Drawing the line: the history of the Jurassic—Cretaceous boundary

Cope, John C. W.

doi:10.1016/s0016-7878(08)80262-3

Cited by 25 publications

(8 citation statements)

References 27 publications

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“…Evidence from fossil data (e.g. Hughes, 1955; Stewart, 1978; Batten, 1982; Morter, 1984; Parkes, 1993; Feist, Lake & Wood, 1995; Horne, 1995; Jarzembowski, 1995; Goldring, Pollard & Radley, 2005; Cope, 2008; Naish & Sweetman, 2011) including work on vertebrate and invertebrate biostratigraphy (e.g. dinosaurs, charophytes, ammonites, molluscs, ostracods, insects), trace fossils and palynology have presented interpretations of the palaeo- and depositional environments similar to the ones presented in this study.…”

Section: Discussionmentioning

confidence: 99%

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

Akinlotan

2017

Geol. Mag.

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The Lower Cretaceous Wealden sideritic ironstones have a wide occurrence and great potential to aid the reconstruction of the depositional environments of the Weald Basin in SE England. However, mineralogical and geochemical datasets on the ironstones are scarce in the literature. Geochemical and mineralogical data on the sideritic ironstones are presented from the Wadhurst Clay Formation within the Weald Basin. The mineralogy of the ironstones was examined using a PANalytical X'Pert Pro X-ray diffractometer and PANalytical's HighScore Plus software. Elemental composition of the ironstones was measured using a PANalytical MiniPal2 ED-XRF (benchtop X-ray spectrometer). The examination of the mineralogy of the Wealden ironstones confirms the presence of early diagenetic siderites. The trace-element assemblage shows that the sideritic ironstones are chemically pure pointing to a freshwater origin. The sideritic ironstones reveal anoxic conditions and palaeo-salinity in the basin. More generally, it is suggested that the composition of the host rocks has significant controls on the composition of sideritic ironstones in sedimentary basins. This work reinforces the importance of the composition of sideritic ironstones as useful non-traditional data for understanding the depositional settings of sedimentary basins, especially when traditional datasets are not readily available or insufficient.

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Section: Discussionmentioning

confidence: 99%

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

Akinlotan

2017

Geol. Mag.

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“…Kirkaldy, , ; Worssam, ; Allen, , ; Stewart, , b, ; Lake and Shephard‐Thorn, ) and fossil data (e.g. Hughes, ; Stewart, ; Batten, ; Morter, ; Parkes, ; Feist et al ., ; Horne, ; Jarzembowski, ; Cope, ; Naish and Sweetman, ). Work on fossils which used vertebrate and invertebrate biostratigraphy (e.g.…”

Section: Introductionmentioning

confidence: 99%

Multi‐proxy approach to palaeoenvironmental modelling: the English Lower Cretaceous Weald Basin

Akinlotan

2017

Geological Journal

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Palaeoenvironmental reconstructions of the Wealden (Lower Cretaceous) in southeast England have been previously based mainly on field and fossil data. This study presents new interpretations of multi-proxy data sets such as sandstone petrography, elemental geochemistry and sideritic ironstones, supplemented by outcrop and clay mineralogical data. The dominance of quartz arenites, kaolinite and thorium and the presence of Zr in the sediments suggest that they were sourced mainly from granitic and/or gneissic rocks. Materials from metamorphic sources are secondary in abundance. The mineral and textural maturity of the sediments coupled with inferred short transport distances suggests reworking from older sources. Palaeoclimatic conditions in the source areas were generally warm and humid in nature, which supported an intensive weathering regime. The nature of the sediments suggests they may have been sourced directly or indirectly from a stable craton. The lithology, facies, sedimentary structures, architecture and gamma ray data confirm the freshwater origin of the sediments. Redox-sensitive trace elements such as Mo, U, V and Co suggest anoxic conditions in the basin. The results presented in this paper reinforce the importance of integrating multi-proxy data sets for interpreting the palaeoenvironmental conditions of sedimentary basins: when traditional data sets such as field and fossil data are not readily available or insufficient to enable adequate interpretations, the integration of petrographic, mineralogical and geochemical data sets may prove to be useful in similar palaeoenvironmental studies.

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“…The site exposes a 27 m thick succession of Portland Limestone, which is overlain by basal beds of the Purbeck Limestone Group (Lulworth Formation) ( Benton, Cook & Hooker, 2005 ; Wimbledon, 1976 ). The rocks are attributed to the latter part of the Tithonian Stage (Jurassic Period), known locally as Portlandian ( Wright & Cox, 2001 ; Benton, Cook & Hooker, 2005 ; Cope, 2008 ), which approximates to an age of between 145 and 152 million years. The stratigraphy of the quarry was described in detail and the succession was correlated with other Portlandian sequences in the UK by Wimbledon (1976) and Wimbledon (1980) .…”

Section: Methodsmentioning

confidence: 99%

X-ray Synchrotron Microtomography of a silicified Jurassic Cheirolepidiaceae (Conifer) cone: histology and morphology ofPararaucaria collinsonaesp. nov.

Steart

Spencer

Garwood

et al. 2014

PeerJ

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We document a new species of ovulate cone (Pararaucaria collinsonae) on the basis of silicified fossils from the Late Jurassic Purbeck Limestone Group of southern England (Tithonian Stage: ca. 145 million years). Our description principally relies on the anatomy of the ovuliferous scales, revealed through X-ray synchrotron microtomography (SRXMT) performed at the Diamond Light Source (UK). This study represents the first application of SRXMT to macro-scale silicified plant fossils, and demonstrates the significant advantages of this approach, which can resolve cellular structure over lab-based X-ray computed microtomography (XMT). The method enabled us to characterize tissues and precisely demarcate their boundaries, elucidating organ shape, and thus allowing an accurate assessment of affinities. The cones are broadly spherical (ca. 1.3 cm diameter), and are structured around a central axis with helically arranged bract/scale complexes, each of which bares a single ovule. A three-lobed ovuliferous scale and ovules enclosed within pocket-forming tissue, demonstrate an affinity with Cheirolepidiaceae. Details of vascular sclerenchyma bundles, integument structure, and the number and attachment of the ovules indicate greatest similarity to P. patagonica and P. carrii. This fossil develops our understanding of the dominant tree element of the Purbeck Fossil Forest, providing the first evidence for ovulate cheirolepidiaceous cones in Europe. Alongside recent discoveries in North America, this significantly extends the known palaeogeographic range of Pararaucaria, supporting a mid-palaeolatitudinal distribution in both Gondwana and Laurasia during the Late Jurassic. Palaeoclimatic interpretations derived from contemporaneous floras, climate sensitive sediments, and general circulation climate models indicate that Pararaucaria was a constituent of low diversity floras in semi-arid Mediterranean-type environments.

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Drawing the line: the history of the Jurassic—Cretaceous boundary

Cited by 25 publications

References 27 publications

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

Multi‐proxy approach to palaeoenvironmental modelling: the English Lower Cretaceous Weald Basin

X-ray Synchrotron Microtomography of a silicified Jurassic Cheirolepidiaceae (Conifer) cone: histology and morphology ofPararaucaria collinsonaesp. nov.

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