Emplacement of the Cleveland Dyke: Evidence from Geochemistry, Mineralogy, and Physical Modelling

Macdonald, Ray; Wilson, Lionel; Thorpe, R. S.; Martin, Andrew J.

doi:10.1093/petrology/29.3.559

Cited by 56 publications

(55 citation statements)

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“…MacGregor (1930; suggested that the sections may form a single, unified dyke but he identified a third section in order to explain the behaviour of the dyke near the Southern Upland Fault. These three sections have become referred to as the Stevenston-Coylton, New Cumnock and Cleveland dykes, respectively (MacDonald et al, 1988). The Stevenston-Coylton section, which crosses the Midland Valley, is shown on the 1:50 000 geological map (British Geological Survey, 2005) as the Cumbrae-Stevenston Dyke (Monro, 1999) (Fig.…”

Section: Trace Of the Clevelend Dykementioning

confidence: 99%

A new high-resolution aeromagnetic dataset over central Ayrshire: insights into the concealed geology

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Akhurst

Walker

2009

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Section: Trace Of the Clevelend Dykementioning

confidence: 99%

A new high-resolution aeromagnetic dataset over central Ayrshire: insights into the concealed geology

Busby

Akhurst

Walker

2009

SJG

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“…Theoretical studies of emplacements of dykes indicate that magma flow distances of about 5 000 km can be achieved without freezing of magma, assuming normal dyke widths of >10 m and moderate magma overpressure and a topographically high source magma chamber (such as within up-domed crust above a rising mantle plume) (Macdonald et al 1988;Fialko & Rubin 1999). The 200 000 km 3 volume of magma represented by the Ferrar LIP was certainly to large to have been held in one magma chamber at one time, and batches of magma must have repeatedly been expelled from one or more compositionally similar magma chambers.…”

Section: Transport Mechanisms and Geochemical Relationshipsmentioning

confidence: 99%

On the long-distance transport of Ferrar magmas

Leat

2008

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Abstract:The distribution and geochemical relationships of the Early Jurassic Ferrar large igneous province (LIP) are examined and it is concluded that they support the lateral flow model for the emplacement of the province, with a source along the strongly magmatic Early Jurassic Antarctica-Africa rifted margin. Published data and new analyses from the Pensacola Range are used to show that the dominant magma type in the Ferrar, the Mount Fazio chemical type (MFCT) occurs in the Theron Mountains, Shackleton Range, Whichaway Nunataks, Pensacola Mountains (all Antarctica), and South Africa, as well as well-known outcrops in Victoria Land, Antarctica, southeast Australia and New Zealand. Chemical compositions are shown to be somewhat varied, but similar enough for them to be considered as representing closely related magmas. Examination of geochemical trends with distance from the interpreted magma source indicates that Mg# and MgO abundances decline with distance travelled, and it is argued that this is consistent with the lateral flow model. The Scarab Peak chemical type (SPCT) occurs as sills in the Theron Mountains and Whichaway Nunataks, and as lavas in Victoria Land, is geochemically very homogeneous. Despite this, Mg#, MgO, Ti/Y and Ti/Zr all fall with distance from the interpreted source, consistent with fractional crystallisation occurring during the lateral flow of the magmas. Flow took place in dykes or (more likely) sills. No feeder dyke swarm has been identified. The distances flowed, at least 4 100 km for MFCT and 3 700 km for SPCT are the longest interpreted lateral magma flows on Earth.End of abstract

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“…Many regional dykes in Iceland and Britain (Macdonald et al 1988) and elsewhere are discontinuous in lateral sections, and commonly offset by large distances relative to their thickness. Such dykes are usually longer at depth than nearer the surface, and also become thinner with depth, with a roughly Y-shaped geometry (Gudmundsson 1990;Ernst et al 1995;Fig.…”

Section: Thermal Erosionmentioning

confidence: 99%

Structure and emplacement of the Nandurbar–Dhule mafic dyke swarm, Deccan Traps, and the tectonomagmatic evolution of flood basalts

2006

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Flood basalts, such as the Deccan Traps of India, represent huge, typically fissure-fed volcanic provinces. We discuss the structural attributes and emplacement mechanics of a large, linear, tholeiitic dyke swarm exposed in the Nandurbar-Dhule area of the Deccan province. The swarm contains 210 dykes of dolerite and basalt >1 km in length, exposed over an area of 14,500 km 2 . The dykes intrude an exclusively basaltic lava pile, largely composed of highly weathered and zeolitized compound pahoehoe flows. The dykes range in length from <1 km to 79 km, and in thickness from 3 to 62 m. Almost all dykes are vertical, with the others nearly so. They show a strong preferred orientation, with a mean strike of N88°. Because they are not emplaced along faults or fractures, they indicate the regional minimum horizontal compressive stress (σ 3 ) to have been aligned ∼N-S during swarm emplacement. The dykes have a negative power law length distribution but an irregular thickness distribution; the latter is uncommon among the other dyke swarms described worldwide. Dyke length is not correlated with dyke width. Using the aspect ratios (length/thickness) of several dykes, we calculate magmatic overpressures required for dyke emplacement, and depths to source magma chambers that are consistent with results of previous petrological and gravity modelling. The anomalously high source depths calculated for a few dykes may be an artifact of underestimated aspect ratios due to incomplete along-strike exposure. However, thermal erosion is a mechanism that can also explain this. Whereas several of the Nandurbar-Dhule dykes may be vertically injected dykes from shallow magma chambers, others, particularly the long ones, must have been formed by lateral injection from such chambers. The larger dykes could well have fed substantial (≥1,000 km 3 ) and quickly emplaced (a few years) flood basalt lava flows. This work highlights some interesting and significant similarities, and contrasts, between the Nandurbar-Dhule dyke swarm and regional tholeiitic dyke swarms in Iceland, Sudan, and elsewhere.

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Emplacement of the Cleveland Dyke: Evidence from Geochemistry, Mineralogy, and Physical Modelling

Cited by 56 publications

References 0 publications

A new high-resolution aeromagnetic dataset over central Ayrshire: insights into the concealed geology

A new high-resolution aeromagnetic dataset over central Ayrshire: insights into the concealed geology

On the long-distance transport of Ferrar magmas

Structure and emplacement of the Nandurbar–Dhule mafic dyke swarm, Deccan Traps, and the tectonomagmatic evolution of flood basalts

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