As an ecotone, the region between the Amazon Rainforest and Tropical Savanna (Cerrado) biomes is, by definition, more susceptible to climate change. Therefore, understanding palaeoenvironmental dynamics is essential to address the future responses of such transition areas to climatic fluctuations. In this context, we present a new sediment record for the Late-Holocene retrieved from Barro-Preto, currently an oxbow lake located in an ecotone at the southern Brazilian Amazon border. Our multi-proxy data include carbon and nitrogen isotopes, as well as bulk TOC, chlorophyll derivatives, grain-size and microcharcoal analyses, all anchored on a radiocarbon-dated chronology. The sedimentary process recorded at the Barro-Preto Lake responded to both local and regional climate dynamics. It was influenced by river excursions associated to local responses to precipitation changes by the activation of the palaeochannel connecting the main-stem river and the Barro-Preto lake. This activation was evidenced by the presence of different colour lithology laminations accompanied by coarser sediments and also by climate conditions known to influence the Amazon region. Depositional processes linked to lake dynamics and different oxbow lake cycle stages were also important to explain the changes verified in the Barro-Preto record, endorsing the use of this lake formation for palaeoclimatic reconstructions. The record indicated a rising humidity trend, reflected by a progressive increase in lacustrine productivity, in accordance to other studies carried out in the Amazon region concerning the Late-Holocene, associated with a more southward displacement of the Intertropical Convergence Zone. Despite this rising humidity trend, dry episodic events during the Late-Holocene were evidenced by charcoal data, also coherent with regional Amazon studies, albeit exhibiting increased intensity, suggesting that the transitional nature of the environment might have influenced susceptibility to fires.

作为一个生态过渡带，亚马逊雨林和热带稀树草原（塞拉多）生物群落之间的区域，根据定义，更容易受到气候变化的影响。因此，了解古环境动力学对于解决此类过渡地区对气候波动的未来反应至关重要。在这种情况下，我们提出了从 Barro-Preto 取回的晚全新世的新沉积物记录，Barro-Preto 目前是一个位于巴西亚马逊南部边界交错带的牛轭湖。我们的多代理数据包括碳和氮同位素，以及整体 TOC、叶绿素衍生物、粒度和微炭分析，所有这些都以放射性碳年代学为基础。Barro-Preto 湖记录的沉积过程对当地和区域气候动态做出了反应。它受到连接主干河和 Barro-Preto 湖的古河道的激活与当地对降水变化的响应相关的河流漂移的影响。这种激活的证据是不同颜色的岩性层理的存在以及较粗的沉积物，以及已知影响亚马逊地区的气候条件。与湖泊动力学和不同牛轭湖循环阶段相关的沉积过程对于解释 Barro-Preto 记录中验证的变化也很重要，支持将这种湖泊形成用于古气候重建。根据在亚马逊地区进行的关于晚全新世的其他研究，该记录表明湿度呈上升趋势，反映为湖泊生产力的逐步增加，与热带辐合带更向南的位移有关。尽管湿度呈上升趋势，但木炭数据证明了晚全新世期间发生的干燥偶发事件，这也与亚马逊地区的研究一致，尽管强度增加，表明环境的过渡性质可能影响了对火灾的敏感性。