Massif des Maures and Bassin de l'Arc Practice Flashcards

Comprehensive vocabulary flashcards covering the Variscan orogeny in the Massif des Maures and the sedimentary evolution of the Bassin de l'Arc.

Variscan Chain

A mountain range formed between $-380$ and $-280$ Ma by the collision of Laurussia and Gondwana during the assembly of Pangea.

Micaschist

A foliated metamorphic rock with visible, folded schistosity, representing regional metamorphism during collision.

Staurotide (St)

Elongated black automorphic crystals found in schistosity; an indicator of MP-MHT (Medium Pressure, Medium High Temperature) conditions during the Variscan collision.

Garnet

A globular, red-brown, dense mineral that remains in sand after erosion; signals MP-MHT conditions.

Disthène / Kyanite (Ky)

A blue-grey, elongated mineral that serves as a specific indicator of High Pressure.

Andalousite

A pink mineral found in quartz veins that crosscut schistosity; an indicator of BP-HT (Low Pressure, High Temperature) during decompression and exhumation.

Placer

A concentration of dense or chemically resistant minerals, such as garnets, through hydrodynamic sorting during transport.

Arène granitique

A coarse, rusty-brown sand found at the surface resulting from the chemical and physical weathering of granite.

Anatexie

The partial melting of the continental crust that produces granitic magma.

Rhyolite

An volcanic rock with a microlithic texture and red color, indicating rapid cooling at the surface during the Permian period.

Inversion de relief

A geological phenomenon where a resistant layer, such as a conglomerate channel floor, becomes a high point in the landscape due to differential erosion of surrounding softer materials.

Piggyback basin

A sedimentary basin carried by a thrust fault, such as the Bassin de l'Arc located between the Sainte-Victoire and Massif de l'Étoile.

Micrite

Very fine carbonate mud (< 4 ext{ µm}) deposited by settling in calm environments.

Bauxite

An Al-rich rock resulting from intense tropical weathering, indicating emergence and a stratigraphic gap.

Miliolidés

Benthic foraminifera with a porcelain-like texture, indicating warm, shallow marine waters.

Rudiste

A reef-building bivalve from the Cretaceous indicating a warm, shallow, and well-oxygenated environment.

Loi de Walther

A geological principle stating that facies that coexist laterally at a given time will also be found superimposed vertically in the stratigraphic record.

Oncolithe

A spherical carbonate structure formed by cyanobacteria growing in concentric layers on a clast rolled by a current; indicates a lacustrine environment.

Unio

A large, smooth bivalve that is an exclusive indicator of a freshwater environment.

Rhabdodontes

Herbivorous dinosaurs whose remains and eggs indicate a continental environment during the Maastrichtian (terminal Cretaceous).

Poudingue de la Galante

A polygenic conglomerate found at the K/Pg boundary, characterized by a lack of sorting and a sharp contact, signifying a catastrophic, high-energy event.

Foliation / Schistosité

A planar fabric or texture developed in a metamorphic rock due to deformation.

Protolithe

The original parent rock before it underwent metamorphism.

Hydrolyse des feldspaths

A chemical weathering mechanism where crystalline feldspar combined with $H_2O$ and $CO_2$ produces kaolinite (clay), silica, and cations.

Ride de courant

An asymmetric sedimentary structure indicating unidirectional flow, typical of fluvial systems.