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<p>Results from two geographical study areas are presented in this dissertation, contributing
important new information about the Cenozoic geological, environmental and biological
regime. At the first locality along the Manu River (11.90°S, 71.34°W) I present a
revised age and reinterpret the depositional environment. Age determination consisted
of radiometrically dating detrital zircons, pushing the technical boundaries of this
technique, paired with radiocarbon analyses of depositional organic material. Constraining
the depositional environment relied on geochemical and sedimentological analyses.
The revised age, 0.13±0.04 Ma instead of ~9 Ma, and depositional environment, as a
fluvial overbank deposit instead of estuarine or marginal-marine deltaic deposits,
have major implications for research previously published on the outcrop. </p><p>A
second section is realized along the Alto Madre de Dios river and is situated in a
piggyback basin belonging to the frontmost active deformation zone of the Sub Andean
Zone, located approximately 12.8°S and 71.3°W. The section spans from the Paleocene
to the Quaternary in time and allows a constraint on the influence of the Andean orogeny
on the Madre de Dios foreland basin and the fauna and flora it contained through the
Cenozoic. Field work has yielded a series of fossil localities that have been constrained
in age through use of U/Pb dating of detrital zircons. Notable fossil finds include
Early Miocene marsupials, xenarthrans, rodents, notoungulates, and bats. A new primate
recovered from the section is the first record of a primate from the Early Miocene
of the Amazon Basin. Reconstruction of the depositional environment for each formation
was performed by a combined use of sedimentology, geochemistry, and paleontology.
Stable isotopic analyses on depositional organic material indicates continental depositional
settings for all formations, whereas stable isotopic analyses on abiogenic carbonates
provide constraints on the degree of diagenetic alteration of sediments varying with
age and structural setting. Sedimentary facies are consistent with deposits being
formed in fluvial and overbank environments, consisting of fine-grained floodplain
deposits, point bar deposits, conglomerate channels and fossil-bearing channel lag
deposits. Average grain size for the section shows a coarsening trend towards younger
deposits, consistent with the approach of, and incorporation into an active orogen,
as supported by provenance data from detrital zircon analyses.</p>
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