Evidence for the volcanoclastic genesis of the Carnian diamondiferous bed in the Ust鈥?Olenek area (from petrographic and geochemical data)
- 作者：V.F. Proskurnin ; vasily_proskurnin@vsegei.ru ; N.P. Vinogradova ; A.V. Gavrysh ; M.V. Naumov
- 关键词：diamonds ; volcanoclastic deposits ; freatomagmatic eruption ; Siberian Platform ; Triassic
- 刊名：Russian Geology and Geophysics
- 出版年：2012
- 期刊代码：10_10687971
- 类别：ear
- 出版时间：June, 2012
- 卷：53
- 期：6
- 页码：535-545
- 文件大小：6312 K
摘要
A detailed petrographic study of a 0.4-1.2 m thick Carnian diamondiferous bed of the Angardam-Tasa Ridge (Ust鈥?Olenek area, northern Siberia) was performed. It showed that the bed earlier referred to as a terrigenous deposit might be interpreted as an intensely altered volcanoclastic lapilli tuff of basic and, probably, ultrabasic composition. The tuff occurs within a 100 m thick Ladinian-Carnian volcanosedimentary sequence. It consists mainly of resurgent material: altered lithoclasts (nodules of basic-ultrabasic? lithology), devitrified volcanic glass, fragments of autolithic breccia, etc. The thin volcanoclastic sheet is supposed to have formed within a sedimentation basin as a result of phreatomagmatic eruptions of kimberlite volcanoes. The substantiation of the volcanogenic origin of the Carnian diamondiferous bed might be a new approach to elucidate the primary source of widespread placer diamonds in Arctic Siberia.