The geology of Antigua

The geology of Antigua

van der Looij, K.J.R.

Molengraaff Fonds

2019

Antigua is an island located on the volcanically extinct part of the lesser Antilles volcanic arc. The island contains a transition from volcanic, to volcaniclastic and pyroclastic and to carbonate rocks. Since the mapping of Martin-Kaye (1959) no research focusing on the whole island has been done. This study provides new data trough fieldwork and thin section investigating. We provide a complete stratigraphy of the island, providing a fence diagram showing lateral lithological differences. Next to this provide evidence for both extensional (e.g. normal faults, boudinage) and compressional deformation (reverse faults, folds) , of which we argue that first extension occurred, this was followed by compression, and this was followed by extension. Next to this we date the island from paleontological investigation of foraminifera the oldest carbonate rocks are deposited in P18-20, the youngest in the late Oligocene. We combine the lithological observations with structural measurements and ages to construct cross sections trough the island. These cross sections show that the island has been largely affected by series of tilted fault blocks, with normal faults separating them. We conclude with suggestions for future researches which can be done thanks to the generated data set.

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Utrecht University

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