Structure of the Dingle Peninsula, SW Ireland: evidence for the nature and timing of Caledonian, Acadian and Variscan tectonics

2014 ◽  
Vol 152 (2) ◽  
pp. 242-268 ◽  
Author(s):  
S.P. Todd
Keyword(s):  
Deep Water ◽  
Volcanic Rocks ◽  
Fault Zones ◽  
Early Devonian ◽  
Shallow Marine ◽  
Red Sandstone ◽  
Early Ordovician ◽  
The North ◽  
Tectonic History ◽  
Extensional Structures

AbstractThe Palaeozoic rocks of the Dingle Peninsula provide a record of the evolution of the Caledonides, Acadides and Variscides. The succession ranges from Early Ordovician deep-water sediments, through Silurian shallow marine to non-marine sediments and volcanic rocks to an Old Red Sandstone (ORS) succession topped by Carboniferous marine shales. Comparison of structural styles in the unconformity-bounded groups, together with a detailed analysis of fault zones, allows the tectonic history to be deduced. The older rocks record Caledonian processes on the margin of Avalonia during Early Ordovician time and convergence then soft collision with Laurentia during Silurian time. The Dingle Basin was developed during the late Silurian – Early Devonian transtension in the Iapetus suture zone and was inverted in the latest Emsian Acadian orogenic episode. Post-Dingle Group ORS groups in the north of the peninsula were deposited in a syn-rift footwall block to the main Munster Basin. The Acadian transpressional and Munster Basin extensional structures were reactivated or overprinted in the Variscan deformation such that Acadian folds are transected by Variscan cleavage in both plan and vertical views. After Iapetus closure, changes in the tectonic regime are believed to be a result of adjustments in the geometry of subduction of the Rheic Ocean.

scholarly journals Mesozoic Paleo-Pacific Subduction Beneath SW Borneo: U-Pb Geochronology of the Schwaner Granitoids and the Pinoh Metamorphic Group

2020 ◽  
Vol 8 ◽  
Author(s):  
H. Tim Breitfeld ◽  
Lorin Davies ◽  
Robert Hall ◽  
Richard Armstrong ◽  
Marnie Forster ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Large Igneous Province ◽  
Metamorphic Rocks ◽  
Volcanic Arc ◽  
The North ◽  
Tectonic History ◽  
Igneous Province ◽  
Magmatic History ◽  
Nw Australia ◽  
C 78

The Schwaner Mountains in southwestern Borneo form a large igneous province with a complex magmatic history and poorly known tectonic history. Previously it was known that Cretaceous granitoids intruded metamorphic rocks of the Pinoh Metamorphic Group assumed to be of Paleozoic age. Jurassic granitoids had been reported from the southern Schwaner Mountains. Most ages were based on K-Ar dating. We present new geochemistry, zircon U-Pb and 40Ar/39Ar age data from igneous and metamorphic rocks from the Schwaner Mountains to investigate their tectono-magmatic histories. We subdivide the Schwaner Mountains into three different zones which record rifting, subduction-related and post-collisional magmatism. The Northwest Schwaner Zone (NWSZ) is part of the West Borneo Block which in the Triassic was within the Sundaland margin. It records Triassic to Jurassic magmatism during early Paleo-Pacific subduction. In contrast, the North Schwaner Zone (NSZ) and South Schwaner Zone (SSZ) are part of the SW Borneo (Banda) Block that separated from NW Australia in the Jurassic. Jurassic granitoids in the SSZ are within-plate (A-type) granites interpreted to have formed during rifting. The SW Borneo (Banda) Block collided with eastern Sundaland at c. 135 Ma. Following this, large I-type granitoid plutons and arc volcanics formed in the NWSZ and NSZ between c. 90 and 132 Ma, associated with Cretaceous Paleo-Pacific subduction. The largest intrusion is the c. 110 to 120 Ma Sepauk Tonalite. After collision of the East Java-West Sulawesi (Argo) Block, subduction ceased and post-collisional magmatism produced the c. 78 to 85 Ma Sukadana Granite and the A-type 72 Ma Sangiyang Granite in the SSZ. Rocks of the Pinoh Metamorphic Group mainly exposed in the NSZ, previously assumed to represent Paleozoic basement, contain abundant Early Cretaceous (110 to 135 Ma) zircons. They are interpreted as volcaniclastic sediments that formed contemporaneously with subduction-related volcanic rocks of the NSZ subsequently metamorphosed during intrusion of Cretaceous granitoids. There are no igneous rocks older than Cretaceous in the NSZ and older than Jurassic in the SSZ and there is no evidence for a continuation of a Triassic volcanic arc crossing Borneo from Sundaland to the east.

Role of the Midland Valley of Scotland in the Caledonian orogeny

1983 ◽  
Vol 74 (3) ◽  
pp. 119-136 ◽  
Author(s):  
B. J. Bluck
Keyword(s):  
Volcanic Rocks ◽  
Substantial Contribution ◽  
Volcanic Arc ◽  
Early Devonian ◽  
Red Sandstone ◽  
Metamorphic Basement ◽  
Caledonian Orogeny ◽  
Southward Extension ◽  
Trench Slope

ABSTRACTThe Midland Valley of Scotland was an arc–interarc region during most of Ordovician—Devonian time. This arc terrane extends beneath the allochthonous Southern Uplands and probably beneath the southern Highlands. Models of Caledonian plate tectonism which regard the Midland Valley as a fore-arc basin are rejected principally on the grounds that (i) the Ordovician sequence at Girvan, in the very SW of the Midland Valley, was generated in a proximal fore-arc basin to the immediate S of a contemporaneous plutonic–volcanic arc, and (ii) the source for Silurian sediments in the southern part of the Midland Valley could not have been a rising trench-slope-break, but igneous basement and conglomerates with clasts of metamorphic basement, i.e. the southward extension of the Midland Valley.The Midland Valley arc first comprised mainly plutonic rocks, some of which may have been basic but most of which were certainly granitic. Little is known of the ages of volcanic clasts in Silurian conglomerates (this time may have been a period of relative volcanic quiescence), but the Silurian–Devonian sequence is considered to have formed in an interarc basin which, like many other basins of this kind, began as marine (Early Silurian) and ended as fluvial (Devonian). At this final Silurian–Devonian stage, the Midland Valley arc was dominated by effusive rocks which made a substantial contribution to the sediments.In this interpretation, the present Old Red Sandstone volcanic rocks are seen as the final stage of a volcanic arc which occupied the position of the present Midland Valley from at least Llanvirn to Early Devonian time.

Chapter 16 Devonian history

1997 ◽  
Vol 17 (1) ◽  
pp. 289-309 ◽  
Author(s):  
W. Brian Harland
Keyword(s):  
Early Devonian ◽  
East Greenland ◽  
Red Sandstone ◽  
North East ◽  
The North ◽  
Fossil Fish ◽  
Red Bay ◽  
The Many ◽  
Orogenic Events ◽  
North Greenland

Svalbard is part of the Old Red Sandstone province with affinities in East Greenland, Norway, Appalachian North America and, of course, the British Isles where the Devonian Period was defined. This allows Devonian history in this region, controlled by Caledonian events, to form a neat and natural chapter, though not necessarily a global one. Old Red Sandstone environments in each area were already becoming established in Late Silurian time. Olaf Holtedahl was the prime author of both Caledonian tectogenesis in Svalbard and the Old Red Sandstone aftermath.Of the many and varied biotas of Svalbard the fossil fish have made remarkable and classic contributions to Spitsbergen geology.The earliest 'Old Red Sandstone' Spitsbergen strata have yet to yield evidence of age and so may be latest Silurian (Siktefjellet Group). But the earliest Devonian strata to be identified biostratigraphically begin with the Red Bay Group. Similarly the (major) Ny Friesland Orogeny and the various late orogenic granite emplacements, while initially Silurian, continued at least to cool in Devonian time. For convenience the orogenic events that may continue as early Devonian are treated in the Silurian chapter and the sedimentary events that may be Silurian are treated here.Devonian successions in Svalbard are known only from terranes which are postulated to have originated from the North East Greenland Province. No record has yet been established for Devonian strata in Svalbard either from the eastern terranes (East Greenland Province) or from the western terranes (North Greenland-Pearya Province). Moreover, the East Greenland succession lacks

A palaeoenvironmental interpretation of the Silurian rocks in the Pentland Hills, near Edinburgh, Scotland

1989 ◽  
Vol 80 (2) ◽  
pp. 127-141 ◽  
Author(s):  
Gary Robertson
Keyword(s):  
Marine Sediments ◽  
Red Beds ◽  
Submarine Fan ◽  
Shallow Marine ◽  
Red Sandstone ◽  
The North ◽  
Southern Margin ◽  
Shallow Marine Sediments ◽  
Sandstone Facies

ABSTRACTSilurian sediments up to 2500 m thick are exposed in the Pentland Hills, SW of Edinburgh. These sediments, the North Esk Group, are here sub-divided into five well-defined formations: the Reservoir Formation, Deerhope Formation, Cock Rig Formation, Wether Law Linn Formation and Henshaw Formation. The Wether Law Linn Formation is further sub-divided into three members. Based on limited palaeontological evidence, the sediments appear to be late Llandovery (crenulata Biozone) to Wenlock in age. The Silurian sediments represent a regressive sequence, passing from offshore submarine-fan turbidite facies, through shallow marine sediments, with an abundant flora and fauna, possibly a barrier complex, to terrestrial red beds of Old Red Sandstone facies. Changing faunal associations in the shallow marine sediments reflect the availability of different substrates. The regression occurred on the southern margin of the Midland Valley graben.

XXIV.—On Old Red Sandstone Plants showing Structure, from the Rhynie Chert Bed, Aberdeenshire. Part I. Rhynia Gwynne-Vaughani, Kidston and Lang

1996 ◽  
Vol 87 (3) ◽  
pp. 427-450 ◽  
Author(s):  
R. Kidston ◽  
W. H. Lang
Keyword(s):  
Volcanic Rocks ◽  
Red Sandstone ◽  
The Public ◽  
The Road ◽  
Right Of Way ◽  
The North ◽  
Public Road ◽  
Plant Remains ◽  
Rhynie Chert ◽  
The Right

The chert of the Muir of Rhynie, containing plant-remains, was discovered by Dr W. MACKIE of Elgin while investigating the sedimentary and volcanic rocks of Craigbeg and Ord Hill which occur in that area. The original discovery was made on loose specimens, built into the dykes or scattered over the fields, especially those lying to the north of the road which runs from Rhynie to Cabrach, and east and west of the right-of-way that here connects Windyfield Farm with the public road.

scholarly journals XII.—On the Carboniferous Volcanic Rocks of the Basin of the Firth of Forth—their Structure in the Field and under the Microscope

1880 ◽  
Vol 29 (1) ◽  
pp. 437-518 ◽  
Author(s):  
Geikie
Keyword(s):  
North Sea ◽  
Geographical Area ◽  
Volcanic Rocks ◽  
The South ◽  
The West ◽  
Red Sandstone ◽  
Lower Silurian ◽  
The North ◽  
The North Sea ◽  
Firth Of Forth

The geographical area embraced in the present memoir forms a well-marked basin traversed along its centre by the estuary of the Forth. It is bounded on the north by the chain of the Ochil Hills, on the south by the range of the Pentland and Lammermuir uplands. Towards the west it joins along a low watershed the basin of the Clyde, while eastwards it dips under the waters of the North Sea. Within this defined space the Carboniferous rocks occupy what may be described as one great synclinal trough, varied by innumerable smaller synclines and anticlines. Save where cut out by powerful dislocations, their lower members rise up along the margins of the basin, while their highest portions cover a smaller area in the centre. The older formations forming the northern and southern boundaries of the area belong chiefly to the Lower Old Red Sandstone, in the Lammermuir district to the Lower Silurian. The Carboniferous rocks everywhere rest upon them unconformably.

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.

Deep- versus shallow-marine sandstone provenance in the mid-Carboniferous Clare Basin, western Ireland

2021 ◽  
pp. jgs2020-216
Author(s):  
Martin Nauton-Fourteu ◽  
Shane Tyrrell ◽  
David M. Chew ◽  
Foteini Drakou ◽  
Katharina Pfaff ◽  
...  
Keyword(s):  
Deep Water ◽  
Temporal Variations ◽  
Heavy Mineral ◽  
The South ◽  
Deep Basin ◽  
Content Type ◽  
Shallow Marine ◽  
Red Sandstone ◽  
Source To Sink ◽  
Supplementary Material

In a ‘source to sink’ sedimentary system, multiple processes have the potential to modify the sediment composition during sediment generation at the source, through transport, deposition and burial. To investigate these issues, a multi-proxy provenance study of deep-water and shallow-marine sandstones from the mid-Carboniferous Clare Basin was undertaken, utilising zircon and apatite U-Pb geochronology, heavy mineral analysis (including apatite trace element data) and petrography. Data from the deep-water submarine fans show a similar provenance signal to the shallow marine sandstones. Data, from across the Clare Basin stratigraphy indicate sands were likely and consistently derived from the south and SW, with a portion of the detritus being recycled from Old Red Sandstone basins to the south. The provenance signal, however, shows spatial and temporal variations across the basin that are explained by fluctuations in the amount of recycled sediments and are linked with the evolving Variscan Orogenic Belt. Heavy mineral data from both shallow marine and deep-water sandstones suggest a basin configuration with a delta system feeding directly into the deep basin.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5446739

Environmental framework of the diversification of the Osteostraci during the Silurian and Devonian

1985 ◽  
Vol 309 (1138) ◽  
pp. 259-272 ◽  
Keyword(s):  
North Atlantic ◽  
Marine Species ◽  
Early Devonian ◽  
Intertidal Zones ◽  
Red Sandstone ◽  
Clear Cut ◽  
The North ◽  
Geological Event ◽  
Pass Through ◽  
Sandstone Facies

The beginning of the Devonian is marked by the sudden occurrence of abundant vertebrate faunas, often associated with detritic facies of Old Red Sandstone type. A few groups, already represented in the Silurian and even in the Ordovician, pass through the Silurian-Devonian boundary and seem to undergo an important diversification at this particular moment of their history. The case of the Osteostraci, a group of fossil jawless vertebrates, is examined in detail to show whether or not its phylogenetic pattern displays a radiation that coincides with the extension of the Old Red Sandstone facies over the North Atlantic continent. It appears that this geological event may have triggered the radiation of the cornuate osteostracans, although this monophyletic group must have already begun to diversify in the Middle Silurian. A review of the analyses of three osteostracan-bearing localities (Welsh Borderland, Spitsbergen and Saaremaa) is presented, and it is concluded that the Osteostraci may have consisted of both fresh water and marine species. When marine, the environment of the Osteostraci may have been vast intertidal zones, hardly having any Recent equivalent. The difficulty in assigning the Old Red Sandstone (from Britain and elsewhere) to any clear-cut environment may be because the physical constants of the Earth or the amplitudes of the tide were not the same in early Devonian times as they are now.

XXIV.—On Old Red Sandstone Plants showing Structure, from the Rhynie Chert Bed, Aberdeenshire Part I. Rhynia Gwynne-Vaughani, Kidston and Lang

1917 ◽  
Vol 51 (3) ◽  
pp. 761-784 ◽  
Author(s):  
R. Kidston ◽  
W. H. Lang
Keyword(s):  
Volcanic Rocks ◽  
Red Sandstone ◽  
The Public ◽  
The Road ◽  
Right Of Way ◽  
The North ◽  
Public Road ◽  
Plant Remains ◽  
Rhynie Chert ◽  
The Right

The chert of the Muir of Rhynie, containing plant-remains, was discovered by Dr W. Mackie of Elgin while investigating the sedimentary and volcanic rocks of Craigbeg and Ord Hill which occur in that area. The original discovery was made on loose specimens, built into the dykes or scattered over the fields, especially those lying to the north of the road which runs from Rhynie to Cabrach, and east and west of the right-of-way that here connects Windyfield Farm with the public road.

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