Isotope chemostratigraphy of marbles in northeastern Mozambique: Apparent depositional ages and tectonostratigraphic implications

Melezhik, Victor A.; Bingen, Bernard; Fallick, Anthony E.; Горохов, И. М.; Кузнецов, А. Б.; Sandstad, Jan Sverre; Solli, Arne; Bjerkgård, T.; Henderson, I. H. C.; Boyd, Rognvald; Jamal, D.; Moniz, A. C.

doi:10.1016/j.precamres.2007.11.002

Cited by 52 publications

(21 citation statements)

References 41 publications

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“…Marble horizons, also interlayered with supracrustal rocks, have apparent deposition ages, as estimated by chemostratigraphic methods, of 850 to 750 Ma in the north of the Xixano Complex and ca. 740 Ma in the south (Melezhik et al, 2008 Frost et al (2001).…”

Section: Xixano Complexmentioning

confidence: 99%

“…In addition, a later regional northwest to southeast extensional phase was also documented by Viola et al (2008) postdating thrusting and marking the collapse of the overthickened crust. Therefore these shear zones are likely to record (Melezhik et al, 2008) evidence of a complex, long-lived structural history with several periods of reactivation.…”

Section: M'sawize Complexmentioning

confidence: 99%

“…The biotite gneiss includes graphite-bearing units which are exploited in the Ancuabe area. The timing of deposition of the supracrustal sequences has been estimated using chemostratigraphic methods on two thin marble layers which yielded deposition ages of around 740 Ma (Melezhik et al, 2008). An orthogneiss yielded a U-Pb zircon intrusion age of 696 ± 13 Ma (Norconsult, 2007a).…”

Section: Lalamo Complexmentioning

confidence: 99%

“…This rock probably represents an aluminous meta sediment, and forms the top of a well-defined transgressive sequence that starts with the conglomerate at the structural base, grading into arenitic sandstone, (Melezhik et al, 2008).…”

Section: Lalamo Complexmentioning

confidence: 99%

“…Possible evidence includes the ca. 1.1 to 1.05 Ga Montepuez marbles (Melezhik et al, 2008). Establishing the presence of a "basement" in these complexes is nevertheless a key element to reconstruct their paleogeography (oceanic vs. pericontinental arc complexes), and is a task for future research.…”

Section: South African Journal Of Geology the Geology And Geochemistrmentioning

confidence: 99%

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The Geology and Geochemistry of the East African Orogen in Northeastern Mozambique

Boyd

Nordgulen

Thomas

et al. 2010

South African Journal of Geology

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Section: Xixano Complexmentioning

confidence: 99%

Section: M'sawize Complexmentioning

confidence: 99%

Section: Lalamo Complexmentioning

confidence: 99%

Section: Lalamo Complexmentioning

confidence: 99%

Section: South African Journal Of Geology the Geology And Geochemistrmentioning

confidence: 99%

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The Geology and Geochemistry of the East African Orogen in Northeastern Mozambique

Boyd

Nordgulen

Thomas

et al. 2010

South African Journal of Geology

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C–O isotope geochemistry of the Dashiqiao magnesite belt, North China Craton: implications for the Great Oxidation Event and ore genesis

et al. 2013

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The worldwide 2.33−2.06 Ga unique positive δ13Ccarb excursion has been correlated with the Great Oxidation Event (GOE). The Dashiqiao Formation in the Liaohe Group of the northeastern North China Craton formed at 2.2−2.174 Ga and hosts one of the world‐class magnesite deposits. Here we present major element and C and O isotope analyses of 22 samples from the Dashiqiao Formation and use the data to evaluate the impact of the GOE in the North China Craton, as well as the genesis of the Dashiqiao giant magnesite deposits. Six dolomitic marble samples from a ~600 m thick interval with 1.10 ± 0.04 of MgO/CaO (mol) ratios show higher δ13CPDB values of 0.6−1.4‰ (average 1.2 ± 0.3‰) than those of normal marine carbonates over the globe. However, they display lower δ18OSMOW of 16.4−19.5‰ (average 18.2 ± 1.1‰) as compared to their contemporaneous counterparts, suggesting that the primary carbonates in the Dashiqiao Formation should possess a positive δ13C anomaly (possibly 4.2‰) reflecting the impact of the GOE, and that the δ13C and δ18O values have been depleted in post‐sedimentation diagenesis and/or regional metamorphism. The >550 m thick magnesite layer in the studied section has MgO/CaO ratios ranging from 4.45−200.00. These rocks show δ13C and δ18O values of 0.1−0.9‰ and 9.2−16.9‰, with average values of 0.4 ± 0.2‰ and 13.3 ± 2.5‰, respectively, obviously lower than those of the underlying dolomites. The depletions of 13C and 18O in magnesites relative to dolomitic marbles are interpreted to be the result of hydrothermal alteration related to regional metamorphism leading to rock recrystallization and mass exchange. This interpretation is further confirmed from the hanging‐wall dolomitic marble and the veinlet‐filled magnesite from the ore layer. The former contains mega‐crystals of cylindrical talc and has δ13C of −2.6‰ and δ18O of 14.1‰, indicating that a local fluid–rock interaction between (argillaceous) dolomite and (siliceous) hydrothermal fluids poor in 13C and 18O resulted in the formation of talc and further depletion both in δ13C and in δ18O. The veinlet‐filled magnesite yields δ13C and δ18O values of −2.7‰ and 16.2‰, respectively, showing lower δ13C but higher δ18O than those of massive magnesite in the adjacent strata. Our observation thus strongly supports the interpretation that the massive magnesite interacted with low‐δ13C fluids which were possibly sourced from meteoric water at low temperature during post‐ore time. Thus, the formation of the Dashiqiao magnesite deposits involved primary sedimentation, diagenesis, regional metamorphism, hydrothermal replacement and local post‐ore fluid–rock interaction. Copyright © 2013 John Wiley & Sons, Ltd.

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The Southern Part of the Arabian–Nubian Shield in Kenya and Tanzania

Fritz¹,

Hauzenberger²

2021

The Geology of the Arabian-Nubian Shield

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Isotope chemostratigraphy of marbles in northeastern Mozambique: Apparent depositional ages and tectonostratigraphic implications

Cited by 52 publications

References 41 publications

The Geology and Geochemistry of the East African Orogen in Northeastern Mozambique

The Geology and Geochemistry of the East African Orogen in Northeastern Mozambique

C–O isotope geochemistry of the Dashiqiao magnesite belt, North China Craton: implications for the Great Oxidation Event and ore genesis

The Southern Part of the Arabian–Nubian Shield in Kenya and Tanzania

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