同驱动的。

更新日期:2021-03-10
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