Ferrar magmatic province rocks discovered in New Zealand: Implications for Mesozoic Gondwana geology

Mortimer, N.; Parkinson, David L.; Raine, J. I.; Adams, Chris J.; Graham, Ian; Oliver, P. J.; Palmer, K.

doi:10.1130/0091-7613(1995)023<0185:fmprdi>2.3.co;2

Cited by 63 publications

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“…6a), with correlatives in southern Australia and Tasmania (Brauns, 2000;Hergt et al, 2001) and New Zealand (Mortimer et al, 1995). The Ferrar belongs to a group of Jurassic magmatic provinces which also includes the Karoo (Southern Africa, with correlatives in the Weddell Sea sector of Antarctica) and the Chon Aike (South America and Antarctic Peninsula).…”

Section: -Ferrarmentioning

confidence: 99%

Mafic volcaniclastic deposits in flood basalt provinces: A review

Ross

Ukstins

McClintock

et al. 2005

Journal of Volcanology and Geothermal Research

137

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Flood volcanic provinces are assumed generally to consist exclusively of thick lavas and shallow intrusive rocks (mostly sills), with any pyroclastic rocks limited to silicic compositions. However mafic volcaniclastic deposits (MVDs) exist in many provinces, and the eruptions that formed such deposits are potentially meaningful in terms of potential atmospheric impacts and links with mass extinctions. The province where MVDs are the most voluminousthe Siberian Traps -is also the one temporally associated with the greatest Phanerozoic mass extinction. A lot remains to be learned about these deposits and eruptions before a convincing genetic link can be established, but as a first step, this contribution reviews in some detail the current knowledge on MVDs for the provinces in which they are better known, i.e. the North Atlantic Igneous Province (including Greenland, the Faeroe Islands, the British Isles, and tephra layers in the North Sea basin and vicinity), the Ontong Java plateau, the Ferrar, and the Karoo. We also provide a brief overview of what is known about MVDs in other provinces such as the Columbia River Basalts, the Afro-Arabian province, the Deccan Traps, the Siberian Traps, the Emeishan, and an Archean example from Australia. The thickest accumulations of MVDs occur in flood basalt provinces where they underlie the lava pile (Faeroes: >1 km, Ferrar province: ≥400 m, Siberian Traps: 700 m). In the Faeroes case, the great thickness of MVDs can be attributed to accumulation in a local sedimentary basin, but in the Ferrar and Siberian provinces the deposits are widespread (>3 x 10 5 km 2 for the latter). On the Ontong Java plateau over 300 m of MVDs occur in one drill hole without any overlying lavas. Where the volcaniclastic deposits are sandwiched between lavas, their thickness is much less. In most of the cases reviewed, primary MVDs are predominantly of phreatomagmatic origin, as indicated by the clast assemblage generally consisting of basaltic clasts of variable vesicularity (dominantly non-to poorly-vesicular) mixed with abundant country rock debris. The accidental lithic components often include loose quartz particles derived from poorly consolidated sandstones in underlying sedimentary basins (East Greenland, Ferrar, Karoo). These underlying sediments or sedimentary rocks were not only a source for debris but also aquifers that supplied water to fuel phreatomagmatic activity. In the Paraná-Etendeka, by contrast, the climate was apparently very dry when the lavas were emplaced (aeolian sand dunes) and no MVDs are reported. Volcanic vents filled with mafic volcaniclastic material, a few tens of metres to about 5 km across, are documented in several provinces (Deccan, North Atlantic, Ferrar, Karoo); they are though to have been excavated in relatively soft country rocks (rarely in flood lavas) by phreatomagmatic activity in a manner analogous to diatreme formation.

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Section: -Ferrarmentioning

confidence: 99%

Mafic volcaniclastic deposits in flood basalt provinces: A review

Ross

Ukstins

McClintock

et al. 2005

Journal of Volcanology and Geothermal Research

137

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“…The Kiwans dolerite belongs to the MFCT Ferrar group, based on its age, isotope composition, major and trace element abundances (Table 1), and association with a sedimentary sequence correlated with the Beacon Supergroup (Mortimer et al 1995;Mortimer & Smale 1996).…”

Section: New Zealandmentioning

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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“…Orthogneiss of at least two different ages, Cretaceous and mid Paleozoic, is present in these exposures. The mid-Paleozoic and Early Cretaceous ages of orthogneiss correspond to the two main periods of plutonic and metamorphic activity recognised in the Westland-Nelson portion of the Western Province (Aronson 1968), although Triassic and Jurassic age igneous activity is not unknown (Tulloch 1979;Mortimer & Raine 1994). Intrusion of voluminous, predominantly S-type granitoids of Karamea Suite occurred in the middle Paleozoic, followed by Early Cretaceous emplacement of predominantly I-type Rahu and Separation Point Suite granitoids (Tulloch 1983(Tulloch , 1988.…”

Section: Age Of High-grade Metamorphic Rocks In West Landsouthwest Nementioning

confidence: 89%