The incised valley of Baffin Bay, Texas: a tale of two climates

Abstract

Baffin Bay, Texas is the flooded Last Glacial Maximum incised valley of the Los Olmos, San Fernando and Petronila Creeks along the north-western Gulf of Mexico. Cores up to 17 m in length and high-resolution seismic profiles were used to study the history of Baffin Bay over the last 10 kyr and to document the unusual depositional environments within the valley fill. The deposits of the Baffin Bay incised valley record two major and two minor events. Around 8AE0 ka, the estuarine environments backstepped more than 15 km in response to an increase in the rate of sea-level rise. Around 5AE5 ka, these estuarine environments changed from environments similar to other estuaries of the northern Gulf of Mexico to the unusual suite of environments found today. Another minor flooding event occurred around 4AE8 ka in which several internal spits were flooded. Some time after 4AE0 ka, the upper-bay mud-flats experienced a progradational event. Because of its semi-arid climate and isolation from the Gulf of Mexico, five depositional environments not found in the other incised-valley fills of the northern Gulf of Mexico are found today within Baffin Bay. These deposits include well-laminated carbonate and siliciclastic open-bay muds, ooid beaches, shelly internal spits and barrier islands, serpulid worm-tube reefs and prograding upper-bay mud-flats. Based on these unusual deposits, and other characteristics of Baffin Bay, five criteria are suggested to help identify incised valleys that filled in arid and semi-arid climates. These criteria include the presence of: (i) hypersaline-tolerant fauna; (ii) aeolian deposits; and (iii) carbonate and/or evaporite deposits; and the absence of: (iv) peat or other organic-rich deposits in the upper bay and bay-margin areas; and (v) well-developed fluvially dominated bayhead deltas.

Recycling sediments between source and sink during a eustatic cycle: Systems of late Quaternary northwestern Gulf of Mexico Basin

“…Christi and Baffin bays). The overall stratigraphic architecture of these valleys have been studied in detail (Milliken et al, 2008a,b;Maddox et al, 2008;Simms et al, 2008Simms et al, , 2010Troiani et al, 2011) and are characterized by deepening-upward successions of fluvial, bayhead delta, bay and tidal deposits that back-step landward (Fig. 20).…”

“…Our early research focused on stratigraphic variability of the continental shelf and upper slope across the northern Gulf (Anderson et al, 2004). Since then, we have completed detailed studies of the onshore Calcasieu (Milliken et al, 2008a), Sabine (Milliken et al, 2008b), Trinity , Brazos (Taha and Anderson, 2008), Colorado (previously unpublished), Lavaca (Maddox et al, 2008), Copano (Troiani et al, 2011), Nueces (Simms et al, 2008) and Baffin Bay (Simms et al, 2010) fluvial valleys. We have also conducted extensive research on barrier islands and peninsulas, shelf banks, tidal deltas and the Brazos wave-dominated delta (e.g., Siringan and Anderson, 1993;Rodriguez et al, 2000aRodriguez et al, ,b, 2004Simms et al, 2006a;Wallace et al, 2009Wallace and Anderson, 2010, 7 2013; summarized in Anderson et al, 2014).…”

Long-range dependence in coastal framework geology: Asymmetries and implications for barrier island resiliency

“…It is plausible that paleo-channels acted as sediment sinks during barrier island formation. Simms et al (2010) presented seismic profiles extending from north to south across the ancestral LOSP Creeks, which exhibit a series of onlapping reflectors on the northern edge of the seismic 25 profiles. These onlapping reflectors are indicative of deposition on the northern edge of the paleo-channel, and support the hypothesis that alongshore spit development occurred within the LOSP Creeks paleo-channel.…”

“…15 A series of studies in the Gulf of Mexico have focused on extracting a buried ravinement surface, also referred to as the marine isotope stage (MIS) II paleo-surface and buried Pleistocene surface, including the area offshore of PAIS ( Fig. 1; Anderson et al, 2016;Fisk, 1959;Simms et al, 2010). Maps of the MIS II surface indicate that PAIS is dissected by at least two substantial paleo-channels.…”

“…Based on knick points in the MIS II paleo-surface, this large channel appears to meander from a northeasterly orientation to easterly orientation as it crosses PAIS, eventually flowing into a large paleo-channel adjacent to Baffin Bay. The large paleo-channel forming Baffin Bay is the combined ancestral Los Olmos, San Fernando, and Patronila Creeks (LOSP), which was drowned during sea level transgression and eventually filled with sediment (Simms et al, 2010). Complexities in the framework geology and modern island 25 geomorphology make PAIS an ideal location to examine how framework geology influences barrier island geomorphology.…”