A U–Pb age for the Late Caledonian Sperrin Mountains minor intrusions suite in the north of Ireland: timing of slab break-off in the Grampian terrane and the significance of deep-seated, crustal lineaments
0
Citation
0
Reference
10
Related Paper
Abstract:
An intrusion of trachy-andesite, representative of a newly discovered suite of high-K–Ba–Sr, calc-alkaline minor intrusions (termed herein the Sperrin Mountains suite), hosted within the Grampian terrane in the north of Ireland, has been dated by U–Pb zircon at 426.69 ± 0.85 Ma (mid-Silurian; Wenlock–Ludlow boundary). Geochemistry reveals a close association with the Fanad, Ardara and Thorr plutons of the Donegal Batholith and the Argyll and Northern Highlands Suite of Scotland. The deep-seated Omagh Lineament appears to have limited eastward propagation of the Sperrin Mountains suite from beneath the main centre of granitic magmatism in Donegal. A Hf depleted mantle model age (TDMHf) of c. 800 Ma for trachy-andesite zircons indicates partial melting from a source previously separated from the mantle. Whole-rock geochemistry of the suite is consistent with a model of partial melting, triggered by slab break-off, following thrusting of Ganderia–Avalonia under the Southern Uplands–Down–Longford accretionary prism (i.e. Laurentian margin). The new age constrains the timing of this event in the north of Ireland and is consistent with the petrogenesis of Late Caledonian high-K granites, appinites and minor intrusions across the Caledonides of northern Britain and Ireland.Keywords:
Slab
Several narrow terranes occur along the Denali fault in the Eastern and Central Alaska Range in Southern Alaska. These terranes are the Aurora Peak, Cottonwood Creek, Maclaren, Pingston, and Windy terranes, and a terrane of ultramafic and associated rocks. Exterior to the narrow terranes to the south is the major Wrangellia island arc composite terrane, and to the north is the major Yukon-Tanana metamorphosed continental margin terrane. Overlying mainly the northern margin of the Wrangellia composite terrane are the Kahiltna overlap assemblage to the west, and the Gravina-Nutzotin-Gambier volcanic-plutonic-sedimentary belt to the east and southeast. The various narrow terranes are...
North American Plate
Continental Margin
Ultramafic rock
Cite
Citations (17)
A widely accepted definition of tectonostratigraphic terrane is that of Howell, Jones, and Schermer (1985): a fault-bounded package of rocks of regional extent characterized by a geologic history that differs from that of neighboring terranes. The word terrane has, of course, a very long history of use in non-specific contexts in geological literature.
Cite
Citations (6)
Devonian
Cite
Citations (5)
Based on the great thickness crustal struture and complex geophysical character,this paper points out the principle for dividing terranes in Qinghai─Xizang Plateau according to earthquake activities and wave field sign,lithospheric structure and velocity character,palemagnetic mark,potential field sign ,temperature sign, geological and tectonics character. From north to south of the Qinghai─Xizang Plateau and its neighbouring regions can be devided in seven terranes, ie, Qaidam terrane, Kunlun terrane, Hon Xil-Bayan Har terrane, Qangtang terrane, Lhasa-Gangdise terrane, Himalayan terrane and Ganges Plain terrane. The distribution and character of these terranes have important rools for the studies of the formation and evolution.of the plateau and plate movement and dynamic mechanism.
Cite
Citations (7)
Based on abundant geological data,this paper divides geologically Fujian province into four distinct terranes,namely,Northwest Fujian terrane,Southwest Fujian terrane,East Fujian terrane and Southeast Fujian terrane,and correlates their geological features in detail respectively.Through the study on collision-amalgamation history of each terrrane,it can be concluded that they mainly underwent three stages:(1)in Late Proterozoic,the Southwest Fujian terrane and Northwest Fujian terrane collided and amalgamated along the Nanping-Ninghua fracture zone,being accompanied by submarine and continental volcanic eruptions;(2)in Triassic,the East Fujian terrane collided and amalgamated with the Southwest Fujian terrane and Northwest Fujian terrane along the Zhenghe-Dapu fracture belt,and the Southeast Fujian terrane amalgamated simultaneously with the East Fujian terrane;(3)in Cretaceous,the Southwest Fujian terrane underwent a left-lateral strike slip along the Pingtan-Dongshan fracture zone.
Cite
Citations (7)
Radiogenic nuclide
Island arc
Back-arc basin
Cite
Citations (261)
Abstract The Chrystalls Beach‐Brighton coastal block in southeast Otago has commonly has been placed in Caples Terrane, but has recently been described as a geochemically anomalous area of uncertain terrane affinity. Data points on discriminant diagrams occupy fields centred between those for type Caples Group and Torlesse Terrane, overlapping both. The psammites average 71.9% SiO2, closely comparable to Torlesse Terrane psammites, in contrast to the majority of type Caples Group psammites (av. 64.3%) and Waipapa Terrane psammites (64.4%). QFL plots show the Chrystalls Beach psammites as a petrofacies distinct from those described hitherto for Torlesse Terrane (lithic feldsarenites) and Caples Group and Murihiku Terrane (volcarenites). Keywords: Caples TerraneTorlesse TerraneChrystalls Beach ComplexMurihiku TerranegeochemistryOtago SchistWaipapa Terrane
Cite
Citations (28)
In southern Alaska, multiple terranes—slabs that have broken off from larger tectonic plates and shuffed around—create a complex patchwork that makes it challenging for scientists to untangle the tectonic history and structure of the region. One of these, the Yakutat terrane, which lies just offshore southern Alaska in the Gulf of Alaska, is converging with the North American plate and driving the growth of the Chugach–St. Elias mountains. The structure of this terrane has not been well studied until now. Worthington et al. conducted seismic studies to create a two‐ dimensional seismic velocity model of the Yakutat terrane. The model allows them to constrain the crustal thickness and composition of the terrane.
Cite
Citations (0)
Regional magnetic and gravity map patterns, combined with modeling of magnetic and gravity data constrained by measured magnetic susceptibility and density information, are used to develop a better understanding of the three-dimensional character of major lithostratigraphic subdivisions (terranes) in southern New Brunswick. Models and long wavelength map patterns indicate that the boundaries between the Caledonia, Brookville, Kingston, and New River terranes are sub-vertical or dip slightly to the southeast, and that some map units in each terrane extend to depths ranging from 50008000 m. The Mascarene and St. Croix terranes are less well constrained than the more outboard terranes on the models, in part because of limited physical property data but also because of the presence of the Saint George Batholith, which obscures relationships among stratigraphic units. The models are consistent with the Mascarene terrane being a cover sequence over the boundary between the St. Croix and New River terranes, the specific location and nature of which is now revealed by the geophysical models. The terranes appear to be associated at depth with geophysically distinct bodies that are interpreted to correspond to the basements, from southeast to northwest, of Avalon terrane sensu stricto, BrookvilleBras d'Or terrane, and ExploitsGander composite terrane. The latter "Gander basement" underlies the Kingston, New River, Mascarene, and St. Croix terranes.
Basement
Cite
Citations (23)