L'evolution de l'Ardenne au cours des diverses phases des plissements caledoniens et hercyniens

1945 ◽  
Vol S5-XV (1-3) ◽  
pp. 3-44 ◽  
Author(s):  
Gerard Waterlot
Keyword(s):  
Large Scale ◽  
Lower Devonian ◽  
Late Paleozoic ◽  
Early Paleozoic ◽  
Crustal Movements ◽  
Intense Deformation

Abstract The Ardennes region was subjected to three successive phases of Caledonian (early Paleozoic) orogenic activity during which large-scale gentle crustal movements directed from south to north caused uplift of the upper Ardennes region at the beginning of the Caradocian (Ordovician), of the southern Condroz region (France) at the end of the lower Ludlow (Silurian), and of the northern Condroz and Brabant (Belgium) regions in the lower Devonian. Hercynian (late Paleozoic) structures of the region are the product of intense deformation of pre-existing synclinal basins which were formed during a long pre-Hercynian period of gentle crustal movements.

Chapter 6 Conclusions, differences between the Jabal Akhdar and Saih Hatat domes and unanswered questions

10.1144/m54.6 ◽  
2021 ◽  
Vol 54 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Andreas Scharf ◽  
Frank Mattern ◽  
Mohammed Al-Wardi ◽  
Gianluca Frijia ◽  
Daniel Moraetis ◽  
...  
Keyword(s):  
Large Scale ◽  
Late Paleozoic ◽  
Future Research ◽  
Early Paleozoic ◽  
Chronological Order ◽  
Oman Mountains ◽  
Tectonic Events ◽  
Major Fault ◽  
Tethys Ocean ◽  
Semail Ophiolite

AbstractThis chapter provides the conclusions/outlines of the tectonics, affecting the Southeastern Oman Mountains, including the Jabal Akhdar and Saih Hatat domes. The main tectonic events include amongst others (1) Neoproterozoic rifting, (2) two distinct early Paleozoic compressive events, (3) large-scale open ‘Hercynian’ folding and formation of a pronounced unconformity during the late Paleozoic, (4) rifting preceding the opening of the Neo-Tethys Ocean during the late Paleozoic, (5) late Cretaceous obduction of the Semail Ophiolite and the response of the Arabian lithosphere as well as (6) post-obductional tectonics. Also of major geological significance are the three major glaciations (Sturtian, Marinoan and Late Paleozoic Gondwana glaciation) which have been recorded in the rocks of northern Oman. Moreover, major lithological, structural and metamorphic differences exist between the Jabal Akhdar and Saih Hatat domes. It appears likely that a major fault, striking parallel to the eastern margin of the Jabal Akhdar Dome, probably originating during Neoproterozoic terrain accretion, acted as a divide between both domes until present. This fault was multiple times reactivated and could explain the differences between the two domes. A catalogue of unanswered questions is included in chronological order to express that many geological aspects need further investigation and future research projects.

Early Paleozoic Volcanism and Metamorphism of the Moretons Harbour–Twillingate Area, Newfoundland

1973 ◽  
Vol 10 (9) ◽  
pp. 1363-1379 ◽  
Author(s):  
D. F. Strong ◽  
J. G. Payne
Keyword(s):  
Oceanic Crust ◽  
Volcanic Rocks ◽  
Metal Sulfides ◽  
Early Paleozoic ◽  
Extensive Area ◽  
Sea Floor ◽  
Pillow Lavas ◽  
Intense Deformation ◽  
Sea Floor Spreading ◽  
Harbour Area

In the Moretons Harbour area, at the eastern end of the Lushs Bight terrane of central Newfoundland, the volcanic rocks of the "Lushs Bight Supergroup" are divided into two new groups, viz, the Moretons Harbour Group and the Chanceport Group. The former is separable into four formations, consisting primarily of variable proportions of basaltic pillow lavas and volcanoclastic sediments, with a composite thickness in excess of 6 km, or around 8 km including an extensive area of 'sheeted' diabase dikes. These formations are steeply dipping and face southwest; they are separated by the Chanceport fault from the Chanceport Group to the south. The latter consists of interbedded basaltic pillow lavas with graywackes and banded red and green cherts, all facing north and steeply dipping to overturned, with a composite thickness of approximately 3 km.The Moretons Harbour Group has been intruded by the Twillingate trondhjemitic granite–granodiorite pluton and abundant basic dikes intrude the granite, indicating that the mafic and felsic magmatism were coeval. Both have undergone intense deformation and the volcanics show a change from greenschist to amphibolite facies mineralogy within a distance of 2 km on approaching the pluton, a result of buttressing by the pluton during deformation, and not an intrusive effect.Base metal sulfides are common throughout the area, but the main occurrences of Cu, As, Sb, and Au are concentrated in the Little Harbour Formation, a 2600 m thick sequence of volcanoclastic rocks within the Moretons Harbour Group.The great thickness of volcanic rocks is interpreted as having formed in an island arc environment, although it is possible that the lowermost parts of the sequence represent oceanic crust. It is unlikely that the sheeted diabases of the Moretons Harbour area were produced by sea-floor spreading.

Age of xenocrystic zircon from diatremes of western Canada

1991 ◽  
Vol 28 (8) ◽  
pp. 1232-1238 ◽  
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.

La metallogenie de la France

1966 ◽  
Vol S7-VIII (1) ◽  
pp. 53-72 ◽  
Author(s):  
Pierre Laffitte
Keyword(s):  
Ore Deposits ◽  
Late Paleozoic ◽  
Early Paleozoic ◽  
Alpine Zone ◽  
Ore Deposition

Abstract A regional metallogenic study of the ore deposits of France in relation to their geologic settings is presented. Twenty-three areas, subdivided into 100 districts, are thus defined and 300 deposits or possible deposits are categorized. Five metallogenic provinces are suggested. Two formed during the Hercynian (late Paleozoic)--the Gaules and the Sardo-Provencal; a fractured border; an internal Alpine zone; and a Pyrenean trough. Particular attention is given to regional zonation which is manifested in the chemistry of the successive Paleozoic mineralizations. The fracturing of the crust prior to the Caledonian (early Paleozoic) is discussed. Examples are presented of the relation of ore deposition to tectonics.

Biodiversity, systematics, and new taxa of cladid crinoids from the Ordovician Brechin Lagerstätte

2019 ◽  
Vol 94 (2) ◽  
pp. 334-357 ◽  
Author(s):  
David F. Wright ◽  
Selina R. Cole ◽  
William I. Ausich
Keyword(s):  
New Species ◽  
New Taxa ◽  
Large Scale ◽  
Unexpected Result ◽  
Taxonomic Study ◽  
New Genera ◽  
Early Paleozoic ◽  
Upper Ordovician ◽  
Major Lineage ◽  
Lake Simcoe

AbstractUpper Ordovician (Katian) strata of the Lake Simcoe region of Ontario record a spectacularly diverse and abundant echinoderm fauna known as the Brechin Lagerstätte. Despite recognition as the most taxonomically diverse Katian crinoid paleocommunity, the Brechin Lagerstätte has received relatively little taxonomic study since Frank Springer published his classic monograph on the “Kirkfield fauna” in 1911.Using a new collection of exceptionally preserved material, we evaluate all dicyclic inadunate crinoids occurring in the Brechin Lagerstätte, which is predominantly comprised of cladids (Eucladida and Flexibilia). We document 15 species across 11 genera, including descriptions of two new genera and four new species. New taxa include Konieckicrinus brechinensis n. gen. n. sp., K. josephi n. gen. n. sp., Simcoecrinus mahalaki n. gen. n. sp., and Dendrocrinus simcoensis n. sp.Although cladids are not commonly considered major components of the Early Paleozoic Crinoid Macroevolutionary Fauna, which is traditionally conceived as dominated by disparids and diplobathrid camerates, they are the most diverse major lineage of crinoids occurring in the Brechin Lagerstätte. This unexpected result highlights the important roles of specimen-based taxonomy and systematic revisions in the study of large-scale diversity patterns.UUID: http://zoobank.org/09dda7c2-f2c5-4411-93be-3587ab1652ab

scholarly journals Two-phase late Paleozoic magmatism (~ 313–312 and ~ 299–298 Ma) in the Lusatian Block and its relation to large scale NW striking fault zones: evidence from zircon U–Pb CA–ID–TIMS geochronology, bulk rock- and zircon chemistry

2021 ◽  
Author(s):  
A. Käßner ◽  
M. Tichomirowa ◽  
M. Lapp ◽  
D. Leonhardt ◽  
M. Whitehouse ◽  
...  
Keyword(s):  
Fault Zone ◽  
Large Scale ◽  
Age Groups ◽  
Spatial Relation ◽  
Shear Zones ◽  
Igneous Rocks ◽  
Geochemical Data ◽  
Late Paleozoic ◽  
Two Phase ◽  
Saxothuringian Zone

AbstractLate Paleozoic (Variscan) magmatism is widespread in Central Europe. The Lusatian Block is located in the NE Bohemian Massif and it is part of the Saxothuringian Zone of the Variscan orogen. It is bordered by two major NW-trending shear zones, the Intra-Sudetic Fault Zone towards NE and the Elbe Fault Zone towards SW. The scarce Variscan igneous rocks of the Lusatian Block are situated close to these faults. We investigated 19 samples from Variscan plutonic and volcanic rocks of the Lusatian Block, considering all petrological varieties (biotite-bearing granites from the Koenigshain and Stolpen plutons, amphibole-bearing granites from three boreholes, several volcanic dykes, and two volcanites from the intramontane Weissig basin). We applied whole-rock geochemistry (18 samples) and zircon evaporation dating (19 samples). From the evaporation data, we selected six representative samples for additional zircon SHRIMP and CA–ID–TIMS dating. For the Koenigshain pluton, possible protoliths were identified using whole-rock Nd-isotopes, and zircon Hf- and O-isotopes. The new age data allow a subdivision of Variscan igneous rocks in the Lusatian Block into two distinct magmatic episodes. The spatial relation of the two age groups to either the Elbe Fault Zone (298–299 Ma) or the Intra-Sudetic Fault Zone (312–313 Ma) together with reports on the fault-bound character of the dated intrusions suggests an interpretation as two major post-collisional faulting episodes. This assumption of two distinct magmatic periods is confirmed by a compilation of recently published zircon U–Pb CA–ID–TIMS data on further Variscan igneous rocks from the Saxothuringian Zone. New geochemical data allow us to exclude a dominant sedimentary protolith for the Koenigshain pluton as supposed by previous investigations. This conclusion is mainly based on new O- and Hf-isotope data on zircon and the scarcity of inherited zircons. Instead, acid or intermediate igneous rocks are supposed as the main source for these I-type granitoids from the Koenigshain pluton.

Early Mesozoic granitoids from SW Vietnam and SE Cambodia – an example of the southeastern extension of the Southeast Asian granite belt

2020 ◽  
Author(s):  
Anh Nong ◽  
Christoph Hauzenberger ◽  
Daniela Gallhofer ◽  
Sang Dinh
Keyword(s):  
Large Scale ◽  
Early Stage ◽  
Tectonic Setting ◽  
Biotite Granite ◽  
Coarse Grained ◽  
Late Triassic ◽  
Late Paleozoic ◽  
Western Boundary ◽  
Early Mesozoic ◽  
Granite Belt

<p>Early Mesozoic magmatism in Indochina and its vicinities in Sundaland (SE Asia) has been usually ascribed to be in connection with one of three approximately coeval tectonic regimes: 1) the Indochina-Sibumasu amalgamation leading to the closure of the Paleotethys during the Late Paleozoic – Early Mesozoic forming the Thai-Malaysia tin-bearing granite belt, 2) the Indochina-South China amalgamation along the northern boundary of Indochina closing another branch of the Paleotethys during Late Paleozoic – Triassic times, and 3) the early stage of an active margin with subduction of the Paleo-Pacific plate during Triassic-Jurassic times.</p><p>Scattered granitic plutons (185–210 Ma) located in southern Cambodia and some islands in southernmost Vietnam are distributed along the N-S Rach Gia-Nam Can fault which is a large-scale fault active during the Early Mesozoic. The studied rocks can be distinguished based on petrological features: weakly foliated biotite-rich granite (Hon Khoai Island, SW Vietnam), biotite-tourmaline-bearing granite (Hon Da Bac Island, SW Vietnam), and coarse-grained biotite granite (Tamao, SE Cambodia). The Honkhoai granites are a range of dark to light coloured granites due to a variation in biotite content and display a foliation. They usually contain amphibole, ilmenite, and monazite. The Hondabac granites comprise dark-colored granodiorites and granites with biotite, tourmaline, ilmenite, apatite, fluorite, epidote, and subordinate titanite. The Tamao granites are mainly composed of biotite aggregates with sporadic muscovite and accessory phases such as ilmenite, apatite, and fluorite.</p><p>Zircon U-Pb ages yield 189 ± 1 to 206 ± 2 Ma for the Honkhoai rocks, 192 ± 1 to 202 ± 1 Ma for the Hondabac rocks, and 189 ± 2 Ma for the Tamao rocks. Apparently, these Late Triassic - Early Jurassic granitoids are chronologically consistent with all three tectonic events. However, geographical and geochemical arguments favor a connection to the Thai-Malaysia tin-bearing granites. Similarities include high silica content and predominantly high-K to calc-alkaline affinities. Trace element composition is characterized by enrichments in Cs, Rb, Th, U, and Pb, and depletion in Ba, Sr, Nb, P, and Ti. All analyzed rock samples show (La/Yb)n values of 4.05–17.27 and negative Eu anomalies (Eu/Eu*=0.15–0.65). The whole-rock and biotite chemistry point to an arc-related tectonic setting for the Hondabac rock, while the Honkhoai and Tamao rocks are ambiguous in the tectonic regime but likely close to syn-collision and within-plate field, respectively. Geobarometry of the Honkhoai rocks using the Al-in-amphibole geobarometer yields crystallization pressure up to 3 kbar.</p><p>We conclude that the studied rocks formed during the closure of the Palaeotethys along the western boundary of the Indochina block, particularly similar to the Thai-Malaysia granite belt. Hence, the Sukhothai-Chantaburi Terrane may be extended southeastward as far as to the Hon Khoai Island (Southernmost Vietnam).</p>

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