A área em estudo localiza-se entre o embasamento mesoarqueano do Núcleo Serrinha e o Greenstone Belt do Rio Itapicuru (BA). O Núcleo Serrinha é constituído pelo Complexo Santa Luz, caracterizado por rochas metamórficas gnáissico-migmatíticas (Mascarenhas 1979), cobertas pelas vulcânicas do Grupo Capim (Winge 1984, apud. Cruz Filho et al. 2003) e pelas seqüências vulcano-sedimentares do Greenstone Belt do Rio Itapicuru (Brito Neves et al. 1980), intrudidas por granitóides diversos e recobertas por unidades fanerozóicas. Embora vários estudos tenham sido feitos, ou estão em desenvolvimento no GBRI, pouco se conhece sobre as rochas sedimentares do mesmo e quase nada sobre as relações de contato do GBRI e o embasamento. Por este motivo, foi planejado um projeto de cartografia geológica da transição embasamento-greenstone que resultou em um mapa geológico de uma área com cerca de 700 km2 entre as cidades de Nordestina, Queimadas e Santa Luz, a oeste da exposição principal do greenstone belt do Rio Itapicuru. Nesta região foi mapeada uma sequência de rochas sedimentares clásticas metamorfisadas denominada Sequência Metassedimentar Monteiro por Grisolia (2007) e Moreto (2007) em seus trabalhos de conclusão de curso de Geologia. Estudos de proveniência de sedimentos...
The Verulam Formation (Middle Ordovician) at the Lakefield Quarry
and Gamebridge Quarry, southern Ontario, is comprised of five main
lithofacies. These include shoal deposits consisting of Lithofacies 1,
winnowed crinoidal grainstones and, shelf deposits consisting of:
Lithofacies 2, wackestones, packstones, grainstones, and rudstones;
Lithofacies 3, laminated calcisiltites; Lithofacies 4, nodular wackestones
and mudstones; and, Lithofacies 5, laminated mudstones and shales. The
distribution of the lithofacies was influenced by variations in storm
frequency and intensity during a relative sea level fall.
Predominant convex-up attitudes of concavo-convex shells within
shell beds suggest syndepositional reworking during storm events. The
bimodal orientations of shell axes on the upper surfaces of the shell beds
indicates deposition under wave-generated currents. The sedimentary
features and shell orientations indicate that the shell beds were deposited
during storm events and not by the gradual accumulation of shelly material.
Cluster and principal component analysis of relative abundance data
of the taxa in the shell beds, interbedded nodular wackestones and
mudstones, and laminated mudstones and shales, indicates one biofacies
comprised of three main assemblages: a strophomenid (Sowerbyelladominated)
The Dummer Complex extends 180 km along the Precambrian -
Paleozoic contact from Tamworth to Lake Simcoe. It is composed
of coarse, angular Paleozoic clasts in discontinuous, pitted, hummocky
deposits. Deposits are usually separated by bare or boulder
strewn bedrock, but have been found in the southern drumlinized
till sheet. Dummer Complex deposits show rough alignment with
ice-flow. Eskers cross-cut many of the deposits.
Dummer sediment subfacies are defined on the basis of dominant
coarse grain size and lithology, which relate directly to
the underlying Paleozoic formation. Three subglacial tills are
identified based on the degree of comminution and distance of
transport; the immature facies of the Dummer Complex; the mature
facies of the drumlinized till sheet and; the submature facies
which is transitional.
Carbonate geochemistry was used for till-bedrock correlation
in various grain sizes. Of the 3 Paleozoic formations underlying
the Dummer Complex, the Gull River Fm. is geochemically distinctive
from the Bobcaygeon and Verulam Formations using Ca, Mg, Sr, Cu,
Mn, Fe and Na. The Bobcaygeon Fm. and Verulam Fm. can be
differentiated using Ca and the Sr/Ca ratio. The immature facies
from 1.0 phi and finer is dominated by the non-carbonate...
The lower Silurian Whirlpool Sandstone is composed of two main units: a fluvial unit and
an estuarine to transitional marine unit. The lowermost unit is made up of sandy braided
fluvial deposits, in shallow valleys, that flowed towards the northwest. The fluvial channels
are largely filled by cross-bedded, well sorted, quartzose sands, with little ripple crosslaminated
or overbank shales.
Erosionally overlying this lower unit are brackish water to marine deposits. In the east,
this unit consists of estuarine channels and tidal flat deposits. The channels consist of fluvial
sands at the base, changing upwards into brackish and tidally influenced channelized
sandstones and shales. The estuarine channels flowed to the southwest. Westwards, the unit
contains backbarrier facies with extensive washover deposits. Separating the backbarrier
facies from shoreface sandstone facies to the west, are barrier island sands represented by
barrier-foreshore facies. The barrier islands are dissected by tidal inlets characterized by
fining upward abandonment sequences. Inlet deposits are also present west of the barrier
island, abandoned by transgression on the shoreface. The sandy marine deposits are replaced
to the west by carbonates of the Manitoulin Limestone.
During the latest Ordovician...
The Oak Ridges Moraine is a major physiographic feature of south-central
Ontario, extending from Rice Lake westward to the Niagara Escarpment. While
much previous work has largely postulated a relatively simple the origin of the
moraine, recent investigations have concentrated on delineating the discernible
glacigenic deposits (or landform architectural elements) which comprise the
complex mosaic of the Oak Ridges Moraine. This study investigates the
sedimentology of the Bloomington fan complex, one of the oldest elements of the
Oak Ridges Moraine.
The main sediment body of the Bloomington fan complex was deposited
during early stages of the formation of the Oak Ridges Moraine, when the ice
subdivided, and formed a confined, interlobate lake basin between the northern and
southern lobes. Deposition from several conduits produced a fan complex
characterized by multiple, laterally overlapping, fan bodies.
It appears that the fans were active sequentially in an eastward direction,
until the formation of the Bloomington fan complex was dominated by the largest
fan fed by a conduit near the northeastern margin of the deposit. Following
deposition of the fan complex, the northern and southern ice margins continued to
Surficial sediments east of Dunnville, Ontario representing a
limited deltaic/lacustrine/aeolian system are investigated with
the aim of defining and interpreting their geological history by
means of exarrrrning their sedimentology and interrelationships.
The Folk and oJard grain size statistics of samples fran the area
were calculated. These sample parameters were e1en plotted on
maps to detennine regional patterns. The strongest pattern
observed was one of distinct fining to the east, away fran the
sand source. Aeolian deposits were fourrl to be better sorted than
the surrcunding sediments. The grain size parameter values were
also plotted on bivariate graphs in an attempt to separate the
samples according to depositional environment. This exercise met
with little success, as rrost of the sediments sampled in the area
have similar grain size parameters. This is believed to be
because the sediment sources for the different environments
(delta, distal delta, aeolian dune) are intimately related, to the
point that nnst dunes appear to have been sourcErl fran immediately
local sediments. It is FOstulated that in such a srrall
sedimentological sub-system, sediments were not involved in active
transport for a length of time sufficient for the rraterial to cane
to equilibritnn with its transporting medium. Thus...
The steeply dipping, isoclinally folded early Precambrian
(Archean) Berry Creek Metavolcanic Complex comprises
primary to resedimented pyroclastic, epiclastic and
autoclastic deposits. Tephra erupted from central
volcanic edifices was dumped by mass flow mechanisms into
peripheral volcanosedimentary depressions. Sedimentation
has been essentially contemporaneous with eruption and
transport of tephra.
The monolithic to heterolithic tuffaceous horizons
are interpreted as subaerial to subaqueous pumice and ash
flows, secondary debris flows, lahars, slump deposits and
turbidites. Monolithic debris flows, derived from crumble
breccia and dcme talus, formed during downslope collapse
and subsequent gravity flowage. Heterolithic tuff, lahars
and lava flow morphologies suggest at least temporary
emergence of the edifice. Local collapse may have
accompanied pyroclastic volcanism.
The tephra, produced by hydromagmatic to magmatic
eruptions, were rapidly transported, by primary and
secondary mechanisms, to a shallow littoral to deep water
subaqueous fan developed upon the subjacent mafic
metavolcanic platform. Deposition resulted from traction,
traction carpet, and suspension sedimentation from laminar
to turbulent flows. Facies mapping revealed proximal
(channel to overbank) to distal facies epiclastics
Thesis (Ph.D.1977) from the Dept. of Geology and Minerology, University of Adelaide; 2 v. : maps, plates, 6 fold maps in end pocket ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 2004; "February 2001"; Bibliography: p. 335-349.; xxix, 394 p. : ill. (some col.), maps (some col.), plates (col.) ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
During deposition of the mixed carbonate - clastic sequence of the Mundallio Subgroup, the " Adelaide Geosyncline " was a very shallow, elongate sedimentary basin, flanked to the west and east by older Precambrian basement.
In much of the southern and northern Flinders Ranges, clastic deposition predominated in the lower Mundallio Subgroup. In the north, alternating development of shallow mudflats and sandflats ( Nankabunyana Formation ) depended on the interplay between the sediment supply and winnowing processes, while dolomite mudstones were locally deposited in the shallowest areas. In the eastern half of the Willouran Ranges, massive shales were deposited as the environment remained persistently below wave base ( Camel Flat Shale ), but a renewed sand influx led to deposition of
the Tilterana Sandstone. In the southern Flinders Ranges, terrigenous clay and silt were deposited on submergent mudflats which shallowed into intermittently exposed dolomite mudflats ( Nathaltee Formation ). Dolomite mudflats were a more persistent feature in areas more distal from the terrigenous source, and sometimes contained isolated, ephemeral lakes which were sites of magnesite deposition ( Yadlamalka Formation ). Dolomite and magnesite mudstone deposition of the Yadlamalka Formation became wide spread in the northern and southern Flinders Ranges in the upper Mundallio Subgroup...
A sequence of Late Precambrian sedimentary rocks, reaching a total thickness of 7,000 ft., was mapped at Depot Creek, on the western scarp of the Flinders Ranges, South Australia. A review of studies on or near the area by previous authors is presented. Ten formations were recognized and mapped. Formations (4) to (10) have been placed in the Adelaide Supergroup, formations (7) to (9) belonging to the Sturt Group, and formation (10) belonging to the Marino Group. From the oldest to the youngest, these are:- (1) Pre-Adlaide Supergroup Redbed Sequence. A shallow water deposit with minor dolomite sedimentation. (2) Dolerite. Intrudes (1), but upper age is uncertain. Extensively altered, possibly by reactions during cooling. (3) Depot Creek Volcanics. Subaerial trachytic lavas, which have undergone extensive post-depositional alteration. The origin of amygdales and tuffaceous rocks is discussed. (4) Emeroo Quartzite. A transgressive shallow marine sand body unconformably overlying the volcanics. (5) Dolomite-Magnesite Sequence. Continuous dolomite sedimentation with minor magnesite conglomerates and classics, probably deposited in a lagoonal environment. Dolomitic Sandstone. Possibly also lagoonal, but with a more constant influx of arkosic sand. (7) Tillitic Sequence. Overlies (6) with possible disconformity...
Mapping and section measuring south of Mt. Chambers Gorge has detailed 2,900 feet of Lower Cambrian carbonates, ranging from the massive carbonates of the Wilkawillina Limestone to the purple shales of the Billy Creek Formation. Carbonates include thinly laminated, oolitic and pelletal limestones and previously unreported mega-breccias. An autochthonous sedimentary pattern, typical of deposition in epeiric seas has been imprinted on the vertical sequence by a marine regression. This tends to be masked by allochthonous sediments, dominantly silts, clay and a coarse quartz sand, possibly eroded from diapers. Brecciolas (slumps) with archaeocyathid limestone megaclasts (to 70ft.) occur locally in the upper beds of the Parara Formation and may help to date diapiric movements. Late phase dole rites intrude diapers and cut related faults; mineralization is also diaper associated and includes copper and lead sulphides.; Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Earth and Environmental Sciences, 1970; This item is only available electronically.
The Endicott Mountains allochthon is an east-west striking stack of north-northwest vergent thrust sheets which were emplaced during late Mesozoic and Cenozoic (Brookian) orogenesis. Thrust sheets in the allochthon are composed of clastic and carbonate rocks which track the progressive evolution of a Late Devonian and Early Carboniferous continental margin. Sedimentary facies in lower Upper Devonian rocks of the Beaucoup Formation delimit a volcanically active depositional basin. Volcaniclastic sediments within the Beaucoup were apparently derived from the south; whereas siliciclastic sediments were derived from the north. By the late Late Devonian, the Beaucoup depositional basin had developed into a south-facing continental margin. Southwestward progradation of the Kanayut-Hunt Fork delta system deposited thick conglomerates, sandstones, and shales on the margin and created a lithofacies pattern in which the Kanayut Conglomerate is thicker in the north and the Hunt Fork Shale is thicker in the south. Transgression of the Lower Mississippian Kayak Shale over the Kanayut Conglomerate occurred as sea level rose during the Early Mississippian. Subsequent transgressive-regressive cycles in carbonates of the Lisburne Group indicate that the margin had evolved into a stable passive margin by the middle Mississippian.
The style of Brookian structures in the Endicott Mountains allochthon changes from imbricate thrust sheets and large single-phase folds in the north to a thick...
Indiana Geological Survey Guidebook 8; Devonian rocks in southern Indiana have presented many problems of correlation; their stratigraphy has been studied during recent years by T. A. Dawson and
John B. Patton. General conditions of sedimentation of the Devonian rocks
are reviewed in this guidebook by Haydn H. Murray. Other aspects of the Devonian rocks and the general area of the conference also are discussed; these reports include geochemistry, economic geology, and the physiography and Pleistocene history. Staff members of the Indiana Geological Survey and the Department of Geology, Indiana University, will talk briefly at each of the scheduled stops; they will review such aspects of the chemical composition, petrology, mineralogy, and stratigraphic nomenclature as are most applicable to the locality and exposure.; Indiana Department of Conservation
Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology and Geophysics, 1996; Copies of author's previously published works inserted.; Bibliography: leaves 153-165.; ix, 165,  leaves,  leaves of plates : ill. (chiefly col.), maps ; 30 cm.
Recent detailed work has attempted to elucidate the structural and stratigraphic relationships within the Kanmantoo Group of the southern Adelaide fold belt, and to help solve some of the problems outlined above. The present study is partly a continuation of this program of investigation. Detailed structural investigations were carried out within the chosen 3x9 km field area, situated on the north-west coast of Kangaroo Island. The region was chosen specifically to examine a recently discovered shear zone east of Cape Forbin, and its possible implications for local and regional geological relationships within the Kanmantoo Group. Geological mapping at a scale of 1:10 000, appropriate strain analysis techniques, and thin-section microstructural analysis were implemented to determine the geometric, kinematic and tectonic evolution of the area. Additional brief investigations were conducted outside of the original study area in order to clarify various geological relationships. The aims of this study also encompass sedimentological and stratigraphic aspects of the Cape Forbin area. Such studies are, in part, intended to provide some understanding of the (disputed) depositional environments of the Kanmantoo Group. Consequently...
Since the first offshore Lake Erie well was drilled in 1941, the Grimsby and
Thorold formations of the Cataract Group have been economically important to the oil
and gas industry of Ontario. The Cataract Group provides a significant amount of
Ontario's gas production primarily from wells located on Lake Erie.
The Grimsby - Thorold formations are the result of nearshore estuarine processes
influenced by tides on a prograding shelf and are composed of subtidal channel complexes,
discrete tidal channels, mud flats and non-marine deposits. Deposition was related to a
regressive - transgressive cycle associated with eustatic sea level changes caused by the
melting and resurgence of continental glaciation centred in Africa in the Late
Ordovician/Early Silurian. Grimsby deposition began during a regression with the
deposition of subtidal channel complexes incised into the marine deposits of the Cabot
Head Formation. The presence of mud drapes and mud couplets suggest that these
deposits were influenced by tides. These deposits dominate the lower half of the Grimsby.
Deposition continued with a change from these subtidal channel complexes to laterally
migrating, discrete, shallow tidal channels and mud flats. These were in turn overlain by
the non-marine deposits of the Thorold Formation. Grimsby - Thorold deposition ended
with a major transgression replacing siliciclastic deposition with primarily carbonate
Sediment was sourced from the east and southeast and associated with a
continuation of the Taconic Orogeny into the Early Silurian. The fluvial head of the
estuary prograded from a shoreline that was located in western New York and western
Pennsylvania running NNE-SSW and then turning NW-SE and paralleling the present day
Lake Erie shoreline.
The facies attributed to the Grimsby - Thorold formations can be ascribed to the
three zones within the tripartite zonation suggested by Dalrymple et ale (1992) for
The drumlin sediments at Chimney Bluffs, New York appear to represent a block-inmatrix
style glacial melange. This melange comprises sand stringers, lenses and intraclasts
juxtaposed in an apparently massive diamicton. Thin section examination of these glacigenic
deposits has revealed microstructures indicative of autokinetic subglacial defonnation which
are consistent with a deformable bed origin for the diamicton. These features include banding
and. necking of matrix grains, oriented plasma fabrics and the formation of pressure shadows
at the long axis ends of elongate clasts. Preservation of primary stratification within the sand
intraclasts appears to suggest that these features were pre-existing up-ice deposits that were
frozen, entrained, then deposited as part of a defonning till layer beneath an advancing ice
sheet. Multi-directional micro-shearing within the sand blocks is thought to reflect the frozen
nature of the sand units in such a high strain environment.
It is also contended that dewatering of the sediment pile leading to the eventual
immobilisation of the defonning till layer was responsible for opening sub-horizontal fissures
within the diamicton. These features were subsequently infilled with mass flow poorly sorted
sands and silts which were subjected to ductile defonnation during the waning stages of an
actively deforming till layer. Microstructures indicative of the dewatering processes in the
sand units include patches of fine-grained particles within a coarser-grained matrix and the
presence of concentrated zones of translocated clays. However...