Field Occurrence of High- and Ultrahigh-Temperature Metamorphic Rocks and Related Igneous Rocks from the Kontum Massif, Central Vietnam

AbstractHigh-grade basic and acidic meta-igneous rocks are widespread in the bimodal amphibolitic—felsic gneiss complexes, which are characteristic formations of the ‘Middle Allochthonous Unit’ from eastern and southern French Massif Central. The metabasites from the Lyonnais and Doux complexes are chemically diverse and range from N-MORB type tholeiitic to transitional types. The two populations are not related by fractional crystallization or crustal contamination processes and their chemical characteristics reflect differences in their mantle sources. An ensialic setting is supported by the crustally-derived character of some of the associated felsic rocks, but the presence of N-MORB-type metabasites argues for an extensional environment. This bimodal association compares well with the magmatism of rifted continental margins and may reflect a transitional stage between continental rifting and oceanic crust formation during the Cambro-Ordovician spreading event.

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Revised stratigraphy of the Mesozoic rocks of southern Cyprus

Geological Magazine ◽

10.1017/s0016756800028892 ◽

1980 ◽

Vol 117 (6) ◽

pp. 547-563 ◽

Cited By ~ 40

Author(s):

R. E. Swarbrick ◽

A. H. F. Robertson

Keyword(s):

Oceanic Crust ◽

Continental Margin ◽

Late Cretaceous ◽

Sedimentary Cover ◽

Igneous Rocks ◽

Late Triassic ◽

Metamorphic Rocks ◽

Southern Cyprus

SummaryRecent resurgence of interest in the Mesozoic rocks of SW and southern Cyprus necessitates redefinition of the Mesozoic sedimentary and igneous rocks in line with modern stratigraphical convention. Two fundamentally different rocks associations are present, the Troodos Complex, not redefined, a portion of late Cretaceous oceanic crust, and the Mamonia Complex, the tectonically dismembered remnants of a Mesozoic continental margin. Based on earlier work, the Mamonia Complex is divided into two groups, each subdivided into a number of subsidiary formations and members. The Ayios Photios Group is wholly sedimentary, and records the evolution of a late Triassic to Cretaceous inactive continental margin. The Dhiarizos Group represents Triassic alkalic volcanism and sedimentation adjacent to a continental margin. Several other formations not included in the two groups comprise sedimentary mélange and metamorphic rocks. The Troodos Complex possesses an in situ late Cretaceous sedimentary cover which includes two formations of ferromanganiferous pelagic sediments, radiolarites and volcaniclastic sandstones. The overlying Cainozoic calcareous units are not redefined here.

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Early Paleozoic or Early-Middle Triassic collision between the South China and Indochina Blocks: The controversy resolved? Structural insights from the Kon Tum massif (Central Vietnam)

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2018.07.015 ◽

2018 ◽

Vol 166 ◽

pp. 162-180 ◽

Cited By ~ 26

Author(s):

Michel Faure ◽

Van Vuong Nguyen ◽

Luong Thi Thu Hoai ◽

Claude Lepvrier

Keyword(s):

South China ◽

Middle Triassic ◽

Early Paleozoic ◽

The South ◽

Massif Central ◽

Central Vietnam ◽

Early Middle Triassic ◽

Structural Insights

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Gneiss, marbres, prasinites en coussins et polymetamorphisme dans la partie sud-occidentale du massif Dora-Maira (Alpes cottiennes piemontaises)

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.s7-iii.4.345 ◽

1961 ◽

Vol S7-III (4) ◽

pp. 345-354

Author(s):

Andre Michard ◽

P. Vialon

Keyword(s):

White Mica ◽

Igneous Rocks ◽

Metamorphic Rocks ◽

Retrograde Metamorphism ◽

Po River ◽

Alpine Metamorphism

Abstract Igneous rocks of the Dora-Maira massif in the Po river headwater region in the Cottian Alps of Piedmont, Italy, are surrounded, and in many places surmounted, by gneiss, marble, and other associated metamorphic rocks of controversial age. The evidence is considered conclusive that the age of the rocks ranges from Permo-Carboniferous to Triassic. Criteria for discrimination of successive periods of metamorphism, including retrograde metamorphism, are reviewed. Carbonatized rocks and phengitic conglomeratic quartzite serve as "metamorphic thermometers" useful locally for discriminating successive periods of metamorphism. Cataclastic effects are also useful for determining time relationships, as are also optical peculiarities of quartz, feldspar, white mica, and biotite in various rocks. It is concluded that the region has been subjected to two major periods of metamorphism, and that the Alpine metamorphism in general was less intensive, and in certain aspects was retrograde compared with the pre-Alpine metamorphism.

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