Nasser M. Mahdy , Yasser Abd El-Rahman , Matthias Frische , Martin Ondrejka , Hamid I. Mira , Tsuyoshi Iizuka , Sergey G. Skublov , Gehad M. Saleh , Mohamed M. Ghoniem , Mohammed Mitwally , Hassan El-Sundolly , Hassan Eliwa , Mohammed Hassan , Taher Nasr , Hanaa A. El-Dokouny
{"title":"埃及东沙漠北部新新生代岛弧的残根:来自加塔尔辉长岩全岩和闪石化学的证据","authors":"Nasser M. Mahdy , Yasser Abd El-Rahman , Matthias Frische , Martin Ondrejka , Hamid I. Mira , Tsuyoshi Iizuka , Sergey G. Skublov , Gehad M. Saleh , Mohamed M. Ghoniem , Mohammed Mitwally , Hassan El-Sundolly , Hassan Eliwa , Mohammed Hassan , Taher Nasr , Hanaa A. El-Dokouny","doi":"10.1016/j.chemer.2024.126113","DOIUrl":null,"url":null,"abstract":"<div><p>The tectonic settings and petrogenesis of Neoproterozoic gabbroic rocks are critical to understand the formation and evolution of the Arabian-Nubian accretionary orogen. We present the whole-rock chemistry and amphibole chemistry of the Gattar gabbro in the northern Eastern Desert of Egypt to better understand the formation of this part of the orogen. The Gattar gabbro is composed of variable proportions of amphibole and plagioclase, which imply the hydrous nature of its parent magma. Trace element patterns of the gabbro and the calculated liquids in equilibrium with its amphibole show enrichment in large ion lithophile elements relative to high field strength elements, which indicate that the Gattar magma formed above a subduction zone. The low abundances of high field strength element in the gabbro are consistent with a depleted mantle source similar to intra-oceanic island arc rocks. However, the high Nb/La ratio of the Gattar gabbro (0.46–10.71) is reminiscent to Nb-enriched mafic rocks from subduction settings. The amphibole chemistry suggests that the hydrous magma of the gabbro crystallized at temperature and pressure estimates of 930 °C and 8 kbar and under oxidizing conditions. The Gattar gabbro is affiliated with the Tonian-Cryogenian arc-related mafic gabbro, which is rarely recorded in this northernmost segment of the Arabian-Nubian orogen. In terms of comparison with the Ediacaran post-orogenic gabbros from the northern Eastern Desert, the Gattar gabbro shows lower concentrations of incompatible elements and Ti/V ratio.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 2","pages":"Article 126113"},"PeriodicalIF":2.6000,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"A remnant root of a Neoproterozoic island arc in the Northern Eastern Desert of Egypt: Evidence from the whole-rock and amphibole chemistry of the Gattar gabbro\",\"authors\":\"Nasser M. Mahdy , Yasser Abd El-Rahman , Matthias Frische , Martin Ondrejka , Hamid I. Mira , Tsuyoshi Iizuka , Sergey G. Skublov , Gehad M. Saleh , Mohamed M. Ghoniem , Mohammed Mitwally , Hassan El-Sundolly , Hassan Eliwa , Mohammed Hassan , Taher Nasr , Hanaa A. El-Dokouny\",\"doi\":\"10.1016/j.chemer.2024.126113\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>The tectonic settings and petrogenesis of Neoproterozoic gabbroic rocks are critical to understand the formation and evolution of the Arabian-Nubian accretionary orogen. We present the whole-rock chemistry and amphibole chemistry of the Gattar gabbro in the northern Eastern Desert of Egypt to better understand the formation of this part of the orogen. The Gattar gabbro is composed of variable proportions of amphibole and plagioclase, which imply the hydrous nature of its parent magma. Trace element patterns of the gabbro and the calculated liquids in equilibrium with its amphibole show enrichment in large ion lithophile elements relative to high field strength elements, which indicate that the Gattar magma formed above a subduction zone. The low abundances of high field strength element in the gabbro are consistent with a depleted mantle source similar to intra-oceanic island arc rocks. However, the high Nb/La ratio of the Gattar gabbro (0.46–10.71) is reminiscent to Nb-enriched mafic rocks from subduction settings. The amphibole chemistry suggests that the hydrous magma of the gabbro crystallized at temperature and pressure estimates of 930 °C and 8 kbar and under oxidizing conditions. The Gattar gabbro is affiliated with the Tonian-Cryogenian arc-related mafic gabbro, which is rarely recorded in this northernmost segment of the Arabian-Nubian orogen. In terms of comparison with the Ediacaran post-orogenic gabbros from the northern Eastern Desert, the Gattar gabbro shows lower concentrations of incompatible elements and Ti/V ratio.</p></div>\",\"PeriodicalId\":55973,\"journal\":{\"name\":\"Chemie Der Erde-Geochemistry\",\"volume\":\"84 2\",\"pages\":\"Article 126113\"},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2024-05-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Chemie Der Erde-Geochemistry\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0009281924000370\",\"RegionNum\":3,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"GEOCHEMISTRY & GEOPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chemie Der Erde-Geochemistry","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0009281924000370","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
A remnant root of a Neoproterozoic island arc in the Northern Eastern Desert of Egypt: Evidence from the whole-rock and amphibole chemistry of the Gattar gabbro
The tectonic settings and petrogenesis of Neoproterozoic gabbroic rocks are critical to understand the formation and evolution of the Arabian-Nubian accretionary orogen. We present the whole-rock chemistry and amphibole chemistry of the Gattar gabbro in the northern Eastern Desert of Egypt to better understand the formation of this part of the orogen. The Gattar gabbro is composed of variable proportions of amphibole and plagioclase, which imply the hydrous nature of its parent magma. Trace element patterns of the gabbro and the calculated liquids in equilibrium with its amphibole show enrichment in large ion lithophile elements relative to high field strength elements, which indicate that the Gattar magma formed above a subduction zone. The low abundances of high field strength element in the gabbro are consistent with a depleted mantle source similar to intra-oceanic island arc rocks. However, the high Nb/La ratio of the Gattar gabbro (0.46–10.71) is reminiscent to Nb-enriched mafic rocks from subduction settings. The amphibole chemistry suggests that the hydrous magma of the gabbro crystallized at temperature and pressure estimates of 930 °C and 8 kbar and under oxidizing conditions. The Gattar gabbro is affiliated with the Tonian-Cryogenian arc-related mafic gabbro, which is rarely recorded in this northernmost segment of the Arabian-Nubian orogen. In terms of comparison with the Ediacaran post-orogenic gabbros from the northern Eastern Desert, the Gattar gabbro shows lower concentrations of incompatible elements and Ti/V ratio.
期刊介绍:
GEOCHEMISTRY was founded as Chemie der Erde 1914 in Jena, and, hence, is one of the oldest journals for geochemistry-related topics.
GEOCHEMISTRY (formerly Chemie der Erde / Geochemistry) publishes original research papers, short communications, reviews of selected topics, and high-class invited review articles addressed at broad geosciences audience. Publications dealing with interdisciplinary questions are particularly welcome. Young scientists are especially encouraged to submit their work. Contributions will be published exclusively in English. The journal, through very personalized consultation and its worldwide distribution, offers entry into the world of international scientific communication, and promotes interdisciplinary discussion on chemical problems in a broad spectrum of geosciences.
The following topics are covered by the expertise of the members of the editorial board (see below):
-cosmochemistry, meteoritics-
igneous, metamorphic, and sedimentary petrology-
volcanology-
low & high temperature geochemistry-
experimental - theoretical - field related studies-
mineralogy - crystallography-
environmental geosciences-
archaeometry