Chemical and Sr-Nd compositions and 40Ar/39Ar ages of NW-trending dolerite dikes of Burkina Faso: Evidence for a Mesoproterozoic magmatism in the West African Craton

Boukare Tapsoba, Ching Hua Lo, Urbain Wenmenga, Yoshiyuki Iizuka, Sun Lin Chung, Gregory Shellnutt

Research output: Contribution to journalArticle

Abstract

The Paleoproterozoic basement of the northeastern part of the Leo-Man craton is intruded by generally NW-trending dikes. These regional scale dikes extend over 1000 km in Burkina Faso, Mali and Niger. We present chemical and Sr-Nd isotope compositions, as well as 40Ar/39Ar ages of these dikes with the following strikes N98°-N112°, and N114°-N124° in NE Burkina Faso. Field relationships show that the dikes are posterior to all other rock types dated between 2.26 Ga and 2.0 Ga. Chemical data indicate that the dikes are continental flood basalts and composed of low-Ti (TiO2 ≤ 2 wt.%) sub-alkaline basalts and andesites. They exhibit a minor negative Europium anomaly (0.86-0.99) and slightly fractionated REE patterns ((La/Yb)N = 2.5-9.1; YbN = 9.5-19.9). The ratios of Th/Ta (1.3-11.4) and Ce/Pb (5.2-58.5) suggest a varying crustal assimilation of the dike magmas during ascent in the continental crust for all studied samples. Calculated P-T conditions indicate that the magma reached temperatures of 1285 °C (calculated from olivine compositions) and pressures of 6.9 kbar (calculated for pyroxene minerals). Calculated initial 87Sr/86Sr (0.70040-0.70260) and ε Nd(t) = +2.1 to -3.5 at 1575 Ma, also point to a crustal contamination with the most primitive samples showing T DM values of 1946 Ma and 2154 Ma. The low values of La/Ba (<0.2) and Nb/La (<1.0), contrast with the low Th/Nb (<0.9), and suggest a lithospheric mantle or subduction-modified mantle as possible source for the dikes. Sr-Nd data, Mg# and Nb-Ta-Zr-Y-Th-Tb-Yb compositions further suggest that the most primitive samples were emplaced in a none orogenic setting and their magmas were subjected to variable crustal contaminations. Literature and the present whole rock 40Ar/39Ar age determinations show that the dikes were emplaced during a widespread Mesoproterozoic magmatism between 1.6 Ga and 1.2 Ga, and were affected by a thermal event causing the argon systematics resetting, best constrained by the date of sample KK1 (1236 ± 20 Ma, 40Ar/36Ar = 294 ± 13, MSWD = 2.2). Contemporaneous 1590-1570 Ma extensive magmatism is reported in other crustal blocks in Baltica (Sveconorw-Goth, svecofennian) NW Laurentia (Slave craton, Yukon), and Australia (Gawler craton), and together with the 1575 studied dikes, are related to the breakup of the supercontinent Nuna.

LanguageEnglish
JournalGeoscience Frontiers
DOIs
Publication statusAccepted/In press - 2018 Jan 1

Fingerprint

diabase
craton
dike
magmatism
crustal contamination
mantle
chemical
Svecofennian
europium
resetting
slave
Baltica
flood basalt
Laurentia
supercontinent
P-T conditions
age determination
argon
andesite
rock

Keywords

  • Continental tholeiites
  • Depleted mantle
  • Mafic dike swarm
  • Mesoproterozoic
  • Nuna
  • West African Craton

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

Cite this

Chemical and Sr-Nd compositions and 40Ar/39Ar ages of NW-trending dolerite dikes of Burkina Faso : Evidence for a Mesoproterozoic magmatism in the West African Craton. / Tapsoba, Boukare; Lo, Ching Hua; Wenmenga, Urbain; Iizuka, Yoshiyuki; Chung, Sun Lin; Shellnutt, Gregory.

In: Geoscience Frontiers, 01.01.2018.

Research output: Contribution to journalArticle

@article{6d962160db1e43fa94e051c25f4f2862,
title = "Chemical and Sr-Nd compositions and 40Ar/39Ar ages of NW-trending dolerite dikes of Burkina Faso: Evidence for a Mesoproterozoic magmatism in the West African Craton",
abstract = "The Paleoproterozoic basement of the northeastern part of the Leo-Man craton is intruded by generally NW-trending dikes. These regional scale dikes extend over 1000 km in Burkina Faso, Mali and Niger. We present chemical and Sr-Nd isotope compositions, as well as 40Ar/39Ar ages of these dikes with the following strikes N98°-N112°, and N114°-N124° in NE Burkina Faso. Field relationships show that the dikes are posterior to all other rock types dated between 2.26 Ga and 2.0 Ga. Chemical data indicate that the dikes are continental flood basalts and composed of low-Ti (TiO2 ≤ 2 wt.{\%}) sub-alkaline basalts and andesites. They exhibit a minor negative Europium anomaly (0.86-0.99) and slightly fractionated REE patterns ((La/Yb)N = 2.5-9.1; YbN = 9.5-19.9). The ratios of Th/Ta (1.3-11.4) and Ce/Pb (5.2-58.5) suggest a varying crustal assimilation of the dike magmas during ascent in the continental crust for all studied samples. Calculated P-T conditions indicate that the magma reached temperatures of 1285 °C (calculated from olivine compositions) and pressures of 6.9 kbar (calculated for pyroxene minerals). Calculated initial 87Sr/86Sr (0.70040-0.70260) and ε Nd(t) = +2.1 to -3.5 at 1575 Ma, also point to a crustal contamination with the most primitive samples showing T DM values of 1946 Ma and 2154 Ma. The low values of La/Ba (<0.2) and Nb/La (<1.0), contrast with the low Th/Nb (<0.9), and suggest a lithospheric mantle or subduction-modified mantle as possible source for the dikes. Sr-Nd data, Mg# and Nb-Ta-Zr-Y-Th-Tb-Yb compositions further suggest that the most primitive samples were emplaced in a none orogenic setting and their magmas were subjected to variable crustal contaminations. Literature and the present whole rock 40Ar/39Ar age determinations show that the dikes were emplaced during a widespread Mesoproterozoic magmatism between 1.6 Ga and 1.2 Ga, and were affected by a thermal event causing the argon systematics resetting, best constrained by the date of sample KK1 (1236 ± 20 Ma, 40Ar/36Ar = 294 ± 13, MSWD = 2.2). Contemporaneous 1590-1570 Ma extensive magmatism is reported in other crustal blocks in Baltica (Sveconorw-Goth, svecofennian) NW Laurentia (Slave craton, Yukon), and Australia (Gawler craton), and together with the 1575 studied dikes, are related to the breakup of the supercontinent Nuna.",
keywords = "Continental tholeiites, Depleted mantle, Mafic dike swarm, Mesoproterozoic, Nuna, West African Craton",
author = "Boukare Tapsoba and Lo, {Ching Hua} and Urbain Wenmenga and Yoshiyuki Iizuka and Chung, {Sun Lin} and Gregory Shellnutt",
year = "2018",
month = "1",
day = "1",
doi = "10.1016/j.gsf.2017.12.015",
language = "English",
journal = "Geoscience Frontiers",
issn = "1674-9871",
publisher = "China University of Geosciences (Beijing) and Peking University",

}

TY - JOUR

T1 - Chemical and Sr-Nd compositions and 40Ar/39Ar ages of NW-trending dolerite dikes of Burkina Faso

T2 - Geoscience Frontiers

AU - Tapsoba, Boukare

AU - Lo, Ching Hua

AU - Wenmenga, Urbain

AU - Iizuka, Yoshiyuki

AU - Chung, Sun Lin

AU - Shellnutt, Gregory

PY - 2018/1/1

Y1 - 2018/1/1

N2 - The Paleoproterozoic basement of the northeastern part of the Leo-Man craton is intruded by generally NW-trending dikes. These regional scale dikes extend over 1000 km in Burkina Faso, Mali and Niger. We present chemical and Sr-Nd isotope compositions, as well as 40Ar/39Ar ages of these dikes with the following strikes N98°-N112°, and N114°-N124° in NE Burkina Faso. Field relationships show that the dikes are posterior to all other rock types dated between 2.26 Ga and 2.0 Ga. Chemical data indicate that the dikes are continental flood basalts and composed of low-Ti (TiO2 ≤ 2 wt.%) sub-alkaline basalts and andesites. They exhibit a minor negative Europium anomaly (0.86-0.99) and slightly fractionated REE patterns ((La/Yb)N = 2.5-9.1; YbN = 9.5-19.9). The ratios of Th/Ta (1.3-11.4) and Ce/Pb (5.2-58.5) suggest a varying crustal assimilation of the dike magmas during ascent in the continental crust for all studied samples. Calculated P-T conditions indicate that the magma reached temperatures of 1285 °C (calculated from olivine compositions) and pressures of 6.9 kbar (calculated for pyroxene minerals). Calculated initial 87Sr/86Sr (0.70040-0.70260) and ε Nd(t) = +2.1 to -3.5 at 1575 Ma, also point to a crustal contamination with the most primitive samples showing T DM values of 1946 Ma and 2154 Ma. The low values of La/Ba (<0.2) and Nb/La (<1.0), contrast with the low Th/Nb (<0.9), and suggest a lithospheric mantle or subduction-modified mantle as possible source for the dikes. Sr-Nd data, Mg# and Nb-Ta-Zr-Y-Th-Tb-Yb compositions further suggest that the most primitive samples were emplaced in a none orogenic setting and their magmas were subjected to variable crustal contaminations. Literature and the present whole rock 40Ar/39Ar age determinations show that the dikes were emplaced during a widespread Mesoproterozoic magmatism between 1.6 Ga and 1.2 Ga, and were affected by a thermal event causing the argon systematics resetting, best constrained by the date of sample KK1 (1236 ± 20 Ma, 40Ar/36Ar = 294 ± 13, MSWD = 2.2). Contemporaneous 1590-1570 Ma extensive magmatism is reported in other crustal blocks in Baltica (Sveconorw-Goth, svecofennian) NW Laurentia (Slave craton, Yukon), and Australia (Gawler craton), and together with the 1575 studied dikes, are related to the breakup of the supercontinent Nuna.

AB - The Paleoproterozoic basement of the northeastern part of the Leo-Man craton is intruded by generally NW-trending dikes. These regional scale dikes extend over 1000 km in Burkina Faso, Mali and Niger. We present chemical and Sr-Nd isotope compositions, as well as 40Ar/39Ar ages of these dikes with the following strikes N98°-N112°, and N114°-N124° in NE Burkina Faso. Field relationships show that the dikes are posterior to all other rock types dated between 2.26 Ga and 2.0 Ga. Chemical data indicate that the dikes are continental flood basalts and composed of low-Ti (TiO2 ≤ 2 wt.%) sub-alkaline basalts and andesites. They exhibit a minor negative Europium anomaly (0.86-0.99) and slightly fractionated REE patterns ((La/Yb)N = 2.5-9.1; YbN = 9.5-19.9). The ratios of Th/Ta (1.3-11.4) and Ce/Pb (5.2-58.5) suggest a varying crustal assimilation of the dike magmas during ascent in the continental crust for all studied samples. Calculated P-T conditions indicate that the magma reached temperatures of 1285 °C (calculated from olivine compositions) and pressures of 6.9 kbar (calculated for pyroxene minerals). Calculated initial 87Sr/86Sr (0.70040-0.70260) and ε Nd(t) = +2.1 to -3.5 at 1575 Ma, also point to a crustal contamination with the most primitive samples showing T DM values of 1946 Ma and 2154 Ma. The low values of La/Ba (<0.2) and Nb/La (<1.0), contrast with the low Th/Nb (<0.9), and suggest a lithospheric mantle or subduction-modified mantle as possible source for the dikes. Sr-Nd data, Mg# and Nb-Ta-Zr-Y-Th-Tb-Yb compositions further suggest that the most primitive samples were emplaced in a none orogenic setting and their magmas were subjected to variable crustal contaminations. Literature and the present whole rock 40Ar/39Ar age determinations show that the dikes were emplaced during a widespread Mesoproterozoic magmatism between 1.6 Ga and 1.2 Ga, and were affected by a thermal event causing the argon systematics resetting, best constrained by the date of sample KK1 (1236 ± 20 Ma, 40Ar/36Ar = 294 ± 13, MSWD = 2.2). Contemporaneous 1590-1570 Ma extensive magmatism is reported in other crustal blocks in Baltica (Sveconorw-Goth, svecofennian) NW Laurentia (Slave craton, Yukon), and Australia (Gawler craton), and together with the 1575 studied dikes, are related to the breakup of the supercontinent Nuna.

KW - Continental tholeiites

KW - Depleted mantle

KW - Mafic dike swarm

KW - Mesoproterozoic

KW - Nuna

KW - West African Craton

UR - http://www.scopus.com/inward/record.url?scp=85042620438&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85042620438&partnerID=8YFLogxK

U2 - 10.1016/j.gsf.2017.12.015

DO - 10.1016/j.gsf.2017.12.015

M3 - Article

JO - Geoscience Frontiers

JF - Geoscience Frontiers

SN - 1674-9871

ER -