Recognition and implication of tectonic loading-induced reheating in the northern Variscan front (Belgium and northern France), based on an illite K�bler index and oxygen isotope study

Triassic carbonate platforms are superbly exposed in the Southern Alps. A regional paleokarst surface occurs in the Middle Triassic, at the Ladinian-Carnian stage boundary, and is well recognized throughout the Tethyan region. The authors describe the characteristics of the paleokarst and the stratigraphic patterns of the strata deposited immediately after the formation of the surface in the Brembana Valley. The paleokarst cuts up to tens of meters into the underlying Esino Limestone massive platform facies and forms a lens-shaped depression filled by peritidal cyclic facies intensively deformed in tepees. The origin of this geometry can be explained either as a tectonic-controlled feature or as a karst-processes related incised-valley associated to a major eustatic cycle. Depression-filling peritidal facies are intensively deformed in senile tepees and are periodically interbedded with 'terra rossa' soils and tend to pinchout at the margins of the depression. Several orders of cyclicity are recognized in peritidal carbonates. Diagenetic features are exceptionally complex and record a wide variety of superimposing environments ranging from normal marine to early meteoric and can be related to major cyclic stratigraphic patterns. Syndepositional cements form up to 80% of the present rock.

10.1306/0c9b093b-1710-11d7-8645000102c1865d

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Influence of L.V. Pustovalov’s Works on the Development of Petroleum Lithology

Lithology and Mineral Resources (2023)

V. G. Kuznetsov A.N. Dmitrievsky

Lithology

Mineral resource classification

10.1134/s0024490222700018

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Quantifying the diagenetic impact in the late Ediacaran and early Palaeozoic of the Avalon Peninsula using illite “crystallinity”

Canadian Journal of Earth Sciences (2021)

Gregor Austermann Melanie Kling Christina Ifrim Pascale D. Emondt Anne Hildenbrand

The Avalon Peninsula on the island of Newfoundland, Canada, defined as the type zone of Avalonia, is believed to have been impacted by several orogenetic and deformation events since the Neoproterozoic. Previous studies have determined that the lowest degree of metamorphism reached in the successions was of the prehnite–pumpellyite or greenschist facies. We sampled and measured 13 mainly clastic sedimentary sections ranging from the late Ediacaran to the Early Ordovician and analyzed the illite “crystallinity” of 331 samples using the Kübler index. Our results show that the occurrence of diagenetic zones relates to lithology, age and burial depth, and regional setting. Samples adjacent to the fault zones bounding the Holyrood Horst experienced the highest degree of metamorphism (anchizone) in the study area. The lowest degree of thermal alteration occurs in the high stratigraphic sections at the centre of the horst structure where shallow diagenetic conditions are preserved. Fault zones, which were probably active during at least the Acadian Orogeny, may have served as potential paths for hot fluids in bounding areas of the horst, whereas the centre of the horst remained almost unaffected by any metamorphic overprint. The thermal impact decreases from the Bonavista Peninsula west of the study area from greenschist facies to anchizonal and diagenetic. The study area experienced lower metamorphic conditions than those in the major regions of Avalonia south of the study area, namely the mainland of New Brunswick and Maine and eastward in Europe, but is in part consistent with a few other areas of Avalonia, such as the Mira Terrane and the Antigonish Highlands in Nova Scotia.

Greenschist

Conodont

Imbrication

Illite

Orogeny

Horst

Lithology

Massif

10.1139/cjes-2020-0207

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Citations (2)