Development of sedimentary basins in the Archean Abitibi belt, Canada: an overview

1992 ◽  
Vol 29 (10) ◽  
pp. 2249-2265 ◽  
Author(s):  
W. Mueller ◽  
J. A. Donaldson

Sedimentation in the Archean Abitibi greenstone belt occurred during four depositional episodes: (i) sedimentary cycle 1, 2730–2720 Ma; (ii) sedimentary cycle 2, 2715–2705 Ma; (iii) sedimentary cycle 3, 2700–2687 Ma; and (iv) sedimentary cycle 4, 2685–2675 Ma. Records of the first two sedimentary cycles are preserved in basins within the northern volcanic zone, whereas basins formed during the latter two sedimentary cycles are located within the southern volcanic zone of the Abitibi belt. Sedimentary cycles 1 and 3 represent deep-water facies, as indicated by turbidites, resedimented conglomerates, pelagic sediments, and ubiquitous iron-formations; subaerial deposits have not been identified. In contrast, sedimentary cycles 2 and 4 show a prevalence of fluvial to shallow-water marine and (or) lacustrine deposits. Tectono-magmatic influence on sedimentation during cycles 2 and 4 is documented by (i) the presence of numerous unconformities underlain by plutonic and volcanic rocks; (ii) locally voluminous shoshonitic and calc-alkaline volcanic rocks; (iii) abundance of plutonic detritus; (iv) rapid vertical and lateral facies changes; and (v) repetition of successions of large-scale (50–250 m thick) alluvial and shallow-water deposits. Sedimentary cycle 1 represents incipient arc basins dominated by volcaniclastic debris, whereas cycle 2 reflects unroofing of arc volcanoes down to the plutonic roots. The sedimentary basins of cycle 3 have been tentatively interpreted as basins connecting arc terranes, within which small extensional cycle 4 basins of the successor or pull-apart type developed. The sedimentary facies associations, the tectono-magmatic influence on sedimentation, the chronological basin evolution, and overall southward younging of the basins invite comparison with modern island arcs formed by plate-tectonic processes.

1992 ◽  
Vol 29 (10) ◽  
pp. 2211-2225 ◽  
Author(s):  
E. H. Chown ◽  
Réal Daigneault ◽  
Wulf Mueller ◽  
J. K. Mortensen

The Archean Abitibi Subprovince has been divided formally into a Northern Volcanic Zone (NVZ), including the entire northern part of the subprovince, and a Southern Volcanic Zone (SVZ) on the basis of distinct volcano-sedimentary successions, related plutonic suites, and precise U–Pb age determinations. The NVZ has been further formally subdivided into (i) a Monocyclic Volcanic Segment (MVS) composed of an extensive subaqueous basalt plain with scattered felsic volcanic complexes (2730–2725 Ma), interstratified with or overlain by linear volcaniclastic sedimentary basins; and (ii) a Polycyclic Volcanic Segment (PVS) comprising a second mafic–felsic volcanic cycle (2722–2711 Ma) and a sedimentary assemblage with local shoshonitic volcanic rocks.A sequence of deformational events (D1–D6) over a period of 25 Ma in the NVZ is consistent with a major compressional event. North–south shortening was first accommodated by near-vertical east-trending folds and, with continued deformation, was concentrated along major east-trending fault zones and contact-strain aureoles around synvolcanic intrusions, both with a downdip movement. Subsequent dextral strike-slip movement occurred on southeast-trending faults and major east-trending faults which controlled the emplacement of syntectonic plutons (2703–2690 Ma).This study suggests that the NVZ, which is a coherent geotectonic unit, initially formed as a diffuse volcanic arc, represented by the MVZ, in which the northern part, represented by the PVS, evolved into a mature arc as documented by a second volcanic and sedimentary cycle associated with major plutonic accretion. Volcano-sedimentary evolution and associated plutonism, as well as structural evolution, are best explained by a plate-tectonic model involving oblique convergence.


1973 ◽  
Vol 10 (6) ◽  
pp. 817-845 ◽  
Author(s):  
Colin C. Turner ◽  
Roger G. Walker

In the Archean greenstone belt at Sioux Lookout, N.W. Ontario, a lowermost belt of volcanic rocks is unconformably overlain by sediments of the Abram Group. Our mapping has subdivided the Abram Group into three formations. The lowest (Ament Bay Formation) consists of interbedded conglomerates and sandstones. The sandstones contain large-scale cross-stratification, and the conglomerates and sandstones both lack graded bedding. The depositional environment was a subaerial alluvial fan—this is the first description of such a feature based upon modern sedimentological work in Archean rocks. The Daredevil Formation conformably overlies the Ament Bay Formation, and is composed of felsic and basic tuffs, and some interbedded turbidites. The uppermost (Little Vermilion) Formation is composed entirely of turbidites.The petrography of the sand, and large clasts, in the Ament Bay Formation indicates derivation from a dominantly granodioritic terrain. Some granodiorite boulders contain greenstone xenoliths, implying intrusion of the granodiorite after formation of the lowermost belt of volcanic rocks.In a final section of the paper, we define two Archean facies associations—a Resedimented association containing turbidites, pebbly mudstones, resedimented conglomerates, and basinal black argillites; and a Continental association, containing alluvial fan deposits, and possible coastal deposits from South Africa and Australia. The facies sequence in the Sioux Lookout belt is Continental followed by Resedimented facies, the reverse of the normal geosynclinal flysch (resedimented) → molasse (continental) sequence.


2006 ◽  
Vol 29 (2) ◽  
pp. 168-198
Author(s):  
Claudio Cesar S Marques ◽  
Claudio Limeira Mello ◽  
Renato R. Cabral Ramos

This study aims to perform a multi-scale analysis of the sedimentary attributes presented by Paleogene fluvial deposits of the Volta Redonda Basin (Continental Rift of Southeastern Brazil), including the characterization of sedimentary facies, depositional architecture and petrographical features. The results from this study may be applied to the modelling of fluid behaviour inside fluvial reservoir-rocks. Among the studied deposits are the main aquifers of the sedimentary basins which compose the Continental Rift of Southeastern Brazil. The methodologic framework comprised: interpretation of an outcrop by using a photomosaic to the recognition of depositional architecture, emphasizing the stratigraphic surface hierarchy; facies characterization with vertical profiles; and petrographic analysis of selected samples. Two distinct facies associations were recognized, corresponding to Resende and Pinheiral formations. The Resende Formation deposits present a simple complexity heterogeneity style, with a wide lateral continuity. They are composed by decimetric layers of massive sandstones interbedded to clayey sandstones, showing a tabular geometry and few dozen-meters width. The contacts between these deposits are gradual. The Pinheiral Formation deposits present a medium complexity heterogeneity style, exhibiting frequent truncation of architectural elements, characterized by decimetric and dozen-meters width sandy layers with conglomeratic levels interbedded to thin pelitic intervals. These deposits present a extended lenticular geometry and irregular contacts. Microscopically, sandstones from Resende Formation present low porosity, related to the occurrence of clayey matrix resulted from feldspars alteration. The sandstones from Pinheiral Formation show porosities similar to reservoir patterns.


2020 ◽  
Vol 9 (2) ◽  
pp. 1
Author(s):  
Esam O. Abdulsamad ◽  
Saleh A. Emhanna ◽  
Muayid B. Asmaeil ◽  
Ahmed A. Alwddani ◽  
Fuad M. Rasheed ◽  
...  

The Upper Cretaceous to Upper Palaeocene rocks of the Zimam Formation along the southwestern escarpment of the Hun Graben of NW Libya have been stratigraphically investigated from two stratigraphical sections in wadi Tar al Kabir. The field investigations led to the recognition of three members, from the oldest to the youngest, the Lower Tar Member, the Upper Tar Member and the Had Member. Eight sedimentary facies were distinguished at outcrop-scale and several microfacies were recognized and the outcome indicates that the depositions of the Zimam Formation are corresponding to two transgressive-regressive sedimentary cycles. The first cycle is attributed to the Lower Tar Member in which small planktonic foraminifera is quite common in the Campanian whereas the larger benthic foraminifera, namely, Omphalocyclus macroporus and Siderolites calcitrapoides are abundant in the Maastrichtian. The last occurrence of the latter two taxa, however, was used to delineate the contact between the Maastrichtian and Danian stages in the studied sequence. Up-sequence the sediments of the Upper Tar Member along with the overlying Had Member correspond to the second transgressive-regressive sedimentary cycle. Herein, the Upper Tar Member is enriched by small benthic foraminifera; Neoeponides duwi and Cibicides cf. libycus, and has been ascribed to the Danian (Lower Palaeocene). The reaming sediments of Zimam Formation, however, are belonging to the overlying Had Member and is tentatively ascribed to the Selandian (Upper Palaeocene) based on the last occurrence of the Danian fauna and the total range of the codiacean algae Ovulites morelleti.


1986 ◽  
Vol 123 (2) ◽  
pp. 153-166 ◽  
Author(s):  
John Ludden ◽  
Claude Hubert ◽  
Clement Gariépy

AbstractBased on structural, geochemical, sedimentological and geochronological studies, we have formulated a model for the evolution of the late Archaean Abitibi greenstone belt of the Superior Province of Canada. The southern volcanic zone (SVZ) of the belt is dominated by komatiitic to tholeiitic volcanic plateaux and large, bimodal, mafic-felsic volcanic centres. These volcanic rocks were erupted between approximately 2710 Ma and 2700 Ma in a series of rift basins formed as a result of wrench-fault tectonics.The SVZ superimposes an older volcanic terrane which is characterized in the northern volcanic zone (NVZ) of the Abitibi belt and is approximately 2720 Ma or older. The NVZ comprises basaltic to andesitic and dacitic subaqueous massive volcanics which are cored by comagmatic sill complexes and layered mafic-anorthositic plutonic complexes. These volcanics are overlain by felsic pyroclastic rocks that were comagmatic with the emplacement of tonalitic plutons at 2717 ±2 Ma.The tectonic model envisages the SVZ to have formed in a series of rift basins which dissected an earlier formed volcanic arc (the NVZ). Analogous rift environments have been postulated for the Hokuroko basin of Japan, the Taupo volcanic zone of New Zealand and the Sumatra and Nicaragua arcs. The difference between rift related ‘submergent’ volcanism in the SVZ and ‘emergent’ volcanism in the NVZ resulted in the contrasting metallogenic styles, the former being characterized by syngenetic massive sulphide deposits, whilst the latter was dominated by epigenetic ‘porphyry-type’ Cu(Au) deposits.


1987 ◽  
Vol 24 (6) ◽  
pp. 1135-1148 ◽  
Author(s):  
Marylou Coyle ◽  
D. F. Strong

Volcanic–sedimentary facies and structural relationships of the Silurian Springdale Group in west-central Newfoundland are indicative of a large collapse caldera with an area of more than 2000 km2. Basaltic flows, andesite flows and pyroclastic rocks, silicic ash-flow tuffs, high-silica rhyolite domes, and volcanically derived debris flows and breccias, fluviatile red sandstones, and conglomerates make up the group. It is bounded on the east and west by up-faulted basement rocks, which include gneisses, amphibolites, and pillow lavas, and in the northwest it unconformably overlies Lower Orodovician submarine volcanics. These margins are intruded by cogenetic and younger granitoid rocks. The volcanic rocks form a calc-alkaline series, although gaps in silica content at 52–56, 67–68, and 73–74% separate them into four groups: basalts, andesites–dacites, rhyolites, and high-silica rhyolites.The high-silica rhyolites are chemically comparable to melts thought to form the upper parts of large, layered silicic magma chambers of epicontinental regions. Such an environment is also suggested by the large area of the Springdale caldera and the fact that it is one of a number of calderas that make up a large Silurian volcanic field in western Newfoundland. An epicontinental tectonothermal environment for central Newfoundland in Silurian–Devonian times is readily explained by the fact that this magmatic activity followed a period of destruction and closure of the early Paleozoic Iapetus Ocean, with trapped heat and basaltic magma causing large-scale melting of thickened and subducted continental crust in an overall transpressional tectonic regime.


Author(s):  
Iftikhar Ahmed Abbasi ◽  
Abdulrahman Al-Harthy ◽  
Yahya Khalifa Al-Subhi

The Batain coast along the northeastern margin of Oman between Ra’s Al-Hadd and Ra’s Jibsch, is comprised of Permian to Late Cretaceous complex stratigraphy in a tectonically deformed area recording Permian rifting to late Cretaceous Tethys closure events. These rocks are thrust over Mesozoic and older autochthonous sedimentary cover in the form of a major nappe structure known as the Batain Nappe. The uppermost part of the Batain nappe is comprised of isolated outcrops of early Maastrichtian siliciclastic Fayah Formation dominated by gravity flow deposits. The Fayah Formation in the Jabal Fayah area is over four hundred meters thick and comprised of five distinct facies associations; namely, i) coarsening-up sandstone, ii) conglomerate, iii) debris- flow, iv) turbidite, and v) inter-bedded sandstone and shale lithofacies. These lithofacies associations are repeated many times in the section. The sandstone lithofacies association exhibits a coarsening-upward trend making sequences tens of meters thick in various parts of the formation. Waterscape structures are common along with occasional sandstone dykes and convolute bedding, reflecting fluidized conditions of deposition. The conglomerate lithofacies association is comprised of a series of interbedded coarsening-upward pebble to gravel size conglomerates containing chert, limestone, granite and volcanic clasts ranging a few mm to cm in diameter. Occasionally these are interbedded with sandstone lithofacies. The conglomerate lithofacies was deposited by a high-energy channelized flow in a sub-aqueous setting. The debris-flow lithofacies association is a matrix supported chaotic mixture of clay and boulders of granite, limestone and volcanic rocks, some of which are meter-sized in diameter, and possibly derived from the nearby basement rocks such as the Jabal Ja’alan basement rocks. It constitutes the most dominant part of the formation. These sediments were deposited along a slope setting, possibly as olistostrome formed due to submarine slumping and sliding. The turbidite lithofacies association is comprised of monotonous grayish-green to brown coloured clays tens of meters thick interbedded with thin, clean, well-sorted sandstone. The Interbedded sandstone and shale lithofacies association is comprised of a half to one meter thick cross-bedded, burrowed arkosic sandstone and plane laminated shale. The sandstone constitutes about 25% of the association with ripple lamination in the upper part of the unit indicating a fining-upward trend. Dewatering structures are common. This association constitutes the upper 100m of the formation. These sediments were deposited in shallow water conditions by channelized flows. Based on the lithofacies associations described above, especially the dominance of debris-flow units and turbidites, the greater part of the Fayah Formation are interpreted as having been deposited under a sub-marine fan setting. Only the upper part of the formation was deposited in a shallow water setting before the onset of overlying carbonate deposits. The sub-marine fan system was active during the last stages of the Tethys Ocean closure at the time of onset of the Batain nappe.     


2013 ◽  
Vol 47 (2) ◽  
pp. 185-199 ◽  
Author(s):  
HIRONAO SHINJOE ◽  
YUJI ORIHASHI ◽  
JOS^|^Eacute; A. NARANJO ◽  
DAIJI HIRATA ◽  
TOSHIAKI HASENAKA ◽  
...  

2021 ◽  
Vol 36 (5) ◽  
pp. 105-119
Author(s):  
Masab Ali ◽  
Bian Weihua ◽  
Yang Kaikai ◽  
Muhammad Sabeh Khan Panni

Junggar Basin is one of the largest sedimentary basins in Northwest China. Carboniferous oil and gas fields have been found in different areas in the eastern part of the Junggar Basin on a large scale, indicating that the Carboniferous rocks of the Junggar Basin have a huge potential for oil and gas exploration. This study focuses on the Batamayineishan Formation in the eastern part of the Junggar Basin, which contains volcanic rocks and pyroclastic rocks, aiming to investigate the reservoir characteristics and to identify the formation mechanism of the rocks of this formation. The majority of the existent reservoir space in the volcanic rocks of the Batamayineishan Formation is dominated by secondary pores and fractures. Using the methods of petrography, pressure-controlled mercury injection (PMI), and electron probe microanalysis (EPMA), the reservoir characteristics and diagenetic history of the volcanic rocks of the Batamayineishan Formation in the Shuangjingzi area were studied. A theoretical framework is established to provide favorable guidance for exploring Carboniferous volcanic rocks in the Junggar Basin. The results of mercury injection indicate that the average pore throat radius and porosity of the volcanic rocks are 0.068 µm and 6.62%, respectively. Permeability remains stable and does not show a significant change with an increase in porosity. Despite the high porosity, the permeability is relatively low, reflecting isolated and non-connected primary pores. The average value of permeability is relatively low (0.424×10-3 µm2), which typically suggests narrow micro-throats. Primary gas pores fill and develop amygdales on a large scale. In addition, the dissolution pores developed by dissolution and alteration also compensated for the decrease in the original gas pore volume.


1997 ◽  
Vol 134 (2) ◽  
pp. 177-197 ◽  
Author(s):  
R. A. EDWARDS ◽  
G. WARRINGTON ◽  
R. C. SCRIVENER ◽  
N. S. JONES ◽  
H. W. HASLAM ◽  
...  

The lower part of the post-Variscan succession around Exeter, south Devon, England, comprises some 800 m of breccias, with subordinate sandstones and mudstones, which rest upon Devonian and Carboniferous rocks folded during the Variscan Orogeny and are overlain, disconformably, by the Aylesbeare Mudstone Group (Early Triassic?). These deposits comprise the most westerly of the early post-Variscan successions preserved onshore in northwest Europe and lie to the south of the Variscan Deformation Front; they are assigned to the Exeter Group (new term). Geochronological and palaeontological studies, in conjunction with detailed geological mapping, show that the constituent formations comprise a lower (Late Carboniferous(?)–Early Permian) sequence separated from an upper (Late Permian) sequence by an unconformity which represents an hiatus with a duration of at least 20 m.y. The lower sequence contains volcanic rocks dated at between 291 and 282 Ma (Early Permian) and pre-dates intrusion of the nearby Dartmoor Granite (280 Ma). In the overlying, palynologically-dated, Late Permian sequence, older breccias contain clasts of the Dartmoor Granite aureole rocks, and younger ones contain clasts of that granite. The lower sequence occurs mainly within the Crediton Trough, an east–west trending, partly fault-bounded, sedimentary basin that probably formed by extensional reactivation of a Variscan thrust. Breccias in this sequence formed largely on alluvial fans; the common occurrence of debris flows and a down-fan passage from gravity flows into fluvially deposited sediments is typical of deposition on semi-arid fans. The upper (Late Permian) sequence is more widespread but includes similar deposits overlain, at the top of the Exeter Group, by aeolian dune and interdune deposits. Correlation within the laterally variable facies associations which comprise these sequences has been achieved using a combination of sedimentary facies analysis, sedimentary geochemistry, and petrographical and geochemical clast typing. The stratigraphy revealed within the Exeter Group is broadly comparable with that recognized in the early post-Variscan Rotliegend successions elsewhere in Europe. This similarity may, however, be deceptive; the upper part of the Exeter Group may be coeval with the Zechstein, and apparently correlatable major unconformities in the group and the Rotliegend may reflect different events in the Variscan fold-belt and Variscan Foreland areas, respectively.


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