THE LATE HOLOCENE IN CARTAGENA REGION: PALEOENVIRONMENTAL
RECONSTRUCTION OF THE LOW TERRACES.
Andrés A. Gómez*1, J. Ignacio Martínez*2, Yusuke Yokoyama**3.
*Universidad EAFIT, Area de Ciencias del Mar, Medellin, ** University of Tokyo, Department of
Earth and Planetary Sciences, Japon
1
agomezu@eafit.edu.co, 2 jimartin@eafit.edu.co, 3 yokoyama@eps.s.u-tokyo.ac.jp
Coastal dynamics in the Cartagena region are affected by climatic processes such as the path of the
intertropical convergence zone (ITCZ) and trade winds; as well as by coastal processes (e.g. waves and
littoral currents) and regional geological processes such as mud diapirism and the relative movement of
the Nazca, Caribbean, and South American plates. Evidences of sea level changes that took place during
the Late Holocene, can be found in the Cartagena region where there are ~5 and ~3 m.a.s.l. uplifted
terraces. Evidences for former sea levels were studied through the paleoenvironmental reconstruction of
the terraces, and multivariate statistical methods on mollusc assemblages Taphonomic and lithological
characteristics were recorded, and the paleoecological relations were interpreted from nine stratigraphic
sections surveyed in Tierra Bomba, Punta Canoas and The Morros sectors. A paleobathymetric curve was
constructed and uplifting rates were determined, based on chronological control of 22 radiocarbon dates
on molluscs and corals. Evidences suggest spatial and temporal environmental variations during the Late
Holocene. These variations result from coastal dynamic changes, the product of global climate changes,
and tectonic instability evidenced by topographic variations and uplifting rates. Climate changes would be
the result of differences in insolation during the last ~3,6 ka, which affected the Caribbean coast through
the ZCIT, trade winds, NAO and ENSO. The tectonic instability is caused by mud diapirism and regional
neotectonism. The interaction of these natural processes would have driven the spatial heterogeneity of
the ecosystems during the Late Holocene. The spatial and temporal heterogeneity is reflected in
geomorphologic changes, as suggested by lithological, paleontological and taphonomical patterns. These
geomorphologic changes evidence important hydrodynamic differences in the region, as well as the
susceptibility of the Cartagena region to global and regional processes. On the other hand, archaeological
evidences suggest that coastal geomorphology must have been influenced by human action since ~3,7 ka.