Detrital zircon age spectra of middle and upper Eocene outcrop belts, U.S. Gulf Coast region

Abstract

Recently reported detrital zircon (DZ) data help to associate the Paleogene strata of the Gulf of Mexico region to various provenance areas. By far, recent work has emphasised upper Paleocene‐lower Eocene and upper Oligocene strata that were deposited during the two episodes of the highest sediment supply in the Paleogene. The data reveal a dynamic drainage history, including (1) initial routing of western Cordilleran drainages towards the Gulf of Mexico in the Paleocene, (2) an eastward shift of the western continental divide, from the Jura‐Cretaceous cordilleran arc to the eastern edge of the Laramide province after the Paleocene and (3) a southward shift, along the eastern Laramide province, of the headwaters of river systems draining to the Mississippi and Houston embayments at some time between the early Eocene and Oligocene. However, DZ characterisation of most (~20 Myr) of the middle Eocene‐lower Oligocene section remains limited. We present 60 DZ age spectra, most of which are from the middle or upper Eocene outcrop belts, with 50–200‐km spacing. We define six to eight distinct groups of DZ age spectra for middle and upper Eocene strata. Data from this and other studies resolve at least six substantial temporal changes in age spectra at various positions along the continental margin. The evolving age spectra constrain the middle and upper Eocene drainage patterns of large parts of interior North America. The most well‐resolved aspects of these drainage patterns include (1) persistent rivers that flowed from erosional landscapes across the Paleozoic Appalachian orogen either into the low‐lying Mississippi embayment or directly into the eastern Gulf; (2) at least during marine regressions, a trunk channel that likely flowed southward along the axial part of Mississippi Embayment and integrated tributaries from the east and west; and (3) rivers that flowed to the Houston embayment in the middle Eocene that likely originated in the Laramide province in central Colorado and southern Wyoming, as Precambrian basement highs in those source areas were being unroofed.

Quantifying the relative contributions of Miocene rivers to the deep Gulf of Mexico using detrital zircon geochronology: Implications for the evolution of Gulf Basin circulation and regional drainage

“…Previous DZ provenance analyses have greatly improved understanding of the paleo‐drainage network that feeds the GOM and its evolution from the Cretaceous and various periods during the Cenozoic (e.g. Blum & Pecha, 2014; Craddock et al, 2021; Craddock & Kylander‐Clark, 2013; Fan et al, 2019; Sharman et al, 2017; Wahl et al, 2016; Xu et al, 2017). In addition, the abundance of subsurface data has enabled definition of basin architecture and sediment dispersal patterns from basin margin to offshore depocenters (e.g.…”

“…Previous DZ provenance analyses have greatly improved understanding of the paleo-drainage network that feeds the GOM and its evolution from the Cretaceous and various periods during the Cenozoic (e.g. Blum & Pecha, 2014;Craddock et al, 2021;Craddock & Kylander-Clark, 2013;Fan et al, 2019;Wahl et al, 2016;Xu et al, 2017). In addition, the abundance of subsurface data has enabled definition of basin architecture and sediment dispersal patterns from basin margin to from western sediment sources and restriction of locally up-dip Tennessee River sources: (1) regional drainage changes involving middle Miocene capture of the paleo-Red River and its tributaries by the paleo-Mississippi River, which at the same time lost some of its eastern tributaries owing to expansion of the paleo-Tennessee and (2) eastward (clockwise) marine transport of western-sourced sediment along the shelf or slope, which deflected the paleo-Tennessee signal >150 km eastward to feed the deep-sea fan further east, perhaps reflecting intensification of a precursor to the GOM Loop Current.…”

Quantifying the Link Between the Detrital Zircon Record and Tectonic Settings

“…Second, some continental interiors away from a subduction zone develop syn‐sedimentary igneous activity, resulting in the dominance of zircon grains close to the depositional age in sedimentary rocks. For example, samples that belong to category A deposited in middle and upper Eocene outcrop belts, US Gulf Coast region (Figure 3 and Figure S6 in Supporting Information S1) originated from the magmatic provinces in northwestern Mexico, southern Arizona New Mexico border region, and southwest flank of the central Colorado magmatic provinces (Craddock et al., 2021). Other regions where young zircons dominate recent sediments despite appearing to fall far from active subduction are around the India‐Eurasia collision zone (Figure 3 and Figure S6 in Supporting Information S1) where subduction ceased 10–20 Myr earlier, possibly reflecting the lag between changing tectonic settings and sedimentary records.…”

“…EDAs in other 4,860 samples were obtained based on various pieces of evidence, including micropaleontology, paleontology, biostratigraphy (e.g., Blum et al., 2018; Bootes et al., 2019; Clift et al., 2019; Hodges et al., 2017; Jaeger et al., 2014; Leary et al., 2020; Zhang et al., 2018), U‐Pb or 40 Ar/ 39 Ar dating of tuffs or volcanic ash deposits (e.g., Abdullayev et al., 2018; Amidon et al., 2017; Kimbrough et al., 2015; Viglietti et al., 2018; Zhang et al., 2019), magnetostratigraphy (e.g., Abdullayev et al., 2018; Amidon et al., 2017; Clift et al., 2019; Kimbrough et al., 2015; Koshnaw et al., 2020; Zhang et al., 2018), depositional facies analysis and stratigraphy (Olierook et al., 2019), and geologic maps (e.g., Hart et al., 2016). EDAs of 2,468 samples in the data set obtained by estimated age intervals (e.g., Abdullayev et al., 2018; Amato et al., 2013; Bootes et al., 2019; Koshnaw et al., 2020) or the stratigraphy of deposition (e.g., to stage stratigraphy) (e.g., Andersen et al., 2016; Craddock et al., 2021; Leary et al., 2020; Lundmark et al., 2014), which were converted to absolute ages as EDAs using the middle of the age intervals and the ICS International Chronostratigraphic Chart (Cohen et al., 2013) in the data set of Puetz & Condie. (2019) and Puetz et al.…”