bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE LOWER PALAEOZOIC ROCKS OF SOUTH-WEST MURRISK, IRELAND
Authors: STANTON WILLIAM IREDALE 
Published: October 2009

The general geology of an area of Ordovician and Silurian rocks in North Connemara is described. The oldest strata are the Arenigian Sheefry Grits, a thick marine series of slates and greywackes derived from the south. Many of the beds exhibit perfect grading; they are thought to be the deposits of turbidity currents. The Glenummera Slates follow conformably, and are succeeded by the deltaic Mweelrea Grit series, of Middle Ordovician age. Marked facies changes show that the source of sediment lay to the south, and many of the conglomerate pebbles can be referred to the Connemara Schists.
In the lower part of the Mweelrea Grits are thick persistent beds of welded tuff, possibly the products of eruptions of Peléan type. Massive graded tuff-beds in the Sheefry Grits are thought to have had a similar origin.
Silurian (Llandovery?) quartzites and slates, with a basal conglomerate, rest un-conformably on the Ordovician rocks. A small late Caledonian granite pluton was emplaced by stoping, and associated with it are acidic and appinitic dykes.
Minor disturbances occurred during the Upper Ordovician, but the main folding was Caledonian. Right-handed stresses involving the formation of two large tear-faults swung the Caledonian strike round into a west-north-westerly direction.
THE STRUCTURAL GEOLOGY OF THE BOULE AND BOSCHE RANGES IN THE CANADIAN ROCKY MOUNTAINS
Authors: O’BRIEN CHRISTIAN ARTHUR EDGAR 
Published: October 2009

The paper records the results of geological mapping over the Boule and Bosehe Ranges which form a part of the Front Ranges and adjacent foothills of the Rocky Mountains of Canada in an area near the Athabaska River Valley.
The structure of the area comprises a series of individual thrust-blocks, each successively overlying the contiguous block from south-west to north-east. Each block has been subjected to intense folding and faulting. Folding is moderately disharmonic at the surface, with the sedimentary column displaying three competent groups separated by incompetent formations with strong tendencies towards plastic deformation.
Near the base of the column is a thick section of chloritic shales of Lower Cambrian age, whose importance is stressed as a potential lubricating medium for the main thrust movements.

The possibility of the existence of a plane of
décollement
in this lubricating medium is discussed, with the attendant suggestion that the Front Ranges may have been pushed north-eastwards over a largely unbroken Lower Cambrian and Pre-Cambrian basement.
THE STRATIGRAPHY AND STRUCTURE OF THE ORDOVICIAN ROCKS OF THE RHINNS OF GALLOWAY
Authors: KELLING GILBERT 
Published: October 2009

Re-examination of the stratigraphy and structure of Ordovician rocks in the northern part of the Rhinns of Galloway has led to amplification and some reinterpretation of the concepts of succession and structure advocated by Poach and Horne (1899). A stratigraphical succession within the greywackes has been erected on the basis of palaeontological and lithological evidence, and with the aid of “way-up” criteria. Stratigraphical groups have been subdivided on petrological grounds. The intercalation of at least two bands of Glenkiln (black) shale in a relatively thin greywacke sequence has been detected as far north as Broadsea Bay, and it can be demonstrated that a few miles farther north these black shales are represented by at least ten bands of fissile siltstone with black graptolite-bearing films, separated by some 6000 feet of greywackes. Relatively rapid cross-strike variations in thickness and lithological character have been found in several formations, amounting in the Glenkiln rocks to a general southward attenuation and concomitant increase in the proportion of shale and siltstone in the sequence. Palaeontological evidence shows that all the greywackes are of Glenkiln age, with the exception of the uppermost beds, the Portpatrick Group, which is probably Hartfell.
Structurally the area is believed to comprise four main units, namely, three major complex monoclinal structures of Caledonoid trend with vertical northern limb and tightly folded and otherwise complicated southern limb, and one complex synclinal structure. The units are separated by major faults, mainly thrusts but including the Southern Uplands (= Glen App) fault, which is here normal, throwing south. Minor faults, especially wrench-faults, are of considerable importance.
THE GLACIAL DRIFTS OF THE SOUTHERN PART OF THE SHROPSHIRE-CHESHIRE BASIN
Authors: POOLE EINAR GEORGE , WHITEMAN ARTHUR JOHN 
Published: October 2009

Official work on the Nantwich district (Sheet 122) showed t h a t the sequence of two boulder-clays with associated fluvioglacial deposits, previously recognized only in the northern part of the Shropshire–Cheshire basin, also extended into its centre. Subsequent private research has shown that this sequence may be distinguished throughout the whole basin and in a critical region beyond its south-eastern margin—in total an area exceeding 3000 square miles.
The recognition of glacial lake features cut into the Upper Boulder-clay in the Nantwich district and elsewhere necessitates a revision of current ideas about the origin of Lake Lapworth and the age of the Severn terraces above Ironbridge.
Accepted correlations relating to the basin and its adjacent areas, the status of the “Little Welsh Glaciation” and the Newport–Wolverhampton esker chain are discussed. A new interpretation of the Pleistocene and Recent history of the region is presented.
INTRUSIVE LIMESTONES IN THE KESHYA AND MKWISI VALLEYS, NORTHERN RHODESIA
Authors: BAILEY DAVID KENNETH 
Published: October 2009

Two intrusive limestones in the valleys of the Keshya and Mkwisi streams, tributaries of the Kafue River, are described : the Keshya limestone, which intrudes the roof-migmatite zone of the Kafue Gorge granite, and the Mkwisi limestone, which intrudes a series of late Pre-Cambrian metasediments and contains xenoliths of similar granite. Brecciation of the country-rocks is extensive and the intrusions are irregular in form. Xenoliths are abundant in the limestones, which are coarse-grained, impure calcite-marbles with accessory magnetite, haematite, pyrite, apatite, rutile, monazite and xenotime. Alteration of the country-rocks is characterized by the introduction of alkali-feldspars, phlogopite and titanium minerals.
The origin of the limestones is discussed and it is concluded that they represent an unusual type of carbonatite activity, resembling hydrothermal vein-like deposits in some of their characteristics but probably emplaced by a process of fluidization.
AN OUTLINE OF THE LEWISIAN COMPLEX OF THE OUTER HEBRIDES IN RELATION TO THAT OF THE SCOTTISH MAINLAND
Authors: DEARNLEY RAYMOND 
Published: October 2009

The main structural and metamorphic features of the Lewisian rocks of the Outer Hebrides are outlined and compared with those of the Lewisian on the Scottish mainland. In each area three structural zones are recognized, characterized by folding of different styles and periods. The three zones of the Outer Hebrides are closely analogous to the Scourian and Laxfordian zones of the mainland.
Evidence of three periods of folding and metamorphism in varying degrees of intensity may be seen in the Outer Hebrides. The first and second periods were separated in time by the intrusion of a non-orogenic suite of basic sills and dykes of tholeiitic affinities, possibly associated with the plutonic centre in South Harris. This basic suite is regarded as equivalent to the Scourie dykes of the mainland.
The first period of folding and (granulite-facies) metamorphism is recognized in the gneisses above the Outer Isles thrust-plane and in a narrow belt along the Sound of Harris, and is correlated with the Scourian of the mainland. After the intrusion of the basic suite, the rocks were affected by a second period of folding and granulite-facies metamorphism which converted the basic intrusions to garnet-pyroxene-amphibolites. The Scourie dykes of the mainland retain evidence of this metamorphism in the form of corona garnets, garnetiferous border zones, and clouded feldspars. The second folding and metamorphism is regarded as Early Laxfordian because the folding has the same trend as that accompanying the third and last period of metamorphism, which is a retrograde type associated with migmatization and intrusion of granites and pegmatites and is known from absolute age-determinations to be equivalent to the Lax-fordian of the mainland.
The positions of the Lewisian metamorphic and structural zones on the opposite shores of the Minch do not coincide, and the offset can be adequately explained only by later wrench-faulting. Evidence is presented to support the existence of the Minch fault, a sinistral wrench-fault with an approximate displacement of 77 miles, comparable in direction and magnitude with the Great Glen fault.
ON FOLDING DURING THREE-DIMENSIONAL PROGRESSIVE DEFORMATION
Authors: FLINN DEREK 
Published: October 2009

This paper is concerned with the geometry of homogeneous strain in rocks. Equations relating rotation of planes and lines to the deformation of the rock containing them are derived with the aid of the deformation ellipsoid. The Fresnel construction is borrowed from optical mineralogy to determine from the deformation ellipsoid the principal axes of compression and extension in any plane, and an expression is derived for determining the lengths of these axes. Further equations are derived which define the surfaces of no infinitesimal strain and no finite strain for all possible ellipsoids, and it is shown that these surfaces may be used for rapidly determining whether the principal axes in any plane have suffered shortening or extension.
With these tools the rather complex geometry of three-dimensional homogeneous strain is examined in detail. It is shown, for instance, that during deformation planes and lines develop preferred orientations reflecting the symmetry of the deformation, and pre-existing folds rotate bodily in space and either open or close or both during the deformation. In order to draw further conclusions of general interest the condition of homogeneous strain is relaxed in order to consider the deformation of layered rocks with competence differences between the layers. It is argued that during the deformation of such rocks folds and boudinage form parallel to the principal directions of strain in the layers. The conditions that determine whether folds or boudinage are formed are examined and the subsequent development of the structures after their generation is followed. These methods of analysis are used in the construction of models of superimposed fold-systems which are shown to be similar to some recently described field examples.
It is argued that the tectonic axial cross must be replaced by the deformation ellipsoid. The structures treated in the paper are usually derived by shear-plane hypotheses, but it is considered that such hypotheses are superfluous.
The Lower Palaeozoic stratigraphy of central Murrisk, County Mayo, Ireland, and the evolution of the south Mayo trough
Authors: DEWEY JOHN FREDERICK 
Published: October 2009

The Ordovician and Silurian rocks of central Murrisk, County Mayo, Ireland, are described with reference to their stratigraphy, provenance, and conditions of deposition; 36 000 ft of Ordovician rocks are overlain, unconformably, by 5600 ft of Silurian strata.
The Arenig rocks are divided into two series: the Owenmore Series (2000 ft) below and the Murrisk Series (15 000 ft) above. The Owenmore Series (boulder-slides, turbidites, and black slates) was derived entirely from the north; the Murrisk Series (tuffs and turbidites) was derived from the east and south.

The Glenummera Series (4000 ft of green slates with thin psammitic turbidites) follows and is overlain by the Partry Series (15 000 ft). The Partry Series is divided into two groups; the Mweelrea Group below, and the Maumtrasna Group above. The Mweelrea Group (7000 ft of current-bedded deltaic grits) contains six beds of ignimbrite, deposited by
nuées ardentes
with a south-easterly provenance. Periodic westward tilting caused the eastward recession of the delta-front with the concurrent development of boulder-slides and turbidites. The Maumtrasna Group is similar to the Mweelrea Group but contains no ignimbrites, and the grits are coarser, with many interbedded conglomerates.

The Silurian rocks are divided into the Lower Owenduff Group (Upper Llandovery, 0 to 20 ft) below, and the Croagh Patrick Series (Wenlock, 5600 ft) above. The Lower Owenduff Group was deposited in a complex littoral environment and contains a large amount of pyroclastic material. The Croagh Patrick Series is divided into six groups (Cregganbaun Group, 500 ft; Pollanoughty Group, 450 ft; Oughty Group, 360 ft; Fiddaunarinnia Group, 600 ft; Lough Nacorra Group, 1500 ft; Owenwee Group, 2000 ft), the Oughty Group containing five tuff bands. The Croagh Patrick Series was deposited in a northwardly transgressive littoral and sub-littoral belt and was derived exclusively from the north and east.
The Silurian rocks rest unconformably upon the Owenmore Series as the result of strong pre-Upper Llandovery thrusting, concentric folding, and uplift.

During most of Ordovician times, the northern margin of an
e-w
trough (the South Mayo trough) was denned by a normal fault. The southern margin was defined throughout most of Ordovician times and the whole of the Silurian by a rising Cordillera in Conne-mara. Dal radian rocks provided the source for nearly all the clastic material.
Seismic investigations of the rocks beneath the northern part of Cardigan Bay, Wales
Authors: BLUNDELL DEREK JOHN , KING ROY FAVELL , WILSON CHARLES DOUGLAS VERNON 
Published: October 2009

Griffiths, King & Wilson (1961) described geophysical work in Tremadoc Bay resulting in the recognition of three layers of differing seismic velocities. The thickness and velocity of the uppermost, 'layer 1', and the velocity of 'layer 2' beneath it have now been determined more completely by further seismic refraction observations. Layer 1 has been shown to underly Morfa Harlech in the form of a valley, being the southward extension, some 1000 ft deep, of the Glaslyn valley at Portmadoc. This channel probably continues across Morfa Dyffryn and farther to the south-west. It is filled with material having seismic velocities in the range 5000 to 7600 ft/s, the upper 250 ft of which are thought to be of post-glacial age. The lower part may be Pleistocene material, but is more likely to be older.
The seismic velocities found for layer 2 have been compared with measurements made on nearby Ordovician and Cambrian sediments and with results from the Permo-Trias and Carboniferous of the Midlands. This new evidence supports the hypothesis of the previous paper that the northern part of Cardigan Bay is underlain (beneath the more recent cover of layer 1) by Ordovician rocks.
Stratigraphy and structure of the Purbeck inliers of Sussex (England)
Authors: HOWITT FRANK 
Published: October 2009

The Purbeck Beds exposed in Sussex are redescribed together with new sections exposed in gypsum mines workings and boreholes. Comparisons are made with Purbeck Beds elsewhere in southern England in boreholes and at outcrop.
A new map of the Purbeck inliers is presented and the structure is discussed. Conditions of sedimentation are illustrated by isopachyte maps.
DISCUSSION OF PAPERS PUBLISHED IN PREVIOUS PARTS OF THE
QUARTERLY JOURNAL
Authors: Turner D. C. 
Published: October 2009

From Mr C. N. Okezie:
The writer recently mapped a small portion (about 200 square miles) of the basement complex of the Kafanchan area, in the Nigerian Younger Granite province. He also mapped a very small Younger Granite stock, the Nok granite, within this area.

As a result of this work it became apparent to the writer that the trends of some intrusive Older Granites, their consanguineous granitic pegmatite dykes and sills, and the few basic dykes found in the area appear to have been controlled by four main structural planes of weakness in the basement rocks. These planes are the roughly north-south schistosity and foliation and three inferred sets of master-joints striking roughly
nw–se, ne–sw
, and
e
-w.

Careful examination of the Younger Granite complexes of this province as seen on the 1 : 2 000 000 geological map of Nigeria or on pl. vii of the Society’s
Memoir .No
. 1 shows also that these four planes of weakness appear to have exercised a significant control in the emplacement of the Younger Granites. This is shown by the fact that groups of these complexes are often aligned while individual complexes are often elongated parallel to any one of these four directions. The position is illustrated as follows:

Aligned complexes

(1) Banke-Kudaru-Rishua-Kerku-Nok-Afu (N-S)

(2) Banke-Liruei-Suku-Tongolo-Dagga Allah-Kwandon-Kaya-Kofayi (
nw-se
)

(3) Kwandon-Kaya-Jos-Bukuru-Vom-Kagoro (
ne
-sw)

(4) Burra-Ningi-Kila-Wurji-Fagam (
e
-w)

(5) Zuku-Saiya-Shokobo-Jere-Sanga-Buji-Jos-Bukuru-Rop (
n-s
)

(6) Sara-Fier-Sha-Kaleri-South-Mada-Afu (
ne-sw
)

Elongated complexes

(1) Liruei, Kwandon-Kaya, Kofayi (
nw-se
)

(2) Afu, Fagam (
ne
-sw)

(3) Sara–Fier, Nok, Rishua, Kudaru (
n––s
)

(4)
A gabbro—granodiorite association in Singapore Island
Authors: HUTCHISON CHARLES STRACHAN 
Published: October 2009

The syntectonic tin-bearing granite batholith system of the Thai-Malayan orogeny is associated in several places from north Thailand to Singapore with satellitic bodies of basic composition. In Singapore Island such a body of gabbroic composition is marginally situated within the batholith, and exposures indicate that it is pre-orogenic.
The orogenic granodiorite has intruded the gabbro in the form of irregular dykes, producing at the immediate contact a variety of hornblende-rich rocks by thermal metamorphism and hybridization. The dykes are crowded with gabbro xenoliths in every stage of assimilation.
A similar petrogenetic sequence and enrichment in hornblende is to be found in gabbro-granodiorite associations in most orogenic regions of the world.
Some relationships resulting from the intimate association of acid and basic magmas
Authors: BLAKE DAVID HENRY , ELWELL ROYSTON WILLIAM DUNLOP , GIBSON IAN LETHBRIDGE , SKELHORN RAYMOND RICHARD , WALKER GEORGE PATRICK LEONARD 
Published: October 2009

Evidence is presented from Guernsey, Iceland, Ireland, and Scotland that basic and acid magmas have commonly come together. Examples of this are found in surface extrusions and tuffs and in intrusions of various sizes formed at different depths. The basic magma has commonly been chilled against the acid, and the relationships indicate that the acid component was highly mobile; these two facts are thought to be intimately related, in that the mobility of the acid magma is due to the transfer of heat from the basic magma.
Consequences discussed include the question of the relative age of contiguous intrusions where basic rock is veined by acid: the age-sequence may be the reverse of that normally postulated. The possibility is also considered that basic magma may occasionally be necessary for the uprise of acid magma to high crustal levels.
The deformation of some banded gabbros in the northern Somalia fold-belt
Authors: DANIELS JOHN LEONARD , SKIBA WLADYSLAW JAN , SUTTON JOHN 
Published: October 2009

More than 20 layered basic intrusions are known among the crystalline rocks forming an isolated part of the late Pre-Cambrian and Lower Palaeozoic fold-belt in north-east Africa and the Red Sea region.
This paper discusses metamorphic and structural changes in and around five intrusions in an area between 20 and 40 miles north of Hargeisa and some 200 miles south-south-west of Aden: the Dudub, Rakdasafaka, Hamar, Ubali, and Gul Sakar gabbros. These consist largely of melanocratic olivine-gabbro with subordinate pyroxenite, peridotite, troctolite, and anorthositic leucogabbro. They were intruded into rocks that had already reached the amphibolite or granulite metamorphic facies during an early period of regional metamorphism and migmatization. Parts of these gabbros and country-rocks were later metamorphosed and deformed in a period of regional metamorphism that followed the intrusion of the basic rocks and was accompanied by the intrusion of granite. This late metamorphic event was only patchily developed and some gabbros retain many primary features, including rhythmic and cryptic layering, irregular layering, orbicular textures, poikilitic pyroxene, and flow-oriented olivine and plagioclase. The Hamar gabbro retains an incomplete contact-aureole and contains large country-rock inclusions believed to represent projections from a side wall.
The primary layering in all five intrusions now dips steeply and in three intrusions has been folded into structures a mile or two across. During the late movements, parts of the intrusions were converted to metagabbro or amphibolite and developed secondary structures which include shear-belts, minor folds and lineation, and oblique schistosity. Many of these structures have their equivalents in the country-rocks, which were affected by the later metamorphism and in which pre-gabbro high-grade mineral assemblages were partially replaced by lower-grade assemblages. The deformation of country-rock and gabbro is compared and three stages in the conversion of layered gabbro to concordant lineated and foliated metagabbro are recognized. The Somali layered intrusions are compared with deformed basic intrusions in other fold-belts and the deformation of such intrusions is briefly considered.
The Quaternary deposits of the Ballaugh and Kirkmichael districts, Isle of Man
Authors: MITCHELL GEORGE FRANCIS 
Published: October 2009

During the Last Glaciation ice advanced against the Isle of Man from the north, depositing in the north-west of the island large amounts of drift up to an altitude of 150 ft, and smaller isolated amounts of drift up to an altitude of 650 ft. These deposits are well seen in section at Orrisdale Head, and are described as an Orrisdale Series of deposits. Much of the island projected above the ice of the Last Glaciation as a nunatak.
In the coastal cliffs west of Kirkmichael another series of drifts, also derived from the north, is seen below the Orrisdale Series, and since these drifts are similar to the glacial deposits of Gipping age known farther south in the Irish Sea basin, they are regarded as Gipping in age. They are well exposed at Jurby Head and at Ballateare, and are described as a Ballateare Series. The whole island may have been overridden by ice during the Gipping Glaciation.

During the retreat of the Orrisdale ice, marginal lakes, outwash fans, and morainic ridges were formed. Late-glacial deposits accumulated in enclosed basins on the ridges, and these have been given carbon-14 dates ranging from 10 200 to 8300
b.c
.

When the permafrost melted at the end of late-glacial time, large quantities of sand and gravel, which had been built up into terraces in a marginal lake impounded in Glen Wyllin, south of Kirkmichael, were set free. These sands and gravels moved down and built up an early post-glacial alluvial fan at the mouth of the Glen, burying the late-glacial deposits to a depth of 40 ft.