Early Jurassic
The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...
(middle or late
Toarcian
The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma (million years ago) and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian.
The Toarcian ...
)
geological formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...
of the
Mahajanga Basin
Mahajanga (French: Majunga) is a city and an administrative district on the northwest coast of Madagascar. The city of Mahajanga (Mahajanga I) is the capital of the Boeny Region. The district (identical to the city) had a population of 220,629 ...
of
Madagascar
Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...
s of the formation were deposited in a subtidal
lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') ...
Saudi Arabia
Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...
. Fossils of the marine crocodylian '' Andrianavoay'' (originally classed as a species of ''
Steneosaurus
''Steneosaurus'' (from el, στενός , 'narrow' and el, σαῦρος , 'lizard') is a dubious genus of teleosaurid crocodyliform from the Middle or Late Jurassic ( Callovian or early Oxfordian) of France. The genus has been used as a w ...
Geology of Madagascar
The geology of Madagascar comprises a variety of rocks of Precambrian age which make up the larger part of the east and centre of the island. They are intruded by basalts and rhyolites of Mesozoic to Cenozoic age. In contrast, the western part of ...
Toarcian turnover
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period o ...
Posidonia Shale
The Posidonia Shale (german: Posidonienschiefer, also called Schistes Bitumineux in Luxembourg) geologically known as the Sachrang Formation, is an Early Jurassic (Toarcian) geological formation of southwestern and northeast Germany, northern Swit ...
,
Lagerstätte
A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These f ...
in Germany
**
Ciechocinek Formation
The Ciechocinek Formation (also known as the Gryfice Formation at Suliszewo), formerly known in Germany as the Green Series (German: ''Grüne Serie'') is a Jurassic (lower Toarcian) geologic formation that extends across the Baltic coast, from ...
Whitby Mudstone
The Whitby Mudstone is a Toarcian (Early Jurassic; ''Falciferum''-''Bifrons'' in regional chronostratigraphy) geological formation in Yorkshire and Worcestershire, England.Fernie Formation, Alberta and British Columbia
*** Poker Chip Shale
**
Whiteaves Formation
The Whiteaves Formation is a geologic formation in British Columbia. It preserves fossils dating back to the Jurassic period.
See also
* List of fossiliferous stratigraphic units in Italy
* Toarcian turnover
* Toarcian formations
** Marne di M ...
, British Columbia
**
Navajo Sandstone
The Navajo Sandstone is a geological formation in the Glen Canyon Group that is spread across the U.S. states of southern Nevada, northern Arizona, northwest Colorado, and Utah as part of the Colorado Plateau province of the United States.Anonymo ...
, Utah
**
Los Molles Formation
The Los Molles Formation is a geologic formation of Early to Middle Jurassic age, located at northern and central part of Neuquén Basin at Mendoza Shelf in Argentina. It is overlain by the Niyeu–Lajas Formation.McIlroy et al., 2005
Descrip ...
, Argentina
**
Mawson Formation
The Mawson Formation is a geological formation in Antarctica, dating to roughly between 182 and 177 million years ago and covering the Toarcian stages of the Jurassic Period in the Mesozoic Era. Vertebrate remains are known from the formation. T ...
, Antarctica
**
Kota Formation
The Kota Formation is a geological formation in India. The precise age of Kota Formation are uncertain, but it dates from the Early to Middle Jurassic, and is split into a Lower Member and Upper Member.Prasad GVR, and Manhas BK. 2007A new docodont ...
, India
**
Cattamarra Coal Measures
The Cattamarra Coal Measures is an Early Jurassic geological unit in Western Australia. Description
They are part of the Perth Basin, and are a sequence of non-marine, probably fluvial sandstones, shales and silts including bituminous coal, and ...
, Australia
References
Bibliography
*
* {{cite LSA , last=Geiger , first=Markus , year=2004 , title=Sedimentary and stratal patterns in Jurassic successions of western Madagascar - Facies, stratigraphy, and architecture of Gondwana breakup and drift sequences (PhD thesis) , url=http://doc.rero.ch/record/203076/files/PAL_E3919.pdf , publisher=
Universität Bremen
The University of Bremen (German: ''Universität Bremen'') is a public university in Bremen, Germany, with approximately 23,500 people from 115 countries. It is one of 11 institutions which were successful in the category "Institutional Strateg ...