Orbital and sea-level controls on long-term sediment deposition in the Amazon Fan

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change Pub Date : 2025-09-11 DOI:10.1016/j.gloplacha.2025.105068

Gabriel R. Moizinho , Thiago P. Santos , Germain Bayon , Martin Roddaz , Natalia Vázquez Riveiros , Marina Rabineau , Daniel Aslanian , Victor Carreira , Elton L. Dantas , Roberto V. Santos

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引用次数: 0

Abstract

The Amazon Fan, one of the largest deep-sea fans on Earth, is a vital archive of the Amazon Basin's long-term climate and tectonic evolution. However, the factors driving sediment deposition patterns during the Neogene remain poorly understood. Here, we present an astronomical age model for a 4800 m-long sedimentary record (BP-3 well), spanning the past ∼24 million years, a key interval encompassing the Amazon River's evolution into a transcontinental system. Gamma-ray (GR) data reveal strong Milankovitch cyclicity, highlighting the fan's sensitivity to orbital climate variability and enabling correlations with global mean sea level (GMSL). Our analysis shows persistently low sedimentation rates (∼5–13 cm/kyr) during the late Miocene, despite Andean uplift and increased precipitation, likely due to sediment trapping by mega-wetlands in Western Amazonia. A marked increase in sedimentation (∼50 cm/kyr) during the Early Pliocene (5.1–4.8 ± 1.78 Ma) reflects the collapse of these barriers, facilitating sediment transport to the Atlantic despite high GMSL. The GR record also captures the transition from obliquity- to eccentricity-dominated glacial-interglacial cycles during the mid-Pleistocene Transition (∼1.3 Ma). These findings align with GMSL and benthic δ¹⁸O data, supporting a minimal tuning approach and emphasizing the Amazon Fan's sensitivity to global climate changes. Our revised chronology provides a robust framework for understanding the Neogene evolution of the Amazon River and its links to Andean tectonics and climate variability.

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轨道和海平面对亚马逊扇长期沉积物沉积的控制

亚马逊扇是地球上最大的深海扇之一，是亚马逊盆地长期气候和构造演化的重要档案。然而，新近纪沉积模式的驱动因素仍然知之甚少。在这里，我们提出了一个4800米长的沉积记录（BP-3井）的天文年龄模型，跨越了过去~ 2400万年，这是一个涵盖亚马逊河演变为横贯大陆系统的关键区间。伽马射线（GR）数据显示了强烈的米兰科维奇旋回性，突出了扇子对轨道气候变率的敏感性，并使其与全球平均海平面（GMSL）具有相关性。我们的分析表明，在中新世晚期，尽管安第斯山脉隆起和降水增加，但沉积速率持续较低（~ 5-13 cm/kyr），这可能是由于西亚马逊流域的大型湿地捕获沉积物所致。在上新世早期（5.1-4.8±1.78 Ma），沉积显著增加（~ 50 cm/kyr），反映了这些屏障的崩塌，促进了沉积物向大西洋的运输，尽管GMSL很高。GR记录还记录了中更新世过渡时期（~ 1.3 Ma）从斜向主导的冰期-间冰期旋回到偏心率主导的冰期旋回的转变。这些发现与GMSL和底栖生物δ18O数据一致，支持最小调整方法，并强调了亚马逊扇对全球气候变化的敏感性。我们修订的年代学为理解亚马逊河的新近纪演化及其与安第斯构造和气候变化的联系提供了一个强有力的框架。

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来源期刊

Global and Planetary Change 地学天文-地球科学综合

CiteScore

7.40

自引率

10.30%

发文量

226

审稿时长

63 days

期刊介绍： The objective of the journal Global and Planetary Change is to provide a multi-disciplinary overview of the processes taking place in the Earth System and involved in planetary change over time. The journal focuses on records of the past and current state of the earth system, and future scenarios , and their link to global environmental change. Regional or process-oriented studies are welcome if they discuss global implications. Topics include, but are not limited to, changes in the dynamics and composition of the atmosphere, oceans and cryosphere, as well as climate change, sea level variation, observations/modelling of Earth processes from deep to (near-)surface and their coupling, global ecology, biogeography and the resilience/thresholds in ecosystems. Key criteria for the consideration of manuscripts are (a) the relevance for the global scientific community and/or (b) the wider implications for global scale problems, preferably combined with (c) having a significance beyond a single discipline. A clear focus on key processes associated with planetary scale change is strongly encouraged. Manuscripts can be submitted as either research contributions or as a review article. Every effort should be made towards the presentation of research outcomes in an understandable way for a broad readership.