Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia
Loveringite, a rare member of the crichtonite group with nominal formula (Ca,Ce)(Ti,Fe,Cr,Mg)<sub>21</sub>O<sub>38</sub>, was found in the Khamal layered mafic intrusion, the first known locality for this mineral in the Arabian Shield. The Khamal intrusion, a large post-colli...
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| Format: | Article |
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MDPI AG
2023-01-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/13/2/172 |
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| author | Bassam A. Abuamarah Fahad Alshehri Mokhles K. Azer Paul D. Asimow |
| author_facet | Bassam A. Abuamarah Fahad Alshehri Mokhles K. Azer Paul D. Asimow |
| author_sort | Bassam A. Abuamarah |
| collection | DOAJ |
| description | Loveringite, a rare member of the crichtonite group with nominal formula (Ca,Ce)(Ti,Fe,Cr,Mg)<sub>21</sub>O<sub>38</sub>, was found in the Khamal layered mafic intrusion, the first known locality for this mineral in the Arabian Shield. The Khamal intrusion, a large post-collisional mafic complex, is lithologically zoned, bottom to top, from olivine gabbro through gabbronorite, hornblende gabbro, anorthosite, and diorite to quartz diorite. Loveringite is found near the base of the complex, as an intercumulus phase in olivine gabbro. Most loveringite grains are homogeneous, although a few grains are zoned from cores rich in TiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, Cr<sub>2</sub>O<sub>3</sub>, and CaO towards rims rich in FeO*, ZrO<sub>2</sub>, V<sub>2</sub>O<sub>3</sub>, Y<sub>2</sub>O<sub>3</sub>, and rare earth elements (REE). Petrographic relations indicate that loveringite formed after crystallization of cumulus olivine, pyroxenes, and plagioclase. Anhedral and corroded crystals of loveringite are surrounded by reaction rims of Mn-bearing ilmenite and baddeleyite, suggesting that the residual liquid evolved into and subsequently out of the stability field of loveringite. The budget of incompatible elements (Zr, Hf, REE, U, and Th) hosted in loveringite is anomalous for a primitive mafic liquid. Saturation in loveringite is likely the result of early contamination of the primary melt by anatexis of country rock, followed by isolation of evolving liquid in intercumulus space that restricted communication with the overlying magma chamber. The zoned crystals likely reflect diffusive equilibration between residual loveringite grains and their reaction rims of ilmenite. |
| first_indexed | 2024-03-11T08:23:09Z |
| format | Article |
| id | doaj.art-71cd05825923479687593c0a0f9e86df |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-11T08:23:09Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-71cd05825923479687593c0a0f9e86df2023-11-16T22:17:53ZengMDPI AGMinerals2075-163X2023-01-0113217210.3390/min13020172Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi ArabiaBassam A. Abuamarah0Fahad Alshehri1Mokhles K. Azer2Paul D. Asimow3Geology and Geophysics Department, College of Science, King Saud University, Riyadh 11451, Saudi ArabiaGeology and Geophysics Department, College of Science, King Saud University, Riyadh 11451, Saudi ArabiaGeological Sciences Department, National Research Centre, Dokki, Cairo 12622, EgyptDivision of Geological & Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USALoveringite, a rare member of the crichtonite group with nominal formula (Ca,Ce)(Ti,Fe,Cr,Mg)<sub>21</sub>O<sub>38</sub>, was found in the Khamal layered mafic intrusion, the first known locality for this mineral in the Arabian Shield. The Khamal intrusion, a large post-collisional mafic complex, is lithologically zoned, bottom to top, from olivine gabbro through gabbronorite, hornblende gabbro, anorthosite, and diorite to quartz diorite. Loveringite is found near the base of the complex, as an intercumulus phase in olivine gabbro. Most loveringite grains are homogeneous, although a few grains are zoned from cores rich in TiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, Cr<sub>2</sub>O<sub>3</sub>, and CaO towards rims rich in FeO*, ZrO<sub>2</sub>, V<sub>2</sub>O<sub>3</sub>, Y<sub>2</sub>O<sub>3</sub>, and rare earth elements (REE). Petrographic relations indicate that loveringite formed after crystallization of cumulus olivine, pyroxenes, and plagioclase. Anhedral and corroded crystals of loveringite are surrounded by reaction rims of Mn-bearing ilmenite and baddeleyite, suggesting that the residual liquid evolved into and subsequently out of the stability field of loveringite. The budget of incompatible elements (Zr, Hf, REE, U, and Th) hosted in loveringite is anomalous for a primitive mafic liquid. Saturation in loveringite is likely the result of early contamination of the primary melt by anatexis of country rock, followed by isolation of evolving liquid in intercumulus space that restricted communication with the overlying magma chamber. The zoned crystals likely reflect diffusive equilibration between residual loveringite grains and their reaction rims of ilmenite.https://www.mdpi.com/2075-163X/13/2/172Arabian Shieldlayered mafic intrusionKhamal intrusionolivine gabbroloveringite |
| spellingShingle | Bassam A. Abuamarah Fahad Alshehri Mokhles K. Azer Paul D. Asimow Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia Minerals Arabian Shield layered mafic intrusion Khamal intrusion olivine gabbro loveringite |
| title | Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia |
| title_full | Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia |
| title_fullStr | Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia |
| title_full_unstemmed | Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia |
| title_short | Loveringite from the Khamal Layered Mafic Intrusion: The First Occurrence in the Arabian Shield, Northwest Saudi Arabia |
| title_sort | loveringite from the khamal layered mafic intrusion the first occurrence in the arabian shield northwest saudi arabia |
| topic | Arabian Shield layered mafic intrusion Khamal intrusion olivine gabbro loveringite |
| url | https://www.mdpi.com/2075-163X/13/2/172 |
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