Origin, Evolution, and Sedimentary Synchroneity of Cratonic Basins

G. deV. Klein, A. T. Hsui

Tectonic subsidence analysis of cratonic basins demonstrated they formed by initial rifting followed by lithospheric thermal contraction. Most cratonic basins were so formed 540 to 560 Ma. Sediment accumulation rates, temporal sediment volume changes, and commonality of ages of interregional unconformities on a near-global basis suggest parallel temporal subsidence trends. This commonality of basin formation and basin filling on a near-global basis indicates common processes of basin formation.

We propose that formation of most cratonic basins is related to breakup of a large supercontinent around 540 to 560 Ma. This supercontinent acted as a heat shield, causing buildup of excess heat below the lithosphere. Such heating events triggered widespread partial melting of anorogenic granites, causing rifting and thermal subsidence of cratonic basins. Anorogenic granite intrusions weakened lithospheric strength, focusing rifting and subsidence of cratonic basins over anorogenic granite bodies. A possible alternative is that doming developed over intruded granites, causing lithospheric stretching and basin subsidence between anorogenic granite bodies. Both hypotheses account for the synchroneity of sedimentary events and of cratonic basin formation. Lack of available observational ata in the basement below cratonic basins prevents discrimination between the more likely of the two models.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.