Special Issue "Continental Accretion and Evolution"
A special issue of Geosciences (ISSN 2076-3263).
Deadline for manuscript submissions: closed (30 April 2013)
Prof. Dr. David A. Foster
Department of Geological Sciences, University of Florida, 241 WIlliamson Hall, P.O. Box 112120, Gainesville, Florida 32611, USA
Phone: +1 3523922241
Interests: tectonics; geochronology; thermochronology; structural geology; continental evolution; isotope geochemistry
Understanding the evolution of the continental crust continues to be a challenge because of the diversity of environments where continental crust and subcontinental lithosphere is formed, recycled, and stabilized. This is further complicated by long-term changes in continental formation and growth processes over geological time, and subsequent modifications to the continents. Advances over recent years have come from large-scale geophysical experiments, improvements analytical methods for in-situ isotopic and elemental analysis of accessory phases, experimental petrology (igneous and metamorphic), and geodynamic modeling. This special issue will focus on the accretion and evolution of continents in the broadest sense including: (1) continental growth from juvenile materials extracted from the mantle; (2) recycling of continental lithosphere through subduction, sediment subduction/accretion, and delamination; (3) continental evolution in convergent margins through arc magmatism and accretion; and (4) role of large igneous provinces and mantle plumes in the evolution and growth continents.
Prof. Dr. David A. Foster
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
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- continental lithosphere
- arc magmatism
- accretionary orogens
- continental crust
- large igneous provinces
- isotope geochemistry
- granitic magmatism
- continental growth
The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.
Title: Continental accretion at the western margin of South America: case study of the Peruvian Andes
Authors: O. Adrian Pfiffner & Laura Gonzalez
Abstract: Based on the structural style and physiographic criteria, the Central Andes of Peru can be divided into five segments running parallel to the Pacific coast. The westernmost segment, the Coastal Belt, consists of a Late Jurassic – Cretaceous volcanic arc sequence that was accreted to the South American craton in the Cretaceous. Its structural style is characterized by relatively open folds that were intruded by the Coastal Batholith in Late Cretaceous times. The Mesozoic strata of the adjacent Western Cordillera represent an ENE-verging fold-and-thrust belt. In its western part, tight upright folds developed above a detachment horizon in the Early Cretaceous shales of the Oyón Formation. In contrast, more open folds are observed in the eastern part of the Western Cordillera and the neighboring Central Highlands. Here the Mesozoic strata are harmonically folded and a detachment occurred possibly along the Devonian phyllites. The folds in the Western Cordillera are connected at depth to NE-verging thrust faults that level off into the detachment horizons. A completely different style with steeply dipping reverse faults and open folds is observed in the Neoproterozoic crystalline basement and the Paleozoic sediments of the Eastern Cordillera. The reverse faults are in part of transpressive nature and uplifted large blocks of basement rocks next to Paleozoic strata. In the Subandean Zone, Paleozoic and Cenozoic strata are affected by mainly NE-verging imbricate thrusting. A quantitative estimate of the shortening of the orogen was obtained from the construction of two transects that run from the Pacific coast to the undeformed Amazonas foreland. Total shortening of the two transects is 120 – 150 km (24 –27%), roughly 80 km of which is taken up by the Western and Eastern Cordilleras and the Central Highlands. This orogenic shortening occurred in the framework of plate convergence whereby more than 3000 km of oceanic lithosphere of the Nazca plate was subducted beneath the South American Plate.
Title: Testing the existence of the South Gobi Microcontinent: Protolith studies of metamorphic tectonites in southeastern Mongolia
Authors: Joshua P. Taylor1, Laura E. Webb2, Cari L. Johnson3, Matthew J. Heumann3
Affiliations: 1 Department of Earth Sciences, 204 Heroy Geology Lab, Syracuse University, Syracuse, NY 13244
2 Department of Geology, University of Vermont, Burlington, VT 05405
3 Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112
Title: Modification of the Continental Crust by Subduction-Zone Magmatism and Vice-Versa: Across-Strike Geochemical Variations of Silicic Lavas At Individual Eruptive Centers In The Andean Central Volcanic Zone
Authors: Todd Feeley
Abstract: In an effort to better understand the origin of across-strike K2O enrichments in volcanic rocks from the Andean Central Volcanic Zone, we compare geochemical and isotopic compositions of Quaternary (<1.0 Ma) silicic lava flows (60–68 wt.% SiO2) erupted from three well-characterized composite volcanoes situated along a northwest striking transect between 21o and 22oS. From northwest to southeast these are Volcáns Aucanqilcha, Ollagüe, and Uturuncu. Aucanqilcha is located on the arc front entirely within Chile; Ollagüe is located ~25 km to the east of the arc front within the transition zone between the arc front and the Bolivian Altiplano; Uturuncu is located ~75 km east of the arc front on the SW Bolivian Altiplano. Trends observed include the following. At a given SiO2 content lavas erupted with increasing distance from the arc front display systematically higher K2O, P2O5, TiO2, Rb, Th, and REE and HFSE contents, Rb/Sr elemental ratios, and Sr isotopic ratios (0.7055 - 0.7165), in addition to more negative Eu anomalies. In contrast, the lavas display systematically decreasing Al2O3, Na2O, Sr, and Ba contents, Ba/Nb, Ba/Zr, K/Rb, and Sr/Y elemental ratios, and Nd isotopic ratios (0.51239 – 0.51214) with distance from the arc front. It is unlikely that the across-arc geochemical variations solely reflect differences in mantle source compositions or degrees of melting for parental magmas given the highly modified isotopic ratios of the lavas relative to primitive intra-oceanic arc magmas, implying extensive contamination by or derivation within the continental crust. Instead, these data favor a model in which lower crustal source rocks for the silicic lavas become progressively older and more feldspar-rich with increasing distance from the arc front. In this regard, our preliminary interpretation is that silicic magmas erupted along the arc front reflect melting of young, mafic composition amphibiotic source rocks with a garnet- (but not feldspar) bearing residual mineralogy and that the lower crust becomes increasingly older with a more felsic bulk composition in which residual mineralogies are progressively more feldspar-rich, but garnet-poor. One implication of this interpretation is that large-scale regional trends in magma compositions at volcanic arcs may reflect a process wherein the continental crust becomes progressively hybridized beneath frontal arc localities due to protracted intrusion of subduction-derived basaltic magmas, with a diminishing effect behind the arc front because of smaller degrees of mantle partial melting and primary melt generation.
Title: Nd isotope mapping of crustal terranes in the Parent-Clova area, Quebec: implications for the evolution of the Laurentian margin in the central Grenville Province
Authors: Mark Zelek and Alan Dickin
Affiliation: School of Geography & Earth Sciences, McMaster University, Hamilton, Ontario; email@example.com
Title: Evaluating magma mixing in evolving continental crust via polytopic vector analysis (PVA): Papagayo tuff, northern Costa Rica
Authors: David Szymanski
Abstract: Magma mixing is a common process in volcanic arcs. Over the last forty years, research has revealed the importance of magma mixing as a trigger for volcanic eruptions, as well as its role in creating the diversity of magma compositions found in most evolved volcanic arcs. Although sensitive isotopic and microchemical techniques reveal subtle evidence of magma mixing in igneous rocks, more robust statistical techniques for bulk chemical data can help evaluate mixing relationships within and among volcanic units. Relatively new to igneous petrology, polytopic vector analysis (PVA) is a multivariate statistical technique that can be used to evaluate suites of samples that are produced by mixing of two or more magma batches.
Title: Slab Extrusion, Crustal Diapirism and Post-Orogenic Melting: a Spectrum of Mechanisms for the Exhumation of Subducted Continental Crust.
Authors: Hannes K. Brueckner
Affiliations: Lamont-Doherty Earth Observatory of Columbia University
Last update: 27 April 2013