Age and hafnium isotopic evolution of the Didesa and Kemashi Domains, western Ethiopia

Blades, Morgan; Collins, Alan S.; Foden, John; Payne, Justin L.; Xu, Xiaochen; Alemu, Tadesse; Woldetinsae, Girma; Clark, Chris; Taylor, Richard

doi:10.1016/j.precamres.2015.09.018

Cited by 47 publications

(33 citation statements)

References 84 publications

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“…We interpret the igneous suite of Jebel Ja'alan to relate to the Tonian subduction of the Mozambique Ocean that separated Neoproterozoic India from the Neoproterozoic African continents. This tectonic setting is broadly similar to the inferred tectonic setting of many of the terranes of the ANS, which are thought to be predominantly intra-oceanic island arcs formed within the same Mozambique Ocean (Johnson & Woldehaimanot, 2003; Meert, 2003; Collins & Pisarevsky, 2005; Johnson et al 2011; Cox et al 2012; Robinson et al 2014; Blades et al 2015; Robinson, Foden & Collins, 2015 a , b ). P–T paths interpreted in this study are also similar to those interpreted for ANS terranes.…”

Section: Discussionsupporting

confidence: 64%

Origin and tectonic evolution of the NE basement of Oman: a window into the Neoproterozoic accretionary growth of India?

et al. 2017

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The Omani basement is located spatially distant from the dominantly juvenile Arabian–Nubian Shield (ANS) to its west, and its relationship to the amalgamation of those arc terranes has yet to be properly constrained. The Jebel Ja'alan (NE Oman) basement inlier provides an excellent opportunity to better understand the Neoproterozoic tectonic geography of Oman and its relationship to the ANS. To understand the origin of this basement inlier, we present new radiogenic isotopic data from igneous bodies in Jebel Ja'alan. U–Pb and 40Ar/39Ar geochronological data are used to constrain the timing of magmatism and metamorphism in the jebel. Positive εHf and εNd values indicate a juvenile origin for the igneous lithologies. Phase equilibria modelling is used to constrain the metamorphic conditions recorded by basement. Pressure–temperature (P–T) pseudosections show that basement schists followed a clockwise P–T path, reaching peak metamorphic conditions of c. 650–700°C at 4–7.5 kbar, corresponding to a thermal gradient of c. 90–160°C/kbar. From the calculated thermal gradient, in conjunction with collected trace-element data, we interpret that the Jebel Ja'alan basement formed in an arc environment. Geochronological data indicate that this juvenile arc formed during Tonian time and is older than basement further west in Oman. We argue that the difference in timing is related to westwards arc accretion and migration, which implies that the Omani basement represents its own tectonic domain separate to the ANS and may be the leading edge of the Neoproterozoic accretionary margin of India.

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Section: Discussionsupporting

confidence: 64%

Origin and tectonic evolution of the NE basement of Oman: a window into the Neoproterozoic accretionary growth of India?

et al. 2017

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“…R scripts to produce plots are provided in Supplementary File C. Data sourced from the following: Alessio et al (), Archibald et al (), Ashwal et al (), Blades et al (), Huang et al (), Long et al (), Morag et al (), Qi et al (), Robinson et al (), Wang et al (), Wang et al (), Zhao et al (), Zheng et al (), Zheng et al (), and Zhou et al ().…”

Section: Links To Rodiniamentioning

confidence: 99%

Evolving Marginal Terranes During Neoproterozoic Supercontinent Reorganization: Constraints From the Bemarivo Domain in Northern Madagascar

et al. 2019

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Madagascar is a key area for unraveling the geodynamic evolution of the transition between the Rodinia and Gondwana supercontinents as it contains several suites of c. 850–700 Ma magmatic rocks that have been postulated to correlate with other Rodinian terranes. The Bemarivo Domain of northern Madagascar contains the youngest of these units that date to c. 750–700 Ma. We present zircon Hf and O isotope data to understand northern Madagascar's place in the Neoproterozoic plate tectonic reconfiguration. We demonstrate that the northern component of the Bemarivo Domain is distinct from the southern part of the Bemarivo Domain and have therefore assigned new names—the Bobakindro Terrane and Marojejy Terrane, respectively. Magmatic rocks of the Marojejy Terrane and Anaboriana Belt are characterized by evolved εHf(t) signatures and a range of δ18O values, similar to the Imorona‐Itsindro Suite of central Madagascar. These magmatic suites likely formed together in the same long‐lived volcanic arc. In contrast, the Bobakindro Terrane contains juvenile εHf(t) and mantle‐like δ18O values, with no probable link to the rest of Madagascar. We propose that the Bobakindro Terrane formed in a juvenile arc system that included the Seychelles, the Malani Igneous Suite of northwest India, Oman, and the Yangtze Belt of south China, which at the time were all outboard from continental India and south China. The final assembly of northern Madagascar and amalgamation of the Bobakindro Terrane and Marojejy Terrane occurred along the Antsaba subduction zone, with collision occurring at c. 540 Ma.

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“…The black box represents the map area in Figure 2. Adapted from Johnson et al (2011) and Blades et al (2015). …”

Section: Geological Setting/backgroundmentioning

confidence: 99%

The origin of the ultramafic rocks of the Tulu Dimtu Belt, western Ethiopia – do they represent remnants of the Mozambique Ocean?

et al. 2017

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The East African Orogen contains a series of high-strain zones that formed as Gondwana amalgamated. The Tulu Dimtu shear belt is one of these N–S structures within the Barka–Tulu Dimtu zone in western Ethiopia, and contains ultramafic bodies of equivocal origin. Identifying the petrogenetic origin of these enigmatic rocks provides evidence for the geodynamic significance of these shear zones. Owing to their altered state, these ultramafic rocks’ well-preserved chrome spinels provide the only reliable evidence for their source and tectonic affiliation. Chrome spinels have high Cr2O3 (30.04–68.76 wt %), while recalculated Fe2O3 (< 2 %) and TiO2 (0.01–0.51 %) values are low. The Cr# (molar Cr3+/Cr3+ + Al2+) and Mg# (Mg2+/Mg2+ + Fe2+) have averages of 0.88 and 0.22, respectively. Based on olivine–spinel equilibria, the calculated fO2 values (FMQ +3.03) for the dunites reveal a highly oxidized environment. This spinel chemistry (high Cr# > 0.6 and low Ti) supports a supra-subduction origin, with an oxidized mantle source more refractory than depleted MORB mantle (DMM). These spinel compositions indicate that some ultramafic bodies in western Ethiopia, including those from Daleti, Tulu and Dimtu, are serpentinized peridotites emplaced as obducted ophiolite complexes. By contrast, the ultramafic rocks from the Yubdo locality have a different spinel chemistry, with strong affiliation with igneous spinels formed in Alaskan-style mafic intrusions. These collective results suggest that regardless of their origin as supra-subduction ophiolites or as Alaskan-type intrusions, these spinels were formed on a convergent-subduction margin.

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Age and hafnium isotopic evolution of the Didesa and Kemashi Domains, western Ethiopia

Cited by 47 publications

References 84 publications

Origin and tectonic evolution of the NE basement of Oman: a window into the Neoproterozoic accretionary growth of India?

Origin and tectonic evolution of the NE basement of Oman: a window into the Neoproterozoic accretionary growth of India?

Evolving Marginal Terranes During Neoproterozoic Supercontinent Reorganization: Constraints From the Bemarivo Domain in Northern Madagascar

The origin of the ultramafic rocks of the Tulu Dimtu Belt, western Ethiopia – do they represent remnants of the Mozambique Ocean?

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