The Amazon River Basin is the largest drainage system on Earth, covering approximately seven million square kilometers across nine South American countries. This area, predominantly covered by the Amazon rainforest, is underlain by vast sedimentary layers containing natural resources. Among these resources, coal deposits exist within the basin’s geological structure. These deposits are primarily locked away in deep, unexploited formations.
The Geological Context of Formation
The presence of coal in the Amazon Basin resulted from ancient geological processes involving the burial and transformation of plant material. Most of the estimated coal tonnage is of Tertiary age, having formed between 66 and 2.6 million years ago. This period was characterized by extensive, low-lying swamplands and alluvial plains, which allowed for the accumulation of thick layers of peat.
The uplift of the Andes Mountains to the west, beginning around 15 million years ago, dramatically altered the continent’s drainage. This created a massive inland lake and wetland system known as the Pebas Basin. This expansive, freshwater environment was a major site for peat accumulation, which was then buried under subsequent layers of sediment eroded from the rising mountains. Deep burial, pressure, and moderate heat caused the peat to undergo coalification, transforming the organic matter into coal.
Geographical Distribution of Known Deposits
The majority of estimated coal reserves within the Amazon River system are distributed across the Amazonian territories of Brazil, Peru, and Colombia. These deposits are not found on the surface but are contained within the major sedimentary basins underlying the river lowlands. Brazil’s portion of the basin, which holds about 60% of the total area, includes several identified coal-bearing regions.
Deposits are noted in the Upper Amazon region of Brazil, as well as in the Tocantins-Araguaia and Rio Fresco regions, though these remain largely unexploited. The largest estimated tonnage is located deep within sedimentary basins like the Solimões and Amazonas Basins, which contain thick sequences of younger, coal-bearing rock. The Foz do Amazonas Basin, located at the river’s mouth, is another significant sedimentary structure where resources exist, although exploration there has focused mainly on oil and gas.
Characteristics of Amazonian Coal
The coal found in the Amazonian basins is classified as a lower-rank type, consistent with its relatively young Tertiary age. This coal falls into the ranks of lignite or sub-bituminous coal, characterized by lower carbon content and higher moisture levels compared to older, higher-rank coals. The calorific value, which measures the heat released upon combustion, is lower in this Amazonian coal.
The moisture content in sub-bituminous coal can be high, sometimes exceeding 20%, which reduces its efficiency as a fuel source. Total sulfur content varies; coal formed in marine-influenced environments tends to have higher sulfur levels, while coal from freshwater swamps typically has less than 1% sulfur. Detailed chemical analysis of these deposits is limited due to the lack of exploitation, but the geological context suggests the material is often lower in quality than bituminous coals found elsewhere.
Current Exploration and Regulatory Status
Despite the existence of these extensive coal deposits, active commercial exploitation is limited, with most known coal-bearing regions in the Brazilian Amazon remaining unexploited. This low level of activity is due to the challenging regulatory environment and the ecological sensitivity of the region. The Amazon is a globally recognized biome with protected areas and Indigenous territories, making large-scale extractive projects controversial.
Regulatory bodies, such as Brazil’s environmental agency, have opposed resource extraction in sensitive areas, often denying licenses for exploration even for oil and gas projects in the Foz do Amazonas Basin. The potential for environmental damage, including deforestation, greenhouse gas emissions, and water contamination, creates public pressure against the development of these coal reserves. The coal’s remote location and the stringent regulatory framework act as major barriers to its commercial development.