Toarcian

{{short description|Fourth and last age of the Early Jurassic}}

{{Infobox geologic timespan

| name = Toarcian

| color = Toarcian

| time_start = 184.2

| time_start_uncertainty = 0.3

| time_end = 174.7

| time_end_uncertainty = 0.8

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| timeline = Jurassic

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| name_formality = Formal

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| celestial_body = earth

| usage = Global (ICS)

| timescales_used = ICS Time Scale

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| chrono_unit = Age

| strat_unit = Stage

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| timespan_formality = Formal

| lower_boundary_def = Peniche, Portugal

| lower_gssp_location = FAD of the Ammonite D. (E.) simplex

| lower_gssp_coords = {{Coor|39.3708|N|9.3853|W|display=inline}}

| lower_gssp_accept_date = 2014{{cite journal |last1=da Rocha |first1=Rogério Bordalo |last2=Mattioli |first2=Emanuela |last3=Duarte |first3=Luís Vítor |last4=Pittet |first4=Bernard |last5=Elmi |first5=Serge |last6=Mouterde |first6=René |last7=Cabral |first7=Maria Cristina |last8=Comas-Rengifo |first8=Maria José |last9=Gómez |first9=Juan José |last10=Goy |first10=António |last11=Hesselbo |first11=Stephen P. |last12=Jenkyns |first12=Hugh C. |last13=Littler |first13=Kate |last14=Mailliot |first14=Samuel |last15=Veiga de Oliveira |first15=Luiz Carlos |last16=Osete |first16=Maria Luisa |last17=Nicola |first17=Perilli |last18=Pinto |first18=Susana |last19=Ruget |first19=Christiane |last20=Suan |first20=Guillaume |title=Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal) |journal=Episodes |date=September 2016 |volume=39 |issue=3 |pages=460–481 |doi=10.18814/epiiugs/2016/v39i3/99741 |doi-access=free |hdl=10261/140775 |hdl-access=free }}

| upper_boundary_def = FAD of the Ammonites Leioceras opalinum and Leioceras lineatum

| upper_gssp_location = Fuentelsaz, Spain

| upper_gssp_coords = {{Coord|41.1708|N|1.8333|W|display=inline}}

| upper_gssp_accept_date = 2000{{cite journal |last1=Cresta |first1=S. |last2=Goy |first2=A. |last3=Arias |first3=C. |last4=Barrón |first4=E. |last5=Bernad |first5=J. |last6=Canales |first6=M. |last7=García-Joral |first7=F. |last8=García-Romero |first8=E |last9=Gialanella |first9=P. |last10=Gómez |first10=J. |last11=González |first11=J. |last12=Herrero |first12=C. |last13=Martínez |first13=G. |last14=Osete |first14=M. |last15=Perilli |first15=N. |last16=Villalaín |first16=J. |title=The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic) |journal=Episodes |date=September 2001 |volume=24 |issue=3 |pages=166–175 |doi=10.18814/epiiugs/2001/v24i3/003 |doi-access=free |url=https://timescalefoundation.org/references/Aalenian.pdf |access-date=13 December 2020}}

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The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 184.2 Ma (million years ago) and 174.7 ±0.8 Ma.{{cite book|last=Benton|first=Michael J.|title=Prehistoric Life|year=2012|publisher=Dorling Kindersley|location=Edinburgh, Scotland|isbn=978-0-7566-9910-9|pages=44–45}} It follows the Pliensbachian and is followed by the Aalenian.For a detailed geologic timescale see Gradstein et al. (2004)

The Toarcian Age began with the Toarcian Oceanic Anoxic Event, a major anoxic event associated with marine extinctions and increased global temperatures that sets its fossil faunas apart from the previous Pliensbachian age. It is believed to have ended with a global cooling event known as the Comptum Cooling Event, although whether it represented a worldwide event is controversial.{{cite journal |last1=Henriques |first1=Maria Helena Paiva |last2=Canales |first2=Maria Luisa |date=September–October 2013 |title=Ammonite-benthic Foraminifera turnovers across the Lower-Middle Jurassic transition in the Lusitanian Basin (Portugal) |url=https://www.sciencedirect.com/science/article/abs/pii/S0016699513000727 |journal=Geobios |volume=46 |issue=5 |pages=395–408 |doi=10.1016/j.geobios.2013.06.002 |bibcode=2013Geobi..46..395H |access-date=23 November 2022|hdl=10316/27258 |hdl-access=free }}