In Figure 1 of his Comment (Keppie, 2008), Keppie confused the Papalutla fault with the Teloloapan fault in his Comment's Figure. Here (in my Figure 1), I correctly identify the Papalutla fault in south Mexico, which supports my original hypothesis (Silva-Romo, 2008).
Keppie presented a list of questions, which I answer here.
My hypothesis assumes a Caribbean plate stationary relative to the mantle after Chron 18 at 38.4 Ma (Müller et al., 1999).
The ancestral Acapulco trench–Motagua transform fault was dislocated ~70 km by the Chiapas massif southeast displacement, during Neogene convergence of the North America and South America plates after the Chortís block departure (Silva-Romo and Mendoza-Rosales, 2007). Thereafter, the sedimentary sequence of the Gulf of Tehuantepec was northward from the fault zone.
The structural characteristics of the Colon fold belt of Honduras (Rogers et al., 2007a) are congruent with a left strike-slip fault system, which might have displaced the Nicaraguan Rise from a southwest location during Cenozoic time.
In response to Keppie's “Problematical Statements” (1) and (3): Just as the tectonostratigraphic division does, the Papalutla fault may cut the Mixteca terrane (Campa and Coney, 1983; Keppie, 2004) or be a terrane boundary (Sedlock et al., 1993). When comparing my model with the correlation between southern Mexico and the Chortís block (Rogers et al., 2007a), I used the tectonostratigraphic map of Campa and Coney (1983). Here, I claim that Papalutla fault (1) is a major structure that controlled Cretaceous sedimentation in the Guerrero-Morelos platform, which has a different Cretaceous stratigraphic column than the Mixteca terrane (Hernández-Romano, 1999); (2) its main Laramide kinematics were left-slip; (3) its inverse thrust segment near Papalutla town is a right bend in a left-slip fault; (4) its northeast projection is hidden by the eastern sector of the Transmexican volcanic belt (Fig. 1A)—on this sector, the Papalutla fault acted as tear fault in an Eocene Laramide thrust belt, as Mossman and Viniegra (1976) expected; and (5) the Papalutla fault projection was reactivated as a normal fault, and the tectonic front became the Cenozoic complex Veracruz Basin (Jannette, et al., 2003).
In response to Statement 2: Laramide reconstruction by Keppie (2004) invokes a Oaxaca terrane dislocated by a major left-slip fault where the Transmexican volcanic belt is presently located (Fig. 1B). I propose the Papalutla fault is that major structure (Fig. 1A). With this tectonic array, an ~1 Ga basement may extend below Guerrero-Morelos platform and may conciliate with central Chortís terrane basement invoked in Keppie's Comment.
My model allows some rotation of the Chortís block and erosion by subduction after the Chortís block departure, but southern Mexico truncation only by erosion by subduction (Keppie et al., 2007) implies a rate process yet unproven.