The Late Ordovician glacio-eustatic record from a high-latitude storm-dominated shelf succession: The Bou Ingarf section (Anti-Atlas, Southern Morocco)

Loi, Alfredo; Ghienne, Jean‐François; Dabard, Marie‐Pierre; Paris, Florentin; Botquelen, Arnaud; Christ, Nicolas; Elaouad-Debbaj, Zohra; Gorini, A.; Vidal, Muriel; Videt, Blaise; Destombes, Jacques

doi:10.1016/j.palaeo.2010.01.018

Cited by 148 publications

(105 citation statements)

References 101 publications

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“…The Late Ordovician Hirnantian is characterized by the rapid growth of large ice sheets (e.g., Ghienne et al, 2007;Loi et al, 2010;Finnegan et al, 2011). Recent geochemical data suggest an abrupt tropical SST cooling at that time (Trotter et al, 2008;Finnegan et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…As a consequence, the duration of the glaciation is still not well constrained. Two models are still debated: a short-lived (< 2 Myr) glaciation limited to the Late Ordovician Hirnantian (445-443 Ma) (Brenchley et al, 1994(Brenchley et al, , 2003Sutcliffe et al, 2000), or a long-lived glaciation (> 20 Myr) that extended from the Late Ordovician Katian to the Silurian Wenlock, with the Hirnantian only representing the glacial maximum (Saltzman and Young, 2005;Loi et al, 2010;Finnegan et al, 2011) (Fig. 1).…”

Section: The Coupled Climate Model Foammentioning

confidence: 99%

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Effect of the Ordovician paleogeography on the (in)stability of the climate

et al. 2014

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Abstract. The Ordovician Period (485-443 Ma) is characterized by abundant evidence for continental-sized ice sheets. Modeling studies published so far require a sharp CO 2 drawdown to initiate this glaciation. They mostly used nondynamic slab mixed-layer ocean models. Here, we use a general circulation model with coupled components for ocean, atmosphere, and sea ice to examine the response of Ordovician climate to changes in CO 2 and paleogeography. We conduct experiments for a wide range of CO 2 (from 16 to 2 times the preindustrial atmospheric CO 2 level (PAL)) and for two continental configurations (at 470 and at 450 Ma) mimicking the Middle and the Late Ordovician conditions. We find that the temperature-CO 2 relationship is highly non-linear when ocean dynamics are taken into account. Two climatic modes are simulated as radiative forcing decreases. For high CO 2 concentrations (≥ 12 PAL at 470 Ma and ≥ 8 PAL at 450 Ma), a relative hot climate with no sea ice characterizes the warm mode. When CO 2 is decreased to 8 PAL and 6 PAL at 470 and 450 Ma, a tipping point is crossed and climate abruptly enters a runaway icehouse leading to a cold mode marked by the extension of the sea ice cover down to the midlatitudes. At 450 Ma, the transition from the warm to the cold mode is reached for a decrease in atmospheric CO 2 from 8 to 6 PAL and induces a ∼ 9 • C global cooling. We show that the tipping point is due to the existence of a 95 % oceanic Northern Hemisphere, which in turn induces a minimum in oceanic heat transport located around 40 • N. The latter allows sea ice to stabilize at these latitudes, explaining the potential existence of the warm and of the cold climatic modes. This major climatic instability potentially brings a new explanation to the sudden Late Ordovician Hirnantian glacial pulse that does not require any large CO 2 drawdown.

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Section: Discussionmentioning

confidence: 99%

Section: The Coupled Climate Model Foammentioning

confidence: 99%

Effect of the Ordovician paleogeography on the (in)stability of the climate

et al. 2014

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“…Some of them are usually associated with faunas of temperate latitudes in the Late Ordovician, which may suggest that their immigration may have occurred during the cooling episode before expansion of the Holorhynchus Fauna. According to Loi et al (2010, fig. 14, Sequence 4), such an event occurred in the Late, but not the latest, Katian.…”

Section: Late Katianmentioning

confidence: 99%

Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

Popov

Cocks

2017

Acta Geologica Polonica

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ABSTRACT:Popov, L.E. and Cocks, L.R.M. 2017. Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas. Acta Geologica Polonica, 67 (3), 323-380. Warszawa.Detailed biogeographical and biofacies analyses of the Late Ordovician brachiopod faunas with 160 genera, grouped into 94 faunas from individual lithotectonic units within the Kazakh Orogen strongly support an archipelago model for that time in that area. The Kazakh island arcs and microcontinents within several separate clusters were located in the tropics on both sides of the Equator. Key units, from which the Late Ordovician faunas are now well known, include the Boshchekul, Chingiz-Tarbagatai, and Chu-Ili terranes. The development of brachiopod biogeography within the nearly ten million year time span of the Late Ordovician from about 458 to 443 Ma (Sandbian, Katian, and Hirnantian), is supported by much new data, including our revised identifications from the Kazakh Orogen and elsewhere. The Kazakh archipelago was west of the Australasian segment of the Gondwana Supercontinent, and relatively near the Tarim, South China and North China continents, apart from the Atashu-Zhamshi Microcontinent, which probably occupied a relatively isolated position on the south-western margin of the archipelago. Distinct faunal signatures indicate that the Kazakh terranes were far away from Baltica and Siberia throughout the Ordovician. Although some earlier terranes had joined each other before the Middle Ordovician, the amalgamation of Kazakh terranes into the single continent of Kazakhstania by the end of the Ordovician is very unlikely. The Late Ordovician brachiopods from the other continents are also compared with the Kazakh faunas and global provincialisation statistically determined.

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“…2), upper Kralodvorian (global upper Katian,Ka4). For further information on the stratigraphy and locality see Loi et al (2010).…”

Section: Geographical and Geological Settings Of Materialsmentioning

confidence: 99%

The illaenid trilobites Vysocania (Vaněk & Vokáč, 1997) and Octillaenus (Barrande, 1846) from the Upper Ordovician of the Czech Republic, Portugal, Spain and Morocco

Pereira¹,

Silva²,

Sá³

et al. 2017

Bull. Geosci.

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The illaenid trilobite Vysocania is widely represented in the Upper Ordovician of the Czech Republic, Portugal and Spain, and is one of the most characteristic taxa in the high-latitude peri-Gondwana palaeobiogeographical region to which it is endemic. Three species of the genus that were formerly assigned to Stenopareia and Zetillaenus, from the Czech Republic and Spain respectively, are herein revised, and a new species is described from the Czech Republic. The genus Octillaenus, of which a new species is described from the Upper Ordovician of Morocco, is considered to have arisen from Vysocania through paedomorphic (neotenic) processes. The relationships between Vysocania, Octillaenus, Stenopareia and Zetillaenus are reviewed and the criteria used in the definition of these taxa discussed. Species assigned to Vysocania are V. vaneki (type-species), V. iberica, V. moraveci sp. nov. and V. panderi; species assigned to Octillaenus are O. hisingeri (type-species) and O. marocanus sp. nov. Vysocania appears for the first time in the lower Berounian (Sandbian) and has its last undoubted record in the upper Berounian (upper Katian); Octillaenus is presently restricted to the Kralodvorian (upper Katian).•

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The Late Ordovician glacio-eustatic record from a high-latitude storm-dominated shelf succession: The Bou Ingarf section (Anti-Atlas, Southern Morocco)

Cited by 148 publications

References 101 publications

Effect of the Ordovician paleogeography on the (in)stability of the climate

Effect of the Ordovician paleogeography on the (in)stability of the climate

Late Ordovician palaeogeography and the positions of the Kazakh terranes through analysis of their brachiopod faunas

The illaenid trilobites Vysocania (Vaněk & Vokáč, 1997) and Octillaenus (Barrande, 1846) from the Upper Ordovician of the Czech Republic, Portugal, Spain and Morocco

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