Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic.
Stephen P. Hesselbo
(1)
,
Aisha Al-Suwaidi
(2)
,
Sarah J. Baker
(3)
,
Giorgia Ballabio
(4)
,
Claire M. Belcher
(3)
,
Andrew Bond
(5)
,
Ian Boomer
(6)
,
Remco Bos
(7)
,
Christian J. Bjerrum
(8)
,
Kara Bogus
(1)
,
Richard Boyle
(3)
,
James V. Browning
(9)
,
Alan R. Butcher
(10)
,
Daniel J. Condon
(11)
,
Philip Copestake
(12)
,
Stuart Daines
(3)
,
Christopher Dalby
(1)
,
Magret Damaschke
(11)
,
Susana E. Damborenea
(13)
,
Jean-Francois Deconinck
(14)
,
Alexander J. Dickson
(5)
,
Isabel M. Fendley
(15)
,
Calum P. Fox
(16)
,
Angela Fraguas
(17)
,
Joost Frieling
(15)
,
Thomas A. Gibson
(1)
,
Tianchen He
(18)
,
Kat Hickey
(1)
,
Linda A. Hinnov
(19)
,
Teuntje P. Hollaar
(1, 3)
,
Chunju Huang
(20)
,
Alexander J.L. Hudson
(1)
,
Hugh C. Jenkyns
(15)
,
Erdem Idiz
(15)
,
Mengjie Jiang
(1)
,
Wout Krijgsman
(7)
,
Christoph Korte
(8)
,
Melanie J. Leng
(11)
,
Timothy M. Lenton
(3)
,
Katharina Leu
(21)
,
Crispin T.S. Little
(22)
,
Conall Macniocaill
(15)
,
Miguel P. Manceñido
(13)
,
Tamsin A. Mather
(15)
,
Emanuela Mattioli
(23, 24)
,
Kenneth G. Miller
(9)
,
Robert J. Newton
(23)
,
Kevin N. Page
(1)
,
József Pálfy
(25, 26)
,
Gregory Pieńkowski
(27)
,
Richard J. Porter
(1)
,
Simon W. Poulton
(22)
,
Alberto C. Riccardi
(13)
,
James B. Riding
(11)
,
Ailsa Roper
(22)
,
Micha Ruhl
(4)
,
Ricardo L. Silva
(28)
,
Marisa S. Storm
(29)
,
Guillaume Suan
(23)
,
Dominika Szűcs
(1)
,
Nicolas Thibault
(8)
,
Alfred Uchman
(30)
,
James N. Stanley
(9)
,
Clemens V. Ullmann
(1)
,
Bas van de Schootbrugge
(7)
,
Madeleine L. Vickers
(31)
,
Sonja Wadas
(21)
,
Jessica H. Whiteside
(32)
,
Paul B. Wignall
(22)
,
Thomas Wonik
(21)
,
Weimu Xu
(4)
,
Christian Zeeden
(21)
,
Ke Zhao
(20)
1
CSM-UE -
Camborne School of Mines
2 Department of Earth Sciences
3 Department of Geography
4 iCRAG - Irish Centre for Research in Applied Geosciences [UCD]
5 Centre of Climate, Ocean and Atmosphere
6 School of Geography, Earth and Environmental Sciences [Birmingham]
7 Marine Palynology and Paleoceanography
8 IGN - Department of Geosciences and Natural Resource Management [Copenhagen]
9 Department of Earth and Planetary Sciences [Piscataway]
10 GKT - Geological Survey of Finland = Geologian tutkimuskeskus tuottaa
11 BGS - British Geological Survey
12 Merlin Energy Resources Ltd.
13 División Paleozoología Invertebrados
14 BGS - Biogéosciences [UMR 6282]
15 Department of Earth Sciences [Oxford]
16 Biogeochemistry Center
17 Departamento de Biología y Geología [Mostoles]
18 College of Oceanography
19 Department of Atmospheric, Oceanic, and Earth Sciences [Fairfax, USA]
20 State Key Laboratory of Biogeology and Environmental Geology
21 LIAG - Leibniz Institute for Applied Geophysics
22 SEE - School of Earth and Environment [Leeds]
23 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
24 IUF - Institut universitaire de France
25 Department of Geology
26 HUN-REN-MTM-ELTE Research Group of Palaeontology
27 Polish Geological Institute
28 Department of Earth Sciences
29 NIOZ - Royal Netherlands Institute for Sea Research
30 Faculty of Geography and Geology
31 CEED - Centre for Earth Evolution and Dynamics [Oslo]
32 Geology SDSU - Department of Geological Sciences [San Diego State Univ]
2 Department of Earth Sciences
3 Department of Geography
4 iCRAG - Irish Centre for Research in Applied Geosciences [UCD]
5 Centre of Climate, Ocean and Atmosphere
6 School of Geography, Earth and Environmental Sciences [Birmingham]
7 Marine Palynology and Paleoceanography
8 IGN - Department of Geosciences and Natural Resource Management [Copenhagen]
9 Department of Earth and Planetary Sciences [Piscataway]
10 GKT - Geological Survey of Finland = Geologian tutkimuskeskus tuottaa
11 BGS - British Geological Survey
12 Merlin Energy Resources Ltd.
13 División Paleozoología Invertebrados
14 BGS - Biogéosciences [UMR 6282]
15 Department of Earth Sciences [Oxford]
16 Biogeochemistry Center
17 Departamento de Biología y Geología [Mostoles]
18 College of Oceanography
19 Department of Atmospheric, Oceanic, and Earth Sciences [Fairfax, USA]
20 State Key Laboratory of Biogeology and Environmental Geology
21 LIAG - Leibniz Institute for Applied Geophysics
22 SEE - School of Earth and Environment [Leeds]
23 LGL-TPE - Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement
24 IUF - Institut universitaire de France
25 Department of Geology
26 HUN-REN-MTM-ELTE Research Group of Palaeontology
27 Polish Geological Institute
28 Department of Earth Sciences
29 NIOZ - Royal Netherlands Institute for Sea Research
30 Faculty of Geography and Geology
31 CEED - Centre for Earth Evolution and Dynamics [Oslo]
32 Geology SDSU - Department of Geological Sciences [San Diego State Univ]
Stephen P. Hesselbo
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Aisha Al-Suwaidi
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Ian Boomer
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Remco Bos
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Daniel J. Condon
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Jean-Francois Deconinck
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Joost Frieling
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Melanie J. Leng
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Katharina Leu
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Tamsin A. Mather
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Emanuela Mattioli
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Kenneth G. Miller
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Ailsa Roper
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Guillaume Suan
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Nicolas Thibault
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Clemens V. Ullmann
- Fonction : Auteur
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Madeleine L. Vickers
- Fonction : Auteur
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Sonja Wadas
- Fonction : Auteur
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- ORCID : 0000-0001-8519-1536
Weimu Xu
- Fonction : Auteur
- PersonId : 1304344
- ORCID : 0000-0002-3239-0272
Christian Zeeden
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- ORCID : 0000-0002-8617-0443
Résumé
Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.
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