The early igneous and tectonic history of the Rhum Tertiary Volcanic Centre

1985 ◽  
Vol 122 (5) ◽  
pp. 451-457 ◽  
Author(s):  
C. H. Emeleus ◽  
W. J. Wadsworth ◽  
N. J. Smith
Keyword(s):  
Fault System ◽  
Volcanic Centre ◽  
Acid Magma ◽  
The Core ◽  
Tectonic History ◽  
Early Tertiary ◽  
Main Ring ◽  
Igneous Activity ◽  
History Of ◽  
Structural Levels

AbstractEarly Tertiary igneous activity on Rhum was preceded by doming and the formation of a major arcuate fault system, the Main Ring Fault (MRF), within which Lewisian gneisses, Torridonian sediments and younger rocks were uplifted by as much as 2 km. Doming and uplift are attributed to the diapiric rise of acid magma which ultimately formed the granophyres and felsites of Rhum. Felsite emplacement was accompanied and immediately preceded by the formation of explosion breccias and tuffisites. This phase involves massive gas escape along the MRF fractures; it marked a period of major subsidence within the MRF during which fossiliferous Jurassic sediments and relics of Tertiary lava flows were brought to low structural levels within the MRF. Finally, a further period of uplift, again of about 2 km, took place once more bringing gneisses and basal Torridonian sediments within the MRF to high structural levels. The driving force for this last phase of uplift may have been provided by a further uprise of acid magma or, more realistically, may have been directly connected with emplacement of layered ultrabasic rocks which now form the core of the Rhum centre.

scholarly journals Zur Tal- und Reliefgeschichte des Churfirsten-Alvier-Gebietes (Kanton St. Gallen)

1987 ◽  
Vol 42 (2) ◽  
pp. 159-168
Author(s):  
R. Hantke
Keyword(s):  
Southern Slope ◽  
The South ◽  
Helvetic Nappes ◽  
Early Stages ◽  
Tectonic History ◽  
Early Tertiary ◽  
History Of

Abstract. The valley and relief history of the Churfirsten-Alvier ränge (Ct. St. Gallen): Valley formation in the Churfirsten-Alvier range, between the Linth and Rhine rivers. began at the end of the Miocene with the tectonic history of the Helvetic nappes. In early stages. the Cretaceaous sequences became independent of their Jurassic substratums and these from their Verrucano-Tnassic basement. The valley of Lake Walenstadt in the south was initiated between this basement and north-moving younger sequences. The Thur valley, north of the Churfirsten range, which follows a syncline in the highest Helvetic nappe. was filled with early Tertiary Sediments and Pennine Flysch. The Valleys in the Alvier area are formed along synclmes and faults in the Cretaceous sequence; these structures dip towards the Rhme valley. The Churfirsten range forms a limestone shield in the Helvetic nappe. It broke up foUowing ±N/S-onented joints. There inbetween, excavation of kars (cirques) began already during pre-Ouaternary glaciation; they are still intact at the ends of the ränge, but in the middle the kar-walls broke down along the steeper southern slope. During the Mindel and Riss glaciations. no Rhine ice flowed through the saddles between the Churfirsten peaks into the Thur valley; however, this could have been possible in pre- Mindelian cold periods at high ice levels and still lower moun¬ tain relief.

scholarly journals Crustal Deformations and Geomorphological Units of Arabian Plate Foreland Region, North and Northeast of Iraq

2019 ◽  
Vol 54 (5) ◽  
Author(s):  
Ahmed Abbas Hasan ◽  
Mohammed Lateef Hussien ◽  
Linaz Anis Fadhil ◽  
Mariam Isam Hasan ◽  
Cristina Dallos Mosquera
Keyword(s):  
Cross Sections ◽  
Fault System ◽  
Arabian Plate ◽  
Alluvial Fans ◽  
Zagros Mountains ◽  
Flood Plains ◽  
Tectonic History ◽  
Geomorphological Units ◽  
History Of ◽  
Geologic Factor

The crustal shortening in the foreland of Arabian Plate (the Taurus and Zagros Mountains system) in N and NE of Iraq is accommodated in two principal ways: folding and thrusting. The fold and thrust patterns have evolved as an expression of shortening which was approximately NE-SW directed and subparallel to the bedding. In this area, observations of deformations along different cross sections were made using balancing cross sections for the estimation of the total shortening on five cross sections. The authors showed that shortening deformations were irregular and non-identical, which date back to the same age and the same location. This suggests that defects in this region are not homogeneous due to irregular bottom of the sedimentary basin, fault system and the form of the collision zone between the Arabian Plate and Iranian Plate or between the Arabian Plate and the Anatolian Plate. According to these magnitudes, the foreland region of Arabian Plate is affected by inhomogeneous deformations that are related rather to where these structures were developed, than to when they were formed. This study demonstrates the significant influence of geologic factor (especially structure) in forming and developing geomorphological features with a structural origin. These features are associated with tectonic history of the study area, such as units of structural origin. Another features related to the denudational factors, like glacis and badland, in addition to the features of fluvial origin which are alluvial fans, terraces and flood plains.

The age and structural setting of limestones and basalts on the Main Ring Fault in southeast Rhum

1985 ◽  
Vol 122 (5) ◽  
pp. 439-445 ◽  
Author(s):  
N. J. Smith
Keyword(s):  
Complex Structure ◽  
Early History ◽  
Volcanic Centre ◽  
Precambrian Rocks ◽  
Ring Fault ◽  
Thermal Metamorphism ◽  
Main Ring ◽  
History Of ◽  
Layered Complex ◽  
Fossiliferous Limestone

AbstractIn southeast Rhum, a Mesozoic/Tertiary sequence is preserved as a fault-bounded and rotated wedge. This is juxtaposed between Precambrian rocks (Torridonian sediments and Lewisian gneiss) and caught up in the complex structure of the Tertiary Main Ring Fault (MRF), which shows three distinct phases of movement. The Mesozoic rocks comprise fossiliferous limestone, sandstone and shale, which show differing degrees of thermal metamorphism depending on their relationships to the Layered Complex. On the basis of faunal and lithological evidence the Mesozoic sediments have been correlated with the Lower Liassic Broadford Beds. The Rhum sediments are overlain by sheared Tertiary basalts, the contact between them probably representing the original landscape unconformity. The presence of these younger strata caught up along the MRF provides crucial evidence for a major phase of central subsidence in the early history of the Rhum Tertiary volcanic centre.

scholarly journals Burial and exhumation history of the Daday Unit (Central Pontides, Turkey): implications for the closure of the Intra-Pontide oceanic basin

2017 ◽  
Vol 155 (2) ◽  
pp. 356-376 ◽  
Author(s):  
CHIARA FRASSI ◽  
MICHELE MARRONI ◽  
LUCA PANDOLFI ◽  
M. CEMAL GÖNCÜOĞLU ◽  
ALESSANDRO ELLERO ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Tectonic Setting ◽  
Geothermal Gradient ◽  
Suture Zone ◽  
Tectonic Structures ◽  
The North ◽  
Tectonic History ◽  
Oceanic Basin ◽  
History Of ◽  
Structural Levels

AbstractIn northern Turkey, the Intra-Pontide suture zone represents one of the first-order tectonic structures located between the Istanbul–Zonguldak and the Sakarya continental terranes. It consists of an E–W-trending assemblage of deformed and variably metamorphosed tectonic units, including sedimentary rocks and ophiolites derived from a Neo-Tethyan oceanic basin, known as the Intra-Pontide oceanic basin. One of these units is represented by the Daday Unit that consists of a block-in-matrix assemblage derived from supra-subduction oceanic crust and related deep-sea sedimentary cover of Middle Jurassic age. This setting was acquired during Late Jurassic time by tectonic underplating at a depth of 35–42 km associated with blueschist-facies metamorphism (D1 phase). The following D2, D3 and D4 phases produced the exhumation of the Daday Unit up to shallower structural levels in a time span running from the Albian to late Paleocene. The high geothermal gradient detected during the D2 phase indicates that the Daday Unit was exhumed during a continent–arc collisional setting. The tectonic structures of the Intra-Pontide suture zone, resulting from the previously described tectonic history, are unconformably sealed by the upper Paleocene – Eocene deposits. This tectonic setting was intensely reworked by the activity of the North Anatolian Fault Zone, producing the present-day geometrical relationships of the Intra-Pontide suture zone of the Central Pontides.

Structure, petrology, and tectonic history of the Leech River complex northwest of Victoria, Vancouver Island

1982 ◽  
Vol 19 (9) ◽  
pp. 1817-1835 ◽  
Author(s):  
Lee H. Fairchild ◽  
Darrel S. Cowan
Keyword(s):  
Volcanic Rocks ◽  
Low Pressure ◽  
Vancouver Island ◽  
Southern Boundary ◽  
Late Mesozoic ◽  
The North ◽  
Tectonic History ◽  
Early Tertiary ◽  
History Of ◽  
Pelitic Rocks

The Leech River complex 45 km northwest of Victoria consists of metamorphosed pelitic rocks, sandstone, and minor volcanic rocks, chert, and conglomerate of probable Late Jurassic to Cretaceous age. The assemblage experienced two similar deformational events during which regional shortening induced macroscopic east-plunging folds and related coaxial, mesoscopic linear structures, parasitic folds, and axial-plane cleavages. Fragmentation along the developing cleavages disrupted layering and eventually led to transposition during both events. Regional, progressive, low-pressure greenschist- to amphibolite-facies (andalusite–staurolite–biotite) metamorphism began during the first deformation and extended into the waning stages of the second. Intrusion of composite felsic sills was synchronous with deformation and metamorphism, which concluded about 39–41 Ma, according to K–Ar data. The Leech River fault, which forms the southern boundary of the complex, is a zone of two to four subparallel faults. All are relatively straight, narrow faults that appear to dip steeply. This structure is interpreted to be a left-lateral strike-slip fault, active exclusively after the 39–41 Ma conclusion of metamorphism and deformation.The Leech River complex originally may have accumulated somewhere along a late Mesozoic convergent margin, but there is no evidence that it either constitutes a subduction complex per se or was metamorphosed in such a setting in early Tertiary time. The Leech River complex is interpreted to be allochthonous with respect to the bulk of Vancouver Island, since neither older rocks of the Insular Belt (Wrangellia) to the north nor coeval rocks in northwestern Washington record the early Tertiary deformations and synkinematic low-pressure metamorphism. The complex apparently was derived from a cryptic terrane to the west and emplaced against Vancouver Island by left-lateral slip on the San Juan fault after 39–41 Ma.

Tectonic history of basins sited along the western section of the North Anatolian Fault System, Turkey

2014 ◽  
Vol 89 ◽  
pp. 31-41 ◽  
Author(s):  
Gülcan Sarp ◽  
Şule Gürboğa ◽  
Vedat Toprak ◽  
Şebnem Düzgün
Keyword(s):  
North Anatolian Fault ◽  
Fault System ◽  
The North ◽  
Tectonic History ◽  
History Of
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