Petrogenesis and tectonic significance of the calc-alkaline, bimodal Aztec Wash pluton, Eldorado Mountains, Colorado River extensional corridor

1995 ◽  
Vol 100 (B6) ◽  
pp. 10453-10476 ◽  
Author(s):  
Claudia M. Falkner ◽  
Calvin F. Miller ◽  
Joseph L. Wooden ◽  
Matthew T. Heizler
Keyword(s):  
Colorado River ◽  
Calc Alkaline ◽  
Tectonic Significance ◽  
Aztec Wash Pluton

Geochemistry and tectonic significance of the mafic volcanic blocks in the Dunnage mélange, north central Newfoundland

1985 ◽  
Vol 22 (9) ◽  
pp. 1248-1256 ◽  
Author(s):  
Janusz J. Wasowski ◽  
Robert D. Jacobi
Keyword(s):  
Chemical Composition ◽  
Alkali Basalt ◽  
Volcanic Rocks ◽  
Pillow Lava ◽  
Calc Alkaline ◽  
North Central ◽  
Head Formation ◽  
Tectonic Significance ◽  
Low Potassium ◽  
Tuff Breccia

Abundant volcanic blocks are present in the Dunnage mélange. These mafic volcanic rocks consist predominantly of pillow lava, tuff breccia, isolated pillow–tuff breccia, and minor amounts of ropy lava.Major- and trace-element compositions of the basalts reveal that these volcanics do not resemble calc-alkaline or low-potassium island-arc suites. Rather, the majority of the samples are enriched-type ocean-floor tholeiites, whereas some show alkali basalt affinities. Discrimination diagrams suggest that these basalts may have been erupted as within-plate basalts. However, the chemical composition of the volcanic blocks is most similar to that of basalts generated at bathymetric highs located astride (or slightly off) mid-ocean ridges.The geochemistry of the Dunnage mélange basalts is very similar to that of the mafic volcanic rocks from the nearby Summerford Group and the Lawrence Head Formation. This correlation is further supported by sedimentary and petrographic evidence and by partial age equivalency.

Variscan lamprophyres in the Lower Penninic domain (Central Alps): age and tectonic significance

2008 ◽  
Vol 179 (4) ◽  
pp. 369-381 ◽  
Author(s):  
Denise Bussien ◽  
François Bussy ◽  
Henri Masson ◽  
Tomas Magna ◽  
Nickolay Rodionov
Keyword(s):  
Sedimentary Basin ◽  
Crustal Material ◽  
Magmatic Evolution ◽  
Calc Alkaline ◽  
Incompatible Elements ◽  
Tectonic Significance ◽  
Mineral Assemblages ◽  
Primary Mineral ◽  
Alpine Metamorphism

Abstract Lamprophyre dykes have been recently discovered in blocks of gneiss embedded in a calcschist formation of wildflysch type that forms the top of the Mesozoic-Tertiary metasedimentary cover of the Antigorio nappe (the Teggiolo zone) in the Val Bavona (Lower Penninic, NW Ticino, Switzerland). The presence of the lamprophyres gives a clue to the possible source of these blocks. Similar dykes occur in the N part of the Maggia nappe where they are intruded into the Matorello granite and the surrounding gneisses. We studied these lamprophyres at two localities in the Teggiolo zone (Tamierpass and Lago del Zött) and at one locality in the Maggia nappe (Laghetti). Detailed mineralogical and geochemical investigations confirm their great similarity, particularly between the Tamier and Laghetti dykes. They all recrystallized during Alpine metamorphism under amphibolite facies conditions and lost their primary mineral assemblages and textures. The chemistry reveals a calc-alkaline affinity, a limited differentiation range, features of mineral accumulation and intense remobilization in some cases. The lamprophyres are characterized by a high mg# and relatively low contents in REE and other incompatible elements. In situ SHRIMP and LA-ICPMS U-Pb zircon dating yielded ages of 284.8 ± 1.7 Ma (Tamier), 290.0 ± 1.3 Ma (Zött) and 290.5 ± 3.7 Ma (Laghetti). These ages are compatible with the general late- to post-Variscan magmatic evolution of the Helvetic and Lower Penninic domains. The lamprophyres are considered as melts derived from the lithospheric Variscan mantle, variously hybridized and differentiated at the contact with crustal material during late- to post-orogenic extension. These lamprophyres are chemically distinct from earlier lamprophyres of Visean age, emplaced together with their associated granites in transcurrent fault zones during the Variscan orogenic compression. The similarity of these different dykes suggests that the front of the Maggia nappe is a likely source of the gneissic blocks embedded in the calcschists at the top of the Teggiolo zone. They would have been provided by the advancing Maggia nappe during its thrusting over the Antigorio nappe and simultaneous closure of the Teggiolo sedimentary basin.

Geochemistry and tectonic significance of augen gneisses from the southern Menderes Massif (West Turkey)

1995 ◽  
Vol 132 (3) ◽  
pp. 287-301 ◽  
Author(s):  
E. Bozkurt ◽  
J. A. Winchester ◽  
R. G. Park
Keyword(s):  
Lower Crust ◽  
Early Eocene ◽  
Late Oligocene ◽  
Calc Alkaline ◽  
Menderes Massif ◽  
Early Oligocene ◽  
Basement Rocks ◽  
Metamorphic Basement ◽  
Tectonic Significance ◽  
Water Saturated

AbstractThe protoliths of mylonitized augen gneisses exposed in the southern sector of the Menderes Massif (West Turkey) are calc-alkaline, peraluminous, S-type, late- to post-tectonic tourmaline- and garnet-bearing, two-mica leucogranites. They cut and post-date the fabrics of the ‘main Menderes metamorphism’ which took place between the early Eocene and early Oligocene and intrude metamorphic basement rocks comprising the so-called ‘Palaeozoic schist envelope’ of the massif. They are themselves cut by an extensive network of tourmaline-rich dykes. Chemical, mineralogical, isotopic and field relations suggest that the granitic protolith crystallized from a boron-rich, water-saturated melt, derived from partial melting of metagreywacke in the lower crust during peak Barrovian-type metamorphism. The protolith was probably emplaced during lateorogenic extensional collapse of the thickened crust in west Turkey during late Oligocene time.

Discovery of a Neoproterozoic granite in the Northern Alxa region, NW China: its age, petrogenesis and tectonic significance

2015 ◽  
Vol 153 (3) ◽  
pp. 512-523 ◽  
Author(s):  
WEN ZHANG ◽  
VICTORIA PEASE ◽  
QINGPENG MENG ◽  
RONGGUO ZHENG ◽  
TONNY B. THOMSEN ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Calc Alkaline ◽  
Alkaline Pluton ◽  
Crustal Rocks ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Tectonic Significance ◽  
Southern Central ◽  
Plasma Mass Spectrometry ◽  
Very High

AbstractA Neoproterozoic granite (Western Huhetaoergai granite) from the Northern Alxa region, southern Central Asia Orogenic Belt (CAOB) is first recognized by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon dating (889±8 Ma). It is a highly fractionated potassium-rich calc-alkaline pluton with lowεNd(t) (−2.6 to −1.1) and high (87Sr/86Sr)t(0.727305–0.735626), and is probably derived from a mantle source and assimilated crustal rocks with very high87Sr/86Sr. Regional geology implies that it may reflect the existence of a microcontinent, and the formation of the Western Huhetaoergai granite is related to the assembly of Rodinia.

ASSOCIATED A-TYPE SUBALKALINE AND HIGH-K CALC-ALKALINE GRANITES IN THE ITU GRANITE PROVINCE, SOUTHEASTERN BRAZIL: PETROLOGICAL AND TECTONIC SIGNIFICANCE

2009 ◽  
Vol 47 (6) ◽  
pp. 1505-1526 ◽  
Author(s):  
V. de Assis Janasi ◽  
S. R. F. Vlach ◽  
M. da Costa Campos Neto ◽  
H. H.G.J. Ulbrich
Keyword(s):  
Southeastern Brazil ◽  
Calc Alkaline ◽  
High K ◽  
Tectonic Significance
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