Exploring a link between the Middle Eocene Climatic Optimum and Neotethys continental arc flare-up

Abstract. The Middle Eocene Climatic Optimum (MECO), a ∼500 kyr episode of global warming that initiated at ∼ 40.5 Ma, is postulated to be driven by a net increase in volcanic carbon input, but a direct source has not been identified. Here we show, based on new and previously published radiometric ages of volcanic rocks, that the interval spanning the MECO corresponds to a massive increase in continental arc volcanism in Iran and Azerbaijan. Ages of Eocene igneous rocks in all volcanic provinces of Iran cluster around 40 Ma, very close to the peak warming phase of the MECO. Based on the spatial extent and volume of the volcanic rocks as well as the carbonaceous lithology in which they are emplaced, we estimate the total amount of CO2 that could have been released at this time corresponds to between 1052 and 12 565 Pg carbon. This is compatible with the estimated carbon release during the MECO. Although the uncertainty in both individual ages, and the spread in the compilation of ages, is larger than the duration of the MECO, a flare-up in Neotethys subduction zone volcanism represents a plausible excess carbon source responsible for MECO warming.

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Exploring a link between the Middle Eocene Climatic Optimum and Neotethys continental arc flare-up

10.5194/cp-2020-48 ◽

2020 ◽

Author(s):

Annique van der Boon ◽

Klaudia F. Kuiper ◽

Robin van der Ploeg ◽

Margot J. Cramwinckel ◽

Maryam Honarmand ◽

...

Keyword(s):

Global Warming ◽

Carbon Source ◽

Middle Eocene ◽

Volcanic Rocks ◽

Excess Carbon ◽

Arc Volcanism ◽

Continental Arc ◽

Carbon Release ◽

Climatic Optimum ◽

Radiometric Ages

Abstract. The Middle Eocene Climatic Optimum (MECO), a ~500 kyr episode of global warming that initiated at ~40.5 Ma, is postulated to be driven by a net increase in volcanic carbon input, but a direct source has not been identified. Here we show, based on new and previously published radiometric ages of volcanic rocks, that the interval spanning the MECO corresponds to a massive increase in continental arc volcanism in Iran and Azerbaijan. Ages of Eocene extrusive volcanic rocks in all volcanic provinces in Iran cluster around 40 Ma, very close to the peak warming phase of the MECO. Based on the spatial extent and volume of the volcanic rocks as well as the carbonaceous lithology in which they are emplaced, we estimate the total amount of CO2 that could have been released at this time corresponds to between 1500 and 11 300 Pg carbon. This is compatible with the estimated carbon release during the MECO. Although the uncertainty in both individual ages, and the spread in the compilation of ages, is larger than the duration of the MECO, a flare-up in Neotethys subduction zone volcanism represents a plausible excess carbon source responsible for MECO warming.

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Lower Palaeozoic and Precambrian igneous rocks from eastern England, and their bearing on late Ordovician closure of the Tornquist Sea: constraints from U-Pb and Nd isotopes

Geological Magazine ◽

10.1017/s0016756800023190 ◽

1993 ◽

Vol 130 (6) ◽

pp. 835-846 ◽

Cited By ~ 80

Author(s):

S. R. Noble ◽

R. D. Tucker ◽

T. C. Pharaoh

Keyword(s):

Volcanic Rocks ◽

Igneous Rocks ◽

Calc Alkaline ◽

Nd Isotopes ◽

Nd Isotope ◽

Magmatic Arc ◽

The North ◽

Basement Rocks ◽

Continental Arc ◽

Lower Palaeozoic

AbstractThe U-Pb isotope ages and Nd isotope characteristics of asuite of igneous rocks from the basement of eastern England show that Ordovician calc-alkaline igneous rocks are tectonically interleaved with late Precambrian volcanic rocks distinct from Precambrian rocks exposed in southern Britain. New U-Pb ages for the North Creake tuff (zircon, 449±13 Ma), Moorby Microgranite (zircon, 457 ± 20 Ma), and the Nuneaton lamprophyre (zircon and baddeleyite, 442 ± 3 Ma) confirm the presence ofan Ordovician magmatic arc. Tectonically interleaved Precambrian volcanic rocks within this arc are verified by new U-Pb zircon ages for tuffs at Glinton (612 ± 21 Ma) and Orton (616 ± 6 Ma). Initial εNd values for these basement rocks range from +4 to - 6, consistent with generation of both c. 615 Ma and c. 450 Ma groups of rocksin continental arc settings. The U-Pb and Sm-Nd isotope data support arguments for an Ordovician fold/thrust belt extending from England to Belgium, and that the Ordovician calc-alkaline rocks formed in response to subductionof Tornquist Sea oceanic crust beneath Avalonia.

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An Eocene brontothere and tillodonts (Mammalia) from British Columbia, and their paleoenvironments

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2017-0061 ◽

2017 ◽

Vol 54 (9) ◽

pp. 981-992 ◽

Cited By ~ 2

Author(s):

Jaelyn J. Eberle ◽

David R. Greenwood

Keyword(s):

British Columbia ◽

Middle Eocene ◽

Volcanic Rocks ◽

Open Water ◽

Late Eocene ◽

Mean Annual Precipitation ◽

Mean Annual Temperature ◽

Forested Landscapes ◽

Radiometric Ages ◽

Age Range

We describe Eocene fossils of the tillodont Trogosus from the Allenby Formation in Princeton, British Columbia (B.C.), as well as teeth of Brontotheriina from the lower Australian Creek Formation near Quesnel, B.C. These fossils represent the only occurrence of Tillodontia and Brontotheriidae in B.C. Further, the presence of the largest species of Trogosus — T. latidens — as well as a smaller species identified only as Trogosus sp. supports a late early – early middle Eocene (Bridgerian) age for the Vermilion Bluffs Shale of the Allenby Formation. Based on their morphology and large size, the teeth referred here to Brontotheriina represent one of the larger, more derived brontothere genera, and suggest a Uintan–Chadronian (middle–late Eocene) age range for the lower Australian Creek Formation that is consistent with radiometric ages of underlying volcanic rocks. Paleobotanical data from sediments correlative to those that produced these Eocene mammal fossils suggest they inhabited forested landscapes interspersed with swamps and open water environments, under mild and wet temperate climates (mean annual temperature (MAT) ∼10–16 °C; cold month mean temperature (CMMT) −4–4 °C; mean annual precipitation (MAP) >100 cm/year). These mixed conifer–broadleaf forests included tree genera typical of modern eastern North American forests (e.g., Tsuga, Acer, Fagus, and Sassafras), together with genera today restricted to east Asia (e.g., Metasequoia, Cercidiphyllum, Dipteronia, and Pterocarya). The paleobotanical evidence is consistent with the hypothesized habitats of both tillodonts and brontotheres.

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Supplementary material to "Exploring a link between the Middle Eocene Climatic Optimum and Neotethys continental arc flare-up"

10.5194/cp-2020-48-supplement ◽

2020 ◽

Author(s):

Annique van der Boon ◽

Klaudia F. Kuiper ◽

Robin van der Ploeg ◽

Margot J. Cramwinckel ◽

Maryam Honarmand ◽

...

Keyword(s):

Middle Eocene ◽

Continental Arc ◽

Supplementary Material ◽

Climatic Optimum

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Different sources involved in generation of continental arc volcanism: The Carboniferous–Permian volcanic rocks in the northern margin of the North China block

Lithos ◽

10.1016/j.lithos.2015.11.027 ◽

2016 ◽

Vol 240-243 ◽

pp. 382-401 ◽

Cited By ~ 52

Author(s):

Shuan-Hong Zhang ◽

Yue Zhao ◽

Jian-Min Liu ◽

Zhao-Chu Hu

Keyword(s):

North China ◽

Volcanic Rocks ◽

North China Block ◽

Arc Volcanism ◽

Northern Margin ◽

The North ◽

Continental Arc ◽

Different Sources

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Silurian and late Ordovician K-bentonites as a record of late Caledonian volcanism in the British Isles

Transactions of the Royal Society of Edinburgh Earth Sciences ◽

10.1017/s0263593300002212 ◽

1995 ◽

Vol 86 (3) ◽

pp. 167-180 ◽

Cited By ~ 16

Author(s):

N. J. Fortey ◽

R. J. Merriman ◽

W. D. Huff

Keyword(s):

Trace Element ◽

Function Analysis ◽

Volcanic Rocks ◽

Late Ordovician ◽

Trace Element Geochemistry ◽

British Isles ◽

Element Geochemistry ◽

Arc Volcanism ◽

Iapetus Ocean ◽

Continental Arc

AbstractSilurian and late Ordovician K-bentonites of the British Isles provide a record of prolonged volcanism during the convergence of terranes associated with closure of the Iapetus and Tornquist Oceans. In the Southern Uplands–Longford-Down and Midland Valley terranes, they range from late Caradoc to Telychian, withfurther early Homerian occurrences. South of the Iapetus suture, in Eastern Avalonia, the range is Hirnantianto early Ludlow in northern England and early Telychian to earliest Ludfordian in the Welsh Borderland and English Midlands. In both cases, the distributions indicate that volcanism was more long-lived and probably more extensive than is depicted in current plate tectonic reconstructions. Average intervals between K-bentonites are estimated, based on Harland et al. (1990), as: c. 65000 years at Dob's Linn (late Aeronian to early Telychian); c. 39000 years in the Cautley area (Telychian); c. 51000 years in a borehole at Walsall (late Llandovery to Sheinwoodian). Trace element geochemistry suggests mostly subalkaline dacitic to rhyolitic magmas in which LILE-enrichment accompanies variable enrichment in crustally derived elements (Ta, Nb). The geochemistry suggests comparison with continental arc volcanism of ‘withinplate, attenuated lithosphere’ character. Ta–Nb enrichment and an absence of Eu anomalies from REE profiles are consistently present northof the Iapetus suture, but trace element patterns are less consistent south of the suture where negative Eu anomalies are generally present. Discriminant function analysis successfully distinguishes Llandovery, Wenlockand Ludlow K-bentonites from south of the Iapetus suture, and Llandovery K-bentonites from north and south ofthe suture. Those from north of the Iapetus suture probably originated in volcanism along the southern marginof Laurentia before final closure of the Iapetus Ocean. Those from south of the suture may have been derived from volcanism associated with late destruction of Iapetus and Tornquist oceanic crust, although an alternative involving volcanism at the southern margin of Eastern Avalonia or Baltica may accord better with the distribution of K-bentonites and the geographical trend of the fragmentary outcrops of Silurian volcanic rocks from southern Ireland to Belgium.

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Warming, pelagic food webs and deep-sea biota during the Middle Eocene Climatic Optimum in the SE Atlantic (ODP Site 1263)

Rendiconti online della Società Geologica Italiana ◽

10.3301/rol.2014.33 ◽

2014 ◽

Vol 31 ◽

pp. 36-37

Author(s):

Flavia Boscolo Galazzo

Keyword(s):

Food Webs ◽

Deep Sea ◽

Middle Eocene ◽

Pelagic Food Webs ◽

Climatic Optimum

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Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v176.5064 ◽

1997 ◽

pp. 66-74

Author(s):

Henrik Stendal ◽

Wulf Mueller ◽

Nicolai Birkedal ◽

Esben I. Hansen ◽

Claus Østergaard

Keyword(s):

Mineral Exploration ◽

Volcanic Rocks ◽

Shear Zones ◽

Field Work ◽

Igneous Rocks ◽

Border Zone ◽

The South ◽

East Greenland ◽

North West ◽

Arc Setting

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stendal, H., Mueller, W., Birkedal, N., Hansen, E. I., & Østergaard, C. (1997). Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 66-74. https://doi.org/10.34194/ggub.v176.5064 _______________ The multidisciplinary SUPRASYD project (1992–96) focused on a regional investigation of the Palaeoproterozoic Ketilidian orogenic belt which crosses the southern tip of Greenland. Apart from a broad range of geological and structural studies (Nielsen et al., 1993; Garde & Schønwandt, 1994, 1995; Garde et al., 1997), the project included a mineral resource evaluation of the supracrustal sequences associated with the Ketilidian orogen (e.g. Mosher, 1995). The Ketilidian orogen of southern Greenland can be divided from north-west to south-east into: (1) a border zone in which the crystalline rocks of the Archaean craton are unconformably overlain by Ketilidian supracrustal rocks; (2) a major polyphase pluton, referred to as the Julianehåb batholith; and (3) extensive areas of Ketilidian supracrustal rocks, divided into psammitic and pelitic rocks with subordinate interstratified mafic volcanic rocks (Fig. 1). The Julianehåb batholith is viewed as emplaced in a magmatic arc setting; the supracrustal sequences south of the batholith have been interpreted as either (1) deposited in an intra-arc and fore-arc basin (Chadwick & Garde, 1996), or (2) deposited in a back-arc or intra-arc setting (Stendal & Swager, 1995; Swager, 1995). Both possibilities are plausible and infer subduction-related processes. Regional compilations of geological, geochemical and geophysical data for southern Greenland have been presented by Thorning et al. (1994). Mosher (1995) has recently reviewed the mineral exploration potential of the region. The commercial company Nunaoil A/S has been engaged in gold prospecting in South Greenland since 1990 (e.g. Gowen et al., 1993). A principal goal of the SUPRASYD project was to test the mineral potential of the Ketilidian supracrustal sequences and define the gold potential in the shear zones in the Julianehåb batholith. Previous work has substantiated a gold potential in amphibolitic rocks in the south-west coastal areas (Gowen et al., 1993.), and in the amphibolitic rocks of the Kutseq area (Swager et al., 1995). Field work in 1996 was focused on prospective gold-bearing sites in mafic rocks in South-East Greenland. Three M.Sc. students mapped showings under the supervision of the H. S., while an area on the south side of Kangerluluk fjord was mapped by H. S. and W. M. (Fig. 4).

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