Abstract

In western Amazonia, palynology has been the main source of chronological information for the Neogene Period. The Solimões Formation in northwestern Brazil has hundreds of meters of fine-grained rocks that have yielded rich pollen records informing on age and paleoenvironments. Here, we present new pollen data for two boreholes (1-AS-33-AM and 1-AS-37-AM) in the Solimões Basin and one outcrop (Patos) in the Acre Basin, and describe 36 new taxa (two pteridophyte spores and 34 angiosperm pollen) plus one emendation. Palynostratigraphic zonation schemes from Venezuela and Colombia were analyzed critically to provide relative ages for our sections. We found core 33AM to span pollen zones T14 (∼16–14.2 Ma), T15 (14.2–12.7 Ma) and T16 (12.7–7.1 Ma) sensu Jaramillo et al. (2011), while core 37AM spans zones T15? and T16. We also report the widespread occurrence of Cyatheacidites annulatus in outcrops of the Solimões Formation, implying the existence of latest Miocene (∼7 Ma) to Pliocene sedimentation and suggesting ages older than ∼7 Ma for the uppermost sediments of our boreholes. Biostratigraphic relationships also indicate that Echitricolporites mcneillyi and Ladakhipollenites? caribbiensis cannot be used as Pliocene markers as previously assigned. The implications of these results for the palynostratigraphy and paleoenvironmental reconstructions of western Amazonia are discussed.

摘要

在亚马孙州西部，古生物学一直是新近纪时期的年代学信息的主要来源。巴西西北部的Solimões组具有数百米的细粒岩石，这些岩石产生了丰富的花粉记录，可提供有关年龄和古环境的信息。在这里，我们介绍了Solimões盆地中的两个钻孔（1-AS-33-AM和1-AS-37-AM）和Acre盆地中的一个露头（Patos）的新花粉数据，并描述了36个新的类群（两个蕨类植物）孢子和34个被子植物花粉），再加上一项修订。对委内瑞拉和哥伦比亚的古地层划分方案进行了严格分析，以提供我们剖面的相对年龄。我们发现核心33AM至跨度花粉区T14（~16-14.2马），T15（14.2-12.7 MA）和T16（12.7-7.1 Ma）的意义上Jaramillo等。（2011年），而核心37AM跨越T15区？和T16。我们还报道了Solimões组露头中广泛存在的Cyatheacidites annulatus，这意味着上新世沉积存在最新的中新世（约7 Ma），并且表明我们井眼最高沉积物的年龄大于约7 Ma。生物地层关系还表明，棘轮虫纲mcneillyi和Ladakhipollenites？caribbiensis不能用作先前指定的上新世标记。讨论了这些结果对西亚马逊地区古地理地层和古环境重建的影响。