View source for Earth:Mizur Formation

{{infobox rockunit
| name           = Mizur  Formation
| image          = Река Адрон у поселка Бурон (Северная Осетия) - 51353719347.png
| caption        = Ardon River, where exposed layers of the formation are recovered
| type           = Geological Formation
| age            = Late Pliensbachian<br>~{{fossil range|183}}<Small>Domerian Substage</Small>
| period         = Pliensbachian
| overlies       = Sadon Formation
| underlies      = Unnamed Toarcian-Aalenian Layers
| region         = {{Flag|North Ossetia–Alania}}
| country        = {{RUS}}
| prilithology   = [[Earth:Sandstone|Sandstone]]
| otherlithology = [[Chemistry:Kaolinite|Kaolinite]], conglomerates, gravelstones, quartzsandstones
| namedfor       = The Town of Mizur
| namedby        = Beznosov<ref>{{cite journal |last1=Beznosov |first1=N.V. |last2=Kazakova |first2=V.P. |last3=Leonov |first3=Yu.G. |last4=Pan-ov |first4=D.I. |title=Stratigraphy of the Lower and Middle Jurassicrocks in the central North Caucasus |journal=In Materialy Po Geologiigazonosnykh Raionov SSSR (Materials on the Geology of Gas-Bearing Regions in the Soviet Union |date=1960 |volume=18 |issue=2 |pages=109–191}}</ref> 
| coordinates    = 42°51'02.1"N 44°03'25.3"E
| paleocoordinates = 
| subunits       = Fytyn, Faraskat and Mizur members
| map            = {{Location map+ | Russia
| relief = 1
| width   = 250
| float   = center
| places  =
  {{Location map~ | Russia
  | lat_deg = 42.51
  | lon_deg = 44.03
  | mark = Blue pog.svg
  | marksize = 12
  }}
}}
}}

The '''Mizur  Formation''' is a [[Earth:Geological formation|geological formation]] that outcrops in North Ossetia–Alania in the [[Earth:North Caucasus|North Caucasus]], representing a series of marginal marine to coastal layers with terrestrial influence. It is of Late Pliensbachian (Lower Jurassic) age.<ref name=Gav>{{cite journal |last1=Gavrilov |first1=Yu. O |title=Lower and Middle Jurassic deltaic sedi-mentary complex in the NE Caucasus: Communication 1.Sedimentological aspects of the deltaic complex formation |journal=Litol. Polezn. Iskop. |date=1994 |volume=4 |issue=1 |pages=77–104}}</ref> It is notable as the only major unit with preserved dinosaur footprints of various orders not yet ascribed to any concrete [[Biology:Ichnotaxon|ichnogenus]].<ref name=Gav1>{{cite journal |last1=Gavrilov |first1=Yuri O. |title=Dinosaur Footprints in Terrigenous Sediments on the Early Jurassic Shelf of the Central North Caucasus: Sedimentological and Paleoecological Settings |journal=Lithology and Mineral Resources |date=2020 |volume=55 |issue=5 |pages=345–354 |doi=10.1134/S002449022005003X |s2cid=221569067 |url=https://www.researchgate.net/publication/344812048 |access-date=12 December 2021}}</ref>

==Stratigraphy==
===Fytyn Member===
The Fytyn member represent the older layers of the formation, and depending on the outcrop, it overlies the eroded surface of [[Earth:Paleozoic|Paleozoic]] granites or crystalline schists, or the Sinemurian–lower  Pliensbachian  volcanosedimentary rocks of the Sadon Formation.<ref name=Pav>{{cite journal |last1=Panov |first1=D.I. |title=Stratigraphy of the Lower and Middle Jurassicrocks in the central North Caucasus (Digor–Ossetia zone) |journal=Byull. Mosk. O-va Ispyt. Prir., Otd. Geol. |date=1997 |volume=72 |issue=5 |pages=46–55}}</ref> This member is composed mostly of the product of the regional erosion of older layers — conglomerates, gravelstones, quartz sandstones, and others — that were deposited in a mostly continental setting. It is up to a few dozen meters thick.<ref name=Pav/>

===Faraskat Member===
In some outcrops the Fytyn Member is absent, as result of a regional uplift, with the sedimentary material transported from this area to central parts of the Greater Caucasus. Such material ended up accumulating on the Kistin Formation (Sinemurian–lower Pliensbachian), a unit that underlies in some sections the Faraskat Member.<ref name=Pav/> The Faraskat section began its deposition when the local layers were accompanied by a slow subsidence of the land and sedimentation on the previously denuded area.<ref>{{cite book |last1=SSSR |first1=Paleogeografiya |title=Ob"yasnitel'naya zapiska k atlasu li-tologo-paleogeograficheskikh kart SSSR (Paleogeography of the Soviet Union: Explanatory Note to the Atlas of Litho-logic–Paleogeographic Maps of the Soviet Union) |date=1975 |publisher=Nedra |location=Moscow}}</ref> The Faraskat sequence represents the first proper coastal deposit in the unit and is composed by a mixture of coarse material, as well as wood fragments and siderite, with some layers being highly [[Earth:Bioturbation|bioturbated]].<ref name=Pav/>

===Mizur Member===
The transition between the Faraskat and Mizur members is gradual, forming a large sedimentary cycle from clayey to sandstone-dominated rocks.<ref name=Gav/> This layer represents the last unit of the formation and is dominated by fine-grained sandstone horizons, often low-angle crossbedding and scarce fine ripple marks, in contrast to the abundant large wave ripples.<ref name=Gav/> This layers have abundant fragments of terrestrial vegetation in a highly oxidized state. The sedimentation  peculiarities  of  the  Mizur layers indicate their  accumulation  within  a  relatively  wide and  shallow  shelf.<ref name=Gav/> This layer is the only that has provided dinosaur footprints, as well [[Biology:Ammonoidea|ammonites]] and other invertebrates.<ref name=Gav1/>

==Environment==
The Mizur Member contains numerous fragments of plants — stems, wood, and  leaves — suggesting a clear influence of nearby emerged settings. The vegetation in the coeval exposures along the Caucasus and adjacent regions were covered by coniferous forests with abundant underliying [[Biology:Bennettitales|Bennettitales]].<ref>{{cite journal |last1=Vakhrameev |first1=V.A. |last2=Vasina |first2=R.A. |title=The Lower Jurassic and Aalenian f lora in the North Caucasus |journal=Paleontol. Zh. |date=1959 |volume=3 |issue=1 |pages=125‒133}}</ref> The spores and pollen in the sediments are dominated by bennettitales, which likely grew on nearshore lowlands.<ref name=Dom>{{cite journal |last1=Vakhrameev |first1=V.A. |last2=Krasilov |first2=V.A. |title=The Domerian f lorain the North Caucasus |journal=Paleontol. Zh. |date=1961 |volume=3 |issue=1 |pages=103–108}}</ref> The region hosts pollen of several plant groups, notably the [[Biology:Pinaceae|Pinaceae]], [[Biology:Podocarpaceae|Podocarpaceae]], [[Biology:Araucariaceae|Araucariaceae]], with other such as [[Biology:Ginkgoaceae|Ginkgoaceae]] being less common. Beyond trees, the lowlands were covered by thermophilic ferns (''Cibitium'', ''Mattonia'', ''[[Biology:Coniopteris|Coniopteris]]''), lycophytes (''[[Biology:Selaginella|Selaginella]]''), and horsetails (''[[Biology:Neocalamites|Neocalamites]]'').<ref name=Dom/> Invertebrate faunas are linked with the Mediterranean faunal region, with isotope ratios in some specimens ([[Biology:Belemnitida|belemnites]] and [[Biology:Brachiopod|brachiopods]]) yielding estimated average annual temperatures in the North Caucasian–Transcaucasian region of 21.4–23.5&nbsp;°C; that is, a subtropical humid climate.<ref>{{cite journal |last1=Yasamanov |first1=N.A. |title=Temperatures in the habitat of Jurassic–Cretaceous brachiopods, cephalopods, and bivalve mol-luscs in the western Transcaucasian basin |journal=Geokhimiya |date=1973 |volume=5 |issue=2–3 |page=746‒754}}</ref><ref>{{cite book |last1=Yasamanov |first1=N.A . |title=Landshaftno-klimaticheskie usloviyayury, mela i paleogena Yuga SSSR (Jurassic, Cretaceous,and Paleogene Landscape-Climate Conditions in theSouthern Soviet Union) |date=1978 |publisher=Nedra |location=Moscow}}</ref>

== Fossil content ==
=== Ammonites ===
{|class="wikitable" align="center"
|-
! Genus 
! Species 
! Location 
! Section
! Material 
! Notes 
! Images
|-
|  
''[[Biology:Amaltheus|Amaltheus]]''<ref name=Gav/>
|
*''Amaltheus'' spp.
*''Amaltheus margaritatus''
| 
* Urukh river
* Ardon river
* Fiagdon river 
|
*Mizur Member
|
*Isolated shells
*Fragments of shells
|
An ammonite, type member of the family [[Biology:Amaltheidae|Amaltheidae]] within [[Biology:Ammonitida|Ammonitida]]. This genus is the main one used to gauge the depositional age of the local layers.
|
[[File:Amaltheus margaritatus 233454.jpg|thumb|155px|''Amaltheus margaritatus'' specimen]]
|-
|}

=== Dinosauria ===
{|class="wikitable" align="center"
|-
! Genus 
! Species 
! Location
! Section 
! Material 
! Notes 
! Images
|-
| style="background:#FEF6E4;"| 
''Dinosauropedida''<ref name=Gav1/>
| style="background:#FEF6E4;"|
''Dinosauropedida''  [[Biology:Ichnotaxon|ichnog.]] indeterminate
| style="background:#FEF6E4;"| 
* Ardon river
| style="background:#FEF6E4;"| 
*Mizur Member
| style="background:#FEF6E4;"| 
Footprints
| style="background:#FEF6E4;"|
Dinosaur footprints, unassigned to any concrete ichnogenus.  A poorly preserved trackway composed of three tracks whose appearance is completely different to that of any other specimen recovered from the unit. 
| style="background:#FEF6E4;"|
|-
| style="background:#FEF6E4;"| 
''Sauropodomorphidia''<ref name=Gav1/>
| style="background:#FEF6E4;"|
''Sauropodomorphidia'' ichnog. indeterminate
| style="background:#FEF6E4;"| 
* Ardon river
| style="background:#FEF6E4;"| 
*Mizur Member
| style="background:#FEF6E4;"| 
Footprints
| style="background:#FEF6E4;"|
Possible [[Biology:Sauropodomorpha|sauropodomorph]] footprints, unassigned to any concrete ichnogenus. A clear tridactyl track 12&nbsp;cm wide is distinguished among several hollows. 
| style="background:#FEF6E4;"|
[[File:Mussaurus patagonicus life restoration.png|thumb|center|155px| Sauropodomorphs similar to ''[[Biology:Mussaurus|Mussaurus]]'' may have left these footprints]]
|-
| style="background:#FEF6E4;"| 
''Theropodipedia''<ref name=Gav1/>
| style="background:#FEF6E4;"|
''Theropodipedia'' ichnog. indeterminate
| style="background:#FEF6E4;"| 
* Ardon river
| style="background:#FEF6E4;"| 
*Mizur Member
| style="background:#FEF6E4;"| 
Footprints
| style="background:#FEF6E4;"|
Possible [[Biology:Theropoda|theropod]] footprints, unassigned to any concrete ichnogenus. Theropod tracks include several types, from small to medium specimens. Some alterations near the tracks have been interpreted as derived from displaced sediments moved by the dinosaur upper limb during a search for burrowing organisms.  
| style="background:#FEF6E4;"|
[[File:Procompsognathus.jpg|thumb|center|155px| Small theropods similar to ''[[Biology:Procompsognathus|Procompsognathus]]'' may have left these footprints]]
|-
| style="background:#FEF6E4;"| 
''Carnosauripodoidei''<ref name=Gav1/>
| style="background:#FEF6E4;"|
''Carnosauripodoidei'' ichnog. indeterminate
| style="background:#FEF6E4;"| 
* Ardon river
| style="background:#FEF6E4;"| 
*Mizur Member
| style="background:#FEF6E4;"| 
Footprints
| style="background:#FEF6E4;"|
Possible tetanuran footprints, unassigned to any concrete ichnogenus. A relatively large single dinosaur track (35‒40&nbsp;cm wide), its distinctive fingerprints diverging at an angle of 30°‒35° are characteristic of large Jurassic predatory theropods.  
| style="background:#FEF6E4;"|
[[File:Piatnitzkysaurus floresi by Paleocolour.jpg|thumb|center|155px| Medium theropods similar to ''[[Biology:Piatnitzkysaurus|Piatnitzkysaurus]]'' may have left these footprints]]
|-
| style="background:#FEF6E4;"| 
''Ornithischipida''<ref name=Gav1/>
| style="background:#FEF6E4;"|
''Ornithischipida'' ichnog. indeterminate
| style="background:#FEF6E4;"| 
* Ardon river
| style="background:#FEF6E4;"| 
*Mizur Member
| style="background:#FEF6E4;"| 
Footprints
| style="background:#FEF6E4;"|
Possible [[Biology:Ornithischia|ornithischian]] footprints, unassigned to any concrete ichnogenus. A series of tracks whose relatively small size (15&nbsp;cm) and the close position of the left and right limbs suggest they belong to a small herbivorous ornithopod  
| style="background:#FEF6E4;"|
[[File:Lesothosaurus ER670.JPG|thumb|center|155px| Small ornithischians similar to ''Lesothosaurus'' may have left these footprints]]
|-
|}

== See also ==
* List of fossiliferous stratigraphic units in Russia
* [[Earth:Sorthat Formation|Sorthat Formation]], Denmark
* [[Earth:Neringa Formation|Neringa Formation]], Lithuania
** [[Earth:Blanowice Formation|Blanowice Formation]], Southern Poland
** [[Earth:Clarens Formation|Clarens Formation]], South Africa
** [[Earth:Fernie Formation|Fernie Formation]], Canada
** [[Earth:Hasle Formation|Hasle Formation]], Denmark
** Kota Formation, India
** [[Earth:Los Molles Formation|Los Molles Formation]], Argentina
** [[Earth:Mawson Formation|Mawson Formation]], Antarctica
** [[Earth:Rotzo Formation|Rotzo Formation]], Italy
** Whiteaves Formation, British Columbia
** [[Earth:Navajo Sandstone|Navajo Sandstone]], Utah
** [[Earth:Kandreho Formation|Kandreho Formation]], Madagascar
** Kota Formation, India
** [[Earth:Cattamarra Coal Measures|Cattamarra Coal Measures]], Australia

== References ==
{{reflist}}

[[Category:Sandstone formations]]
[[Category:Coal formations]]

{{Sourceattribution|Mizur Formation}}