TY - JOUR
T1 - Geochemistry of the Late Neoproterozoic Hadb adh Dayheen ring complex, Central Arabian Shield
T2 - Implications for the origin of rare-metal-bearing post-orogenic A-type granites
AU - Moghazi, A. M.
AU - Harbi, H. M.
AU - Ali, K. A.
N1 - Funding Information:
This work is part of a research project AR-18-42 supported by King Abdulaziz City for Science and Technology (KACST). The Authors would like to thank the ACME Analytical Lab., Canada for performing the major and trace analyses. The manuscript has been greatly improved by the constructive comments of Editor-in-Chief Prof. Bor-ming Jahn, Prof. Boris Litvinovsky and an anonymous reviewer.
PY - 2011/11/11
Y1 - 2011/11/11
N2 - The Hadb adh Dayheen ring complex (HDRC), Central Arabian Shield, is an alkaline to peralkaline A-type granite complex. It consists of an inner core of monzogranite followed outward by porphyritic alkali feldspar granite (hornblende biotite granite and aegirine riebeckite granite). Field and textural observations indicate that the different granite types were separated from magma reservoir, at different stages, and emplaced at higher levels along pre-existing fractures. The geochemical characteristics indicate that their magma was most plausibly originated by partial melting of juvenile lower crust following collision between East and West Gondwana at the final stage of the Arabian Shield evolution. The alkali feldspar granites have high abundances of albite and fluorite and wide variation of HFSE and REE that indicate interaction with hydrothermal F-rich fluids. Although there are many geochemical, mineralogical and textural evidence of secondary metasomatic alteration superimposed on the granitic rocks, they show textural features such as the arrangement of albite inclusions along growth planes in quartz (snowball texture) and aegirine that indicate early magmatic crystallization of albite. Also, the strong linear positive correlation of Ta vs. Nb and Zr vs. Hf emphasize that the behavior and enrichment of Ta and Nb are largely controlled by magmatic processes. The events that can explain the evolution of these rocks are: (1) during magmatic evolution, F dissolved in the magma and lowered the crystallization temperature causing REE and HFSE to form complexes and thus behave as incompatible elements, (2) prolonged crystallization of the major mineral phases (quartz and feldspar) formed a late-stage magmatic fluid enriched in volatiles (H2O, F) and trace elements, (3) accessory minerals crystallized from such a phase in the interstices between the major mineral phases, and (4) post-magmatic re-equilibration and formation of secondary albite (Na-metasomatism) has probably led to the redistribution of some major elements and limited redistribution of HFSE and REE.
AB - The Hadb adh Dayheen ring complex (HDRC), Central Arabian Shield, is an alkaline to peralkaline A-type granite complex. It consists of an inner core of monzogranite followed outward by porphyritic alkali feldspar granite (hornblende biotite granite and aegirine riebeckite granite). Field and textural observations indicate that the different granite types were separated from magma reservoir, at different stages, and emplaced at higher levels along pre-existing fractures. The geochemical characteristics indicate that their magma was most plausibly originated by partial melting of juvenile lower crust following collision between East and West Gondwana at the final stage of the Arabian Shield evolution. The alkali feldspar granites have high abundances of albite and fluorite and wide variation of HFSE and REE that indicate interaction with hydrothermal F-rich fluids. Although there are many geochemical, mineralogical and textural evidence of secondary metasomatic alteration superimposed on the granitic rocks, they show textural features such as the arrangement of albite inclusions along growth planes in quartz (snowball texture) and aegirine that indicate early magmatic crystallization of albite. Also, the strong linear positive correlation of Ta vs. Nb and Zr vs. Hf emphasize that the behavior and enrichment of Ta and Nb are largely controlled by magmatic processes. The events that can explain the evolution of these rocks are: (1) during magmatic evolution, F dissolved in the magma and lowered the crystallization temperature causing REE and HFSE to form complexes and thus behave as incompatible elements, (2) prolonged crystallization of the major mineral phases (quartz and feldspar) formed a late-stage magmatic fluid enriched in volatiles (H2O, F) and trace elements, (3) accessory minerals crystallized from such a phase in the interstices between the major mineral phases, and (4) post-magmatic re-equilibration and formation of secondary albite (Na-metasomatism) has probably led to the redistribution of some major elements and limited redistribution of HFSE and REE.
KW - Arabian Shield
KW - Geochemistry
KW - Post-collision A-type granite
KW - Rare-metals
KW - Ring complex
KW - Saudi Arabia
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U2 - 10.1016/j.jseaes.2011.07.018
DO - 10.1016/j.jseaes.2011.07.018
M3 - Article
AN - SCOPUS:80053319528
SN - 1367-9120
VL - 42
SP - 1324
EP - 1340
JO - Journal of Asian Earth Sciences
JF - Journal of Asian Earth Sciences
IS - 6
ER -