Barremian–Early Aptian Rudists, Sligo Formation, Texas, U.S.A.

Rudists and carbonate platforms in the Aptian: a case study on biotic interactions with ocean chemistry and climate

“…Beyond the Tethyan region, the stratigraphical resolution of much of the Aptian carbonate platform record needs further refinement for the purposes of the present discussion, although some relevant observations can be highlighted. An extensive rock record of Barremian to Bedoulian platform growth, in places incorporating a rich rudist fauna, exists across the Caribbean Province, ranging geographically from the subsurface of Texas (Sligo Formation; Scott & Hinote, 2007) in the north, via Mexico (for example, the Cupido, Comburindio and El Cajón formations; Lehmann et al. , 2000; Pantoja‐Alor et al.…”

“…The Jamaican and Cuban rudist‐bearing limestones may not even extend above the Barremian (Chartrousse & Masse, 1998a), while the primitive state of the embryonic apparatus in the orbitolinid Palorbitolina lenticularis that abundantly accompanies those of south‐western Mexico (Huetamo region): “indicates a basal early Aptian age for this population” (Alencaster & Pantoja‐Alor, 1996; based on study of the material by Rolf Schroeder and Antonietta Cherchi). Moreover, the Sligo Formation in the subsurface of Texas is overlain by open marine deposits of the Pearsall Formation, which contains the planktonic foraminifer Globuligerina hoterivica (Subbotina) together with Nannoconus bucheri Brönimann, both with a Hauterivian to Lower Aptian range (Scott & Hinote, 2007). Ammonites in the La Peña Formation in north‐eastern Mexico likewise limit the termination of the underlying platform deposits of the Cupido Formation to within the Bedoulian – at least below the level of the Dufrenoyia justinae Taxon Range Zone, regarded as equivalent to the Tethyan furcata Zone (Barragan & Maurrasse, 2008).…”

“…Ammonites in the La Peña Formation in north‐eastern Mexico likewise limit the termination of the underlying platform deposits of the Cupido Formation to within the Bedoulian – at least below the level of the Dufrenoyia justinae Taxon Range Zone, regarded as equivalent to the Tethyan furcata Zone (Barragan & Maurrasse, 2008). Scott & Hinote (2007) state that: “the La Peña shale records chemostratigraphic event OAE 1a”. If correct, that would imply that the underlying platform limestones extend no higher than the lower part of the Upper Bedoulian (close to the foraminiferal blowi / cabri zonal boundary, according to Menegatti et al.…”

“…, 2009, among others). However, another possibility that remains to be tested, given the latest Bedoulian ( furcata Zone) age of the La Peña ammonites cited above (as well as Eprolithus floralis , cited by Scott & Hinote, 2007), is that the OAE in question corresponds not to OAE 1a, but to the slightly younger Upper Bedoulian ‘Aparein level’ identified by Millán et al. (2009).…”

“…Beyond the Tethyan region, the stratigraphical resolution of much of the Aptian carbonate platform record needs further refinement for the purposes of the present discussion, although some relevant observations can be highlighted. An extensive rock record of Barremian to Bedoulian platform growth, in places incorporating a rich rudist fauna, exists across the Caribbean Province, ranging geographically from the subsurface of Texas (Sligo Formation; Scott & Hinote, 2007) in the north, via Mexico (for example, the Cupido, Comburindio and El Cajó n formations; Lehmann et al, 2000;Pantoja-Alor et al, 1994;Pantoja-Alor et al, 2004; respectively; see also Scott & Filkorn, 2007) and the Greater Antilles (for example, Benbow Limestone, Jamaica, and lower Remedios Group limestones of Cuba; Skelton & Rojas et al, 1996;respectively), to Venezuela in the south (Barranquin Formation; Masse & Rossi, 1987). Meanwhile, the apparent impact of OAE 1a has been identified in pelagic to hemipelagic successions in, for example, the Sierra Madre Oriental of northern Mexico (Bralower et al, 1999).…”