Urgonian Facies Research Articles

L'urgonien de Hongrie

A biostratigraphical synthesis of the Hungarian Lower Cretaceous is presented herein. The Urgonian facies are heterochronous and appear later and later from the South to the North of Hungary. We distinguish thus: 1) a southern sector (Villány) where the Urgonian facies (with Orbitolinidae, Dasycladaceae and Rudists) spreads over the Lower Barremian (?), the Upper Barremian-Early Bedoulian ( Orbitolinopsis gr. cuvillieri-kiliani biozone), the Middle Bedoulian ( Palorbitolina lenticularis, Praeorbitolina cormyi and P. lotzei biozone), the Gargasian ( Mesorbitolina minuta biozone) and the Lower/Middle Albian ( Simplorbitolina manasi and Simplorbitolina conulus biozone); 2) a northern sector (Bakony) where the Urgonian facies is restricted to the Upper Albian ( Orbitolina concava biozone) and contains the Floridae Algae association of Vimport. Elsewhere (Tata, Gerecse) the reduced Lower Cretaceous series presents either the formations of external shelf or those of the basin.

De l'étage aux systèmes bio-sédimentairesurgoniens

The fact that the term «Urgonian, created in 1850by A. d'Orbigny for a stage in Lower Cretaceous, is still in use although it has been replaced by Barremian in its original meaning, proves that it corresponds to something real: the Urgonian facies as they have long been called. Taking into account research during the last 25 years: Urgonian biosedimentary systems should be preferred. These systems represent the carbonate platform sedimentation at a particular time (roughly Lower Cretaceous). They are no reefs although some parts may be built up; they are not necessarily separated from the deep sea by a barrier. Their most typical environments are Rudist biotopes where muddy sedimentation (micritic limestones) is predominant. Terrigenous occurrences may combine with carbonate sedimentation. The Urgonian biosedimentation may possibly beexplained by the convergence of several conditions: biologic (a stage of evolution) climatic (a warm and wet climate) and tectonic (the growth and movement of mobile continental margins).

Les faciès urgoniens et leurs variations pendant la transgression aptienne occidentale de la chaîne Ibérique (Espagne)

The present paper is an up to date one on the knowledge about the Urgonian facies and their lateral changes in the west part of the Iberian - Range (Spain), corresponding to an wide and shallow shelf which has its communication to the open sea toward the South East (Betics Ranges). These materials correspond to a complex transgressionof the Aptian age, although it may occur during part of Barremian and Albian and has its maximum extension in Bedoulian. It is possible to distinguish six kinds of Faciesassociation, which change from the reefs to the continentals. Two kinds of basin limits have also been recognized, the western on with notable terrigenous supplies and the north eastern one with scarce supplies.

The corals of the Urgonian faciesof Georgia

Early Cretaceous corals of the Georgian block are mainly connected with the Urgonian facies. Their distribution during Hauterivian and Barremian closely follows the marine transgression from the North to the South i.e. from the geosyncline of the Southern slope of the Great Caucasus to the Georgian block.

Les calcaires urgoniens de géorgie

The Urgonian facies is related to the neritic depositsof the Georgian block and passes laterally into the bedded ammonitic limestones to the North. Urgonian sedimentation starts in the Middle Hauterivian and generally ends at the early Barremian; seldom it may last till the Lower-Upper Barremian boundary, and sometimes even later, but it never reaches the Barremian-Aptian boundary.

Mise en evidence de Campanien continental (facies provencal) a Salavas (Ardeche, S-E de la France): Description, sedimentologie, paleogeographie

The continental sediments in the Northern Alès Basin are dated as Campanian age based on gastropod Melania praelonga MATHERON. The lithology is made up by red shales, conglomerates and pedologic limestones (crusts and nodules) with microcodiums. The conglomerates are heterometric and made up by limestone (Urgonian facies) and standstone boulders of Cenomanian and Turonian age. Also sandy limestones of coniacian age are found, all belonging to the local substratum. This discovery helps to understand the evolution of the Upper Cretaceous paleogeography.

The Urgonian faciesof the Soviet Carpathians

The Urgonian facies (s.s.) in the Soviet Carpathiansis represented by massive zoogenic (bioherms) and well stratified biomicritic limestones. They outcrop in a tectonically effected belt, some 100 km long in the Marmarosch Klippen zone. Their thickness varies from 2 to 150 m. In different localities the transition of limestones to terrigenous deposits is clearly visible. The remains of the organisms found in these indicate a Barremian-Aptian age. Certain assemblages of benthic organisms have been recognized and their principal living conditions proposed.

Le faciès urgonien des nappes helvétiquesen Suisse orientale

The «Schrattenkalk Formation (late Barremian - early Aptian) represents the Urgonian facies in eastern Switzerland. In the northern shore ward regions of the Helvetic platform the Upper members of the Schrattenkalk have been eroded leaving just the Lower Schrattenkalk. This makes it impossible to have a complete evolutionary study of Barremien-early Aptian. Microfacies studies in the central and southernregions suggest a platform sedimentation controled by faults or flexures running approximately parrallel to the shelf edge. Progradation of the platform towards the southeast is documented by the insets of high energy sediments in different profiles. The «Schrattenkalk is the top most part of aBarremian sedimentary cycle (condensation horizon - marls - limestone). Eustatic sea level changes are believed to be responsible for this cyclic facies change. In the southern realm the limestone is intercalated by a marl-sequence of outer shelf facies which replaces parts of the «Schrattenkalk and seems to be the result of synsedimentary deepening of the southern realm.

Sedimentological study of the upper Jurassic sequence of limestone in the pui zone (Romania)

In the points Fundătura and Ciclovina, situated northward of the Pui zone (southern Carpathians, Fig.1), we collected two sections of lithological samples from the Lower Jurassic sequence. Thin-sections effected on these samples formed the subject of a study, the results of which are presented in this paper. The lithological sequence of the Upper Jurassic includes, above the Dogger Formations the following sedimentary terms ( Boldor and Stilla, 1967): 1. (1) Lower?-Middle Callovian, represented by gritty, spathic limestones with abundant siliceous accidents, disposed non-uniformly in the rock mass. 2. (2) Upper Callovian-Lower Oxfordian, composed of marly limestones and fine limestones with Kosmoceras duncani Sow. and Euaspidoceras cf. perarmatum Sow. 3. (3) Upper Oxfordian-Kimmeridgian-Tithonian, comprised in a packet of generally fine, sub-lithographic limestones, with siliceous accidents disposed according to the stratification. In the upper third of this sequence of rosy siliceous limestones, there are distinguished alternances of nodulous limestones. Macrofaunally, the deposits are characterized by the presence of the forms Perisphinctes, Belemnites, Aptychus. Representing a new, transgressive, cycle of sedimentation, there are deposited massive reef limestones with Requienia ammonia Goldf., referred to the Lower Cretaceous in urgonian facies. The section of samples for thin sections included in the Fundătura sector only the upper part of the Malm (Kimmeridgian-Tithonian) deposits, and is concluded by several limestone beds of Early Cretaceous age. Notable in this point is the Fundătura fault which breaks up the Jurassic sequence towards the bottom, and puts it into tectonic contact with the reef limestones of the Lower Cretaceous. In the Ciclovina point, sampling began in the last beds of the Upper Callovian-Lower Oxfordian deposits, continued with the Upper Oxfordian-Kimmeridgian-Tithonian packet of limestones with silica, and comprised also, in its upper part, the first limestone beds of Early Cretaceous age.

Les milieux urgoniens cantabriques

Abstract Rudistid-bearing limestones resembling those characterized by a Urgonian facies which were deposited in lower and middle Cretaceous seas of the Mediterranean region occur in northern Spain, where they are intercalated in a thick sequence of Aptian to Albian formations. In the Cantabrian basin of northern Spain frequent invasions of terrigenous material at irregular intervals interrupted development of the Urgonian reefs.