Document Details

Document Type : Article In Journal 
Document Title :
Rb/Sr Geochronology of Some Gneisses and Felsic Intrusions from Afif-Halaban-Ad-Dawadimi-Ar-Rayn Areas, Saudi Arabia
التاريخ الجيلولوجي بطريقة الروبيديوم ـ استرنشيوم لبعض صخور النيس والتداخلات الفلسية من مناطق عفيف ـ حلبان ـ الدوادمي ـ الرين بالمملكة العربية السعودية
 
Subject : Earth Sciences 
Document Language : English 
Abstract : The earliest recognized older basement rock unit in the eastern region of the Arabian Shield is the Ajal group. It comprises interbedded amphibolite, biotite-schist and para-gneiss. A high grade amphibolite south-southwest of Halaban village gave a Rb/Sr age of 845 :!: 19 Ma. It is the oldest Rb/Sr age reported from the area, so far. It is interpreted as the age of metamorphism during the Early Najd Cycle. It preceded the Hulayfah group deposition. The west Al-Quway'iyah (Ad-Dawadimi Province) and Jabal Al- Humayy (Afif Province), are foliated large semicircular granodiorite-granitic complexes. They form negative geomorphologic features surrounded by high circular ridges of slightly metamorphosed Hulayfah and Murdama group rocks. The Rb/Sr ages obtained for Al-Quway'iyah and Jabal Al- Humayy granodiorite-granitic complexes are 725 :!: 10 Ma and 675 :!: 30 Ma, respectively. These ages are interpreted as post-Hulayfah as well as post-Abt Formation tectonism (Tuluhah orogeny). The east Jabal Bitran gneiss belt (Ar-Rayn Province) extends in N-S trend for a distance of 100 km by 40 km, and probably eastwards below the Phanerozoic cover. The gneiss is granodioritic and in places quartz-dioritic and amphibolitic. It was formerly mapped as old fundamental gneiss, but the Rb/Sr age obtained is 584 :!: 14 Ma suggesting that the gneisses should be considered as post-Murdama. Furthermore, a small pink granite stock cutting the gneiss gave a Rb/Sr age of 492 :!: 12 Ma, indicating that the tectono- thermal event at 510 Ma recognized in the western parts of the Arabian Shield had also affected this area. 
ISSN : 1012-8832 
Journal Name : Earth Sciences Journal 
Volume : 2 
Issue Number : 1 
Publishing Year : 1409 AH
1989 AD 
Number Of Pages : 13 
Article Type : Article 
Added Date : Sunday, October 11, 2009 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
عبدالله عبدالمنعمA. A. ABDEL-MONEMResearcher  
أحمد الشنطي A. M. S. AL-SHANTIResearcher  
عبدالعزيز رادين A. A. RADAINResearcher  

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