Strontium isotope profile of the early Toarcian (Jurassic) oceanic anoxic event, the duration of ammonite biozones, and belemnite palaeotemperatures

McArthur, J. M.; Donovan, D. T.; Thirlwall, M. F.; Fouke, Bruce W.; Mattey, D. P.

doi:10.1016/s0012-821x(00)00111-4

Cited by 319 publications

(305 citation statements)

References 58 publications

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“…7. Sea-level cycles (adapted from Vail et al, 1977;Haq et al, 1987, 198&). along the EES show a Ül3C minimum in the uppennost tenuicostatum and the falciferum zones of the Toarcian Clayton, 1986, 1997;Hesselbo et al, 2000;McArthur et al, 2000;Jenkyns et al, 2002;Rosales et al, 2004). Two explanations have been given for the cause of this negative ül3e excursion:…”

Section: G Tethys Oceanmentioning

confidence: 97%

Pliensbachian–Toarcian ostracod biogeography in NW Europe: Evidence for water mass structure evolution

Arias

2007

Palaeogeography, Palaeoclimatology, Palaeoecology

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AbsfractThis paper examines fue role played by palaeoceanographic and c1imatic conditions on the palaeobiogeography of the Pliensbachian Toarcian ostracods (Early Jurassic) in the European Epicontinental Sea (BES). The infIuence of the palaeogeography, ocean currents and sea level, temperature and salinity variations on ostracod abundance, diversity and migration pattems is reconstructed. Ostracod migration follows an antic10cbvise circulation in the eastem side of the EES, with a leading northeast southwest movement, and fue frequent arrival ofTethyan falUlas into fue central and westem parts ofthe EES during the Pliensbachian. A three-fold c1assification ofwater masses based on salinity, temperature, lithological and fossil data is proposed. The repeated inflow ofTethyan ostracods into the EES ended by the earliest Toarcian. This ostracod event is related to the opening ofthe Hispanic Corridor and to the reorganization ofthe surface and deep circulations that may have generated a cold episode at the beginning of the Toarcian.

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Section: G Tethys Oceanmentioning

confidence: 97%

Pliensbachian–Toarcian ostracod biogeography in NW Europe: Evidence for water mass structure evolution

Arias

2007

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…[20] In order to estimate the duration of units discussed here, we use the timescale of Suan et al [2008], coupled with the Sr isotope stratigraphy of McArthur et al [2000] ( Figure 2). The cyclostratigraphic analysis by Suan et al [2008] assigned a duration of $900 ka (from their detailed discussion, it is 930 ± 40 ka) to the well-defined negative isotopic excursion in d 13 C(org) seen in the exaratum Subzone and the uppermost few meters of the underlying semicelatum Subzone (Figure 2).…”

Section: Timescalementioning

confidence: 99%

“…These authors also estimated that the deposition of the tenuicostatum and falciferum Zones (the Lower Toarcian) occupied 2.05 ± 0.15 Ma, a duration close to that of 2.3 Ma estimated independently by Ogg [2004, Figure 18.1 and Figure 2] is good evidence that sedimentation rates were different within each regression interval. The linearity and slope of each regression shows that exaratum Subzone and overlying 30 cm of the falciferum Subzone of the Toarcian are stratigraphically condensed by a factor of 7 relative to underlying strata and by a factor of 12 relative to overlying strata (Figure 2) [McArthur et al, 2000;McArthur and Wignall, 2007). The rates of change of 87 Sr/ 86 Sr with stratigraphic level (see for a graphic explanation), and an Early Toarcian duration of 2.17 Ma, were used to determine zonal and subzonal durations [McArthur et al, 2000] and these durations, and the zonal and subzonal thicknesses, have been used to derive sediment accumulation rates and so approximate durations for discrete packages of sediment, such as the decimeter-thick Sulfur Bands.…”

Section: Timescalementioning

confidence: 99%

“…The linearity and slope of each regression shows that exaratum Subzone and overlying 30 cm of the falciferum Subzone of the Toarcian are stratigraphically condensed by a factor of 7 relative to underlying strata and by a factor of 12 relative to overlying strata (Figure 2) [McArthur et al, 2000;McArthur and Wignall, 2007). The rates of change of 87 Sr/ 86 Sr with stratigraphic level (see for a graphic explanation), and an Early Toarcian duration of 2.17 Ma, were used to determine zonal and subzonal durations [McArthur et al, 2000] and these durations, and the zonal and subzonal thicknesses, have been used to derive sediment accumulation rates and so approximate durations for discrete packages of sediment, such as the decimeter-thick Sulfur Bands. Such durations are tentative, and systematic uncertainty of around ±10% in the durations of the events we calculate arises simply from the range of the Lower Toarcian durations noted above (1.9 to 2.3 Ma).…”

Section: Timescalementioning

confidence: 99%

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Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

et al. 2008

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[1] Profiles of Mo/total organic carbon (TOC) through the Lower Toarcian black shales of the Cleveland Basin, Yorkshire, United Kingdom, and the Posidonia shale of Germany and Switzerland reveal water mass restriction during the interval from late tenuicostatum Zone times to early bifrons Zone times, times which include that of the putative Early Toarcian oceanic anoxic event. The degree of restriction is revealed by crossplots of Mo and TOC concentrations for the Cleveland Basin, which define two linear arrays with regression slopes (ppm/%) of 0.5 and 17. The slope of 0.5 applies to sediment from the upper semicelatum and exaratum Subzones. This value, which is one tenth of that for modern sediments from the Black Sea (Mo/TOC regression slope 4.5), reveals that water mass restriction during this interval was around 10 times more severe than in the modern Black Sea; the renewal frequency of the water mass was between 4 and 40 ka. The Mo/TOC regression slope of 17 applies to the overlying falciferum and commune subzones: the value shows that restriction in this interval was less severe and that the renewal frequency of the water mass was between 10 and 130 years. The more restricted of the two intervals has been termed the Early Toarcian oceanic anoxic event but is shown to be an event caused by basin restriction local to NW Europe. Crossplots of Re, Os, and Mo against TOC show similar trends of increasing element concentration with increase in TOC but with differing slopes. Together with modeling of 187 Os/ 188 Os and d 98 Mo, the element/TOC trends show that drawdown of Re, Os, and Mo was essentially complete during upper semicelatum and exaratum Subzone times (Mo/TOC regression slope of 0.5). Drawdown sensitized the restricted water mass to isotopic change forced by freshwater mixing so that continental inputs of Re, Os, and Mo, via a low-salinity surface layer, created isotopic excursions of up to 1.3% in d 98 Mo and up to 0.6% for 187 Os/ 188 Os. Restriction thereby compromises attempts to date Toarcian black shales, and possibly all black shales, using Re-Os chronology and introduces a confounding influence in the attempts to use d 98 Mo and initial 187 Os/ 188 Os for palaeo-oceanographic interpretation.

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“…Measurements of 8180 values performed on diagenetically screened belemnite rostra have been considered by many authors as one of the most reliable tools to be used as a proxy for calculation of seawater palaeotemperatures (Scelen et al, 1996;McArthur et al, 2000;Rosales et al, 2001a,b;Bailey et al, 2003;jenkyns, 2003;Rosales et al, 2003Rosales et al, , 2004G6mez et al, 2008).…”

Section: Stable Isotope Record and Seawater Temperaturementioning

confidence: 99%

Palaeoclimatic and biotic changes during the Aalenian (Middle Jurassic) at the southern Laurasian Seaway (Basque–Cantabrian Basin, northern Spain)

Gómez

Canales

Ureta

et al. 2009

Palaeogeography, Palaeoclimatology, Palaeoecology

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The uppermost Toarcian-lowermost 8ajocian deposits have been studied in 10 sections located in the western part of the Basque-Cantabrian Basin (northern Spain). The studied 276 successive recorded ammonite assemblages allowed detailed biostratigraphical subdivision and the correlation of the sections at the ammonite zone and subzone scale. The foraminifers were studied in 96 samples and 55 diagenetically screened belemnite rostra were analyzed for C and 0 isotope.Facies and thickness distribution of the Aalenian sediments suggest that deposition took place in a nearly symmetrical sub-basin included into an intra plate shallow platform, developed over continental crust, on which flexure was the main control responsible for subsidence and basin evolution.Noteworthy negative 613Cb�1 excursions, coinciding with seawater temperature changes, were recorded during the Bradfordensis Biochron, around the Concavum-Limitatum biochron boundary, and around the Aalenian-Bajocian boundary. A close relationship between the changes in seawater temperature and the biotic changes observed in the foraminiferal and in the ammonoids assemblages has been evidenced. During the Comptum Biochron, the 6180�1-based palaeotemperature shows a remarkable cooling interval with an average seawater temperature of 15.7 QC. This cooling favoured the immigration of species of foraminifers that thrived in platforms with colder seawater temperatures located north of the Basque-Cantabrian Basin.As a consequence, a strong increase in the diversity of the foraminiferal assemblages (28.5% of first appearances) occurred. This interval also coincides with the highest ammonoid abundance recorded during the Aalenian. A notable increase in temperature with peak values up to 24.3 QC, was measured during the Bradfordensis Biochron. This warming marks the beginning of progressive loss of foraminifer diversity and the decrease in the abundance of ammonoids. However, the increase in the relative abundances of some foraminiferal taxa such as the genus Spirillina during the warming phase is remarkable. Some of the foraminiferal species that had their last occurrence during this interval seem to be immigrants from NW Europe that arrived during the Comptum cooling interval, and that did not survive to rise of the seawater temperature.Another drop in temperature was recorded during the late Gigantea and the early Concavum biochrons.Coinciding with this cooling interval nearly 20% of the foraminiferal species disappeared while the ammonoid abundance increased. A new and significant warming episode occurred during the latest Aalenian (Limitatum Biochron), extending to the earliest Bajocian (Discites Biochron). Biotic response to this new bT of 2.5 QC is remarkable, marking one of the most important crises of the Aalenian. More than 30% of the foraminiferal species disappeared and no new appearances were recorded. Ammonoids show a decrease in the specimen abundance during the Limitatum-Discites warming, preceding a drastic decrease in the species abundance.The rem...

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Strontium isotope profile of the early Toarcian (Jurassic) oceanic anoxic event, the duration of ammonite biozones, and belemnite palaeotemperatures

Cited by 319 publications

References 58 publications

Pliensbachian–Toarcian ostracod biogeography in NW Europe: Evidence for water mass structure evolution

Pliensbachian–Toarcian ostracod biogeography in NW Europe: Evidence for water mass structure evolution

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

Palaeoclimatic and biotic changes during the Aalenian (Middle Jurassic) at the southern Laurasian Seaway (Basque–Cantabrian Basin, northern Spain)

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