Petrography and the REE-composition of apatite in the Paleoproterozoic Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia
Joosu, Lauri; Lepland, Aivo; Kreitsmann, Timmu; Üpraus, Kärt; Roberts, Nick M.W.; Paiste, Päärn; Martin, Adam P.; Kirsimäe, Kalle. 2016 Petrography and the REE-composition of apatite in the Paleoproterozoic Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia. Geochimica et Cosmochimica Acta, 186. 135-153. 10.1016/j.gca.2016.04.043
Before downloading, please read NORA policies.Preview |
Text
Joosu%20et%20al%20GCA%20author%20version.pdf - Accepted Version Download (1MB) | Preview |
Abstract/Summary
The first globally significant phosphorous-rich deposits appear in the Paleoproterozoic at around 2 Ga, however, the specific triggers leading to apatite precipitation are debated. We examine phosphorous-rich rocks (up to 8 wt% P2O5) in 1.98–1.92 Ga old Pilgujärvi Sedimentary Formation, Pechenga Greenstone Belt, Russia. Phosphates in these rocks occur as locally derived and resedimented sand-to-gravel/pebble sized grains consisting of apatite-cemented muddy sediments. Phosphatic grains can be subdivided into four petrographic types (A–D), each has a distinct REE signature reflecting different early-to-late diagenetic conditions and/or metamorphic overprint. Pyrite containing petrographic type D, which typically has a flat REE pattern, negative Ce anomaly and positive Eu anomaly, is the best preserved of the four types and best records conditions present during apatite precipitation. Type D phosphatic grains precipitated under (sub)oxic basinal conditions with a significant hydrothermal influence. These characteristics are similar to Zaonega Formation phosphates of NW Russia’s Onega Basin, and consistent with phosphogenesis triggered by the development of anoxic(sulfidic)–(sub)oxic redoxclines at shallow sediment depth during the Paleoproterozoic.
Item Type: | Publication - Article |
---|---|
Digital Object Identifier (DOI): | 10.1016/j.gca.2016.04.043 |
ISSN: | 00167037 |
NORA Subject Terms: | Earth Sciences Marine Sciences Biology and Microbiology |
Date made live: | 10 Jun 2016 08:36 +0 (UTC) |
URI: | https://nora.nerc.ac.uk/id/eprint/513786 |
Actions (login required)
View Item |
Document Downloads
Downloads for past 30 days
Downloads per month over past year