The Interplay between Tectonic Activity, Climate and Sea-Level Change in the Suriname River Valley, Tropical South America

Kathleen S Gersie,Ronald T Van Balen,Salomon B Kroonenberg

doi:10.3390/quat4020011

Kathleen S Gersie, Ronald T Van Balen + Show 1 more

Open Access

https://doi.org/10.3390/quat4020011

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Abstract

Suriname is part of the Guiana Shield, a cratonic area in northern South America. It is drained by several major rivers that are characterized by river terraces. The formation of terraces along the Suriname river is closely related to climatic changes during the Quaternary, due to the effects of climate on vegetation and precipitation changes. The terraces along the Suriname River valley show levels of 5, 15, and 20 m above the current mean water level. The reason behind the scarce terrace differentiation is the limited amount of long-term vertical incision. Therefore, each level along the Suriname River valley encompasses multiple climate cycles, which cannot be separated on morphological grounds. The limited incision reflects tectonic stability, which is typical for cratonic areas. Fieldwork along the river combined with topographic maps were used to determine and correlate the various terrace levels. While in the upper part of the river, climatically induced changes in vegetation cover and sediment delivery is dominant. In the lowermost reach, sea level change is especially important.

Highlights

Fluvial landscapes are an important part of the general geomorphological system.Among these, rivers in stable cratonic areas covered by rainforest are among the least studied ones
We present here a case study on the terraces of the Suriname River in the Guiana Shield in tropical South America, with a drainage basin wholly covered by tropical rainforest
Like other rivers in cratonic drainage basins covered with exclusively tropical rainforest, the Suriname River at present is characterized by the virtual absence of bedload transport, because the deeply weathered basement does not provide coarse-grained sediment to the rivers

Summary

Introduction

Fluvial landscapes are an important part of the general geomorphological system.Among these, rivers in stable cratonic areas covered by rainforest are among the least studied ones. Contrary to what these authors state, these rivers are not dominated by bedload but instead by a predominance of suspended load This is due to the fact that the deeply weathered land surfaces hardly provide bedrock gravel but only their weathering products, e.g., sand, silt, and clay. This results in a lack of erosive power of the rivers, even at high discharges, so that when during incision hard bedrock is encountered, they are incapable of eroding them away due to the lack of bedload, and instead the channel splits itself up in several branches in order to avoid the obstacles. A very specific channel form develops, i.e., multibranch cataracts called raudales in Spanish

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