Prior to the MIS 2 lowstand, the Mississippi, Western Louisiana, and Brazos deltas were abandoned by their fluvial sources. Bentley et al. (2016--in this Vialinin A volume) review late Quaternary sedimentation on the Mississippi fan. The Brazos River avulsed to a new location along the eastern margin of its MIS 3 delta and merged with the ancestral Trinity River. Radiocarbon ages indicate that the Brazos River avulsion occurred between ~ 36 ka and 20 ka (Fraticelli and Anderson, 2003) and that the Western Louisiana MIS 3 delta was abandoned by ~ 36 ka (Wellner et al., 2004). Upstream of where the Brazos and Trinity valleys merged on the outer shelf, the Sabine and Calcasieu valleys converged with the Trinity Valley (Fig. 11). Sediment from these combined drainage basins nourished a prominent lowstand delta and slope fan complex net secondary productivity (NSP) occupied four salt-withdrawal minibasins on the upper slope (Satterfield and Behrens, 1990, Anderson et al., 1996, Anderson et al., 2004, Morton and Suter, 1996, Winker, 1996, Beaubouef and Friedmann, 2000, Badalini et al., 2000 and Pirmez et al., 2012) (Fig. 14).
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