Chapter 2.3 Dronning Maud Land Jurassic volcanism: volcanology and petrology

Geological Society London Memoirs ◽

10.1144/m55-2018-89 ◽

2021 ◽

pp. M55-2018-89

Author(s):

Arto V. Luttinen

Keyword(s):

Upper Mantle ◽

Rift Zone ◽

Flood Basalt ◽

Magnetic Polarity ◽

Crustal Material ◽

Magmatic Differentiation ◽

Flood Basalts ◽

Mantle Reservoir ◽

Normal Polarity ◽

Dronning Maud Land

AbstractThe Jurassic igneous rocks of Dronning Maud Land represent Karoo flood basalt magmatism in Antarctica. Fifty years of research has documented systematic differences between magmas associated with the Karoo rift-zone (Vestfjella and Ahlmannryggen) and the rift-shoulder (Sembberget, Kirwanveggen) settings. The 189–182 Ma rift-zone tholeiites were chemically diverse and mainly formed compound-braided flow fields which record several magnetic polarity reversals. In contrast, the c. 181 Ma rift-shoulder tholeiites were chemically uniform and formed thick tabular sheet lavas within a single normal polarity period. The volcanic architecture! records a long initial phase of slow eruptions from shield volcanoes in the initial rift and a brief phase of voluminous fissure eruptions flooding the rift shoulder. All of the major magma types in the rift-zone and rift-shoulder settings belong to a Nb-depleted category of Karoo flood basalts and were mainly derived from depleted convective upper mantle by magmatic differentiation. Pyroxenite-rich mantle components may have been significant sources for the most enriched magma types. Geochemical fingerprints of recycled crustal material imply that the Nb-depleted Karoo tholeiites may have been derived from mildly subduction-modified parts of the same overall upper-mantle reservoir which has been associated with the Ferrar tholeiites.

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Were Karoo flood basalts derived from a LLSVP-related plume source?

10.5194/egusphere-egu2020-18210 ◽

2020 ◽

Author(s):

Arto Luttinen ◽

Jussi Heinonen ◽

Sanni Turunen ◽

Richard Carlson ◽

Mary Horan

Keyword(s):

Oceanic Crust ◽

Mantle Plume ◽

Flood Basalt ◽

Planetary Science ◽

Large Igneous Province ◽

Primitive Mantle ◽

Geochemical Data ◽

Flood Basalts ◽

Depleted Mantle ◽

Mantle Reservoir

Examination of the least-contaminated rocks of the Jurassic Karoo flood basalt province indicates considerable compositional variability in the mantle source. New and previously published Sr, Nd, and Pb isotopic data are suggestive of two main categories of mantle reservoirs: one coincides with the field of depleted mantle (DM) -affinity oceanic crust and the other has low initial eNd (+3.3 to 0.3) and high 87Sr/86Sr (0.7039 to 0.7057) and &#916;8/4 (92 to 138) typical of enriched mantle 1 (EM1) -affinity oceanic crust. Previous studies have proposed the DM type reservoir included domains affected by subduction-related fluids and recycled oceanic components (e.g. Heinonen et al., 2014). The EM1 type reservoir probably also contained subducted crustal components, but the geochemical data are suggestive of an additional primitive mantle (PM) type component (Turunen et al., 2019).Importantly, the two reservoirs can be geochemically linked to a recently identified bilateral compositional asymmetry in the volumious Karoo flood basalts (Luttinen, 2018): The DM type&#160; reservoir is the most likely source of Nb-depleted flood basalts in the southeastern Karoo subprovince (Lebombo rifted margin and Antarctica), whereas the EM1-PM type reservoir has been identified as the principal source of the Nb-undepleted flood basalts in the northwestern subprovince (Karoo-Kalahari-Zambezi basins). The boundary between the flood basalt subprovinces and the occurrences of the DM-affinity and EM1-PM-affinity rocks overlie the Jurassic location of the margin of the Jurassic sub-African LLSVP. Magmas derived from the EM1-PM type reservoir were largely emplaced above the deep mantle anomaly, whereas those derived from the DM type reservoir were emplaced outside the footprint of the LLSVP.Based on isotopic similarity, the EM1-PM type reservoir of the Karoo province may record the same overall LLSVP material as the Gough component in the zoned Tristan da Cunha plume (e.g. Hoernle et al., 2015). Furthermore, it is possible that the DM type reservoir of the Karoo province, which has been interpreted to represent depleted upper mantle heated by mantle plume, could also represent a plume component and that the bilateral Karoo flood basalt province as a whole could thus register melting of a large zoned plume source associated with the margin of the sub-African LLSVP.ReferencesHeinonen, J.S., Carlson, R.W., Riley, T.R., Luttinen, A.V., Horan, M.F. (2014). Subduction-modi&#64257;ed oceanic crust mixed with a depleted mantle reservoir in the sources of the Karoo continental &#64258;ood basalt province. Earth and Planetary Science Letters 394, 229&#8211;241. http://dx.doi.org/10.1016/j.epsl.2014.03.012Hoernl, K., Ronde, J., Hauff, F., Garbe-Sch&#246;nberg, D., Homrighausen, S., Werner, W., Morgan, J.P. (2015). &#160;How and when plume zonation appeared during the 132 Myr evolution of the Tristan Hotspot. Nature Communications 6:7799. doi: 10.1038/ncomms8799Luttinen, A.V. (2018). Bilateral geochemical asymmetry in the Karoo large igneous province. Scientific Reports 8:5223. doi:10.1038/s41598-018-23661-3Turunen, S.T., Luttinen, A.V., Heinonen, J.S., Jamal, D.L. (2019). Luenha picrites, Central Mozambique &#8211; Messengers from a mantle plume source of Karoo continental &#64258;ood basalts? Lithos 346&#8211;347. https://doi.org/10.1016/j.lithos.2019.105152

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Flood Basalts and Mass Extinctions

Annual Review of Earth and Planetary Sciences ◽

10.1146/annurev-earth-053018-060136 ◽

2019 ◽

Vol 47 (1) ◽

pp. 275-303 ◽

Cited By ~ 20

Author(s):

Matthew E. Clapham ◽

Paul R. Renne

Keyword(s):

Environmental Changes ◽

Flood Basalt ◽

Respiratory Physiology ◽

Mass Extinctions ◽

Flood Basalts ◽

Volatile Release ◽

Ocean Carbon ◽

Biological Extinction ◽

Extinction Events ◽

Environmental Disruption

Flood basalts were Earth's largest volcanic episodes that, along with related intrusions, were often emplaced rapidly and coincided with environmental disruption: oceanic anoxic events, hyperthermals, and mass extinction events. Volatile emissions, both from magmatic degassing and vaporized from surrounding rock, triggered short-term cooling and longer-term warming, ocean acidification, and deoxygenation. The magnitude of biological extinction varied considerably, from small events affecting only select groups to the largest extinction of the Phanerozoic, with less-active organisms and those with less-developed respiratory physiology faring especially poorly. The disparate environmental and biological outcomes of different flood basalt events may at first order be explained by variations in the rate of volatile release modulated by longer trends in ocean carbon cycle buffering and the composition of marine ecosystems. Assessing volatile release, environmental change, and biological extinction at finer temporal resolution should be a top priority to refine ancient hyperthermals as analogs for anthropogenic climate change. ▪ Flood basalts, the largest volcanic events in Earth history, triggered dramatic environmental changes on land and in the oceans. ▪ Rapid volcanic carbon emissions led to ocean warming, acidification, and deoxygenation that often caused widespread animal extinctions. ▪ Animal physiology played a key role in survival during flood basalt extinctions, with reef builders such as corals being especially vulnerable. ▪ The rate and duration of volcanic carbon emission controlled the type of environmental disruption and the severity of biological extinction.

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The velocity structure of the upper mantle and regional deep thermodynamics of the Baikal rift zone

Geodynamics & Tectonophysics ◽

10.5800/gt-2012-3-4-0080 ◽

2012 ◽

Vol 3 (4) ◽

pp. 377-383 ◽

Cited By ~ 3

Author(s):

A. V. Pospeev

Keyword(s):

Upper Mantle ◽

Rift Zone ◽

Velocity Structure ◽

Baikal Rift Zone

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New advances on the magnetic chronostratigraphy of cave sediments in Atapuerca Gran Dolina, Spain

10.5194/egusphere-egu21-9682 ◽

2021 ◽

Author(s):

Josep M Pares ◽

Mathieu Duval ◽

Isidoro Campaña ◽

José M. Bermúdez de Castro ◽

Eudald Carbonell

Keyword(s):

Magnetic Polarity ◽

Age Dating ◽

Middle Pleistocene ◽

Geologic History ◽

Cave Sediments ◽

Normal Polarity ◽

Gran Dolina ◽

Geomagnetic Polarity ◽

Quartz Grains ◽

Numerical Dating

Magnetostratigraphy has proven to be a powerful and versatile method as well the first line of defence for dating sediments. When properly anchored to the Geomagnetic Polarity Time Scale (GPTS), chron boundaries provide a basis for numerical dating by correlating the local magnetostratigraphy to the GPTS. A caveat and intrinsic limitation when anchoring magnetic stratigraphy to the GPTS is that we deal with essentially a binary code, a sequence of normal and reverse polarity zones. To overcome such limitation biostratigraphy or (ideally) numerical (absolute) age dating is required. Unfortunately, numerical dating of sediments is typically hampered by the lack of amenable minerals for the application of standard methods such as Ar-Ar, requiring thus the use of less conventional methods. Burial dating is possible using methods such as Electron Spin Resonance (ESR) on optically bleached quartz grains. Similar to luminescence, ESR is a paleodosimetric method that provides the time elapsed since the last exposure of quartz grains to natural sun light. Cave sediments are particularly amenable for paleodosimetric methods, as sediments are preserved in the dark and the ESR signal should survive over the geologic history of the deposits. On the down side, we date the moment when the quartz grain enters the karst system, not its deposition. If the transit time is too long, this might be an issue and we would be significantly overestimating the true burial age. Caves at Atapuerca (N Spain) hold the richest Quaternary paleontological record in Eurasia, including fossils and lithic tools. Sediments in these caves have been traditionally dated via magnetostratigraphy by identifying the Matuyama-Brunhes reversal (0.78 Ma) thus providing the Lower to Middle Pleistocene boundary. Nevertheless, the appearance of older sediments in the caves required the combination of paleomagnetism with methods such as ESR to interpret older intra-Matuyama Subchrons. In the deepest levels of the Gran Dolina cave, close to the floor of the cavity, a number of short intervals of normal polarity have been identified in the fluviatile sediments belonging to TD1 unit, which we interpret in terms of Subchrons using ESR ages of quartz grains. We will discuss both paleomagnetic data and interpret the magnetic polarity stratigraphy in the view of the ESR ages obtained from the Multiple Centre (MC) approach.&#160;

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Upper mantle seismic anisotropy beneath the Kachchh rift zone, Gujarat, India, from shear wave splitting analysis

Journal of Earth System Science ◽

10.1007/s12040-020-1373-5 ◽

2020 ◽

Vol 129 (1) ◽

Cited By ~ 1

Author(s):

Bhoopendra Singh ◽

Prantik Mandal

Keyword(s):

Shear Wave ◽

Upper Mantle ◽

Seismic Anisotropy ◽

Rift Zone ◽

Shear Wave Splitting ◽

Wave Splitting

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Structure of the crust and upper mantle of the Great Slave Lake shear zone, northwestern Canada, from teleseismic analysis and gravity modelling

Canadian Journal of Earth Sciences ◽

10.1139/e03-038 ◽

2003 ◽

Vol 40 (9) ◽

pp. 1203-1218 ◽

Cited By ~ 17

Author(s):

David W Eaton ◽

Jacqueline Hope

Keyword(s):

Shear Zone ◽

Upper Mantle ◽

Receiver Function ◽

Function Analysis ◽

Crustal Material ◽

S Wave ◽

Crust And Upper Mantle ◽

Fast Axis ◽

Great Slave Lake ◽

Basic Features

The Great Slave Lake shear zone (GSLsz) exposes lower crustal rocks analogous to deep-seated segments of modern strike-slip fault zones, such as the San Andreas fault. Extending for 1300 km beneath the Western Canada Sedimentary Basin to the southern margin of the Slave Province, the GSLsz produces one of the most prominent linear magnetic anomalies in Canada. From May to October 1999, 13 three-component portable broadband seismograph stations were deployed in a 150-km profile across a buried segment of the shear zone to investigate its lithospheric structure. Splitting analysis of core-refracted teleseismic shear waves reveals an average fast-polarization direction (N49°E ± 19°) that is approximately parallel to the shear zone. Individual stations near the axis of the shear zone show more northerly splitting directions, which we attribute to interference between regional anisotropy in the upper mantle (fast axis ~N60°E) and crustal anisotropy within the shear zone (fast axis ~N30°E). At the location of our profile, the shear zone is characterized by a 10-mGal axial gravity high with a wavelength of 30 km, superimposed on a longer wavelength 12-mGal low. This gravity signature is consistent with the basic features of the crustal model derived from receiver-function analysis: a Moho that dips inward toward the shear-zone axis and a mid-crustal zone with high S-wave velocity (ΔVs = 0.6 ± 0.2 km/s). The axial gravity high may be related to uplift of deeper crustal material within the shear zone, or protolith-dependent compositional differences between the shear zone and surrounding wall rocks.

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New 42 Ma cratonic North American paleomagnetic pole from the Yukon underscores another Cordilleran paleomagnetism-geology conundrum

Canadian Journal of Earth Sciences ◽

10.1139/e03-047 ◽

2003 ◽

Vol 40 (10) ◽

pp. 1321-1334 ◽

Cited By ~ 6

Author(s):

David TA Symons ◽

Philippe Erdmer ◽

Phil JA McCausland

Keyword(s):

North American ◽

Magnetic Polarity ◽

Eastern Coast ◽

The North ◽

Normal Polarity ◽

Reversed Polarity ◽

North American Craton ◽

Host Rocks ◽

Pacific Plate Subduction ◽

Plate Subduction

Eocene posttectonic plutons of the Beaver River alkalic complex in southeastern Yukon intruded DevonianMississippian and Triassic sandstones in the Foothills of the Canadian Cordillera. A paleomagnetic collection of 27 sites from three separate plutons produced 326 specimens that were analyzed using alternating field and thermal step demagnetization methods. The A component characteristic remanent magnetization (ChRM) resides in magnetite with normal polarity in the 42.6 ± 0.8 Ma Beaver River pluton, reversed polarity in the 42.1 ± 0.7 Ma Larson Creek East pluton, and both polarities in the 41.3 ± 0.4 Ma Larson Creek West pluton, corresponding with magnetic polarity chrons 20n, 19r, and the boundary between chron 19r and 18n, respectively. The ChRMs of the plutons are indistinguishable (2σ) with a mean for the 42.0 ± 0.5 Ma complex of D = 158.8°, I = 73.1° (N = 21 sites, α95 = 3.0°, k = 116.8). A positive paleomagnetic contact test shows the A component to be primary, and the poorly isolated B component suggests the host rocks for Larson Creek West are Early to Middle Devonian. The paleopole for the Beaver River complex at 79.2°N, 145.8°E (N = 21, dp = 4.8°, dm = 5.4°; Q = 7) is concordant with interpolated 42 Ma reference poles for the North American craton. In contrast, paleopoles from the accreted Intermontane and eastern Coast Belt terranes record clockwise rotations of 24° ± 10° (Eocene) and 13° ± 5° (OligocenePliocene), indicating that the allochthonous Intermontane terranes have been progressively driven ~240 ± 120 km eastwards up and over pericratonic and cratonic North American lower crust by Pacific plate subduction since the mid-Eocene.

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The Precambrian–Cambrian boundary problem: magnetostratigraphy of the Amadeus Basin, Central Australia

Geological Magazine ◽

10.1017/s0016756800041200 ◽

1978 ◽

Vol 115 (2) ◽

pp. 139-150 ◽

Cited By ~ 44

Author(s):

J. L. Kirschvink

Keyword(s):

Detailed Comparison ◽

Magnetic Polarity ◽

Geomagnetic Reversal ◽

Upper Proterozoic ◽

Boundary Position ◽

Mixed Polarity ◽

Normal Polarity ◽

Central Australia ◽

Hole Boundary ◽

Stratigraphic Sequences

SummaryA magnetostratigraphic study of Upper Proterozoic to early Cambrian sediments at 4 localities in Central Australia reveals the presence of a magnetic polarity pattern composed of 2 long quiet intervals, first of reversed then of normal polarity, which is then succeeded by a long mixed interval. Lithologic comparisons suggest that this pattern is a reflection of the behaviour of the geomagnetic field at that time, and probably is not a result of varying sedimentation rates. Two sampled sections in the Arumbera Sandstone separated by 80 km both contain the long normal interval followed by the interval of mixed polarity, the detailed comparison of which demonstrates that the Arumbera-Box Hole boundary is unconformable. Elements from the late Precambrian Mt Skinner fauna in the Arumbera Sandstone indicate that the long normal interval is entirely pre-Cambrian, and that the base of the Cambrian occurs within the interval of mixed polarity.A comparison with an additional site sampled across a fossil occurrence in the Central Mount Stuart Formation at Central Mount Stuart indicates that at least 1 of the Upper Proterozoic fossils, Hallidaya brueri, has a considerable vertical distribution in time.If used properly, the magnetic polarity pattern discussed herein offers the possibility of precise intercontinental correlations of stratigraphic sequences near the base of the Cambrian. It is suggested that a stratotype sequence for the base of the Cambrian be chosen in such a manner that the boundary position corresponds to a geomagnetic reversal.

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Late Silurian – Early Devonian rifting during dextral transpression in the southern Gaspé Peninsula (Quebec): petrogenesis of volcanic rocks

Canadian Journal of Earth Sciences ◽

10.1139/e93-198 ◽

1993 ◽

Vol 30 (12) ◽

pp. 2283-2294 ◽

Cited By ~ 16

Author(s):

J. Dostal ◽

R. Laurent ◽

J. D. Keppie

Keyword(s):

Rift Zone ◽

Volcanic Rocks ◽

Significant Proportion ◽

Spinel Peridotite ◽

Initial Surface ◽

Crustal Material ◽

Early Devonian ◽

Ree Patterns ◽

Gaspe Peninsula ◽

Gaspé Peninsula

The Upper Silurian – Lower Devonian volcanic rocks in the southern Gaspé Peninsula of the Quebec Appalachians crop out at the northeast end of the Connecticut Valley – Gaspé Synclinorium. These shallow marine and subaerial sequences reach a thickness of up to at least 2000 m and comprise two groups: (1) the Late Silurian volcanic rocks, which are mainly transitional alkalic–tholeiitic basalts with steeply sloping REE patterns; (2) the Early Devonian volcanic rocks, which include a significant proportion of intermediate rocks in addition to tholeiitic basalts. Compared with the Silurian rocks, the Devonian basalts have lower abundances of strongly incompatible trace elements such as Ba, Th, Ta, Nb, and light REE and relatively flat heavy REE patterns. Basalts of both groups display negative Nb and Ta anomalies (relative to Th and La).Although the basalts of both sequences were derived from lithospheric mantle, the Silurian basalts were generated from garnet peridotite at ~ 80 km depth while the Devonian basalts appear to have resulted from a larger degree of melting of spinel peridotite at a shallower depth (~ 60 km). Devonian intermediate rocks are probably the result of mixing of the basaltic magma with upper crustal material through assimilation – fractional crystallization processes. The basalts are interpreted to have formed in a northwest-trending rift zone located in the Quebec Reentrant during dextral transpression along the Appalachian Orogen. Rotation during and after the volcanism reoriented the rift zone to a northeast trend. The high density layer at the base of the crust under the Magdalen Basin may be the former magma chamber for the Silurian–Devonian volcanism. The change from transitional to tholeiitic volcanism at the Silurian–Devonian boundary suggests that the stretching value (ratio of final to initial surface area) increased from < 2 to > 2 at that time. This boundary is also coincident with the Salinic disturbance that is inferred to have been produced by erosion of the thermally uplifted block associated with rifting.

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