The geochemistry of Jurassic dolerites from Portal Peak, Antarctica

Hergt, Janet; Chappell, B. W.; Faure, Gunter; Mensing, Teresa M.

doi:10.1007/bf00373722

Cited by 68 publications

(42 citation statements)

References 29 publications

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“…We propose that, like their allies the lamproites, Group A calc-alkaline lamprophyres were generated by partial melting of such an enriched subcontinental mechanical boundary layer. It Staudigel et al 1984) and the Ferrar magmatic province (Hergt et al 1989;Hergt, Peat & Hawkesworth, 1991). Symbols as in Figure 6.…”

Section: Discussionmentioning

confidence: 96%

Basement geology and Palaeozoic–Mesozoic mafic dykes from the Cape Meredith Complex, Falkland Islands: a record of repeated intracontinental extension

et al. 1997

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Mafic dykes (Groups A–D) intruded into Mesoproterozoic basement amphibolites, gneisses, and granitoids of the Cape Meredith Complex on the southern tip of West Falkland, provide an important record of at least three periods of lithospheric extension during Palaeozoic and Jurassic times. Group A dykes are calc-alkaline lamprophyres that were generated by partial melting of an enriched subcontinental lithospheric mantle in Cambro-Ordovician times. Group B dykes are Ordovician dolerites derived from an asthenospheric mantle source, perhaps during the same extensional episode as Group A dykes. Group C dykes were also derived from an asthenospheric source and are possibly of Silurian age. The youngest, Group D, dykes are part of the widespread Jurassic Gondwana province. This group contains an oceanic island basalt-like sample and an enriched sample similar to both Group A lamprophyres and to the Jurassic Ferrar province in Antarctica. These correlations have interesting implications for the composition and evolution of mantle sources through time; the co-existence of Cambrian lamprophyres and Jurassic Ferrar-type magmas in the Cape Meredith Complex demonstrate for the first time that the enriched lithospheric mantle source postulated for the Ferrar magmas existed as far back as Cambrian times.

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Section: Discussionmentioning

confidence: 96%

Basement geology and Palaeozoic–Mesozoic mafic dykes from the Cape Meredith Complex, Falkland Islands: a record of repeated intracontinental extension

et al. 1997

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“…This homogeneity is evident whether comparisons are made between lavas or sills in one location, or compositions are compared across the province as a whole. This feature of the province was noted by Kyle (1980), Kyle et al (1983), Hergt et al (1989bHergt et al ( , 1991, Fleming et al (1992Fleming et al ( , 1995 and Hergt & Brauns (2001). The one significant exception to this is the chemical division of the Ferrar LIP into two chemical groups, as discussed below.…”

mentioning

confidence: 76%

“…The sills and lavas are compositionally very close. εSr 183 values for both are in the range 61-109, and εNd 183 values range from -3.2 to -5.8 (Hergt et al 1989b;Fleming et al 1995: Molzahn et al 1996Elliot et al 1999). As outlined above, the sills belong to the MFCT group, whereas both SPCT overlies MFCT chemical groups occur in the lavas -with SPCT always overlying MFCT in the lava succession (Fleming et al 1992(Fleming et al , 1995Elliot et al 1999;Elliot & Fleming 2004).…”

Section: Victoria Landmentioning

confidence: 98%

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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“…No plagioclase compositional data are available. The sill composition is essentially uniform with height (Hergt et al 1989;Faure and Mensing 2010). The principal exception is the lower chilled margin, which has low concentrations of SiO 2 , MgO, Na 2 O and CaO, while Al 2 O 3 and H 2 O + are unusually high.…”

Section: The Portal Peak Sillmentioning

confidence: 96%

The effect of crystallization time on plagioclase grain shape in dolerites

Holness

2014

Contrib Mineral Petrol

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The geochemistry of Jurassic dolerites from Portal Peak, Antarctica

Cited by 68 publications

References 29 publications

Basement geology and Palaeozoic–Mesozoic mafic dykes from the Cape Meredith Complex, Falkland Islands: a record of repeated intracontinental extension

Basement geology and Palaeozoic–Mesozoic mafic dykes from the Cape Meredith Complex, Falkland Islands: a record of repeated intracontinental extension

On the long-distance transport of Ferrar magmas

The effect of crystallization time on plagioclase grain shape in dolerites

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