The geology and geochemistry of the Straumsnutane Formation, Straumsnutane, western Dronning Maud Land, Antarctica and its tectonic setting on the western margin of the Kalahari Craton: additional evidence linking it to the Umkondo Large Igneous Province

The&#160;paleo-position&#160;of&#160;the&#160;North China Craton (NCC) within the Supercontinent Nuna/Columbia is controversial. Hindered by ubiquitous alteration of the very ancient rocks, paleomagnetic studies have not been able yet to conclusively solve this puzzle. Comprehensive analysis&#160;on the relatively limited Precambrian records&#160;is essential&#160;to understand&#160;the geological history of these cratons. Within the NCC, the tectonic setting&#160;of a&#160;~1.78 Ga large igneous province (LIP) is long debated. It is considered to be related to a paleoplume, post-collision extension,&#160;or an Andean continental margin. Knowing its mode of formation constrains the geological evolution of the NCC and its&#160;paleo-position&#160;within the Supercontinent Nuna/Columbia. Here we conduct a study into the anisotropy of magnetic susceptibility&#160;(AMS)&#160;in the dykes and lavas of the ~1.78 Ga LIP, together with systematic rock magnetic experiments, to constrain the geological background&#160;of the igneous event(s), to understand&#160;the tectonic evolution of the NCC, as well as its paleo-position within&#160;the assembly&#160;of the Nuna/Columbia supercontinent.Thirty-three dykes in the northern and middle parts and thirty lavas in the southern part of the NCC were collected. Detailed rock magnetic analyses indicate PSD magnetite to be the dominant magnetic mineral in the samples, occasionally with pyrrhotite in the dykes and hematite in the lavas. The often observed relatively weak anisotropy degree suggests that the AMS ellipsoids probably portray magma flow-related fabrics. The inferred directions from the AMS fabrics of the lavas reveal a radial flow pattern with an eruption center located on the south margin of the NCC. The studied dykes show a predominance of horizontally to subhorizontally northward magma flow, with only few vertical intrusions. These observations imply that the ~1.78 Ga LIP may have formed by magma source(s) at the south margin of the NCC. Some localized magma sub-chambers may have formed during the propagation of the magma and could have been responsible for the less common vertically intruded dykes and the EW-trending dykes. Therefore, we favor a plume-related tectonic setting for the ~1.78 Ga LIP with the eruption center along the margin of the NCC. It can serve as an essential criterion to search for possible neighbour(s) of the NCC within Nuna/Columbia, which should preserve the relics of the ~1.78 Ga LIP. Our study, in combination with extant geological and paleomagnetic results suggests a close linkage of the NCC with the S&#227;o Francisco-Congo, Rio de la Plata and Siberia cratons in the Nuna/Columbia supercontinent.

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An early Paleozoic silicic large igneous province in NE Gondwana: a preliminary synthesis

10.5194/egusphere-egu2020-8193 ◽

2020 ◽

Cited By ~ 1

Author(s):

Wei Dan ◽

J. Brendan Murphy ◽

Gong-Jian Tang ◽

Xiu-Zheng Zhang ◽

Qiang Wang

Keyword(s):

Tectonic Setting ◽

Oceanic Lithosphere ◽

Large Igneous Province ◽

Early Paleozoic ◽

Magmatic Rocks ◽

Igneous Province ◽

Granitoid Rocks ◽

Andean Type ◽

Almost All ◽

The Relationship

Five major oceans (Iapetus, Rheic, Proto-Tethys, Paleo-Tethys and Paleo-Asian) formed during or after assembly of the Gondwana continent. However, the relationship between them is poorly understood, largely due to the complex and disputed evolution of NE Gondwana in the early Paleozoic. Here we present a summary of early Paleozoic tectono-thermal events in the NE Gondwana and discuss their tectonic settings. Early Paleozoic magmatic rocks are widely distributed in the Himalaya, Lhasa, Southern Qiangtang, Baoshan, Sibumasu and Tengchong terranes, and their ages were loosely constrained to be ca. 530-430 Ma. However, after a critical review of these dating results, we propose the magmatic rocks were mostly formed between ca. 500-460 Ma. Although bimodal, they are dominated by granitoid rocks distributed over an area of >2500 km &#215; 900 km. Thus, they constitute a typical silicic large igneous province. Almost all granitoid rocks were derived from partial melting of sedimentary rocks, but a few show A-type characteristics. Coeval amphibolite-facies metamorphic rocks yield ages of 490-465 Ma. A sedimentary hiatus marked by either a disconformity or angular unconformity coeval with the major magmatic flare-up period is evident in all terranes. Thus, present evidence doesn&#8217;t favor either the conventional Andean-type subduction model, in which these magmatic rocks reflect subduction of Proto-Tethys oceanic lithosphere beneath the northern Gondwanan margin, or a post-collision setting, in which extension is associated with the collapse of the Pan-African orogeny in NE Gondwana. The tectonic setting for this magmatic province is tentatively related to a plume in a far-field subduction zone.

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The geochemistry of Middle Jurassic dykes associated with the Straumsvola–Tvora alkaline plutons, Dronning Maud Land, Antarctica and their association with the Karoo large igneous province

Mineralogical Magazine ◽

10.1180/minmag.2009.073.2.205 ◽

2009 ◽

Vol 73 (2) ◽

pp. 206-226 ◽

Cited By ~ 10

Author(s):

T. R. Riley ◽

M. L. Curtis ◽

P. T. Leat ◽

I. L. Millar

Keyword(s):

Southern Africa ◽

Middle Jurassic ◽

Minor Component ◽

Small Degree ◽

Large Igneous Province ◽

Dyke Swarm ◽

Volcanic Event ◽

Igneous Province ◽

Dronning Maud Land ◽

A Minor

AbstractJurassic dykes of western Dronning Maud Land (Antarctica) form a minor component of the Karoo large igneous province. An extensive local dyke swarm intrudes Neoproterozoic gneisses and Jurassic syenite plutons on the margins of the Jutulstraumen palaeo rift in the Svedrupfjella region. The dykes were intruded in three distinct episodes (~204, ~176 and ~170 Ma). The 204 Ma dykes are overwhelminglylow-Ti, olivine tholeiites including some primitive (picritic) compositions (MgO >12 wt.%; Fe2O3 >12 wt.%; Cr >1000 ppm; Ni >600 ppm). This 204 Ma event precedes the main Karoo volcanic event by~25 Ma, so anycorrelations to the wider province are difficult to make. However, it mayrecord the earliest phase of rift activity along the Jutulstraumen. The 176 Ma dyke event is more intimately associated with the two syenite plutons. The dykes are alkaline (basanite/ tephrite) and were small-degree melts from an enriched, locallyderived source and underwent at least some degree of interaction with a syenitic contaminant. This ~176 Ma dyke event is widespread elsewhere in the Karoo (southern Africa and Dronning Maud Land). Later-stage (170 Ma) felsic (phonolite–comendite) dykes intrude the 176 Ma basanite–tephrite suite and represent the last phase of magmatic activityin the region.

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Late Paleoproterozoic mafic magmatism and the Kalahari craton during Columbia assembly

Geology ◽

10.1130/g48811.1 ◽

2021 ◽

Author(s):

Cedric Djeutchou ◽

Michiel O. de Kock ◽

Hervé Wabo ◽

Camilo E. Gaitán ◽

Ulf Söderlund ◽

...

Keyword(s):

Thermal Ionization Mass Spectrometry ◽

Black Hills ◽

Large Igneous Province ◽

Ionization Mass ◽

Data Sets ◽

Geochronological Data ◽

Pb Isotope ◽

Kalahari Craton ◽

Igneous Province ◽

Superior Craton

The 1.87–1.84 Ga Black Hills dike swarm of the Kalahari craton (South Africa) is coeval with several regional magmatic provinces used here to resolve the craton’s position during Columbia assembly. We report a new 1850 ± 4 Ma (U-Pb isotope dilution–thermal ionization mass spectrometry [ID-TIMS] on baddeleyite) crystallization age for one dike and new paleomagnetic data for 34 dikes of which 8 have precise U-Pb ages. Results are constrained by positive baked-contact and reversal tests, which combined with existing data produce a 1.87–1.84 Ga mean pole from 63 individual dikes. By integrating paleomagnetic and geochronological data sets, we calculate poles for three magmatic episodes and produce a magnetostratigraphic record. At 1.88 Ga, the Kalahari craton is reconstructed next to the Superior craton so that their ca. 2.0 Ga poles align. As such, magmatism forms part of a radiating pattern with the coeval ca. 1.88 Ga Circum-Superior large igneous province.

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Congo-São Francisco at 1.11 Ga and the megacontinent Umkondia

10.5194/egusphere-egu21-10714 ◽

2021 ◽

Author(s):

Johanna Salminen

Keyword(s):

Large Igneous Province ◽

Geochronological Data ◽

Qualitative Comparison ◽

Central Brazil ◽

Northern India ◽

Paleomagnetic Pole ◽

Kalahari Craton ◽

Igneous Province ◽

The World ◽

Tholeiitic Magmatism

Currently three supercontinent cycles have been identified and existed supercontinents named from youngest to oldest: Pangea, Rodinia and Nuna/Columbia. Recently Wang et al. (2020) suggested that supercontinent amalgamation were each preceded by ~200 Myr by the assembly of long-lasting megacontinent aking to Gondwana.The Congo-S&#227;o Francisco (C/SF) craton is a main building block in Gondwana due to its central location, but its participation to Rodinia is controversial. Salminen et al. (2018) presented 1.11 Ga paleomagnetic and geochronological data from a prominent Epembe-Huila swarm of gabbronoritic dykes in the southern part of the Congo craton in Namibia and in Angola. This paleomagnetic pole yields a relatively low paleolatitude for the C/SF craton at ca. 1.11 Ga and permits a direct connection between Congo and Kalahari cratons. This connection supports an earlier qualitative comparison (Ernst et al., 2013), that the mafic Epembe-Huila swarm was an integral component of the Umkondo Large Igneous Province (LIP). The 1.11 Ga Umkondo LIP is widespread across Kalahari craton, and coeval mafic magmatism has been identified in several of the world&#8217;s other late Mesoproterozoic cratons: Laurentia, India, Amazonia, and Antarctica (Grunehogna). Were these coeval provinces spatially linked at the time of emplacement during the amalgamation of Rodinia? Robust paleomagnetic and geochronological data from Laurentia and Kalahari have demonstrated substantial separation between those two blocks at 1.11 Ga (Swanson-Hysell et al., 2015). However, based on similar tholeiitic magmatism Choudhary et al. (2019) proposed that Kalahari and C/SF together with Amazonia and northern India constituted &#8220;Umkondia&#8221; at 1.11 Ga. It has been proposed that Umkondia occupied an intermediary &#8220;megacontinental&#8221; role in the Nuna-Rodinia transition analogous to Gondwana in Rodinia-Pangea evolution (Wang et al., 2020). Contradicting Gondwana the proposed Umkondia was not long-lasting, since it has been proposed that Kalahari and Congo separated after 1.10 Ga to form a vast ocean (ca. 6000 km) during the formation of Rodinia and widespread juvenile intra-oceanic magmatism along the present-day central Brazil indicates a large ca. 0.94 Ga ocean between C/SF and Amazonia (Cordani et al., 2003).&#160;Choudhary et al. 2019. Precambrian Research 332, 105382.Cordani et al. 2003. Gondwana Research 6, 275-283.Ernst et al. 2003. Lithos 174 1-14.Salminen et al. 2018. Geology 46, 1011-1014.Swanson-Hysell et al. 2015. Geophysical Journal International 203, 2237-2247.Wang et al. 2020. Geology 49, https://doi.org/10.1130/G47988.1&#160;

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Geochemistry of the 1100 Ma intrusive rocks from the Ahlmannryggen region, Dronning Maud Land, Antarctica

Antarctic Science ◽

10.1017/s0954102013000916 ◽

2014 ◽

Vol 26 (4) ◽

pp. 389-399 ◽

Cited By ~ 3

Author(s):

Teal R. Riley ◽

Ian L. Millar

Keyword(s):

Lithospheric Mantle ◽

Crustal Contamination ◽

Lava Flows ◽

Large Igneous Province ◽

Sedimentary Sequence ◽

Igneous Province ◽

Intrusive Rocks ◽

Dronning Maud Land ◽

Lithospheric Mantle Source ◽

Land Region

AbstractThe recognition of a Mesoproterozoic large igneous province (LIP) across large parts of southern Africa has been strengthened by recent geochronology, geochemistry and petrology. The c. 1100 Ma Umkondo province has been recognized across parts of Botswana, Zimbabwe, South Africa and Mozambique where tholeiitic sills, dykes and rare lava flows have been correlated into a single magmatic province emplaced in the interval 1108–1112 Ma. The extension of the province into the Dronning Maud Land region of Antarctica has been suggested by several workers, but detailed analyses of geochemistry and petrogenesis are lacking, as are comparative studies. This study investigates 25 dykes and sills of the Borgmassivet intrusions which include several of the major diorite sills of the province, up to 300 m in thickness. The dykes and sills are also considered to be c. 1100 Ma and they were emplaced, in part, synchronously with the Ritscherflya Supergroup sedimentary sequence. The Borgmassivet intrusions are characterized by geochemical signatures that suggest the magmas were either extensively contaminated by continental crust or derived from an enriched lithospheric mantle source, where the enrichment was related to earlier subduction. The limited geochemical range of the Borgmassivet and Umkondo intrusions are probably not consistent with significant levels of crustal contamination. Furthermore, the trace element ratios indicate a source in the sub-lithospheric mantle, followed by gabbroic fractionation and interaction with lithospheric wall rocks.

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Magma Plumbing System of Emeishan Large Igneous Province at the End-Permian: Insights from Clinopyroxene Compositional Zoning and Thermobarometry

Minerals ◽

10.3390/min10110979 ◽

2020 ◽

Vol 10 (11) ◽

pp. 979

Author(s):

Jun-Hao Hu ◽

Jing-Wen Liu ◽

Tao Song ◽

Bai-Shun Shi

Keyword(s):

Tectonic Setting ◽

Large Igneous Province ◽

Magma Ascent ◽

Magma Chambers ◽

Flood Basalts ◽

Compositional Zoning ◽

Magma Plumbing System ◽

Emeishan Large Igneous Province ◽

Mafic Intrusions ◽

Igneous Province

The end-Permian Emeishan Large Igneous Province (ELIP) in SW China is widely accepted to have formed by mantle plume activities, forming voluminous flood basalts and rare picrites. Although many studies were performed on the petrogenesis and tectonic setting, the detailed conditions and processes within the magma chamber(s) remain unsolved. In this study, we studied the sector-/oscillatory-zoned clinopyroxene (Cpx) phenocrysts and performed Cpx-liquid thermobarometric calculation to constrain the physicochemical processes within the magma chambers. The results show that Cpx phenocrysts from the high-Mg basalts were crystallized at 4–27 (average 17) km, whilst those from the low-Mg basalt were crystallized at 0–23 (average 9) km depth. The sector and oscillatory Cpx zoning in the high-Mg basalts show that the magma had experienced undercooling and multistage recharge events in the deep-staging chamber(s). The magma replenishments may have eventually led to the eruption of high-Mg basalts, and magma ascent to the upper crust for further fractionation to form the low-Mg basalts and mafic intrusions.

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Early–Middle Jurassic Dolerite Dykes from Western Dronning Maud Land (Antarctica): Identifying Mantle Sources in the Karoo Large Igneous Province

Journal of Petrology ◽

10.1093/petrology/egi023 ◽

2005 ◽

Vol 46 (7) ◽

pp. 1489-1524 ◽

Cited By ~ 91

Author(s):

TEAL R. RILEY ◽

PHILIP T. LEAT ◽

MICHAEL L. CURTIS ◽

IAN. L. MILLAR ◽

ROBERT A. DUNCAN ◽

...

Keyword(s):

Middle Jurassic ◽

Large Igneous Province ◽

Mantle Sources ◽

Igneous Province ◽

Dronning Maud Land

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Zircon U–Pb Geochronology, Geochemistry and Geological Significance of the Anisian Alkaline Basalts in Gejiu District, Yunnan Province

Minerals ◽

10.3390/min10111030 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1030

Author(s):

Zhi Shang ◽

Yongqing Chen

Keyword(s):

Tectonic Setting ◽

Crustal Contamination ◽

Large Igneous Province ◽

Garnet Lherzolite ◽

High Field Strength ◽

Nd Isotope ◽

Enriched Mantle ◽

Isotopic Analyses ◽

Igneous Province ◽

Oceanic Island Basalts

The Gejiu Anisian alkaline basalts (GAAB), distributed in the southern part of the Emeishan large igneous province (ELIP), are crucial to understand the tectonomagmatic activity during the Triassic. Geochronological, geochemical, and Sr-Nd-Pb isotopic analyses were systematically applied to explore the origin, petrogenesis, and tectonic setting of the GAAB, and how they relate to the ELIP. Zircon U-Pb dating set the eruption date at 244 Ma. Most of the samples belonged to alkaline basalts and had high TiO2 (2.14–3.23 wt.%) and MgO (4.43–19.58 wt.%) contents. Large ion lithophile elements (LILEs) were enriched relative to high field strength elements (HFSEs). The rare earth elements (REEs) and trace element signatures in the normalized diagrams were similar to oceanic island basalts (OIB) and Emeishan high-Ti basalts. These samples had consistent Sr-Nd isotope compositions: the initial 87Sr/86Sr values ranged from 0.7044 to 0.7048 and εNd(t) = 3.25–4.92. The Pb isotopes were more complex, the (206Pb/204Pb)t, (207Pb/204Pb)t, (208Pb/204Pb)t ratios were 17.493–18.197, 15.530–15.722, and 37.713–38.853, respectively. Our results indicate that the GAAB originated from the deeper enriched mantle with 5% to 15% partial melting of garnet lherzolite and a segregation depth of 2 to 4 GPa (60–120 km). During the formation of the GAAB, clinopyroxene and Ti-Fe oxides were fractionally crystallized with insignificant crustal contamination. The GAAB were formed in a extensional regime that was related to the Gejiu-Napo rift event in the Triassic.

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