Sprecher
Beschreibung
The extraordinary biodiversity of the Amazon is the product of complex, deep-time interactions between Andean tectonics, climate and biota. The Miocene is a particularly important interval in this history, characterized by ongoing landscape reorganization that gave rise to a western Amazonian mega-wetland (the Pebas system). This system transitioned into the fluvio-lacustrine Acre system and ultimately the modern eastward-flowing Amazon River. Although Andean uplift, drainage reorganization and climate change are recognized as drivers of diversification, interactions between these processes and vegetation dynamics remain poorly constrained.
In this study we present palynological data from the 923m Acre drill core, the first recovered by the Trans-Amazon Drilling Project, and explore how western Amazonian biomes shifted alongside the development of the modern trans-continental river system. Comparison of pollen assemblages in the Acre core to existing regional biostratigraphic zonations suggests the sediments span a younger interval previously unrecorded, of Late Miocene – Pliocene age.
We address three exploratory research questions: (1) What was past vegetation composition and how did biomes shift? (2) Are biome shifts consistent with independent evidence for Late Miocene Andean uplift, climate change and landscape reorganization? (3) How does this record from a site proximal to the Andes compare with basin-wide signals recorded in a distal setting such as the Amazon submarine fan?
The results are intended as a first step towards integrating the Acre core with other regional datasets, highlighting key uncertainties in interpretation and outlining hypotheses for future quantitative testing.