The Tectonic and Geological Environment
of Coastal South America
J.N. KELLOGG and W.U. MOHRIAK
1 Introduction
The tectonic history and geological factors, such as the present-day geomorphology and vertical motions of the coastline, influence the coastal
and marine ecosystems of South America. The continent's Phanerozoic
tectonic history is dominated by its separation from Africa and the MidMiocene uplift of the Andes. Tectonically, South America is divided into
two parts, the Andean chain to the west and a vast stable platform to the
east, consisting of exposed Precambrian rocks and shallow sedimentary
cover rocks. The Pacific Andean coastline is characterized by high relief, a
relatively narrow shelf bordering a deep trench, small drainage basins, and
rapid vertical motions of the coast. Low relief, a broad shelf, and extremely
large drainage basins and alluvial fans characterize the Atlantic coastline.
Today, approximately 93% of South America's drainage is to the Caribbean
and the Atlantic away from the Andes and provides the world's best example of present-day continent-scale drainage control by plate tectonics
(Inman and Nordstrom 1971; Hoorn et al. 1995; Potter 1997).
2 The Atlantic Continental Margin
2.1 Physiographic Features
The breakup of Western Gondwana in the Mesozoic (Rabinowitz and LaBrecque 1979) is characterized by aborted rifts in the onshore northeastern region of Brazil (e. g., Reconcavo-Tucano-Jatoba Rift System) and
several rifts that evolved to form one of the world's largest series of passive
basins (e.g., Pelotas, Santos, Campos, Espfrito Santo, Mucuri, CumuruEcological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
© Springer-Verlag Berlin Heidelberg 2001
of Coastal South America
J.N. KELLOGG and W.U. MOHRIAK
1 Introduction
The tectonic history and geological factors, such as the present-day geomorphology and vertical motions of the coastline, influence the coastal
and marine ecosystems of South America. The continent's Phanerozoic
tectonic history is dominated by its separation from Africa and the MidMiocene uplift of the Andes. Tectonically, South America is divided into
two parts, the Andean chain to the west and a vast stable platform to the
east, consisting of exposed Precambrian rocks and shallow sedimentary
cover rocks. The Pacific Andean coastline is characterized by high relief, a
relatively narrow shelf bordering a deep trench, small drainage basins, and
rapid vertical motions of the coast. Low relief, a broad shelf, and extremely
large drainage basins and alluvial fans characterize the Atlantic coastline.
Today, approximately 93% of South America's drainage is to the Caribbean
and the Atlantic away from the Andes and provides the world's best example of present-day continent-scale drainage control by plate tectonics
(Inman and Nordstrom 1971; Hoorn et al. 1995; Potter 1997).
2 The Atlantic Continental Margin
2.1 Physiographic Features
The breakup of Western Gondwana in the Mesozoic (Rabinowitz and LaBrecque 1979) is characterized by aborted rifts in the onshore northeastern region of Brazil (e. g., Reconcavo-Tucano-Jatoba Rift System) and
several rifts that evolved to form one of the world's largest series of passive
basins (e.g., Pelotas, Santos, Campos, Espfrito Santo, Mucuri, CumuruEcological Studies, Vol. 144
U. Seeliger and B. Kjerfve (eds.)
Coastal Marine Ecosystems of Latin America
© Springer-Verlag Berlin Heidelberg 2001