scholarly journals Multiphase Boudinage: a case study of Amphibolites in Marble in the Naxos Migmatite core

2017 ◽  
pp. 1-31
Author(s):  
Simon Virgo ◽  
Christoph von Hagke ◽  
Janos L. Urai
Keyword(s):  
High Temperature ◽  
Detailed Analysis ◽  
High Strain ◽  
Metamorphic Core Complex ◽  
Ductile Deformation ◽  
Core Complex ◽  
Complex Reconstruction ◽  
Two Phases ◽  
Metamorphic Core

In multiply deformed terrains, multiphase boudinage should be common, but identification and analysis of these is difficult. Here we present an analysis of multiphase boudinage and fold structures in deformed amphibolite layers in marble from the migmatitic center of the Naxos metamorphic core complex. Reconstruction of multiple boudinage generations is possible due to the exceptional 3D outcrop conditions. We identify five distinct generations of boudinage, reflecting the transition from high-strain – high-temperature ductile deformation to medium to low strain brittle boudins on the retrograde path during cooling and exhumation. All boudin generations indicate E-W horizontal shortening and variable directions of bedding parallel extension, evolving from subvertical extension in the earliest boudins to subhorizontal N-S extension during exhumation. Two phases of E-W shortening can be inferred, indicating E-W shortening in the Aegean before activity of the brittle North Anatolian Fault. This study highlights the wealth of information that can be gained from detailed analysis of multiphase boudinage structures.

scholarly journals Multiphase boudinage: a case study of amphibolites in marble in the Naxos migmatite core

Solid Earth ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 91-113 ◽  
Author(s):  
Simon Virgo ◽  
Christoph von Hagke ◽  
Janos L. Urai
Keyword(s):  
High Strain ◽  
Ductile Deformation ◽  
Core Complex ◽  
The North ◽  
Variable Direction ◽  
Convergent Flow ◽  
Two Phases ◽  
Lower Crustal ◽  
Metamorphic Core

Abstract. In multiply deformed terrains multiphase boudinage is common, but identification and analysis of these is difficult. Here we present an analysis of multiphase boudinage and fold structures in deformed amphibolite layers in marble from the migmatitic centre of the Naxos metamorphic core complex. Overprinting between multiple boudinage generations is shown in exceptional 3-D outcrop. We identify five generations of boudinage, reflecting the transition from high-strain high-temperature ductile deformation to medium- to low-strain brittle boudins formed during cooling and exhumation. All boudin generations indicate E–W horizontal shortening and variable direction of bedding parallel extension, evolving from subvertical extension in the earliest boudins to subhorizontal N–S extension during exhumation. Two phases of E–W shortening can be inferred, the first associated with lower crustal synmigmatic convergent flow and the second associated with exhumation and N–S extension, possibly related to movement of the North Anatolian Fault.

scholarly journals The Ikaria high-temperature Metamorphic Core Complex (Cyclades, Greece): Geometry, kinematics and thermal structure

2015 ◽  
Vol 92 ◽  
pp. 18-41 ◽  
Author(s):  
Alexandre Beaudoin ◽  
Romain Augier ◽  
Valentin Laurent ◽  
Laurent Jolivet ◽  
Abdeltif Lahfid ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Structure ◽  
Metamorphic Core Complex ◽  
Core Complex ◽  
Metamorphic Core

scholarly journals Low-grade retrogression of a high-temperature metamorphic core complex: Naxos, Cyclades, Greece

2016 ◽  
Vol 129 (1-2) ◽  
pp. 93-117 ◽  
Author(s):  
Shuyun Cao ◽  
Franz Neubauer ◽  
Manfred Bernroider ◽  
Johann Genser ◽  
Junlai Liu ◽  
...  
Keyword(s):  
High Temperature ◽  
Metamorphic Core Complex ◽  
Low Grade ◽  
Core Complex ◽  
Metamorphic Core

scholarly journals Microstructures of the Lim zone along the contact with Dinaridic Ophiolite nappe

2007 ◽  
pp. 1-7
Author(s):  
Aleksandar Ilic ◽  
Luka Pesic
Keyword(s):  
Microstructural Analysis ◽  
Metamorphic Core Complex ◽  
Ductile Deformation ◽  
Low Grade ◽  
The South ◽  
Core Complex ◽  
Deformation Event ◽  
Metamorphic Core

The Lim Zone is a part of the low-grade metamorphic core complex called the Lim Palaeozoic Unit, overlain by detached Triassic sedimentary successions. The Lim Unit is located in the footwall of overriding Dinaridic Ophiolite nappe. In general, three major ductile deformation phases could be observed on the boundary between the Lim Unit and the overriding Dinaridic Ophiolite nappe. In both, the Lim Unit and the Dinaridic ophiolite nappe, the major deformation event was related to the SSW-directed, oblique thrusting along the Dinaridic ophiolite thrust. The same orientation of the stretching lineation in both units is related to the predominant top-to-the-south shear, which suggests, therefore, oblique thrusting during the emplacement of the ophiolites over the Lim Unit. This paper deals with the results of microstructural analysis of Palaeozoic rocks of Lim Zone along the contact with Dinaridic ophiolite nappe.

Laramide to Miocene syn-extensional plutonism in the Puerta del Sol area, central Sonora, Mexico

2017 ◽  
Vol 34 (1) ◽  
pp. 45 ◽  
Author(s):  
Elizard González-Becuar ◽  
Efrén Pérez-Segura ◽  
Ricardo Vega-Granillo ◽  
Luigi Solari ◽  
Carlos Manuel González-León ◽  
...  
Keyword(s):  
Metamorphic Core Complex ◽  
Primitive Mantle ◽  
Isotopic Ratios ◽  
Magmatic Evolution ◽  
Calc Alkaline ◽  
Core Complex ◽  
High K ◽  
Sierra Madre ◽  
Plutonic Rocks ◽  
Metamorphic Core

Plutonic rocks of the Puerta del Sol area, in central Sonora, represent the extension to the south of the El Jaralito batholith, and are part of the footwall of the Sierra Mazatán metamorphic core complex, whose low-angle detachment fault bounds the outcrops of plutonic rocks to the west. Plutons in the area record the magmatic evolution of the Laramide arc and the Oligo-Miocene syn-extensional plutonism in Sonora. The basement of the area is composed by the ca. 1.68 Ga El Palofierral orthogneiss that is part of the Caborca block. The Laramide plutons include the El Gato diorite (71.29 ± 0.45 Ma, U-Pb), the El Pajarito granite (67.9 ± 0.43 Ma, U-Pb), and the Puerta del Sol granodiorite (49.1 ± 0.46 Ma, U-Pb). The younger El Oquimonis granite (41.78 ± 0.32 Ma, U-Pb) is considered part of the scarce magmatism that in Sonora records a transition to the Sierra Madre Occidental magmatic event. The syn-extensional plutons are the El Garambullo gabbro (19.83 ± 0.18 Ma, U-Pb) and the Las Mayitas granodiorite (19.2 ± 1.2 Ma, K-Ar). A migmatitic event that affected the El Palofierral orthogneiss, El Gato diorite, and El Pajarito granite between ca. 68 and 59 Ma might be related to the emplacement of the El Pajarito granite. The plutons are metaluminous to slightly peraluminous, with the exception of El Oquimonis granite, which is a peraluminous two-mica, garnet-bearing granite. They are mostly high-K calc-alkaline with nearly uniform chondrite-normalized REE and primitive-mantle normalized multielemental patterns that are characteristic of continental margin arcs and resemble patterns reported for other Laramide granites of Sonora. The Laramide and syn-extensional plutons also have Sr, Nd and Pb isotopic ratios that plot within the fields reported for Laramide granites emplaced in the Caborca terrane in northwestern and central Sonora. Nevertheless, and despite their geochemical affinity to continental magmatic arcs, the El Garambullo gabbro and Las Mayitas granodiorite are syn-extensional plutons that were emplaced at ca. 20 Ma during development of the Sierra Mazatán metamorphic core complex. The 40Ar/39Ar and K-Ar ages obtained for the El Palofierral orthogneiss, the Puerta del Sol granodiorite, the El Oquimonis granite, and the El Garambullo gabbro range from 26.3 ± 0.6 to 17.4 ± 1.0 Ma and are considered cooling ages associated with the exhumation of the metamorphic core complex.

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