60 years of the Serbo-Macedonian Unit concept: From Cadomian towards alpine tectonic frameworks

The study represents a summary of the hitherto tectonic concepts revolving around a peri-Gondwanan fragment referred to as the Serbo- Macedonian Unit. The Serbo-Macedonian Unit as a gneiss-dominated basement segment is positioned in the proximity of the Baltican craton (peri-Moesian realm). This area represents a repository of the transferred broadly similar thus highly complex, elongated polycrystalline vestiges of the Pan-African inheritance. This peculiar far-travelled composite crustal fragment of north Gondwana is amalgamated on top of the Supragetic unit during the late Variscan peri-Moesian amalgamation. However, the original early Pa - leozoic tectonostratigraphic configuration of these three intimate green schistand medium- to high-grade gneiss-amphibolite basement vestiges (Serbo-Ma - cedonian/Supragetic and Getic) is further perplexed by the presence of poorly documented pre-Variscan (Ordovician?) lithospheric-scale event. The Pan-African to Lower Paleozoic subduction/magmatic arc stage led to the amalgamation, breakup and dispersal of a cluster of peri-Gondwanan continental and oceanic terranes. Breakup and dispersal from the northern shore of the Gondwanan active margin triggered the development of the Paleozoic deep-marine sedimentary cover (?Kucaj unit? or Getic unit). To make matter more complex, prior the Lower Paleozoic terrane agglomeration and sub - sequent dispersal, it appears that a Lower Paleozoic geodynamic linkage is additionally marked by the poorly investigated cross-lithospheric event. This event connects the outboard oceanic Supragetic/?Kucaj? succession with a segment of the former north Gondwanan protobasin (juvenile Serbo-Ma - cedonian Unit).

Download Full-text

Tethys Belt in the Anatolia-Caucasus-Black Sea Region: Basins, Magmatic Arcs, Ophiolites, and LIPs

10.5194/egusphere-egu21-15058 ◽

2021 ◽

Author(s):

Vahid Teknik ◽

Irina Artemieva ◽

Hans Thybo

Keyword(s):

Sedimentary Cover ◽

Arabian Plate ◽

Magnetic Data ◽

Poor Correlation ◽

Black Sea Region ◽

Nw Iran ◽

Magmatic Arc ◽

Sedimentary Sequences ◽

Mafic Intrusions ◽

Lesser Caucasus

We interpret the paleotectonic evolution and structure in the Tethyan belt by analyzing magnetic data sensitive to the presence of iron-rich minerals in oceanic fragments and mafic intrusions, hidden beneath sedimentary sequences or overprinted by younger tectono-magmatic events. By comparing the depth to magnetic basement (DMB) as a proxy for sedimentary thickness with average crustal magnetic susceptibility (ACMS), we conclude:&#160;(1) Major ocean and platform basins have DMB >10 km. Trapped ocean relics may be present below Central Anatolian micro-basins with DMB at 6-8 km and high ACSM.&#160; In intra-orogenic basins, we identify magmatic material within the sedimentary cover by significantly smaller DMB than depth to seismic basement.(2) Known magmatic arcs (Pontides and Urima-Dokhtar) have high-intensity heterogeneous ACMS. We identify a 450 km-long buried (DMB >6 km) magmatic arc or trapped oceanic crust along the western margin of the Kir&#351;eh&#305;r massif from a strong ACMS anomaly. Large, partially buried magmatic bodies form the Caucasus LIP at the Transcaucasus and Lesser Caucasus and in NW Iran.(3) Terranes of Gondwana affinity in the Arabian plate, S Anatolia and SW Iran have low-intensity homogenous ACMS.(4) Local poor correlation between known ophiolites and ACMS anomalies indicate a small volume of presently magnetized material in the Tethyan ophiolites, which we explain by demagnetization during recent magmatism.(5) ACMS anomalies are weak at tectonic boundaries and faults. However, the Cyprus subduction zone has a strong magnetic signature which extends ca. 500 km into the Arabian plate.

Download Full-text

The tectono-stratigraphic relationships between the upper Precambrian and lower Paleozoic Volta Basin and the Pan-African Dahomeyide orogenic belt (West Africa)

American Journal of Science ◽

10.2475/ajs.280.3.224 ◽

1980 ◽

Vol 280 (3) ◽

pp. 224-248 ◽

Cited By ~ 70

Author(s):

P. Affaton ◽

J. Sougy ◽

R. Trompette

Keyword(s):

West Africa ◽

Orogenic Belt ◽

Lower Paleozoic ◽

Pan African ◽

Volta Basin

Download Full-text

Where are the Eburnian–Transamazonian collisional belts?

Canadian Journal of Earth Sciences ◽

10.1139/e90-148 ◽

1990 ◽

Vol 27 (10) ◽

pp. 1382-1393 ◽

Cited By ~ 53

Author(s):

Jean Michel Bertrand ◽

Emmanuel Ferraz Jardim de Sá

Keyword(s):

West African ◽

High Grade ◽

The West ◽

West African Craton ◽

Early Proterozoic ◽

Late Proterozoic ◽

Nappe Tectonics ◽

Pan African ◽

Orogenic Belts ◽

Lower Crustal

The reconstruction of Early Proterozoic crustal evolution and geodynamic environments, in Africa and South America, is incomplete if cratonic areas alone are studied. If the presence of high-grade gneisses is considered as a first clue to past collisional behaviour, 2 Ga high-grade gneisses are more abundant within the Pan-African–Brasiliano mobile belts than in the intervening pre-Late Proterozoic cratons. The West African craton and the Guiana–Amazonia craton consist of relatively small Archaean nuclei and widespread low- to medium-grade volcanic and volcanoclastic formations intruded by Early Proterozoic granites. By contrast, 2 Ga granulitic assemblages and (or) nappes and syntectonic granites are known in several areas within the Pan-African–Brasiliano belts of Hoggar–Iforas–Air, Nigeria, Cameroon, and northeast Brazil. Nappe tectonics have been also described in the Congo–Chaillu craton, and Early Proterozoic reworking of older granulites may have occurred in the São Francisco craton. The location of the Pan-African–Brasiliano orogenic belts is probably controlled by preexisting major structures inherited from the Early Proterozoic. High-grade, lower crustal assemblages 2 Ga old have been uplifted or overthrust and now form polycyclic domains in these younger orogenic belts, though rarely in the cratons themselves. The Congo–Chaillu and perhaps the São Francisco craton are exceptional in showing controversial evidence of collisional Eburnian–Transamazonian assemblages undisturbed during Late Proterozoic time.

Download Full-text

Basin infilling in the southern-central part of the Sergipano Belt (NE Brazil) and implications for the evolution of Pan-African/Brasiliano cratons and Neoproterozoic sedimentary cover

Journal of South American Earth Sciences ◽

10.1016/s0895-9811(99)00034-6 ◽

1999 ◽

Vol 12 (5) ◽

pp. 453-470 ◽

Cited By ~ 19

Author(s):

Luiz J.H D’el-Rey Silva

Keyword(s):

Sedimentary Cover ◽

Pan African ◽

Southern Central

Download Full-text

Sanaga Fault: Evidence of Neotectonics and Landscape Evolution in Edéa Region (Cameroon, Centre-Africa)

Journal of Geography and Geology ◽

10.5539/jgg.v10n3p57 ◽

2018 ◽

Vol 10 (3) ◽

pp. 57 ◽

Cited By ~ 2

Author(s):

Augustin P. Moussango Ibohn ◽

François Mvondo Owono ◽

Bernard Njom ◽

Simon P. Mbog Bassong ◽

Jean-Paul Sep Nlomngan ◽

...

Keyword(s):

Sedimentary Cover ◽

Active Faults ◽

Drainage System ◽

Passive Margin ◽

Normal Faults ◽

Pan African ◽

Richter Scale ◽

Main Driver ◽

Proterozoic Basement ◽

Set Up

Morphometric parameters extracted fromDEM (90 m) combined with field and literature data of Edéa region, a portion of Cameroonian passive margin located between 3°43’ - 4°00 ’N and 10°00’ - 10°15’E, were used to constraint the present day landscape and forces that have acted and is currently acting on its evolving topography. The obtained results show that the Sanaga Fault is one of the main driver forces responsible for this evolution. Set up during the Pan-African orogeny, this fault which affects a good part of the Proterozoic basement and Tertiary sedimentary cover has developed two systems of secondary active faults different by their nature and characteristics, quite visible in the Edéa region: the Ekitté System, shearing normal faults with a N-S to NNE-SSW strike and the Sanaga-Batignol System shearing directional faults with a NW-SE strike. Most of these faults constitute the river beds and play iteratively, deeply affecting both the drainage system and the landscape. Morphometric indices used reveal that the landscape has been rejuvenated and experiences uplifts and tiltings to present-day due to these reactivations. Structural and petrographical analyses confirm the current role played by the Sanaga Fault and its systems in the segmentation of the region into block tectonics and the occurrence of pseudotachylites and tectonic breccia. Block tectonics, pseudotachylites, tectonic breccias are accompanied with the recent earth tremors with magnitudes comprised between 2.6 and 4.0 on the Richter scale highlighting the neotectonics in this region.

Download Full-text

Age of xenocrystic zircon from diatremes of western Canada

Canadian Journal of Earth Sciences ◽

10.1139/e91-110 ◽

1991 ◽

Vol 28 (8) ◽

pp. 1232-1238 ◽

Cited By ~ 15

Author(s):

R. R. Parrish ◽

I. Reichenbach

Keyword(s):

Sedimentary Cover ◽

Crystalline Basement ◽

Late Paleozoic ◽

Western Canada ◽

Magmatic Activity ◽

Early Paleozoic ◽

Lower Paleozoic ◽

Single Zircon ◽

Crustal Xenoliths ◽

Middle Proterozoic

Numerous diatremes of middle and late Paleozoic age intrude miogeoclinal middle and lower Paleozoic strata in the Canadian Cordillera. In addition to abundant crustal xenoliths and conspicuous mantle-derived mineral xenocrysts, rare zircon grains are present. U–Pb dating of single zircon crystals from many of these diatremes has failed to identify the presence of cogenetic (magmatic) zircons. All dated zircon grains are interpreted as xenocrysts derived from the crust. Their morphologies range from euhedral to very rounded, and their ages range from early Paleozoic to Archean. Most ages fall between 1.8 and 2.1 Ga, with subordinate age groupings in the late Archean (ca. 2.6 Ga), Middle Proterozoic (1.0–1.1 Ga), and early Paleozoic (ca. 470 Ma, 530 Ma). The Proterozoic and Archean zircons could have been derived from either the crystalline basement or its overlying sedimentary cover of Late Proterozoic to early Paleozoic age. Paleozoic zircons were probably derived from either intrusions within the basement or sills that intrude the early Paleozoic sedimentary cover, and they signify magmatic activity possibly related to rifting of the continental margin.

Download Full-text

A review of the Pan-African evolution of the Arabian Shield

GeoArabia ◽

10.2113/geoarabia0701103 ◽

2002 ◽

Vol 7 (1) ◽

pp. 103-124 ◽

Cited By ~ 6

Author(s):

Pierre Nehlig ◽

Antonin Genna ◽

Fawzia Asfirane ◽

C. Guerrot ◽

J.M. Eberlé ◽

...

Keyword(s):

Structural Evolution ◽

Sedimentary Basins ◽

Fault Zones ◽

Fault System ◽

Arabian Shield ◽

Geologic History ◽

Lower Paleozoic ◽

The North ◽

Pan African ◽

History Of

ABSTRACT Recent fieldwork and the synthesis and reappraisal of aeromagnetic, geologic, structural, geochemical, and geochronologic data have provided a new perspective on the structural evolution and geologic history of the Arabian Shield. Although Paleoproterozoic rocks are present in the eastern part of the Shield, its geologic evolution was mainly concentrated in the period from 900 to 550 Ma during which the formation, amalgamation, and final Pan-African cratonization of several tectonostratigraphic terranes took place. The terranes are separated by major NW-trending faults and by N-, NW- and NE-oriented suture zones lined by serpentinized ultramafic rocks (ophiolites). Terrane analysis using the lithostratigraphy and geochronology of suture zones, fault zones, overlapping basins, and stitching plutons, has helped to constrain the geologic history of the Arabian Shield. Ophiolites and volcanic-arcs have been dated at between 900 and 680 Ma, with the southern terrane of Asir being older than the Midyan terrane in the north and the Ar Rayn terrane in the east. Final cratonization of the terranes between 680 and 610 Ma induced a network of anastomosing, strike-slip faults consisting of the N-trending Nabitah belt, the major NW-striking left-lateral transpressive faults (early Najd faults), lined by gneiss domes and associated with sedimentary basins, and N- to NE-trending right-lateral transpressive faults. Following the Pan-African cratonization, widespread alkaline granitization was contemporaneous with the deposition of the Jibalah volcanic and sedimentary rocks in transtensional pull-apart basins. Crustal thinning was governed by the Najd fault system of left-lateral transform faults that controlled the formation of the Jibalah basins and was synchronous with the emplacement of major E- to NW-trending dike swarms throughout the Arabian Shield. The extensional episode ended with a marine transgression in which carbonates were deposited in the Jibalah basins. Continuation of the thinning process may explain the subsequent deposition of the marine formations of the lower Paleozoic cover. Our interpretation of the distribution and chronology of orogenic zones does not correspond entirely to those proposed in earlier studies. In particular, the N-trending Nabitah and NW-trending Najd fault zones are shown to be part of the same history of oblique transpressional accretion rather than being two distinct events related to accretion and dispersion of the terranes.

Download Full-text

Eruptive fluid fracture formations of Nakyn diamondiferous field of Yakutia

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2018-6-37-44 ◽

2018 ◽

pp. 37-44

Author(s):

P. A. Ignatov ◽

K. V. Novikov ◽

N. R. Zaripov ◽

M. S. Khodnia ◽

A. A. Burmistrov ◽

...

Keyword(s):

Sedimentary Cover ◽

Lower Paleozoic ◽

Tectonic Control ◽

Different Ages

In Nakyn diamondiferous field of West-Yakutian province various fluid fracture rocks determined, including kimberlites, eruptive breccias of basites, fluid fracture carbonate breccias and accompanying fluidizite streaks. Shown their characteristic petrographic features and regularity of distribution in the rocks of the lower Paleozoic sedimentary cover. Revealed a predominant tectonic control of fluid fracture formations with bi — and confocal distribution. Suggested the formation of these fluid fracture rocks as a result of different ages directed at faults phreatic explosions.

Download Full-text