China
Africa
Explore chapters and articles related to this topic
Tectonics and Sedimentation
Published in Supriya Sengupta, Introduction to Sedimentology, 2017
Molasse is the product of post-orogenic sedimentation. The deposits, generally several thousand metres thick, consist of many sequences of fining-upward, fluvial and deltaic cycles. The conglomerates contain well-rounded clasts. The fluvial cycles include immature, lithic and feldspathic sandstones, mudstones, coal, caliche, freshwater carbonates and evaporites. In areas of marine transgression the environment may range from paralic to lagoonal. Persistent, well-sorted conglomeratic sandstones dominate the areas of marine transgression.
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
In sedimentological terms, a molasse is defined as a shallow detrital deposit, either marine or lacustrine, that comes from the erosion of a mountain chain and is deposited at the foot of mountains. Molasse includes several different types of rocks: sandstones, siltstones, marls, mudstones, conglomerates, lacustrine limestones and even coal. North of the Alps, most rocks on the plateau between Chambery and Vienna are molasse. This is the molasse basin, as defined by geologists.
Diagenesis and Properties of Sedimentary Rocks
Published in Aurèle Parriaux, Geology, 2018
In sedimentological terms, a molasse is defined as a shallow detrital deposit, either marine or lacustrine, that comes from the erosion of a mountain chain and is deposited at the foot of the mountains. Molasse includes several different types of rocks: sandstones, siltstones, marls, mudstones, conglomerates, lacustrine limestones and even coal. North of the Alps, the majority of the rocks of the plateau between Chambery and Vienna is composed of molasse.
The characteristics and formation of black shale-hosted Bakyrchik-type gold mineralisation
Published in Applied Earth Science, 2019
Zamzagul T. Umarbekova, Kulyash Sh. Dyusembaeva
This deciphering of the genesis of black-shale hosted gold deposits combined with the identification of stratigraphic-lithological and mineralogical-geochemical constraints included some interesting Pb isotopic data that confirm the multistage character of the mineralisation within these large mineral systems as a result of complex multiple processes that concentrated and redistributed the ores in these systems. The following Pb model ages have been obtained for this mineralisation: 560 ± 18 and 437 ± 10 Ma associated with Cambrian and late Ordovician–early Silurian stages of intense destruction and widespread basaltic volcanism, 320 ± 13 Ma, corresponding with the C1–2 stage of molasse sedimentation and syngenetic mineralisation, and 229 ± 20 and 201 ± 28 Ma, associated with post-collisional and intraplate stages of orogeny during P3-T1 and T2-J2 after intense granitoid magmatism the post-collisional and intraplate stages of the orogeny.
A review of the current state of knowledge on gold mineralisation in Benin Republic, West Africa
Published in Applied Earth Science, 2019
Fatchessin Bruno Adjo, Anthony Temidayo Bolarinwa, Luc Adissin Glodji, Franck Wilfried Nguimatsia Dongmo, Jerry Olugbenga Olajide-Kayode
The Volta Basin is split into three groups: two groups (I and II) of Meso- to Neoproterozoic ages (1100–600 Ma), whereas the third group is of the Palaeozoic age (500–300 Ma; Affaton 1990; Affaton et al. 1991). The first group is made up of two sandy sequences interstratified with an argillic to silty sequence, whereas the second group consists of tillite, dolomitic limestone associated with argillite, siltstone and phosphorite. The latter group (III) corresponds to the Pan-African Dahomeyides Belt molasse with argillite, siltstone, sandstone and conglomerate. The Kandi basin is composed of (1) Palaeozoic Wèrè (continental) and Kandi (marine) Formations; (2) Mesozoic Sendé (continental) Formation and (3) Continental terminal and Quaternary formations of Cenozoic age (Institut de Recherches Breda IRB 1982).
Caledonian metamorphism of metasediments from Franz Josef Land
Published in GFF, 2019
Christian Knudsen, David G. Gee, Sarah C. Sherlock, Li Yu
In the southern area, Neoproterozoic siliciclastic successions dominate the Timanides, a NW–SE trending orogen that flanks the northeastern edge of the Baltic Shield (Gee & Pease 2004). Foreland basin molasse (Grazhdankin 2004) was deposited in the late Ediacaran (c. 555–560 Ma), terminating a Timanian tectonothermal history that probably started at c. 620 Ma. A major unconformity separates Ordovician carbonates (locally Upper Cambrian black shales) from the underlying Timanian complex (Bogolepova & Gee 2004). This lower Palaeozoic succession continues up into Devonian Old Red Sandstones (ORS), the latter perhaps being related to the advance of Caledonian thrust sheets from the northwest. There is no unambiguous evidence of Caledonian deformation on land. Likewise, on Novaya Zemlya (Lorenz et al. 2013) there is evidence of a major unconformity on South Island, with Ordovician strata deposited unconformably on Neoproterozoic siliciclastic metasediments; Cambrian strata are also present above the unconformity. On North Island, characteristic 600 Ma granites occur and also some Mesoproterozoic amphibolite-facies rocks (Korago et al. 2004). Relationships to the Lower Palaeozoic successions are not exposed. Cambro-Ordovician turbidites are overlain by Silurian and Devonian successions that are dominated by carbonates, but the latter give way westwards into a partially non-marine succession, with ORS intercalations starting in the Emsian, sourced from the northwest (Gee & Bogelepova 2006). Caledonian deformation has not been reported from Novaya Zemlya, but might be present and obscured by the Triassic thrusting.