{{Short description|Geologic formation in Leicestershire, the United Kingdom}} {{Infobox rockunit | name = Bradgate Formation | image = File:Bradgate park rocks.jpg | caption = Bradgate Park, which gave the name to the formation, which itself can be found here. | type = Formation | age = Ediacaran {{Geological range|561|557|ref=<ref name="Noble2015">{{cite journal |last1=Noble |first1=Stephen R. |last2=Condon |first2=Daniel J. |last3=Carney |first3=John N. |last4=Wilby |first4=Philip R. |last5=Pharaoh |first5=Timothy C. |last6=Ford |first6=Trevor D. |title=U-Pb geochronology and global context of the Charnian Supergroup, UK: Constraints on the age of key Ediacaran fossil assemblages |journal=Geological Society of America Bulletin |date=January 2015 |volume=127 |issue=1-2 |pages=250–265 |doi=10.1130/B31013.1}}</ref>}} | period = Ediacaran | prilithology = Pelite | otherlithology = Tuff, Graywacke, Breccia | namedfor = Bradgate Park | namedby = | region = Leicestershire | country = United Kingdom | coordinates = | unitof = Maplewell Group | subunits = See: Members | underlies = Hanging Rocks Formation<ref name="MoseleyFord">{{cite web |last1=Moseley |first1=John |last2=Ford |first2=Trevor |title=The Sedimentology of the Charnian Supergroup |url=https://www.emgs.org.uk/uploads/1/4/9/1/149143154/mg11_4_1989_251_moseley_ford_sedimentology_of_the_charnian_supergroup_2.pdf |publisher=Mercian Geologist}}</ref> | overlies = Beacon Hill Formation<ref name="MoseleyFord"/> | thickness = {{cvt|649|m|ft}}<ref name="MoseleyFord"/> | extent = | area = | map = | map_caption = }}
The '''Bradgate Formation''' is a geologic formation in Leicestershire, and lies within the wider Bradgate Park area. It also preserves fossils dating back to the late Ediacaran period.
== Geology == The formation is composed of various volcaniclastic rocks, like tuff, and is broken up into two members.<ref name="MoseleyFord"/> It is overlain by the Hanging Rocks Formation, whilst it is underlain by the Beacon Hill Formation.<ref name="MoseleyFord"/><ref name="Noble2015"/>
=== Members === The Bradgate Formation is formally split up into two members, which are as follows, in ascending stratigraphic order (lowest to highest):
*'''Sliding Stone Slump Breccia Member:''' This member, also sometimes referred to as "Park Breccia Member", is the thinnest of the two, only getting up to {{cvt|9|m|ft}} thick. The lower {{cvt|4|m|ft}} of this member is primarily composed of slump breccias as the name suggests, which contain clasts that are composed of dust tuff, alongside tuffaceous pelites, set into a matrix of coarse-grained tuffs and medium-grained graywackes.<ref name="MoseleyFord"/> Meanwhile the upper {{cvt|5|m|ft}} of this member sees the breccias fade away, only being composed of coarse-grained tuffs that are andesitic in nature, and slowly turn into medium-grained tuffaceous graywackes.<ref name="MoseleyFord"/>
*'''Hallgate Member:''' This member is the thickest of the two, getting up to {{cvt|640|m|ft}} thick. It is predominated by tuffaceous pelites, as well as pelites and dust tuffs. Through-out, there are also thin layers coarse-grained tuffs and medium-grained graywackes.<ref name="MoseleyFord"/>
== Dating == At the base of the Bradgate Formation, zircon samples were collected to take U-Pb dating on them and determine the overall age of the formation and fossils. The zircon sample JNC 912, from the base of the formation, returned a date of {{val|561.85|0.33|ul=Ma}}. Meanwhile a zircon sample, JNC 846, collected from near the base of the overlying Hanging Rocks Formation returned an age of {{val|556.6|6.4|ul=Ma}}, which would constrain the Bradgate Formation entirely within the Avalon assemblage, and correlating it roughly with the Trepassey Formation.<ref name="Noble2015"/>
== Paleobiota == The Bradgate Formation contains the richest fossil beds within the Charnian Supergroup, from frondose organisms like ''Bradgatia'' and ''Charnia'', which when the latter was discovered, showed definitive proof that macroscopic life did indeed exist before the Cambrian,<ref name="Ford">{{cite journal |last1=Ford |first1=T. D. |title=PRE-CAMBRIAN FOSSILS FROM CHARNWOOD FOREST |journal=Proceedings of the Yorkshire Geological Society |date=September 1958 |volume=31 |issue=3 |pages=211–217 |doi=10.1144/pygs.31.3.211}}</ref> to discoid forms like ''Aspidella''.
{{Paleobiota-key-compact}}
=== Petalonamae ===
{| class="wikitable" style="width:70%;" |- !Genus !Species !Notes !Images |- |''Bradgatia''<ref name="Kenchington">{{cite journal |last1=Kenchington |first1=Charlotte G. |last2=Harris |first2=Simon J. |last3=Vixseboxse |first3=Philip B. |last4=Pickup |first4=Chris |last5=Wilby |first5=Philip R. |title=The Ediacaran fossils of Charnwood Forest: Shining new light on a major biological revolution |journal=Proceedings of the Geologists' Association |date=June 2018 |volume=129 |issue=3 |pages=264–277 |doi=10.1016/j.pgeola.2018.02.006}}</ref> | *''B. linfordensis'' |Sessile frondose organism. |center|100px |- |''Charnia<ref name="Ford"/>'' | *''C. masoni'' |Sessile frondose organism, and first organism found within this formation. |center|100px |- |''Charniodiscus<ref name="Ford"/>'' | *''C. concentricus'' |Sessile frondose organism. |center|100px |- |''Hylaecullulus''<ref>{{cite journal |last1=Kenchington |first1=Charlotte G. |last2=Dunn |first2=Frances S. |last3=Wilby |first3=Philip R. |title=Modularity and Overcompensatory Growth in Ediacaran Rangeomorphs Demonstrate Early Adaptations for Coping with Environmental Pressures |journal=Current Biology |date=October 2018 |volume=28 |issue=20 |pages=3330–3336.e2 |doi=10.1016/j.cub.2018.08.036|doi-access=free }}</ref> | *''H. fordi'' |Sessile frondose organism. | |- |''Primocandelabrum''<ref>{{cite journal |last1=Kenchington |first1=Charlotte G. |last2=Wilby |first2=Philip R. |title=Rangeomorph classification schemes and intra-specific variation: are all characters created equal? |journal=Geological Society, London, Special Publications |date=January 2017 |volume=448 |issue=1 |pages=221–250 |doi=10.1144/SP448.19|doi-access=free }}</ref> | *''P. aelfwynnia'' *''P. aethelflaedia'' *''P. boyntoni'' |Sessile frondose organism. | |- |''Vinlandia''<ref>{{cite journal |last1=Brasier |first1=Martin D. |last2=Antcliffe |first2=Jonathan B. |last3=Liu |first3=Alexander G. |title=The architecture of Ediacaran Fronds |journal=Palaeontology |date=September 2012 |volume=55 |issue=5 |pages=1105–1124 |doi=10.1111/j.1475-4983.2012.01164.x}}</ref> | *''V. antecedens'' |Sessile frondose organism. |center|100px |- |}
=== Cnidaria ===
{| class="wikitable" style="width:70%;" |- !Genus !Species !Notes !Images |- |''Auroralumina''<ref>{{cite journal |last1=Dunn |first1=F. S. |last2=Kenchington |first2=C. G. |last3=Parry |first3=L. A. |last4=Clark |first4=J. W. |last5=Kendall |first5=R. S. |last6=Wilby |first6=P. R. |title=A crown-group cnidarian from the Ediacaran of Charnwood Forest, UK |journal=Nature Ecology & Evolution |date=25 July 2022 |volume=6 |issue=8 |pages=1095–1104 |doi=10.1038/s41559-022-01807-x|pmc=9349040 }}</ref> | *''A. attenboroughii'' |Early sessile crown-group medusozoan cnidarian. |center|100px |- |}
=== ''incertae sedis'' ===
{| class="wikitable" style="width:70%;" |- !Genus !Species !Notes !Images |- |''Aspidella''<ref name="Wilby">{{cite journal |last1=Wilby |first1=Philip R. |last2=Carney |first2=John N. |last3=Howe |first3=Michael P.A. |title=A rich Ediacaran assemblage from eastern Avalonia: Evidence of early widespread diversity in the deep ocean |journal=Geology |date=1 July 2011 |volume=39 |issue=7 |pages=655–658 |doi=10.1130/G31890.1}}</ref> | *''Aspidella sp.'' |Enigmatic discoidal fossil. |center|100px |- |''Thectardis<ref name="Wilby"/>'' | *''T. avalonensis'' |Discoid organism, possibly holdfasts of petalonamids. |center|100px |- |}
=== Undescribed forms ===
{| class="wikitable" style="width:70%;" |- !Genus !Species !Notes !Images |- |Gladius form<ref name="Kenchington"/> | *''???'' |Enigmatic fossil, described to be in the shape of a gladius sword. | |- |Hemispherical form<ref name="Kenchington"/> | *''???'' |Enigmatic fossil, described to be hemispherical in shape, with bifurcating radial ribs. | |- |Lanceolate frond<ref name="Bowers">{{cite web |last1=Bowers |first1=Aron |title=Further Precambrian (Ediacaran) fossil discoveries in Charnwood Forest, Leicestershire |url=https://www.monash.edu/__data/assets/pdf_file/0009/85626/mercian-2014-v18-p175-further-ediacaran-fossils-charwood-forest-bowers.pdf |website=Monash University |publisher=Mercian Geologist |access-date=5 May 2025}}</ref> | *''???'' |Enigmatic frondose fossil, described to be in the shape of a lance head, which has collapsed in onto itself. | |- |}
==See also== {{Portal|Earth sciences|United Kingdom|Paleontology|}} * List of fossiliferous stratigraphic units in England
==References== * {{cite web|title= Fossilworks: Gateway to the Paleobiology Database|author= ((Various Contributors to the Paleobiology Database))|url= https://www.fossilworks.org|access-date= 17 December 2021}} <references/>
Category:Ediacaran Europe Category:Geologic formations of England Category:Geology of Leicestershire