Liassic


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Related to Liassic: Lower Jurassic

Liassic

[lī′as·ik]
(geology)
The Lower Jurassic period of geologic time. Also known as Lias.

Liassic

 

Lower Jurassic. It was identified at the end of the 18th century by the English engineer W. Smith in Somersetshire (Great Britain). A typical section consists of regularly alternating flaglike limestones and argillites. The Liassic is divided into six stages—Hettangian, Sinemurian, Lotharingian, Pliensbachian, Domerian, and Toarcian—and is characterized by ammonites. Sediments were deposited almost everywhere during the age of regression of the sea and are represented chiefly by dark-colored sandy-argillaceous formations. Liassic deposits are known on virtually all continents. In the USSR, Liassic deposits are found in the Carpathians, the Crimea, the Caucasus, western Kazakhstan, and Eastern Siberia. Coal, oil, and gas deposits are associated with Liassic deposits.

References in periodicals archive ?
The first one is defined by the presence of significant natural gas volumes in the drilling mud within the Lower Dogger/Upper Liassic zone, which occurs over a gross interval of approximately 100 metres.
The geological characteristics of these formations compare favourably to oil-rich shale formations such as the Bakken Shale in the Williston Basin and Liassic Shale in the Paris Basin.
(2006): Anatomy, phylogeny, and palaeoecology of the basal thalattosuchians (Mesoeucrocodylia) from the Liassic of Central Europe.
Also, the Liassic drilling programme, comprising six wells (without the use of hydraulic fracturing), is expected to commence by year-end pending final review of permits by the French Administration.
The geological characteristics of these formations compare favorably to oil-rich shale formations such as the Bakken Shale in the Williston Basin and Liassic Shale in the Paris Basin.
Loeblich and Tappan (1987) report the genus Pseudocyclammina to be from the Early Jurassic (Liassic) to the Coniacian.
(1997): Entolium beds--hiatal shell concentrations in starved pelagic settings (Middle Liassic, SE Spain).