TY - JOUR
T1 - Zircon U-Pb geochronology and Nd isotope systematics of the Abas terrane, Yemen
T2 - Implications for Neoproterozoic crust reworking events
AU - Yeshanew, Fitsum G.
AU - Pease, Victoria
AU - Whitehouse, Martin J.
AU - Al-Khirbash, Salah
N1 - Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/9/1
Y1 - 2015/9/1
N2 - High-spatial-resolution secondary-ion mass spectrometry (SIMS) UPb zircon ages, whole-rock Nd isotopic and geochemical data are reported for granites and granitic gneisses from a traverse across the Abas terrane, Yemen, a part of the Precambrian basement of southern Arabian Peninsula. SIMS U-Pb dating identifies two magmatic episodes, the first at c. 790-725Ma represented by granitic gneisses, the second clearly post-tectonic at c. 625-590Ma. The oldest sample in the post-tectonic group is slightly deformed while younger samples are undeformed indicating that penetrative deformation ceased at c. 625Ma in the Abas region. Whole-rock Nd(t) values between -11 and +0.8, Nd model ages of 1.70-1.13Ga indicate a significant contribution of evolved continental material in the genesis of the Abas granitoids, unlike most of the juvenile Arabian-Nubian Shield (ANS), although there are few inherited zircons. Secular variation in e{open}Nd(t) reflects a change in magma source with increasing juvenile magma and diminishing crustal input during post-tectonic (625-590Ma) magmatism. The combination of subduction zone chemistry, absence of older rocks, paucity of inherited zircons, evolved Nd isotopic signatures and the I-type characteristics of the samples suggest that assimilation occurred at depth.
AB - High-spatial-resolution secondary-ion mass spectrometry (SIMS) UPb zircon ages, whole-rock Nd isotopic and geochemical data are reported for granites and granitic gneisses from a traverse across the Abas terrane, Yemen, a part of the Precambrian basement of southern Arabian Peninsula. SIMS U-Pb dating identifies two magmatic episodes, the first at c. 790-725Ma represented by granitic gneisses, the second clearly post-tectonic at c. 625-590Ma. The oldest sample in the post-tectonic group is slightly deformed while younger samples are undeformed indicating that penetrative deformation ceased at c. 625Ma in the Abas region. Whole-rock Nd(t) values between -11 and +0.8, Nd model ages of 1.70-1.13Ga indicate a significant contribution of evolved continental material in the genesis of the Abas granitoids, unlike most of the juvenile Arabian-Nubian Shield (ANS), although there are few inherited zircons. Secular variation in e{open}Nd(t) reflects a change in magma source with increasing juvenile magma and diminishing crustal input during post-tectonic (625-590Ma) magmatism. The combination of subduction zone chemistry, absence of older rocks, paucity of inherited zircons, evolved Nd isotopic signatures and the I-type characteristics of the samples suggest that assimilation occurred at depth.
KW - Arabian Shield
KW - Nd isotopes
KW - Post-tectonic magmatism
KW - Precambrian crustal evolution
KW - U-Pb zircon
KW - Yemen
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U2 - 10.1016/j.precamres.2015.05.037
DO - 10.1016/j.precamres.2015.05.037
M3 - Article
AN - SCOPUS:84932629108
SN - 0301-9268
VL - 267
SP - 106
EP - 120
JO - Precambrian Research
JF - Precambrian Research
ER -