Trans-Amazon Drilling Project: origin and evolution of the forests, climate, and hydrology of the South American tropics

Abstract

The Amazon Rainforest biome hosts the highest species diversity on Earth and strongly contributes to global climate as a major reservoir of carbon storage. In addition, the Amazon Rain Forest is crucial for atmospheric moisture production and distribution over South America, which supplies surface waters to the world´s largest river system connecting the Andes with the equatorial Atlantic Ocean. The evolution of the Amazonian environments and landscape is the basis of the origin of its species richness, since it determines speciation, extinction and species migration. Thus, the evolution of Amazonian landscapes is a key issue in science to explain the origin of tropical biodiversity and how it responds to long-term climate changes, both past and in the future. Additionally, the Amazon region during the Mesozoic was part of the Central Atlantic Magmatic Province (CAMP), one of Earth's largest magmatic complexes that impacted atmospheric gas composition and may have contributed to the mass extinction at the Triassic/Jurassic boundary. The fundamental questions still enigmatic in current research and addressed by the Trans-Amazon Drilling Project (TADP) are summarized as: (1) how did Cenozoic geologic and climatic history, including uplift of the Andes, development of the Amazon fluvial system, and widening of the Atlantic Ocean, influence the origins of the Amazon rainforest and its incomparable biodiversity?; (2) What was the origin of the Amazonian CAMP diabase sills complex and its impact on the atmospheric gas composition and mass extinction at the Triassic/Jurassic boundary? These questions can only be investigated by drilling on offshore and onshore sites to generate a spatially representative record of the Amazon during the entire Cenozoic, as well as the subsurface diabase sills. The TADP will traverse the entire near-equatorial Amazon region of Brazil, from the Andean foreland to the Atlantic Ocean margin, nearly 10% of the Earth's equatorial circumference. Along this east-west transect, we will continuously sample (1) the complete Cenozoic stratigraphic sequence of Amazonia, comprising between 370 and 2000 m of sediment in the proposed localities; and (2) the complete Mesozoic CAMP diabase sill/host sediment complex that underlies the Cenozoic sequence throughout much of the region. This will be the first time that the Cenozoic sedimentary strata of the Amazon will be continuously drilled, cored, and analyzed for scientific purposes. These new systematic analyses will challenge our understanding of the key period of initiation and expansion of the neotropical rainforest and proto-Amazon drainage. Thus, this research initiative has far-reaching scientific significance across multiple disciplines, addressing essential questions about the geologic, environmental and climatic evolution of the Amazon, the origins and stability of the Amazon rainforest biome and its incomparable biodiversity, the uplift of the Andes and its contribution to environmental changes in lowlands, as well as the causes of the mass extinction at the Triassic/Jurassic boundary. (AU)