“…2 and 3) indicate syntectonic deposition of growth strata with deposition occurring above a fault-propagation fold . Growth strata and associated progressive unconformities have been recognized in similar deposits to the SW and NE of Rodamunts (Anadón et al, 1986;Lawton et al, 1999;Lopez-Blanco, 2002).…”
Section: Stratigraphy and Structural Geologymentioning
confidence: 89%
“…resampled and reanalyzed the magnetostratigraphy of a similar interval at a higher density than was reported in Jones (1997) and added an additional overlying section of interfingering deposits of the Guadalope-Matarranya fluvial system (Fig. 5, Anadón et al, 1989;Jones, 1997;, which composes a fundamentally different depositional system that debouched sediment into the southern Ebro basin near the Linking Zone-CCR syntaxis ∼50 km to the southwest (Anadón et al, 1986(Anadón et al, , 1989. This effort resulted in a significantly different LMPS that Jones et al used to reinterpret short-term variations in sedimentation rates without diverging from the previous overall age range of the foreland basin succession (ca.…”
Section: Stratigraphy and Structural Geologymentioning
confidence: 96%
“…The Ebro basin formed concurrently with uplift and crustal shortening attributed to the Late CretaceousPaleogene collision of Iberia with western Europe and deformation in the Pyrenean, Iberian and CCR of northeastern Spain (Anadón et al, 1986;Lopez-Blanco, 2002). This deformation was partly coincident with 35°of anticlockwise rotation that translated the Iberian Peninsula from its Cretaceous position west of France to its current location via rotational opening of the Bay of Biscay (Srivastava et al, 1990;Roest and Srivastava, 1991).…”
Section: Plate Tectonics Thrust Belts and Basin Formationmentioning
confidence: 98%
“…Although the Pyrenees have been the focus of Iberia-Europe convergence, broadly coeval deformation is recorded by cross-cutting relationships and growth strata in the CCR (Anadón et al, 1985(Anadón et al, , 1986Lawton et al, 1999), and suggests a complicated Paleogene deformational regime in northern Iberia. The CCR may have developed contemporaneously with the Pyrenees (Zoetemeijer et al, 1990;García-Castellanos et al, 2003) by intraplate deformation along pre-existing crustal weaknesses associated with Mesozoic rift-basins (Gaspar-Escribano et al, 2004).…”
Section: Plate Tectonics Thrust Belts and Basin Formationmentioning
confidence: 99%
“…Variations in thrust-belt structural style and kinematic history can introduce along-strike age gradients in synorogenic strata (Butler et al, 2001;Nichols, 2002). Growth structures, which are common in alluvial-fan strata, often contain local intraformational unconformities (Anadón et al, 1986;DeCelles et al, 1991b;Lawton et al, 1999;. Despite these hazards, numerous researchers have utilized alluvial-fan magnetostratigraphy to develop sedimentary histories and theoretical models by assuming lateral continuity and chronostratigraphic significance of proximal strata.…”
Alluvial-fan strata contain valuable proxy data for kinematic, climatic and sediment-flux phenomena associated with high-relief source regions. Proper application of this data is dependent upon acquisition of accurate high-resolution chronostratigraphic data, best achieved through magnetostratigraphy. Collection of magnetostratigraphic and other proxy data from composite alluvial-fan sections assumes the chronostratigraphic significance of lithostratigraphy. We present the first test of this assumption with new magnetostratigraphy collected from Paleogene rocks of the southeastern Ebro basin. We report five new magnetostratigraphic sections that collectively sample 850 m of alluvial-fan and associated fluvial strata. One-hundred meters of lithostratigraphic overlap between these sections reveals equivalent magnetic polarities over short along-strike distances (∼200-2000 m). However, lithostratigraphic correlation of these sections with the magnetostratigraphy of continuously exposed strata eight km away reveals discrepancies in magnetic polarity trends and age interpretations.Correlation of our 760 m composite magnetostratigraphic section with the Paleogene geomagnetic polarity time scale suggests that this section spans from ca. 31.3 to 27.7 Ma (C12r-C9n; early to late Oligocene). This correlation implies steady sedimentation rates of ∼12 cm/ka for fluvial facies and ∼32 cm/ka for alluvial-fan facies. Alternative interpretations that force chronostratigraphic correlation with the lithostratigraphically equivalent interval generate unsteady and/or unlikely sedimentation rates in one or both of the stratigraphies and require rejection of multiple well-constrained polarity zones. The absence of significant surfaces of erosion or paleosol development argue against these alternative interpretations and suggest that even in the best exposed study areas, alluvial-fan successions may be diachronous and preclude lateral extrapolation of chronostratigraphic and other proxy data. Interpretations and models based upon data collected from alluvial-fan strata may be tenuous unless supported by sufficient spatial overlap to constrain the relationship between time surfaces and rock surfaces.
“…2 and 3) indicate syntectonic deposition of growth strata with deposition occurring above a fault-propagation fold . Growth strata and associated progressive unconformities have been recognized in similar deposits to the SW and NE of Rodamunts (Anadón et al, 1986;Lawton et al, 1999;Lopez-Blanco, 2002).…”
Section: Stratigraphy and Structural Geologymentioning
confidence: 89%
“…resampled and reanalyzed the magnetostratigraphy of a similar interval at a higher density than was reported in Jones (1997) and added an additional overlying section of interfingering deposits of the Guadalope-Matarranya fluvial system (Fig. 5, Anadón et al, 1989;Jones, 1997;, which composes a fundamentally different depositional system that debouched sediment into the southern Ebro basin near the Linking Zone-CCR syntaxis ∼50 km to the southwest (Anadón et al, 1986(Anadón et al, , 1989. This effort resulted in a significantly different LMPS that Jones et al used to reinterpret short-term variations in sedimentation rates without diverging from the previous overall age range of the foreland basin succession (ca.…”
Section: Stratigraphy and Structural Geologymentioning
confidence: 96%
“…The Ebro basin formed concurrently with uplift and crustal shortening attributed to the Late CretaceousPaleogene collision of Iberia with western Europe and deformation in the Pyrenean, Iberian and CCR of northeastern Spain (Anadón et al, 1986;Lopez-Blanco, 2002). This deformation was partly coincident with 35°of anticlockwise rotation that translated the Iberian Peninsula from its Cretaceous position west of France to its current location via rotational opening of the Bay of Biscay (Srivastava et al, 1990;Roest and Srivastava, 1991).…”
Section: Plate Tectonics Thrust Belts and Basin Formationmentioning
confidence: 98%
“…Although the Pyrenees have been the focus of Iberia-Europe convergence, broadly coeval deformation is recorded by cross-cutting relationships and growth strata in the CCR (Anadón et al, 1985(Anadón et al, , 1986Lawton et al, 1999), and suggests a complicated Paleogene deformational regime in northern Iberia. The CCR may have developed contemporaneously with the Pyrenees (Zoetemeijer et al, 1990;García-Castellanos et al, 2003) by intraplate deformation along pre-existing crustal weaknesses associated with Mesozoic rift-basins (Gaspar-Escribano et al, 2004).…”
Section: Plate Tectonics Thrust Belts and Basin Formationmentioning
confidence: 99%
“…Variations in thrust-belt structural style and kinematic history can introduce along-strike age gradients in synorogenic strata (Butler et al, 2001;Nichols, 2002). Growth structures, which are common in alluvial-fan strata, often contain local intraformational unconformities (Anadón et al, 1986;DeCelles et al, 1991b;Lawton et al, 1999;. Despite these hazards, numerous researchers have utilized alluvial-fan magnetostratigraphy to develop sedimentary histories and theoretical models by assuming lateral continuity and chronostratigraphic significance of proximal strata.…”
Alluvial-fan strata contain valuable proxy data for kinematic, climatic and sediment-flux phenomena associated with high-relief source regions. Proper application of this data is dependent upon acquisition of accurate high-resolution chronostratigraphic data, best achieved through magnetostratigraphy. Collection of magnetostratigraphic and other proxy data from composite alluvial-fan sections assumes the chronostratigraphic significance of lithostratigraphy. We present the first test of this assumption with new magnetostratigraphy collected from Paleogene rocks of the southeastern Ebro basin. We report five new magnetostratigraphic sections that collectively sample 850 m of alluvial-fan and associated fluvial strata. One-hundred meters of lithostratigraphic overlap between these sections reveals equivalent magnetic polarities over short along-strike distances (∼200-2000 m). However, lithostratigraphic correlation of these sections with the magnetostratigraphy of continuously exposed strata eight km away reveals discrepancies in magnetic polarity trends and age interpretations.Correlation of our 760 m composite magnetostratigraphic section with the Paleogene geomagnetic polarity time scale suggests that this section spans from ca. 31.3 to 27.7 Ma (C12r-C9n; early to late Oligocene). This correlation implies steady sedimentation rates of ∼12 cm/ka for fluvial facies and ∼32 cm/ka for alluvial-fan facies. Alternative interpretations that force chronostratigraphic correlation with the lithostratigraphically equivalent interval generate unsteady and/or unlikely sedimentation rates in one or both of the stratigraphies and require rejection of multiple well-constrained polarity zones. The absence of significant surfaces of erosion or paleosol development argue against these alternative interpretations and suggest that even in the best exposed study areas, alluvial-fan successions may be diachronous and preclude lateral extrapolation of chronostratigraphic and other proxy data. Interpretations and models based upon data collected from alluvial-fan strata may be tenuous unless supported by sufficient spatial overlap to constrain the relationship between time surfaces and rock surfaces.
The temporal evolution of the Zagros Simply Folded Belt is constrained by a magnetostratigraphic sequence containing a progressive unconformity on the southern limb of the Kuh-e Ghol Ghol anticline, in the Central Fars. The investigated~1400 m thick sequence exposes a regressive megacycle containing, from bottom to top, open and shallow marine marls and sandy limestones, fine-to coarse-grained fluvial deposits and alluvial conglomerates. Correlating the magnetostratigraphic section with the geomagnetic polarity time scale constrains the transition from marine to fluvial sediment deposition at~6 Ma. This transition was accompanied by a change in the accumulation rate from~15 cm/ka to~40 cm/ka, as measured on lithified sediments. Alluvial river deposits first occurred at~3.2 Ma. The Kuh-e Ghol Ghol anticline began to grow at~3.8 Ma, witnessing fastest limb rotation rates of 40°/Ma at~3.3 Ma. Reporting magnetostratigraphic sections and ages of growth strata on a map of NE Fars reveal an~1 cm/a, southwestward migration rate of the deformation front during the middle and late Miocene.
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