GSA Bulletin

Journal: GSA Bulletin

Abbreviation

Geol. Soc. Am. Bull.

Publisher

Geological Society of America

ISSN

0016-7606
1943-2674

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Publications 1 - 10 of 36

The 600 yr eruptive history of Villarrica Volcano (Chile) revealed by annually laminated lake sediments
Van Daele, M.; Moernaut, J.; Silversmit, G.; et al. (2014)
GSA Bulletin
Sediment production and delivery in the Amazon River basin quantified by in situ-produced cosmogenic nuclides and recent river loads
Wittmann, Hella; von Blanckenburg, Friedhelm; Maurice, Laurence; et al. (2011)
GSA Bulletin
Evolution of a terminal Neoproterozoic carbonate ramp system (Buah Formation, Sultanate of Oman)
Cozzi, Andrea; Grotzinger, John P.; Allen, Philip A. (2004)
GSA Bulletin
Cosmogenic Be-10 chronology of the last deglaciation of western Ireland, and implications for sensitivity of the Irish Ice Sheet to climate change
Clark, Jorie; McCabe, A. Marshall; Schnabel, Christoph; et al. (2009)
GSA Bulletin
A waning Saxothuringian Ocean evidenced in the Famennian tephra-bearing siliceous succession of the Bardo Unit (Central Sudetes, SW Poland)
Racki, Grzegorz; Mazur, Stanisław; Narkiewicz, Katarzyna; et al. (2022)
GSA Bulletin
A tephra-rich cherty-clayey Famennian succession within the major Brzeźnica olistostrome in the Bardo Mountains, Central Sudetes, SW Poland, preserves a record of the lost ocean later incorporated into the Variscan orogenic belt. Fluctuating but mostly oligotrophic regimes and low primary production levels were influenced by weak upwelling below the perennial oxygen minimum zone, which controlled the interplay between biosiliceous and siliciclastic deposition in the oceanic basin, with episodic oxygen deficiency. The Hangenberg Black Shale has been identified in this oceanic setting based on its characteristics described worldwide (including mercury enrichments). A tectonic uplift of the sediment source area near the Devonian-Carboniferous boundary, recorded in the distinguishing provenance signal of old continental crust, was paired with a global transgression, anoxia, and volcanic episode in an interglacial interval. Assuming paleogeographic affinity with the Bavarian facies of the Saxothuringian terrane, we interpret the allochthonous sediments as part of an accretionary prism that was gravitationally redeposited into the late orogenic basin in front of advancing Variscan nappes. The oceanic basin parental to the Bardo pelagic succession is therefore thought to represent a tract of the waning Saxothuringian Ocean in the Peri-Gondwanan paleogeographic domain that was eventually subducted beneath the Brunovistulian margin of Laurussia. The sediments of the Bardo Ocean basin also include a distal record of Famennian explosive volcanic activity that was likely related to a continental magmatic arc whose remnants are preserved as the Vrbno Group of the East Sudetes.
Pliocene growth of the Dowlatabad syncline in Frontal Fars arc: Folding propagation across the Zagros Fold Belt, Iran
Najafi, Mahdi; Beamud, Elisabet; Ruh, Jonas; et al. (2021)
GSA Bulletin
The integration of biostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy allowed for the precise dating of the >3.0-km-thick marine to non-marine foreland sedimentary succession within the Dowlatabad growth syncline along the Frontal Fars arc in the Zagros Fold Belt that extends from eastern Turkey to southern Iran. This area was the missing link to complete the dating of syntectonic deposits in the Fars arc and quantify the migration of sedimentary belts as well as the propagation of folding across the entire Mesopotamian foreland basin. Both are essential for defining the interplay of basin evolution and sequence of folding. Deposition of the foreland marine marls in the Mishan Formation started at ca. 11.5 Ma. The transition to a non-marine basin infill occurred at 4.9 Ma by the progradation of thick fluvial deposits of the Aghajari Formation with a fast accumulation rate of 63 cm/k.y. The beginning of growth strata deposition and thus the onset of folding in the Dowlatabad syncline is dated at 4.65 Ma. The first appearance of carbonate conglomerates sourced from the Guri limestone at 2.8 Ma marked the progressive dismantling of the nearby growing anticlines. The tectonic deformation in the front of the Fars arc was active for at least 2.85 m.y. and ceased at 1.8 Ma before the deposition of the discordant and slightly folded Bakhtyari conglomerates characterized by a clast composition derived from the Zagros hinterland. The compilation of magnetostratigraphic ages reveals that both the migration of the Aghajari-Bakhtyari sedimentary belts and the propagation of the folding front was in-sequence toward the foreland at a rate close to 20 mm/yr in the Fars arc and 15 mm/yr in the Lurestan arc, in the last 20 m.y. These high rates of folding propagation are about one order of magnitude larger than age equivalent shortening rates (∼4 mm/yr in Fars arc and ∼2 mm/yr in Lurestan arc) and thus imply an efficient detachment level at the base of the deformed Arabian sedimentary cover. Numerical experiments on both the cover and basement sequences are designed to test the influence of inherited basement structures on the deformation propagation within the cover sequence, providing clues on the partly coeval in-sequence deformation of the Zagros Simply Folded Belt and the local out-of-sequence Mountain Frontal Fault system as illustrated by regional and local geology.
Tethyan magnetostratigraphy from Pizzo Mondello (Sicily) and correlation to the Late Triassic Newark astrochronological polarity time scale
Muttoni, Giovanni; Kent, Dennis V.; Olsen, Paul E.; et al. (2004)
GSA Bulletin
We present the magnetostratigraphy and stable isotope stratigraphy from an expanded (∼430-m-thick) Upper Triassic marine limestone section at Pizzo Mondello, Sicily, and review published biostratigraphic information that can be used to define the location of the conodont Carnian-Norian and Norian-Rhaetian boundaries in this section. Pizzo Mondello offers good potential for magneto-stratigraphic correlation of marine biostratigraphic and chemostratigraphic data with the continental Newark astrochronological polarity time scale (APTS) for development of an integrated Late Triassic time scale. The relatively stable average values of δ18O centered on 0‰ are a strong indication that the Cherty Limestone at Pizzo Mondello suffered very little diagenetic overprinting. The conodont Carnian-Norian boundary is located 12.5 m above a positive shift of δ13C. A statistical approach was applied to evaluate various Pizzo Mondello to Newark magnetostratigraphic correlations. Two correlation options have the highest correlation coefficients. In option #1, the base of Pizzo Mondello correlates with the middle part of the Newark APTS, whereas in option #2, the base of Pizzo Mondello starts toward the early part of the Newark APTS. We prefer option #2 in which the Carnian-Norian boundary based on conodonts, as well as its closely associated positive δ13C shift, correspond to Newark magnetozone E7 at ca. 228–227 Ma (adopting Newark astrochronology), implying a long Norian with a duration of ∼20 m.y., and a Rhaetian of ∼6 m.y. duration. These ages are in fact not inconsistent with the few high-quality radiometric dates that are available for Late Triassic time scale calibration. Based on its good exposure, accessibility, stratigraphic thickness and continuity, and multiple chronostratigraphic correlation possibilities, we propose Pizzo Mondello as global stratigraphic section and point for the base of the Norian. © 2004 Geological Society of America.
The Kumaun and Garwhal Lesser Himalaya, India
Célérier, Julien; Harrison, T. Mark; Beyssac, Olivier; et al. (2009)
GSA Bulletin
Geomorphological evidence and cosmogenic Be-10/Al-26 exposure ages for the Last Glacial Maximum and deglaciation of the Antarctic Peninsula Ice Sheet
Bentley, Michael J.; Fogwill, Christopher J.; Kubik, Peter W.; et al. (2006)
GSA Bulletin
Multiple climatic changes around the Permian-Triassic boundary event revealed by an expanded palynological record from mid-Norway
Hochuli, Peter A.; Vigran, Jorunn Os; Hermann, Elke; et al. (2010)
GSA Bulletin

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