Elsevier

Lithos

Volume 232, 1 September 2015, Pages 306-318
Lithos

Mid-Cretaceous oblique rifting of West Antarctica: Emplacement and rapid cooling of the Fosdick Mountains migmatite-cored gneiss dome

https://doi.org/10.1016/j.lithos.2015.07.005Get rights and content

Highlights

  • 40Ar/39Ar thermochronology records cooling rates of > 100 °C/m.y. for Fosdick dome

  • Emplacement of migmatites and granites in shallow crust preceded rapid cooling

  • Fosdick detachment structures and fabrics record rotation of local strain field due to emplacement within dilatant structure

Abstract

In Marie Byrd Land, West Antarctica, the Fosdick Mountains migmatite-cored gneiss dome was exhumed from mid- to lower middle crustal depths during the incipient stage of the West Antarctic Rift system in the mid-Cretaceous. Prior to and during exhumation, major crustal melting and deformation included transfer and emplacement of voluminous granitic material and numerous intrusions of mantle-derived diorite in dikes. A succession of melt- and magma-related structures formed at temperatures in excess of 665 ± 50 °C based on Ti-in-zircon thermometry. These record a transition from wrench to oblique extensional deformation that culminated in the development of the oblique South Fosdick Detachment zone. Solid-state fabrics within the detachment zone and overprinting brittle structures record translation of the detachment zone and dome to shallow levels.

To determine the duration of exhumation and cooling, we sampled granite and gneisses at high spatial resolution for U–Pb zircon geochronology and 40Ar/39Ar hornblende and biotite thermochronology. U–Pb zircon crystallization ages for the youngest granites are 102 Ma. Three hornblende ages are 103 to 100 Ma and 12 biotite ages are 101 to 99 Ma. All overlap within uncertainty. The coincidence of zircon crystallization ages with 40Ar/39Ar cooling ages indicates cooling rates > 100 °C/m.y. that, when considered together with overprinting structures, indicates rapid exhumation of granite and migmatite from deep to shallow crustal levels within a transcurrent setting. Orientations of structures and age-constrained crosscutting relationships indicate counterclockwise rotation of stretching axes from oblique extension into nearly orthogonal extension with respect to the Marie Byrd Land margin. The rotation may be a result of localized extension arising from unroofing and arching of the Fosdick dome, extensional opening within a pull-apart zone, or changes in plate boundary configuration.

The rapid tectonic and temperature evolution of the Fosdick Mountains dome lends support to recently developed numerical models of crustal flow and cooling in orogenic crust undergoing extension/transtension, and accords with numerous studies of migmatite-cored gneiss domes in transcurrent settings.

Introduction

Extension of thickened and hot crust commonly leads to the formation of migmatite-cored metamorphic core complexes (MCC) (Coney and Harms, 1984, Lister and Davis, 1989, Whitney et al., 2004, Whitney et al., 2013). Within these crustal-scale structures, detachment zones record significant amounts of localized extension and preserve an interface between cool upper crust and hot middle to lower crust (Lister and Davis, 1989, Malavieille, 1993, Mulch et al., 2006). Studies in the Basin and Range (e.g. Crittenden et al., 1980), the northern Cordillera (USA and Canada) (e.g. Foster et al., 2001, Vanderhaeghe et al., 1999), and the Aegean region (e.g. Brichau et al., 2008, Denele et al., 2011) have shown a spatial and temporal link between extensional detachment tectonics and the emplacement of gneiss/migmatite domes and granite bodies. Field, thermochronologic, and numerical modeling studies suggest the intrusion of granites may initiate the formation of detachment zones (e.g. Foster et al., 2001, Lister and Baldwin, 1993, Tirel et al., 2006, Tirel et al., 2008) and the presence of a low-viscosity layer in the crust (partially molten) may enhance strain localization and the development of rolling-hinge detachment systems (Whitney et al., 2013).

In extending orogens, regions with migmatite-cored gneiss domes and MCCs typically record cooling rates that range from 30 °C/m.y. to > 100 °C/m.y. where granite intrusion and detachments may be linked (Whitney et al., 2013). This includes areas such as the northern Cordilleran core complexes (Fayon et al., 2004, Foster et al., 2001, Gordon et al., 2008, Kruckenberg et al., 2008, Norlander et al., 2002), the Basin and Range province (Foster et al., 1990, Foster et al., 1992), the Liaodong Peninsula in NE China (Charles et al., 2012, Yang et al., 2007), and the Aegean domain (Brichau et al., 2008, Lister et al., 1984). In addition, recent thermomechanical numerical models have shown that gneiss domes are exhumed over short timescales (a few m.y.) in cases of localized extension (Rey et al., 2009a, Rey et al., 2009b). These systems are characterized by localized upper crustal deformation, isothermal decompression, advection of heat (solidus) toward the surface, and crystallization of partially molten crust at shallow depths (Rey et al., 2009a, Rey et al., 2009b, Whitney et al., 2013).

In order to evaluate the timing of detachment tectonics, cooling, and exhumation of the Fosdick dome, we present new 40Ar/39Ar hornblende and biotite data combined with previously obtained U–Pb data on zircon, titanite, and monazite, 40Ar/39Ar data on hornblende, biotite, muscovite, and K-feldspar, and fission-track data on apatite from the Fosdick Mountains region. The new 40Ar/39Ar data clarify the Fosdick dome history from emplacement to cooling, expand understanding of the significant thermal event in the mid-Cretaceous West Antarctic region, assess the mid-crustal response to the initiation of West Antarctic rifting, and inform the cooling history of gneiss domes and MCCs.

Section snippets

Geologic setting

Cretaceous extension and crustal heating affected the wide accretionary zone developed in Paleozoic–Mesozoic time along the East Gondwana margin of West Antarctica and Zealandia (Davey and Brancolini, 1995, Luyendyk, 1995, Mortimer et al., 2006, Siddoway, 2008, Tulloch et al., 2006). A Jurassic–Cretaceous magmatic arc developed along the West Antarctica–Zealandia margin (Bradshaw et al., 1997, Mortimer et al., 1999). The magmatic arc included emplacement of the subduction-related Median

Fosdick Mountains migmatite-cored gneiss dome

The Fosdick Mountains preserve lithologies and structures associated with the Devonian-Carboniferous and Cretaceous crustal melting and deformation episodes. Cretaceous granites and migmatites are more voluminous than Devonian-Carboniferous granites and migmatites in the Fosdick Mountains and most fabrics and structures record Cretaceous deformation. However, kilometer-scale domains of migmatitic paragneiss, migmatitic orthogneiss, and granites associated with Devonian-Carboniferous crustal

Structures and kinematics within the Fosdick dome

Within the Fosdick Mountains, fabrics and structures are characterized relative to emplacement of the leucogranite sheets and movement along the SFD. These are: 1) “Early” syn-kinematic footwall/detachment fabrics and structures; 2) “Late” syn-kinematic footwall/detachment fabrics and structures; and 3) “Latest” post-kinematic hanging wall fabrics and structures.

Thermochronology

Previous studies concluded that the Fosdick dome sustained high temperatures during detachment tectonics and then underwent rapid cooling (McFadden et al., 2010a, Richard et al., 1994, Siddoway et al., 2004b). This study confirms and refines this rapid cooling history from zircon crystallization through biotite closure temperature in the Fosdick dome.

Titanium-in-zircon thermometry

Titanium concentrations from zircon grains were obtained by SHRIMP II at the Research School or Earth Sciences of the Australian National University (RSES-ANU) using methods similar to Hiess et al. (2008). Previous U–Th–Pb analytical spots (McFadden et al., 2010a) were lightly polished and then the same area within the grains was analyzed. The Ti concentrations were used to calculate the crystallization temperatures for zircon assuming TiO2-saturated conditions according to:T(°C) = [(4800 ± 

Cooling of the Fosdick dome

In the Fosdick Mountains, temperature (T)–time (t) paths interpreted from combined geochronologic data indicate that the youngest suite of voluminous migmatites and granites crystallized between ca. 109 and 102 Ma and underwent rapid cooling between ca. 102 and 95 Ma (Fig. 9). Rapid cooling proceeded from granite crystallization through biotite closure temperature from ca. 102 to 99 Ma followed by slower cooling from biotite closure temperature through K-feldspar closure temperature from ca. 99 to

Summary

U–Pb zircon crystallization ages and 40Ar/39Ar hornblende and biotite cooling ages, over the time interval ca. 102–99 Ma, indicate cooling rates ranging from 85 to 155 °C/m.y. Rapid cooling followed a period of near-isothermal decompression and detachment tectonics that brought hot, deep migmatites and granites toward the surface. These migmatites and crustally-derived granites were emplaced at shallow levels in the crust, which led to rapid cooling owing to conductive heat loss. Below the

Acknowledgments

Research was funded by the National Science Foundation Office of Polar Programs grants NSF-OPP 0337488 to C. Teyssier and NSF-OPP 0338279 to C.S. Siddoway. We thank Mike Roberts, Forrest McCarthy, and Allen O'Bannon for field coordination and safety. For logistical support, we thank employees of Raytheon Polar Services, ANG 109th, and Kenn Borek Air crews. Reviews by B. Reno and N. Charles greatly improved the quality of this manuscript. Any use of trade, product, or firm names is for

References (99)

  • S. Keay et al.

    The timing of partial melting, Barrovian metamorphism and granite intrusion in the Naxos metamorphic core complex, Cyclades, Aegean Sea, Greece

    Tectonophysics

    (2001)
  • D.L. Kimbrough et al.

    Early Cretaceous age of orthogneiss from Charleston Metamorphic Group, New Zealand

    Earth and Planetary Science Letters

    (1989)
  • F.J. Korhonen et al.

    Modeling multiple melt loss events in the evolution of an active continental margin

    Lithos

    (2010)
  • J.-Y. Lee et al.

    A redetermination of the isotopic abundances of atmospheric Ar

    Geochimica et Cosmochimica Acta

    (2006)
  • G.S. Lister et al.

    The origin of metamorphic core complexes and detachment faults formed during Tertiary continental extension in the northern Colorado River region, U.S.A

    Journal of Structural Geology

    (1989)
  • K. Min et al.

    A test for systematic errors in 40Ar/39Ar geochronology through comparison with U/Pb analysis of a 1.1-Ga rhyolite

    Geochimica et Cosmichimca Acta

    (2000)
  • N. Mortimer et al.

    Overview of the Median Batholith, New Zealand: a new interpretation of the geology of the Median Tectonic Zone and adjacent rocks

    Journal of African Earth Sciences

    (1999)
  • B. Norlander et al.

    Partial melting and decompression of the Thor-Odin dome, Shuswap metamorphic core complex, Canadian Cordillera

    Lithos

    (2002)
  • P. Rey et al.

    The role of partial melting and extensional strain rates in the development of metamorphic core complexes

    Tectonophysics

    (2009)
  • F. Roger et al.

    Timing of formation and exhumation of the Montagne Noire double dome, French Massif Central

    Tectonophysics

    (2015)
  • S. Saito et al.

    Petrogenesis of Cretaceous mafic intrusive rocks, Fosdick Mountains, West Antarctica: melting of the sub-continental arc mantle along the Gondwana margin

    Gondwana Research

    (2013)
  • F.Y. Wu et al.

    Geochronology, petrogenesis and tectonic implications of Jurassic granites in the Liaodong Peninsula, NE China

    Chemical Geology

    (2005)
  • C. Yakymchuk et al.

    Leucosome distribution in migmatitic paragneisses and orthogneisses: a record of self-organized melt migration and entrapment in a heterogeneous partially molten crust

    Tectonophysics

    (2013)
  • J.D. Bradshaw et al.

    Swanson Formation and related rocks of Marie Byrd Land and a comparison with the Robertson Bay Group of northern Victoria Land

  • J.D. Bradshaw et al.

    New Zealand superterranes recognized in Marie Byrd Land and Thurston Island

  • S. Brichau et al.

    Timing slip rate, displacement and cooling history of the Mykonos detachment footwall, Cyclades, Greece, and implications for the opening of the Aegean Sea basin

    Journal of the Geological Society of London

    (2008)
  • P.J. Coney et al.

    Cordilleran metamorphic core complexes: Cenozoic extensional relics of Mesozoic compression

    Geology

    (1984)
  • M.D.J. Crittenden et al.
  • G.B. Dalrymple et al.

    Irradiation of samples for 40Ar/39Ar dating using the Geological Survey TRIGA reactor

  • F.J. Davey et al.

    The Late Mesozoic and Cenozoic structural setting of the Ross Sea region

  • A.K. Fayon et al.

    Exhumation of orogenic crust: diapiric ascent versus low-angle normal faulting

  • J. Ferry et al.

    New thermodynamic models and revised calibrations for the Ti-in-zircon and Zr-in-rutile thermometers

    Contributions to Mineralogy and Petrology

    (2007)
  • P.G. Fitzgerald et al.

    Detachment fault model for the evolution of the Ross embayment

  • R.M. Flowers et al.

    Temperature of burial and exhumation within the deep roots of a magmatic arc, Fiordland, New Zealand

    Geology

    (2005)
  • M.A. Forster et al.

    Cretaceous metamorphic core complexes in the Otago Schist, New Zealand

    Australian Journal of Earth Sciences

    (2003)
  • D.A. Foster et al.

    The 40Ar/39Ar thermochronology of the eastern Mojave Desert, California, and adjacent western Arizona with implications for the evolution of metamorphic core complexes

    Journal of Geophysical Research

    (1990)
  • D.A. Foster et al.

    40Ar/39Ar thermochronology and thermobarometry of metamorphism, plutonism, and tectonic denudation in the Old Woman Mountains area, California

    Geological Society of America Bulletin

    (1992)
  • G.M. Gibson et al.

    Age constraints on metamorphism and the development of a metamorphic core complex in Fiordland, southern New Zealand

    Geology

    (1988)
  • E.T. Goergen et al.

    Corona networks as three-dimensional records of transport scale and pathways during metamorphism

    Geology

    (2012)
  • S.M. Gordon et al.

    Timescales of migmatization, melt crystallization, and cooling in a Cordilleran gneiss dome: Valhalla complex, southeastern British Columbia

    Tectonics

    (2008)
  • R. Gottardi et al.

    Preservation of an extreme transient geotherm in the Raft River detachment shear zone

    Geology

    (2011)
  • J.A. Hollis et al.

    The regional significance of Cretaceous magmatism and metamorphism in Fiordland, New Zealand, from U–Pb zircon geochronology

    Journal of Metamorphic Geology

    (2004)
  • T.R. Ireland et al.

    SHRIMP monazite and zircon geochronology of high-grade metamorphism in New Zealand

    Journal of Metamorphic Geology

    (1998)
  • K.E. Karlstrom et al.

    Pluton emplacement along an active ductile thrust zone, Piute Mountains, southeastern California: interaction between deformational and solidification processes

    Geological Society of America Bulletin

    (1993)
  • F.J. Korhonen et al.

    Multiple generations of granite in the Fosdick Mountains, Marie Byrd Land, West Antarctica: implications for polyphase intracrustal differentiation in a continental margin setting

    Journal of Petrology

    (2010)
  • F.J. Korhonen et al.

    Separating metamorphic events in the Fosdick migmatite–granite complex, West Antarctica

    Journal of Metamorphic Petrology

    (2011)
  • S.C. Kruckenberg et al.

    Metamorphic evolution of sapphirine-bearing orthoamphibole-cordierite gneiss, Okanogan dome, Washington, USA

    Journal of Metamorphic Geology

    (2011)
  • S.C. Kruckenberg et al.

    Paleocene-Eocene migmatite crystallization, extension, and exhumation in the hinterland of the northern Cordillera: Okanogan dome, Washington, USA

    Geological Society of America

    (2008)
  • K.F. Kuiper et al.

    Synchronizing rock clocks of earth history

    Science

    (2008)
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