Provenance Evolution During Progressive Rifting and Hyperextension Using Bedrock and Detrital Zircon U-Pb GEOSPHERE; V
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Research Paper THEMED ISSUE: Anatomy of Rifting: Tectonics and Magmatism in Continental Rifts, Oceanic Spreading Centers, and Transforms GEOSPHERE Provenance evolution during progressive rifting and hyperextension using bedrock and detrital zircon U-Pb GEOSPHERE; v. 12, no. 4 geochronology, Mauléon Basin, western Pyrenees doi:10.1130/GES01273.1 Nicole R. Hart1, Daniel F. Stockli1, and Nicholas W. Hayman2 12 figures; 1 supplemental file 1Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, 2275 Speedway C9000, Austin, Texas 78712, USA 2Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, 10100 Burnet Road, Austin, Texas 78712, USA CORRESPONDENCE: hartnic4@ utexas .edu ABSTRACT nental rifted margins and their transition to passive margins. For magma-poor CITATION: Hart, N.R., Stockli, D.F., and Hayman, margins in particular, the processes that occur during continental extension, N.W., 2016, Provenance evolution during progres- sive rifting and hyperextension using bedrock and The responses of sedimentary systems to rifting at continental margins break-up, and margin development have long been debated and modeled on detrital zircon U-Pb geochronology, Mauléon Basin, are three-dimensional and involve the mixing of various sediment sources the basis of observations from rifted margins such as the Iberia-Newfound- western Pyrenees: Geosphere, v. 12, no. 4, p. 1166– through tectonic drivers and sediment response. Such sedimentary responses land or northwest Australian margins, and exhumed fossil rifted margins 1186, doi:10.1130/GES01273.1. have not been well studied along magma-poor, hyperextended margins where such as in the eastern Alps, as well as numerical models (e.g., Froitzheim and the crust is stretched and thinned to ≤10 km. The asymmetric Mauléon Basin Eberli, 1990; Driscoll and Karner, 1998; Whitmarsh et al., 2001; Pérez-Gussinyé Received 24 September 2015 Revision received 22 April 2016 of the western Pyrenees is the product of such magma-poor hyperextension and Reston, 2001; Huismans and Beaumont, 2002; Lavier and Manatschal, Accepted 24 May 2016 resulting from lateral rift propagation from the Bay of Biscay during Cretaceous 2006; Osmundsen and Ebbing, 2008; Péron-Pinvidic and Manatschal, 2009; Published online 23 June 2016 time. After rifting, limited shortening during Cenozoic Pyrenean inversion up- Unternehr et al., 2010). These geological and numerical models have focused lifted the basin, resulting in preservation of outcrops of rift basin fill, upper and on the processes accommodating lithospheric break-up as well as structural lower crustal sections, serpentinized lithospheric mantle, and basic rift-fault evolution during progressive strain localization from diffusive rifting, crustal relationships. In this study ~5800 new zircon U-Pb ages were obtained from necking (extension and thinning that leads to a zone of crustal thinning from prerift, synrift, and postrift strata; the ages constrain the proximal to distal ~30 km to ≤10 km and an inflection point in the seismic Moho), hyperextension evolution of the Mauléon Basin and define a general model for sediment rout- (crustal thinning to ≤10 km), mantle exhumation, and eventual lithospheric ing during rifting. Zircon U-Pb analyses from lower crustal granulites indicate separation to seafloor spreading (Péron-Pinvidic and Manatschal, 2009; that granulite plutons crystallized at 279 ± 2 and 274 ± 2 Ma, and paragneissic Mohn et al., 2010). While this structural and geometric evolution has been granulites yielded zircon rim ages of ca. 295 Ma. Detrital zircon U-Pb ages from discussed (e.g., Whitmarsh et al., 2001), the spatial and temporal complexi- western Pyrenean prerift strata show age modes of ca. 615 and ca. 1000 Ma, ties of tectonically controlled sedimentation, such as the relative amounts of suggesting continual recycling and/or well-mixed Gondwanan-sourced sedi- mixing between proximal and distal sources, recycling between subbasins, ments throughout the Paleozoic and early Mesozoic; additional Paleozoic age spatial and temporal basin compartmentalization, and subbasin reintegration components (ca. 300 and ca. 480 Ma) are also observed. The variation of detri- during progressive rifting remain unknown. Such sedimentary routing vari- tal zircon U-Pb ages in synrift and postrift strata illustrates that during rifting, ations could have implications for stratigraphic models of basin evolution, provenance varied spatially and temporally, and sediment routing switched structural controls on subsidence, and the progressive geometric evolution from being regionally, to locally, and then back to regionally derived within of rifted margins. individual structurally controlled subbasins. Where preserved and exposed, hyperextended systems offer a window into the synrift and early postrift sedimentary records of rifted continental margins that are generally inaccessible due to their submarine locations and INTRODUCTION burial by thick passive margin sediments (e.g., Iberian-Newfoundland margin and the Gulf of Mexico). This has restricted tectonic sedimentation studies to Stratigraphy at rifted and passive continental margins is an important re- reflection and refraction seismic surveys and/or sparse boreholes that gener- corder of continental extension and breakup. The stratigraphic record can be ally do not penetrate the synrift sedimentary sections within the necking do- used to reconstruct the temporal variations in the interplay between exten- main or the distal rifted margin. In contrast, fossil rifted margins preserved in For permission to copy, contact Copyright sional tectonics and sedimentation, and to provide a more complete under- orogens offer the opportunity to explore and characterize the complexities of Permissions, GSA, or [email protected]. standing of the tectonic, climatic, thermal, and geomorphic evolution of conti- the tectonic and stratigraphic evolution of hyperextended margins. Such fossil © 2016 Geological Society of America GEOSPHERE | Volume 12 | Number 4 Hart et al. | Provenance evolution, Mauléon Basin Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/4/1166/4178124/1166.pdf 1166 by guest on 23 September 2021 Research Paper margins, such as in the Eastern Alps, tend to be variably tectonized and over- Matte, 1986; Ziegler, 1990). Permian extension and orogenic collapse was fol- printed by later orogenic deformation, and often preserve only a fragmented lowed first by the northward propagation of North Atlantic rifting, resulting in synrift basin record (e.g., Masini et al., 2012). The Early Cretaceous Mauléon rift Jurassic to Early Cretaceous exhumation and marine incursion, and then later basin in the western Pyrenees is therefore noteworthy because it offers access by the initiation of Cretaceous rifting and seafloor spreading in the Bay of Bis- to a relatively complete synrift to postrift sedimentary record in a setting where cay (Jammes et al., 2009; Filleaudeau et al., 2011; Vacherat et al., 2014). While the postrift inversion and shortening-related structural and thermal overprint- diffuse extensional faulting has been suggested in the northern and southern ing seem to be relatively modest (e.g., Teixell, 1998; Lagabrielle and Bodinier, Pyrenees during Early Cretaceous time from 145 to 132 Ma, which may rep- 2008; Jammes et al., 2009; Masini et al., 2014; Tugend et al., 2014; Vacherat resent early stages of Cretaceous extension (Vergés and García-Senz, 2001; et al., 2014), making it an ideal locality for the reconstruction of synrift and Jammes et al., 2009; Vacherat et al., 2014), the future Mauléon Basin area was postrift sedimentation and for the understanding of rift-related basin evolution characterized by stable carbonate platforms with some evidence for limited at hyperextended rift margins. Early Cretaceous salt mobility. The onset of dramatic synrift subsidence, how- To better understand the evolution of the Mauléon Basin during rifting, we ever, clearly postdates the deposition of lower Aptian carbonates (Ducasse and apply a combination of bedrock and detrital zircon (DZ) U-Pb dating. DZ U-Pb Velasque, 1988; Canérot et al., 2001; Masini et al., 2014). analyses have evolved over the past decade into a powerful tool in process-ori- Continental extension in the Bay of Biscay, leading to break-up and sea- ented provenance analyses (e.g., Gehrels, 2014, and references therein) and floor spreading, propagated eastward and resulted in large-magnitude re- studies have employed these techniques to focus on source-to-sink problems gional crustal extension (~120%) in southwestern France and northern Spain, at passive margins and in intercontinental rifts (e.g., Cawood and Nemchin, local thinning of the crust to 0–10 km, and local exhumation of sublithospheric 2000; Lamminen and Köykkä, 2010; Craddock et al., 2013; Lamminen et al., mantle rocks (Lagabrielle and Bodinier, 2008; Jammes et al., 2009; Masini 2015); however, no systematic study has focused on a high-resolution interpre- et al., 2014). Such dramatic crustal thinning is now widely referred to as hyper- tation of sedimentary provenance at hyperextended continental rifted margins extension (e.g., Sutra and Manatschal, 2012). One of these areas of western with the emphasis on source-to-sink changes during progressive rifting. This Pyrenean hyperextension is the Mauléon-Arzacq rift system, which is charac- study aims to fill this gap by presenting zircon U-Pb data