Correlation of Northern Belize's Cretaceous-Paleogene ('KT') Boundary Sections

摘要

In northern Belize, there is a remarkable record of primary continuous ejecta and re-worked (or secondary) discontinuous ejecta, which comprises the Cretaceous-Paleogene ('KT') boundary interval that lies directly on top of the local Maastrichtian bedrock. These boundary deposits, which are preserved in a series of north-trending grabens, occur at three key stratigraphic sections--on Albion Island, at Progresso Lagoon, and in the village of Armenia. On Albion Island, fine-grained deposits of lapilli-bearing clays are overlain by impactoclastic carbonate breccia beds (i.e., ejecta curtain deposits). At Progresso Lagoon, a clay bed is overlain by similar impactoclastic carbonate breccia, which in turn is overlain by secondary deposits of re-sedimented discontinuous ejecta (comprised of polished limestone pebbles). In the village of Armenia, a lapilli-bearing clayey fine carbonate bed is overlain by beds of re-sedimented discontinuous ejecta akin to those at Progresso Lagoon. Correlation among these key stratigraphic sections provides a rare view inside the stratigraphy of a large impact crater's ejecta deposits. A proposed stratigraphic correlation of these key sections is presented in this paper.