Aalenian


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Aalenian

[ȯ′lēn·ē‚ən]
(geology)
Lowermost Middle or uppermost Lower Jurassic geologic time.
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This succession can be interpreted as largely marine in nature, with punctuated episodes of marginal marine to lacustrine sedimentation and subaerial exposure during Aalenian to Bajocian times.
After the ETMEE, during the Middle-Upper Toarcian and even in the Aalenian, the distribution of the brachiopod faunal successions in the Iberian Range is markedly conditioned by the depositional sequences, particularly by the frequent variations on the bedding thickness and facies (Garcia Joral et al.
Overlying this hardground there are nodular and well bedded platy, bioturbated limestones of the Gorg Blau Formation with fauna of the early to middle Aalenian and the Bajocian (Discites to Humphriesianum zones), the Concavum Zone of the late Aalenian was not found (Alvaro et al.
The studied stratigraphic interval, ranging from upper Toarcian to middle Aalenian, corresponds to the Povoa da Lomba Formation (sensu Azeredo et al.
e Anisian, Aalenian, Norian, and Olenekian; because of a probable rejuvenation of the K/Ar system during the late tectonosedimentary events.
The Opalinus Clay is an indurated clay, upper Aalenian (180-170 Ma), deposited in a shallow marine environment.
International Subcommission on Jurassic Stratigraphy, 1st Toarcian and 4th Aalenian working groups meeting.