This complex deposit controlled by tectonic features associated to the Cerrejón and Ranchería thrust faults and Tabaco folding zone. The deposit is limited to the north by the Oca fault, to the southeast by the Cerrejón thrust fault and to the northwest by an abrupt topographic change due to the occurrence of calcareous rocks of the Manantial Formation. In addition, there are strike-slip faults, which split the deposit into blocks, maintaining its stratigraphic continuity.

The Cesar–Ranchería Basin mainly consists of a sedimentary succession of Paleocene age and unconsolidated recent deposits. The Cerrejón Formation (Upper Paleocene) is approximately 900 m in thickness and forms part of the Triassic to mid-Miocene sequence of sediments that filled a regional basin in the northern part of South America (extending eastwards to Los Llanos Basin in Venezuela). The coal-bearing sequence forms part of this sedimentary unit, which consists of shales, sandy mudstones, grey sandstones and coal, with notable absence of a conglomeratic siliciclastic succession. Coal seams of economic interest are actually in exploitation, being more or less regularly distributed and present variable thickness.

The Cerrejón Formation has been divided into three groups (lower, middle, and upper) based on the thickness and distribution of the coal beds. Overall coal bed thickness averages 3 m and ranges from 0.7 to 10 m (Weaver, 1993), although the thickest coal beds (1.4 to 10 m) is in the upper part of this sedimentary sequence.

Cerrejón currently operates five large open-pits: The Patilla Pit, the NAM Pit (consisting of Tabaco Pit and La Puente Pit), the Oreganal Pit and the Comunidad Pit. To access the coal, more than 230 million cubic metres (Mm3) of overlying rock and soil must be removed annually. Waste rock is placed in disposal sites or used as backfill in mined-out pits.

The subsequent mining and transportation (“coal chain”) process currently employed by Cerrejón involves the sequential activities:

Drilling and blasting of rock and coal to break it up and facilitate removal;

Extraction, loading and transport of waste rock and coal using high-capacity shovels and a fl eet of haul trucks that transport the material to disposal sites and coal-handling areas, respectively;

Coal preparation, which includes mixing, grinding and, for a small percentage of the product, washing to remove ash content;

Loading of rail cars and transport to the port by train;

Coal storage and ship loading in Puerto Bolívar.

Cerrejón’s coal chain transportation infrastructure includes a road system, two crushing plants at the mine, a wash plant, conveyor belts from the crushers to two 12,500 tonne capacity storage silos that load the rail cars, the railway and the coal export terminal and a commodities pier at Puerto Bolívar.

A 125 km on-site dirt road system is used for transportation of soil, rock and coal to and from pits and storage sites. Currently, two bridges cross the Ranchería River to facilitate the transport of coal from the Oreganal, Comunidad and NAM open-pits to the coal handling facilities.

Coal-handling at Puerto Bolívar includes rail car unloading, storage, and transport to a single ship loader. The coal may be temporarily stored or sent directly from the unloading station to the cargo hold of ocean going vessels with capacities of up to 180,000 tonnes.