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Vargas Formation

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Journal Article
Journal: GSA Bulletin
Published: 01 April 1993
GSA Bulletin (1993) 105 (4): 547–562.
...DOUGLAS P. SMITH; CATHY J. BUSBY Abstract Marine, mid-Cretaceous fore-arc strata on Cedros Island (Vargas and Pinos Formations) record the onset of extensional brittle deformation of the upper crust concomitant with initial uplift of blueschist-grade rock from great depth. The pre-extensional...
Journal Article
Published: 01 September 2002
Bulletin de la Société Géologique de France (2002) 173 (5): 407–414.
... Paraguay. The sedimentology and palynology have been studied in three boreholes from the central part of Paraguay. The Itacurubí Group consists of the Euzébio Ayala, Vargas Peña and Cariy Formations. It corresponds to a complete transgressive – regressive cycle with maximum flooding in the Vargas Peña...
Journal Article
Published: 18 September 2018
Journal of Paleontology (2019) 93 (1): 37–47.
...M. Cichowolski; N.J. Uriz; M.B. Alfaro; J.C. Galeano Inchausti Abstract Ascocerid cephalopods are described for the first time from high paleolatitudes of Gondwana. Studied material was collected from the Hirnantian?–Llandovery strata of the Eusebio Ayala and Vargas Peña formations, Paraná Basin...
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First thumbnail for: Ascocerid cephalopods from the Hirnantian?–Llandov...
Second thumbnail for: Ascocerid cephalopods from the Hirnantian?–Llandov...
Third thumbnail for: Ascocerid cephalopods from the Hirnantian?–Llandov...
Journal Article
Published: 01 November 2006
Journal of Paleontology (2006) 80 (6): 1152–1171.
.... With a growing understanding of the fairly limited range of true intraspecific variation evident in large silicified samples, a species from the Windfall Formation previously ( Adrain and Westrop, 2004 ) assigned to varga can now be confidently discriminated based on considerably narrower anterior areas...
FIGURES
First thumbnail for: NOTCHPEAKIA , A NEW GENUS OF UPPER CAMBRIAN (SUNWA...
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Image
(1–7) ?Probillingsitinae Flower, 1941 gen. et sp. indet. from the Paraná Basin. (1, 2) MLP 35795 from the Vargas Peña Formation, San Fernando Quarry, Llandovery Stage; (1) rock with specimens in a positive, showing 35795 consisting in both parts of the conch slightly displaced. Arrow points to the proposed septum of truncation; (2) counterpart of (1); (3–5) MLP 35796 from the Eusebio Ayala Formation, Santa Elena Quarry, Hirnantian?–early Llandovery stages; (3) internal mold of the brevicone with the beginning of the cyrtocone attached before removing the matrix and breakage; arrows point to possible sutures, posterior one could correspond to the septum of truncation, the other could be related to a sigmoid suture; (4) external mold of the brevicone showing the probable septum of truncation and part of the cyrtocone attached, with siphuncle visible as cavities of the segments; (5) external mold of the brevicone of the other side (after removing the internal mold) showing the mark of the possible septum of truncation and other lines and fractures that make the interpretation difficult; (6, 7) MLP 35797 from the Eusebio Ayala Formation, Santa Elena Quarry, Hirnantian?–early Llandovery stages; (6) external mold of a probable isolated cyrtocone, representing the juvenile portion of an ascocerid; (7) counterpart of (6) with part of the internal mold hosted with the external mold. Note the straight sutures. Scale bars = 1 cm.
Published: 18 September 2018
Figure 4. ( 1–7 ) ?Probillingsitinae Flower, 1941 gen. et sp. indet. from the Paraná Basin. ( 1, 2 ) MLP 35795 from the Vargas Peña Formation, San Fernando Quarry, Llandovery Stage; ( 1 ) rock with specimens in a positive, showing 35795 consisting in both parts of the conch slightly displaced
Image
Photos of field exposures and thin sections of Cape Vargas rocks. a, Photo of thin section and BSE image (inset) of metamorphosed mafic rock, in which garnet retained omphacite; indices near Omp and Cpx show the Jd content at the site of clinopyroxene analysis (mol.%); b, undeformed part of the metagabbro dike from which geochronological sample D17-1 was taken; c, photo of a thin section of a Grt–Cpx–Pl rock at the boundary of a phengite-bearing leucosome (sampling site is shown in panel e; compositions of coexisting minerals are shown in Table 3); numbers near the minerals correspond to the number of the microprobe analysis in thin section, Table 3; d, photo of a deformed and migmatized metagabbro dike; e, part of the metagabbro dike penetrated by veinlets of the phengite-bearing leucosome from which geochronological sample D17-4 was taken; f, BSE image of the phengite-bearing leucosome; indices near Ph and Bt show Fe/(Fe + Mg) at the site of phengite or biotite analysis. Note the recrystallization of primary phengite with the formation of a quartz–phengite aggregate.
Published: 01 October 2012
Fig. 8. Photos of field exposures and thin sections of Cape Vargas rocks. a , Photo of thin section and BSE image (inset) of metamorphosed mafic rock, in which garnet retained omphacite; indices near Omp and Cpx show the Jd content at the site of clinopyroxene analysis (mol.%); b , undeformed
Journal Article
Journal: Interpretation
Published: 09 April 2025
Interpretation (2025) 13 (2): SA47–SA67.
...Carlos Alberto Vargas; Alexander Caneva; Carlos Augusto Zuluaga Abstract Serpentine bodies, primarily formed through the hydration of mafic and ultramafic rocks, exhibit distinctive geophysical properties in the convergent margin of NW South America. This region features a complex subduction zone...
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First thumbnail for: Unraveling the depths: Serpentinite distribution a...
Second thumbnail for: Unraveling the depths: Serpentinite distribution a...
Third thumbnail for: Unraveling the depths: Serpentinite distribution a...
Journal Article
Journal: GSA Bulletin
Published: 11 July 2025
GSA Bulletin (2025)
..., flattening of the subducting slab, chocking of subduction, and the formation of a new subduction zone) in the global subduction system (Espurt et al., 2008; Timm et al., 2014; Levin et al., 2021; Hines et al., 2023; Fan et al., 2022; Taylor and Benyshek, 2024). Recent geophysical studies have shown...
Journal Article
Published: 01 November 1995
Journal of the Geological Society (1995) 152 (6): 923–932.
..., hydrother- mal alteration. A shallow detachment, at the base of the sheeted ykes (Moores et al. 1990; Varga 1991) indicates the presence of a shallow brittle-ductile transition zone which implies formation of the graben in hot (i.e. on-axis), young crust. The abrupt change in orientation between domains 2...
Journal Article
Journal: Geology
Published: 01 September 2013
Geology (2013) 41 (9): 1011–1014.
... the Kyushu-Palau Ridge immediately to the east ( Ishizuka et al., 2011a ). The Philippine Sea plate in the western Pacific Ocean has been a target for investigations into the formation and evolution of intraoceanic arc-backarc systems (e.g., Hilde and Lee, 1984 ; Okino et al., 1999 ; Deschamps...
FIGURES
First thumbnail for: Upwelling, rifting, and age-progressive magmatism ...
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Journal Article
Journal: Palynology
Published: 01 January 2000
Palynology (2000) 24 (1): 147–176.
... Ayala Formation and underlies the Cariy Formation. Fossils from these predominantly arenaceous sequences are poorly known, but they are in general considered as Silurian s.l . Together with the Vargas Peña Shale they form the Itacurubí Group. The stratigraphic concept of the Silurian of the Paraná...
FIGURES
First thumbnail for: SILURIAN AND LOWER DEVONIAN CHITINOZOAN BIOSTRATIG...
Second thumbnail for: SILURIAN AND LOWER DEVONIAN CHITINOZOAN BIOSTRATIG...
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Journal Article
Journal: GSA Bulletin
Published: 17 November 2020
GSA Bulletin (2021) 133 (7-8): 1421–1440.
...Ryan J. Waldman; Kathleen M. Marsaglia; Rosemary Hickey-Vargas; Osamu Ishizuka; Kyle E. Johnson; Anders McCarthy; Gene Yogodzinski; Eshita Samajpati; He Li; Kate Laxton; Ivan P. Savov; Sebastien Meffre; Richard J. Arculus; Alexandre N. Bandini; Andrew P. Barth; Kara Bogus; Philipp A. Brandl...
FIGURES
First thumbnail for: Sedimentary and volcanic record of the nascent Izu...
Second thumbnail for: Sedimentary and volcanic record of the nascent Izu...
Third thumbnail for: Sedimentary and volcanic record of the nascent Izu...
Journal Article
Journal: Geosphere
Published: 28 December 2017
Geosphere (2018) 14 (1): 1–22.
... lithologies, and serpentinized peridotites is found in mélanges and the deep roots of overthrust oceanic terranes. In mélanges, such as the Catalina schist and Franciscan Formation in California, variably metamorphosed lower-plate rocks become interspersed within matrices derived from ultramafic...
FIGURES
First thumbnail for: Geodynamic implications of crustal lithologies fro...
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Journal Article
Published: 01 October 2012
Russ. Geol. Geophys. (2012) 53 (10): 1023–1054.
...Fig. 8. Photos of field exposures and thin sections of Cape Vargas rocks. a , Photo of thin section and BSE image (inset) of metamorphosed mafic rock, in which garnet retained omphacite; indices near Omp and Cpx show the Jd content at the site of clinopyroxene analysis (mol.%); b , undeformed...
FIGURES
First thumbnail for: The Belomorian eclogite province: sequence of even...
Second thumbnail for: The Belomorian eclogite province: sequence of even...
Third thumbnail for: The Belomorian eclogite province: sequence of even...
Journal Article
Published: 01 October 2014
Journal of Sedimentary Research (2014) 84 (10): 897–909.
...Valentina Flores-Aqueveque; Gabriel Vargas; Stephane Alfaro; Sandrine Caquineau; Jorge Valdés A bstract : Lithic particles in marine laminated sediments provide the opportunity to reconstruct ocean-climate processes like wind dynamics from the sedimentary record. In Mejillones Bay (23° S), located...
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First thumbnail for: Assessing the Origin and Variability of Eolian Lit...
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Journal Article
Published: 01 July 2006
Geological Magazine (2006) 143 (4): 509–529.
... deichaii ) from the type locality of the Vargas Peña Formation. An additional assemblage was discussed by Wood & Miller (1997) . Ordovician and Silurian chitinozoans from Brazil are well known and described from the Solimões, Amazonas, Parníba and Paraná basins. Published information...
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First thumbnail for: Ordovician and Silurian chitinozoan biozones of we...
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Journal Article
Journal: Geology
Published: 16 January 2024
Geology (2024) 52 (3): 210–215.
.... , Morrissey , L. , Kelsey , D.E. , and Hand , M. , 2021 , Pressure–temperature–time constraints on gneiss dome formation in an intracontinental orogen : Journal of Metamorphic Geology , v. 40 , p. 457 – 488 , https://doi.org/10.1111/jmg.12635 . Varga , J. , Raimondo , T. , Hand...
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First thumbnail for: From dome to duplex: Convergent gravitational coll...
Second thumbnail for: From dome to duplex: Convergent gravitational coll...
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Journal Article
Published: 01 November 2017
The Journal of Geology (2017) 125 (6): 681–700.
... . Deluca , M. J. 2013 . Thermal evolution and provenance revealed through detrital zircon fission track dating of the Upper Cretaceous Shumagin Formation, Nagai Island Alaska . In Varga , R. J. , ed. Keck Geology Consortium Undergraduate Research Symposium, 26th (Claremont, CA, 2013), Proc...
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First thumbnail for: Age and Origin of the Resurrection Ophiolite and A...
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Journal Article
Published: 03 April 2019
Geological Magazine (2019) 156 (11): 1821–1838.
...Bingshan Ma; Jiafu Qi; Jiawang Ge Abstract We investigate the formation and deformation of transfer zones and their impact on sedimentation during multiphase rifting using a three-dimensional seismic dataset in the Baxian Sag, the onshore part of the Bohai Bay Basin, northern China. The fault...
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First thumbnail for: Development of two-phase transfer zones during mul...
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Series: Geological Society, London, Special Publications
Published: 11 June 2020
DOI: 10.1144/SP500-2019-189
EISBN: 9781786204998
... 1150 From Restrepo and Lopez (2008) . We tested different κ values reported by Mitchell (1996) , McAdoo and Simpson (2005) , Vargas et al. (2012) and Vargas and Idárraga-Garcia (2014) to calculate relative ages associated with the formation of the fault scarps reported in Table...