Paralic parasequences associated with Eocene sea-level oscillations in an active margin setting: Trihueco Formation of the Arauco Basin, Chile

Roux, J.P. Le; Elgueta, Sara

doi:10.1016/s0037-0738(96)00086-3

Cited by 15 publications

(5 citation statements)

References 14 publications

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“…Similar facies have been interpreted as washover deposits in ancient barrier complexes (Noe-Nygaard and Surlyk, 1988;Le Roux and Elgueta, 1997). On the other hand, homogeneous or mottled sandy mud, comparable to the sandy lime mudstones mentioned above, is found in the muddy 'swampy areas' (Shepard and Moore, 1955) or 'stagnant outer fringe zone' of hurricane washover fans (e.g., on St. Joseph Island, Texas; Andrews, 1970), which are covered by a maze of permanent ponds and creeks surrounded by dense growth of typical marsh plants.…”

Section: Backbarrier Lagoon Deposits (Fa 4)mentioning

confidence: 69%

Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees

Díaz-Molina¹,

Kälin²,

Benito³

et al. 2007

Sedimentary Geology

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Section: Backbarrier Lagoon Deposits (Fa 4)mentioning

confidence: 69%

Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees

Díaz-Molina¹,

Kälin²,

Benito³

et al. 2007

Sedimentary Geology

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“…The Arauco Basin contains over 3 km of late Cretaceous to Holocene continental and marine sediments, and has been a major center of coal mining and hydrocarbon exploration for over a century. This depocenter includes the Campanian to Maastrichtian Quiriquina Formation, the Paleocene to Eocene synextensional Lebu Group, the late Miocene to early Pliocene synextensional Ranquil Formation, and the late Pliocene to Pleistocene syncontractional Tubul Formation [e.g., Biró , 1979; Elgueta and Arcos , 1994; Encinas et al , 2008; Finger et al , 2007; Le Roux and Elgueta , 1997; Melnick and Echtler , 2006a; Pineda , 1986] (Figure 2b). During Miocene to early Pliocene time, low amounts of trench fill and high plate convergence velocity caused subduction erosion resulting in over 1.5 km of fore‐arc subsidence and synextensional deposition of the Ranquil Formation, comprising mainly lower bathyal turbidites [ Encinas et al , 2008; Finger et al , 2007; Melnick and Echtler , 2006a].…”

Section: Seismotectonic Geologic and Geomorphic Settingmentioning

confidence: 99%

Segmentation of megathrust rupture zones from fore‐arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile

et al. 2009

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[1] This work explores the control of fore-arc structure on segmentation of megathrust earthquake ruptures using coastal geomorphic markers. The Arauco-Nahuelbuta region at the south-central Chile margin constitutes an anomalous fore-arc sector in terms of topography, geology, and exhumation, located within the overlap between the Concepción and Valdivia megathrust segments. This boundary, however, is only based on $500 years of historical records. We integrate deformed marine terraces dated by cosmogenic nuclides, syntectonic sediments, published fission track data, seismic reflection profiles, and microseismicity to analyze this earthquake boundary over 10 2 -10 6 years. Rapid exhumation of Nahuelbuta's dome-like core started at 4 ± 1.2 Ma, coeval with inversion of the adjacent Arauco basin resulting in emergence of the Arauco peninsula. Here, similarities between topography, spatiotemporal trends in fission track ages, Pliocene-Pleistocene growth strata, and folded marine terraces suggest that margin-parallel shortening has dominated since Pliocene time. This shortening likely results from translation of a fore-arc sliver or microplate, decoupled from South America by an intra-arc strike-slip fault. Microplate collision against a buttress leads to localized uplift at Arauco accrued by deep-seated reverse faults, as well as incipient oroclinal bending. The extent of the Valdivia segment, which ruptured last in 1960 with an M w 9.5 event, equals the inferred microplate. We propose that mechanical homogeneity of the fore-arc microplate delimits the Valdivia segment and that a marked discontinuity in the continental basement at Arauco acts as an inhomogeneous barrier controlling nucleation and propagation of 1960-type ruptures. As microplate-related deformation occurs since the Pliocene, we propose that this earthquake boundary and the extent of the Valdivia segment are spatially stable seismotectonic features at million year scale.Citation: Melnick, D., B. Bookhagen, M. R. Strecker, and H. P. Echtler (2009), Segmentation of megathrust rupture zones from fore-arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile,

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“…Isla Santa María is in the Coastal Platform, part of the Arauco Basin, a late Cretaceous to Quaternary forearc depocenter fi lled with at least 3.1 km of marine and continental sediments, as revealed by ENAP exploration wells (Mordojovich, 1981;González, 1989;Elgueta and Arcos, 1994). The Arauco Basin contains the Campanian to Maastrichtian Quiriquina Formation, the Paleocene to Eocene Lebu Group, the late Miocene to early Pliocene Ranquil Formation, and the late Pliocene to Pleistocene Tubul Formation (e.g., Biró, 1979;Pineda, 1986;Elgueta and Arcos, 1994;Le Roux and Elgueta, 1997;Finger et al, 2006) ( Fig. 2A).…”

Section: Regional Tectonic and Geologic Settingmentioning

confidence: 99%

Coastal deformation and great subduction earthquakes, Isla Santa Maria, Chile (37 S)

Melnick

Bookhagen

Echtler

et al. 2006

Geological Society of America Bulletin

121

158

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Isla Santa María at the active margin of south-central Chile is the result of earthquake-related uplift and deformation in the forearc since at least late Pleistocene time. Field mapping, dating of key depositional horizons, and analysis of seismic-refl ection profi les reveal ongoing deformation in this sector of the Chilean forearc. The 30 km 2 island is located ~12 km above the interplate seismogenic zone and 75 km landward of the trench. It is situated near the southern termination of the Concepción earthquake rupture segment, where Charles Darwin measured 3 m of coseismic uplift during a M > 8 megathrust earthquake in 1835. Permanent postearthquake deformation from this earthquake and an earlier event in 1751 is registered by emerged, landward-tilted abrasion surfaces. Uplift at ~2 m/k.y. and tilting at ~0.025°/k.y. of the island have been fairly constant throughout the late Quaternary and have resulted in emergence of the island above sea level ~31 k.y. ago. The island is composed of a late Pleistocene upper, tilted surface with two asymmetric tilt domains, and Holocene lowlands characterized by uplifted and tilted strandlines. Industry offshore seismic-refl ection profi les covering an area of ~1800 km 2 and crustal seismicity reveal active reversefault cored anticlines surrounding Isla Santa María; the principal fault apparently roots in the plate-interface thrust. These reverse faults in the upper plate result from inversion of late Cretaceous to early Pliocene normal faults and rift structure of the Arauco forearc basin. Positive inversion of these inherited structures started between 3.6 and 2.5 Ma and resulted in continuous shortening rates of ~0.8 mm/yr. The seismic-refl ection profi les show that the asymmetric tilt domains and progressive syntectonic sedimentation are linked to the position of the island in the forelimbs of two converging anticlines, whereas their backlimbs have been removed by cliff retreat. The 2 m uplift contour of the 1835 earthquake is parallel to the strike of active faults and antiforms in the Arauco-Concepción region. The close relation among the asymmetric uplift and tilt of the island, modern deformation patterns, and reverse faults rooted in the plate interface suggests that slip on the plate interface thrust infl uences, localizes, and segments surface deformation during large interplate earthquakes. Furthermore, the link between positive inversion of pre-existing structures, uplift, and tilt patterns in the forearc emphasizes the importance of inherited structural fabrics in guiding plate-boundary deformation.

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Paralic parasequences associated with Eocene sea-level oscillations in an active margin setting: Trihueco Formation of the Arauco Basin, Chile

Cited by 15 publications

References 14 publications

Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees

Depositional setting and early diagenesis of the dinosaur eggshell-bearing Aren Fm at Bastus, Late Campanian, south-central Pyrenees

Segmentation of megathrust rupture zones from fore‐arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile

Coastal deformation and great subduction earthquakes, Isla Santa Maria, Chile (37 S)

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