An Acadian mountain front in the English Lake District: the Westmorland Monocline

1993 ◽  
Vol 130 (2) ◽  
pp. 203-213 ◽  
Author(s):  
B. C. Kneller ◽  
A. M. Bell
Keyword(s):  
Shear Zone ◽  
Foreland Basin ◽  
Lake District ◽  
Volcanic Group ◽  
The North ◽  
English Lake District ◽  
Mountain Front ◽  
Group A ◽  
Lower Palaeozoic ◽  
Wide Zone

AbstractThe structure of the southern and central English Lake District is that of a southeast-facing monocline, named here the Westmorland Monocline. This 10 km wide zone of highly cleaved, southeast-dipping rocks separates gently dipping, poorly cleaved Borrowdale Volcanic Group to the north from extensively folded but regionally subhorizontal Windermere Group (foreland basin) rocks to the south. The monocline formed early in the local Acadian deformation sequence, and accommodates at least 8 km of uplift. It coincides with the steep concealed margin of the Lake District batholith. A major northwest-dipping shear zone is revealed in the deepest levels now exposed within the monocline, in the Skiddaw Group rocks of the Black Combe inlier.The monocline has the characteristics of a mountain front, providing significant tectonic elevation across a foreland-dipping panel of rocks, with no hinterland-dipping thrust visible at the surface. We interpret the uplift as the consequence of a southeast-vergent thrust with a gently northwest-dipping ramp beneath the central Lake District, continuing southeastwards as a flat detachment beneath the Windermere Group. A displacement up the ramp of about 20 km is accommodated by backthrusting within the monocline and by shortening within the Windermere Group of the hangingwall southeast of the monocline. The tip lies beyond the limit of the Lower Palaeozoic inlier, beneath Carboniferous cover.

The early Palaeozoic evolution of northwest England

1993 ◽  
Vol 130 (5) ◽  
pp. 711-724 ◽  
Author(s):  
A. H. Cooper ◽  
D. Millward ◽  
E. W. Johnson ◽  
N. J. Soper
Keyword(s):  
Foreland Basin ◽  
Lake District ◽  
Volcanic Group ◽  
The North ◽  
Iapetus Ocean ◽  
Granitic Intrusions ◽  
Deformation Event ◽  
Lower Palaeozoic ◽  
Early Palaeozoic ◽  
Uplift And Erosion

AbstractThe Lake District and smaller Craven inliers of northwest England contain a Lower Palaeozoic sequence deposited on the Gondwanan side of the Iapetus Ocean, close to the junction with the Tornquist Sea. The Tremadoc to Llanvirn Skiddaw and Ingleton groups are deep water assemblages of turbidite, olistostrome and slump deposits, formed at a continental margin. They experienced uplift and erosion as a precursor to the eruption of two largely subaerial Llandeilo-Caradoc volcanic sequences: the tholeiitic Eycott Volcanic Group in the north and the calc–alkaline Borrowdale Volcanic Group in the central Lake District. The volcanic episodes are the earliest part of a major episode of magmatism, extending through to the early Devonian and responsible for a major batholith underpinning the Lake District. Subsidence in an intra-arc rift zone preserved the subaerial volcanic sequences. A marine transgression marks the base of the Windermere Group, which comprises a mixed carbonate–clastic shelf sequence of Ashgill age, passing upwards through the Silurian into a thick, prograding foreland basin sequence of Ludlow turbidites. Deformation of the Lower Palaeozoic sequences was possibly diachronous from north to south. It is attributed to the late Caledonian (Acadian) Orogeny and resulted in folding, cleavage and thrust development. Granitic intrusions, including those at Shap, Skiddaw and beneath the hydrothermal Crummock Water Aureole, are partly syntectonic and were therefore penecontemporaneous with this deformation event. Some thrust faulting post-dates the intrusive phase. Post-deformation Devonian conglomerates are also present locally.

Foreland basin development and tectonics on the northwest margin of eastern Avalonia

1993 ◽  
Vol 130 (5) ◽  
pp. 691-697 ◽  
Author(s):  
B. C. Kneller ◽  
L. M. King ◽  
A. M. Bell
Keyword(s):  
Foreland Basin ◽  
Suture Zone ◽  
Lake District ◽  
Early Devonian ◽  
Basin Inversion ◽  
The North ◽  
Orogenic Wedge ◽  
Mountain Front ◽  
Thrust System ◽  
Early Palaeozoic

AbstractThe early Palaeozoic convergence of Avalonia and Laurentia created a foreland basin at the suture zone of the former lapetus Ocean. Sedimentological and stratigraphic evidence of shallowing and contemporaneous shortening suggests that the southern part of the basin (the Windermere Group) became detached from its basement in the late Ludlow, and began to invert. The detachment beneath the basin rooted into a northwest-dipping mid-crustal thrust system. Contemporaneous uplift to the north of the late Silurian basin involved shortening of the Avalonian foreland basement by thrusting. Basin inversion occurred ahead of a southeastward-advancing mountain front. We postulate a foreland (southeast) prograding sequence of thrusting through the Ludlow in the Lake District. The basin continued to migrate onto the Avalonian foreland through the early Devonian, ahead of an advancing orogenic wedge, finally coming to a stop in the Emsian.

Field and biostratigraphic evidence for an unconformity at the base of the Eycott Volcanic Group in the English Lake District

1992 ◽  
Vol 129 (1) ◽  
pp. 77-92 ◽  
Author(s):  
David Millward ◽  
Stewart G. Molyneux
Keyword(s):  
Volcanic Rocks ◽  
Tectonic Deformation ◽  
Lake District ◽  
Critical Data ◽  
Volcanic Group ◽  
Late Cambrian ◽  
Water Formation ◽  
English Lake District ◽  
Volcaniclastic Rocks ◽  
Lower Palaeozoic

AbstractThe Eycott Volcanic Group of the Lake District Lower Palaeozoic inlier consists of basaltic and andesite and and andesite sheets and associated, mainly coarse, volcaniclastic rocks. The volcanic rocks have been regarded previously as interdigitated with, and equivalent in age to, mudrocks of the upper part of the Skiddaw Group (Tremadoc–Llanvirn). Microfloral evidence has been quoted in support of this interpretation, but has not been substantiated by re-assessment of the critical data. Furthermore, a recent examination of the base of the Eycott Volcanic Group has shown that it rests with angular unconformity on the Skiddaw Group. Skiddaw Group rocks beneath the unconformity range in age from possible late Cambrian to early Llanvirn. The lowest part of the Eycott Volcanic Group, the Over Water Formation, consists of siltstones and tuffaceous sandstones yielding a diverse microflora, and is intercalated with two andesite sheets interpreted herein as sills. Since the currently accepted Llanvirn age for the Eycott Volcanic Group cannot be confirmed, the volcanism may have been penecontemporaneous with the Llandeilo–Caradoc Borrowdale Volcanic Group episode. There are implications for a pre-volcanic tectonic deformation episode.

Non-marine arthropod traces from the subaerial Ordovician Borrowdale Volcanic Group, English Lake District

1994 ◽  
Vol 131 (3) ◽  
pp. 395-406 ◽  
Author(s):  
E. W. Johnson ◽  
D. E. G. Briggs ◽  
R. J. Suthren ◽  
J. L. Wright ◽  
S. P. Tunnicliff
Keyword(s):  
Trace Fossils ◽  
The Other ◽  
Lake District ◽  
Lacustrine Environment ◽  
Volcanic Group ◽  
English Lake District ◽  
Group A ◽  
Colonization Of Land ◽  
Made In

AbstractArthropod trace fossils are described from the Borrowdale Volcanic Group, a sequence otherwise devoid of faunal evidence. Two forms, both made by the same probably myriapod-like organism, are assigned to the ichnogenera Diplichnites and Diplopodichnus. The lithologies preserving the trace fossils are non-marine and may have been deposited in a freshwater lacustrine environment; some of the traces were probably made in temporarily emergent conditions. The change from one form of trace to the other reflects drying out of the substrate. The trace fossils probably record some of the earliest freshwater arthropods, before the widespread colonization of land by the group.

A pre-caldera plateau-andesite field in the Borrowdale Volcanic Group of the English Lake District

1992 ◽  
Vol 149 (6) ◽  
pp. 889-906 ◽  
Author(s):  
M. G. PETTERSON ◽  
B. BEDDOE-STEPHENS ◽  
D. MILLWARD ◽  
E. W. JOHNSON
Keyword(s):  
Lake District ◽  
Volcanic Group ◽  
English Lake District

II.—Note on the Recent Volcanic Eruption in New Zealand

1886 ◽  
Vol 3 (9) ◽  
pp. 398-402
Keyword(s):  
New Zealand ◽  
Early Morning ◽  
Considerable Change ◽  
Lake District ◽  
Historic Period ◽  
North East ◽  
The North ◽  
The One ◽  
Wide Zone ◽  
White Island

The “Lake District” of the North Island is too well known to all students of volcanic phenomena, especially of that branch comprising hydrothermal action, to need a detailed description. It will be sufficient to say that it forms a belt, crossing the island from north-east to south-west, and forms a portion of the Middle and Upper Waikato Basins of Hochstetter. The district has been recently brought into prominent notice by the disastrous eruption of Mount Tarawera, very full accounts of which have appeared in New Zealand papers lately received. The eruption commenced in the early morning of Thursday, June 10th, but premonitory symptoms showed themselves a few days before in a tidal wave, three feet high, on Lake Tarawera, great uneasiness of the springs at Ohinemutu, and the reported appearance of smoke issuing from Euapehu, the highest of the great trachytic cones at the extreme south-westerly end of the system. The belt of activity extends from Mount Tongariro at the one end to White Island, in the Bay of Plenty, at the other, a distance of about 150 miles. White Island has undergone considerable change from volcanic action during recent years, and Tongariro was last in eruption in July, 1871; whilst its snowclad sister cone Euapehu has never manifested volcanic action within the historic period until now. This wide zone in the centre of the North Island has, ever since the arrival of the Maoris, been the scene of such extraordinary phenomena, that it has of late been the resort of visitors from all quarters of the globe.

Stable isotope compositions of alteration fluids in low-grade Lower Palaeozoic rocks, English Lake District

1985 ◽  
Vol 49 (352) ◽  
pp. 425-434 ◽  
Author(s):  
L. J. Thomas ◽  
R. S. Harmon ◽  
G. J. H. Oliver
Keyword(s):  
Stable Isotope ◽  
Fluid Inclusion ◽  
Isotopic Composition ◽  
Low Grade ◽  
Secondary Phases ◽  
Lake District ◽  
English Lake District ◽  
Lower Palaeozoic ◽  
Hydrogen And Oxygen Isotope ◽  
Isotope Analyses

AbstractA combination of hydrogen and oxygen isotope analyses and fluid inclusion studies has defined the composition of fluids involved in the metamorphism of Lower Palaeozoic rocks in the English Lake District. Three fluid fields have been defined from secondary phases: 1, syn-burial metamorphic D-enriched fluids from epidote and chlorite at a temperature between 250 and 350°C; D-depleted fluid measured from groundmass and quartz inclusions; 3, a mixed magmatic-meteoric fluid with an intermediate H-isotopic composition estimated from W/R granite data and calculated from illite.

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