Dynamic melting of proterozoic upper mantle: Evidence from rare earth elements in oceanic crust of Eastern Newfoundland

✍ Scribed by D. F. Strong; J. Dostal

• Publisher: Springer
• Year: 1980
• Tongue: English
• Weight: 835 KB
• Volume: 72
• Category: Article
• ISSN: 0010-7999
• DOI: 10.1007/bf00399476

✦ Synopsis

Rare Earth Element (REE) data confirm earlier suggestions from major and trace elements that the Proterozoic Burin Group in the southwestern Avalon Zone is similar to modern oceanic tholeiites, and also exhibit a systematic evolution through the sequence. The Group forms a 60-km long belt consisting of four formations of pillowed basalt, two of subaqueous volcaniclastic and minor stromatolitic sediments and pyroclastics, and a thick gabbro-quartz diorite sill, with a total thickness of about 5000 m. Basalts of the oldest formation are enriched in light (LREE) with a chondrite-normalized pattern similar to alkali basalts. REE patterns through the rest of the sequence can be matched by those of modern ocean basins, with a steady decrease in total REE and a distinct depletion in LREE at the top of the sequence. REE patterns of the gabbroic sill are similar to those of oceanic gabbros, with LREE depletion and a small positive Eu anomaly. This evolutionary pattern can be interpreted as the result of progressive 'dynamic' partial melting and depletion of a single mantle source region.