Burial Diagenesis of the Eocene Sobrarbe Delta (Ainsa Basin, Spain) Inferred From Dolomitic Concretions

Little attention has been focused on the burial diagenesis of deltas deposited on active foreland-basin margins, where tectonics is likely to strongly impact fluid–rock interactions. A petrographic, geochemical, and microthermometric study of several fractured dolomite concretions and enclosing prodelta marls provides insights into the evolution of burial diagenesis in the Eocene Sobrarbe deltaic complex (Ainsa Basin, Spain), and more generally, on the paleohydrology of the South Pyrenean foreland basin. Shallow burial diagenesis was controlled by microbial activity in marine-derived porewaters. Microbial sulfate reduction was first responsible for the formation of pyrite and early calcite, followed by the growth of dolomite concretions during methanogenesis. Subsequent diagenesis was limited to temperatures and depth of less than approximately 75°C and 2 km, respectively. Diagenesis was recorded in porous bioturbation traces and septarian fractures found inside dolomite concretions, as well as in tectonic shear fractures. Neomorphic tabular barite, found only in the bioturbation traces, is interpreted to have formed early in marine-derived porewaters. Septarian fractures were then filled by Fe-rich calcite and centimeter-size celestine. Stable isotopes indicate that calcite probably formed in meteoric-derived waters coming from the overlying fluvial delta plain. The sulfur isotope composition of celestine is compatible with precipitation in waters of mixed parentage, but the exact origin of dissolved sulfate remains poorly constrained. In tectonic fractures, celestine precipitated coevally with calcite displaying evidence of strong fluid–rock interaction. Dissolved sulfate may have migrated to the fractures during active tectonics from the late Eocene to the Oligocene. The paragenesis and the proposed paleohydrologic model are similar to those previously described for other deltaic systems deposited in active foreland basins, including the South Pyrenean foreland basin. These features point to common diagenetic processes in syntectonic foreland-basin deltas, involving both meteoric and marine fluid sources. Similar to passive margin settings, early diagenesis appears to be controlled mainly by relative variations of sea level, whereas during further burial, the development of permeable tectonic fractures is likely to facilitate the influx of basinal or continental waters into fine slope deposits, impacting the diagenetic record. These results emphasize the importance of fracture development in the fluid-flow regime of syntectonic foreland-basin deltas. They demonstrate the necessity to take this parameter into account in fluid-flow modeling of foreland-basin margins.

[1]  John M. McArthur,et al.  Strontium isotope stratigraphy , 2012 .

[2]  B. Lacroix,et al.  Syntectonic fluid-flow along thrust faults: Example of the South-Pyrenean fold-and-thrust belt , 2014 .

[3]  J. Muñoz,et al.  The Ainsa Fold and thrust oblique zone of the central Pyrenees: Kinematics of a curved contractional system from paleomagnetic and structural data , 2013 .

[4]  S. Morad,et al.  Distribution of carbonate cements within depositional facies and sequence stratigraphic framework of shoreface and deltaic arenites, Lower Miocene, the Gulf of Suez rift, Egypt , 2013 .

[5]  M. Strecker,et al.  Accommodation of transpressional strain in the Arabia‐Eurasia collision zone: new constraints from (U‐Th)/He thermochronology in the Alborz mountains, north Iran , 2013 .

[6]  K. Bjørlykke,et al.  Open or closed geochemical systems during diagenesis in sedimentary basins: Constraints on mass transfer during diagenesis and the prediction of porosity in sandstone and carbonate reservoirs , 2012 .

[7]  Moyra E. J. Wilson,et al.  Diagenesis of Neogene Delta-Front Patch Reefs: Alteration of Coastal, Siliciclastic-Influenced Carbonates from Humid Equatorial Regions , 2012 .

[8]  F. Mouthereau,et al.  Oxygen isotopes of marine mollusc shells record Eocene elevation change in the Pyrenees , 2012 .

[9]  Yuanfeng Cai,et al.  PORE‐LINING CHLORITE CEMENTS IN LACUSTRINE‐DELTAIC SANDSTONES FROM THE UPPER TRIASSIC YANCHANG FORMATION, ORDOS BASIN, CHINA , 2012 .

[10]  R. Norris,et al.  Evolution of middle to Late Cretaceous oceans—A 55 m.y. record of Earth's temperature and carbon cycle , 2012 .

[11]  Tania Mochales,et al.  Rotational velocity for oblique structures (Boltaña anticline, Southern Pyrenees) , 2012 .

[12]  G. Pe‐Piper,et al.  Controls on regional variability in marine pore-water diagenesis below the seafloor in Upper Jurassic–Lower Cretaceous prodeltaic sandstone and shales, Scotian Basin, Eastern Canada , 2012 .

[13]  B. Lacroix,et al.  Microtectonic and geochemical characterization of thrusting in a foreland basin: Example of the South-Pyrenean orogenic wedge (Spain) , 2011 .

[14]  L. Siebenaller,et al.  Insights into fluid flow and water-rock interaction during deformation of carbonate sequences in the Mexican fold-thrust belt , 2011 .

[15]  R. Labourdette.  Stratigraphy and static connectivity of braided fluvial deposits of the lower Escanilla Formation, south central Pyrenees, Spain , 2011 .

[16]  K. Bjørlykke.  Petroleum Geoscience: From Sedimentary Environments to Rock Physics , 2011 .

[17]  S. Morad,et al.  Provenance of siliciclastic and hybrid turbiditic arenites of the Eocene Hecho Group, Spanish Pyrenees: implications for the tectonic evolution of a foreland basin , 2010 .

[18]  K. Pickering,et al.  End‐signature of deep‐marine basin‐fill, as a structurally confined low‐gradient clastic system: the Middle Eocene Guaso system, South‐central Spanish Pyrenees , 2009 .

[19]  O. Lacombe,et al.  From outcrop and petrographic studies to basin-scale fluid flow modelling: The use of the Albanian natural laboratory for carbonate reservoir characterisation , 2009 .

[20]  A. Maillard,et al.  Three‐dimensional architecture of submarine slide surfaces and associated soft‐sediment deformation in the Lutetian Sobrarbe deltaic complex (Ainsa, Spanish Pyrenees) , 2009 .

[21]  C. Monnin,et al.  Dolomitic concretions in the Eocene Sobrarbe delta (Spanish Pyrenees): Fluid circulation above a submarine slide scar infilling , 2009 .

[22]  S. Morad.  Carbonate Cementation in Sandstones: Distribution Patterns and Geochemical Evolution , 2009 .

[23]  D. Schrag,et al.  Dolomite formation in the dynamic deep biosphere: results from the Peru Margin , 2007 .

[24]  J. Vergés,et al.  Fluid Systems in Foreland Fold-and-Thrust Belts: An Overview from the Southern Pyrenees , 2007 .

[25]  H. Strauss,et al.  Insights from stable S and O isotopes into biogeochemical processes and genesis of Lower Cambrian barite-pyrite concretions of South China , 2006 .

[26]  M. J. Pearson,et al.  Jurassic septarian concretions from NW Scotland record interdependent bacterial, physical and chemical processes of marine mudrock diagenesis , 2006 .

[27]  Kai W. Wirtz,et al.  Cretaceous black shales as active bioreactors: A biogeochemical model for the deep biosphere encountered during ODP Leg 207 (Demerara Rise) , 2006 .

[28]  M. Malo,et al.  Multiple origin and regional significance of bedding parallel veins in a fold and thrust belt: The example of a carbonate slice along the Appalachian structural front , 2005 .

[29]  K. Pickering,et al.  Mass-Transport Complexes (MTCs) and Tectonic Control on Basin-Floor Submarine Fans, Middle Eocene, South Spanish Pyrenees , 2005 .

[30]  M. J. Pearson,et al.  Fatty acids in sparry calcite fracture fills and microsparite cement of septarian diagenetic concretions , 2005 .

[31]  S. Bernasconi,et al.  Calibration of the δ18O paleothermometer for dolomite precipitated in microbial cultures and natural environments , 2005 .

[32]  J. Muñoz,et al.  Three-dimensional reconstruction of geological surfaces: An example of growth strata and turbidite systems from the Ainsa basin (Pyrenees, Spain) , 2004 .

[33]  J. Hanor.  A Model for the Origin of Large Carbonate- and Evaporite-Hosted Celestine (SrSO4) Deposits , 2004 .

[34]  R. Bakker.  Package FLUIDS 1. Computer programs for analysis of fluid inclusion data and for modelling bulk fluid properties , 2003 .

[35]  S. Morad,et al.  Distribution of Diagenetic Alterations in Fluvial, Deltaic, and Shallow Marine Sandstones Within a Sequence Stratigraphic Framework: Evidence from the Mullaghmore Formation (Carboniferous), Nw Ireland , 2002 .

[36]  J. Hendry.  Geochemical trends and palaeohydrological significance of shallow burial calcite and ankerite cements in Middle Jurassic strata on the East Midlands Shelf (onshore UK) , 2002 .

[37]  M. Thirlwall,et al.  Celestite formation, bacterial sulphate reduction and carbonate cementation of Eocene reefs and basinal sediments (Igualada, NE Spain) , 2002 .

[38]  L. Sloan,et al.  Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present , 2001, Science.

[39]  B. Pratt.  Septarian concretions: internal cracking caused by synsedimentary earthquakes , 2001 .

[40]  R. Howarth,et al.  Strontium Isotope Stratigraphy: LOWESS Version 3: Best Fit to the Marine Sr‐Isotope Curve for 0–509 Ma and Accompanying Look‐up Table for Deriving Numerical Age , 2001, The Journal of Geology.

[41]  J. M. Carmona,et al.  Fluid flow processes at basin scale , 2001 .

[42]  C. Pin,et al.  Middle/Late Cambrian intracontinental rifting in the central West Sudetes, NE Bohemian Massif (Czech Republic): geochemistry and petrogenesis of the bimodal metavolcanic rocks , 2001 .

[43]  M. Talbot,et al.  The sequence stratigraphic framework of carbonate diagenesis within transgressive fan-delta deposits: Sant Llorenç del Munt fan-delta complex, SE Ebro Basin, NE Spain , 2000 .

[44]  João Marcelo Ketzer,et al.  Spatial and temporal distribution of diagenetic alterations in siliciclastic rocks: implications for mass transfer in sedimentary basins , 2000 .

[45]  Q. Fisher,et al.  Mudrock‐hosted carbonate concretions: a review of growth mechanisms and their influence on chemical and isotopic composition , 2000, Journal of the Geological Society.

[46]  J. Hanor.  Barite–Celestine Geochemistry and Environments of Formation , 2000 .

[47]  S. Mazzullo.  Organogenic Dolomitization in Peritidal to Deep-Sea Sediments , 2000 .

[48]  P. Arbués,et al.  Architecture of the tectonically influenced Sobrarbe deltaic complex in the Ainsa Basin, northern Spain , 1999 .

[49]  C. Taberner,et al.  Coral reef diagenesis records pore-fluid evolution and paleohydrology of a siliciclastic basin margin succession (Eocene South Pyrenean foreland basin, northeastern Spain) , 1999 .

[50]  C. Monnin,et al.  A thermodynamic model for the solubility of barite and celestite in electrolyte solutions and seawater to 200°C and to 1 kbar , 1999 .

[51]  A. Paytan,et al.  Sulfur isotopic composition of cenozoic seawater sulfate , 1998, Science.

[52]  C. Marignac,et al.  The H 2 O-NaCl-MgCl 2 ternary phase diagram with special application to fluid inclusion studies , 1997 .

[53]  C. Curtis.  Post-depositional evolution of mudstones l: early days and parental influences , 1995, Journal of the Geological Society.

[54]  C. Ayora,et al.  Modeling the sulfur and oxygen isotopic composition of sulfates through a halite-potash sequence: Implications for the hydrological evolution of the Upper Eocene Southpyrenean Basin , 1995 .

[55]  R. Goldstein,et al.  Systematics of fluid inclusions in diagenetic minerals , 1994 .

[56]  J. Pueyo,et al.  Oxygen and sulphur isotope compositions as indicators of the origin of Mesozoic and Cenozoic evaporites from Spain , 1992 .

[57]  J. Edmond,et al.  Controls over the strontium isotope composition of river water , 1992 .

[58]  J. Muñoz.  Evolution of a continental collision belt: ECORS-Pyrenees crustal balanced cross-section , 1992 .

[59]  H. Shaw,et al.  Diagenesis of Namurian fluvio-deltaic sandstones from the Trumfleet Field, South Yorkshire , 1991 .

[60]  P. Scholle,et al.  Origin of Major Karst-Associated Celestite Mineralization in Karstryggen, Central East Greenland , 1990 .

[61]  R. Bodnar,et al.  The system NaClCaCl2H2O: I. The ice liquidus at 1 atm total pressure , 1990 .

[62]  R. Bodnar,et al.  Systematics of stretching of fluid inclusions; II, Barite at 1 atm confining pressure , 1988 .

[63]  R. Aller,et al.  Evidence for localized enhancement of biological associated with tube and burrow structures in deep-sea sediments at the HEEBLE site, western North Atlantic , 1986 .

[64]  S. Sheppard,et al.  An isotopic study of siderites, dolomites and ankerites at high temperatures☆ , 1986 .

[65]  Jack Oliver,et al.  Fluids expelled tectonically from orogenic belts: Their role in hydrocarbon migration and other geologic phenomena , 1986 .

[66]  H. Brumsack.  The inorganic geochemistry of Cretaceous black shales (DSDP Leg 41) in comparison to modern upwelling sediments from the Gulf of California , 1986, Geological Society, London, Special Publications.

[67]  H. Krouse,et al.  Isotope composition of sulphates generated by bacterial and abiological oxidation , 1985, Nature.

[68]  D. Hammond,et al.  Early oxidation of organic matter in pelagic sediments of the eastern equatorial Atlantic: suboxic diagenesis , 1979 .

[69]  M. Coleman,et al.  Isotopic evidence for source of diagenetic carbonates formed during burial of organic-rich sediments , 1977, Nature.

[70]  J. R. O'neil,et al.  Compilation of stable isotope fractionation factors of geochemical interest , 1977 .

[71]  N. Shackleton,et al.  Paleotemperature History of the Cenozoic and the Initiation of Antarctic Glaciation: Oxygen and Carbon Isotope Analyses in DSDP Sites 277, 279 and 281 , 1975 .