Figure F21. QFL plots showing distributions of rift and young ocean basin sand compositions and models for passive margin provenance. See text for discussion. A. Schematic summary of sand petrofacies outlined by Ingersoll (1990) within the modern Rio Grande Rift. B. Schematic summary of sand petrofacies (circled end members and mixing lines) within the Red Sea and Gulf of Aden, from Garzanti et al. (2001). C. Synthesis of modern data presented in A and B with Newfoundland/Iberian margin data used to expand undissected rift field. These exemplify ranges of sediment compositions possible in rift-to-drift settings. D. Schematic showing evolutionary paths that sand compositions may take within rift-to-drift successions. The arrows are labeled according to the type area on which they are based (e.g., Red Sea craton vs. volcanic based on Garzanti et al., 2001; Iberia based on data presented in Fig. F22). Newfoundland example lacks arrow because trends uncertain. E. Conceptual rift-to-drift transition proposed by Dickinson (1985). Such compositional changes would be expected in mature rift stages in plutonic terranes with increased maturity (quartz content) as a function of enhanced weathering and transport.

Figure F21. QFL plots showing distributions of rift and young ocean basin sand compositions and models for passive margin provenance. See text for discussion. A. Schematic summary of sand petrofacies outlined by Ingersoll (1990) within the modern Rio Grande Rift. B. Schematic summary of sand petrofacies (circled end members and mixing lines) within the Red Sea and Gulf of Aden, from Garzanti et al. (2001). C. Synthesis of modern data presented in A and B with Newfoundland/Iberian margin data used to expand undissected rift field. These exemplify ranges of sediment compositions possible in rift-to-drift settings. D. Schematic showing evolutionary paths that sand compositions may take within rift-to-drift successions. The arrows are labeled according to the type area on which they are based (e.g., Red Sea craton vs. volcanic based on Garzanti et al., 2001; Iberia based on data presented in Fig. F22). Newfoundland example lacks arrow because trends uncertain. E. Conceptual rift-to-drift transition proposed by Dickinson (1985). Such compositional changes would be expected in mature rift stages in plutonic terranes with increased maturity (quartz content) as a function of enhanced weathering and transport.