Sedimentary environment of basal Ediacaran barite growth on Baltica in E. Finnmark, N. Norway, and subsequent dissolution/reprecipitation

verfasst von

A. Hugh N. Rice, Sebastian Viehmann, Yongbo Peng, Huiming Bao

Abstract

Basal Ediacaran barite, which has mass-anomalous depleted ¹⁷O, supporting Snowball Earth models, likely grew in shallow-marine settings, but sedimentological constraints lack details. Environmental conditions in the Varanger Palaeovalley during the basal Ediacaran are well preserved in the Nyborg Formation, where barite forms < 15 mm high synsyn-sedimentary crystal fans on Archean basement or thin intervening sediments. Sedimentary evidence suggests crystal fans formed in low-energy, very shallow-marine to subaerial facies. Rare earth element and yttrium signatures in associated carbonates suggest non-saline growth environments. Post-depositional fluid-flow replaced crystal fan barite with silica (now quartz) and redeposited barite as: <1 × 0.2 mm “dispersed” grains in sediments below fans; <5 mm grains replacing calcite filling desiccation cracks; <1 mm grains in basement fissures; <3 µm grains replacing matrix calcite; irregular grains in detrital sheet-silicate + calcite grains. Caledonian dissolution-reprecipitation reworked barite into brittle fractures and stylolites. Barite Δ¹⁷O values are amongst the most negative (-0.9 – -1.25 ‰) and δ¹⁸O values the lowest recorded (9.9 – 16.9 ‰) anywhere, consistent with a high latitude Baltica at ∼ 635 Ma. δ³⁴S values (17.7 – 24.5 ‰) lie within the known range for basal Ediacaran barite.

Organisationseinheit(en)

Institut für Mineralogie
AG Geochemie

Externe Organisation(en)

Universität Wien
Nanjing University

Typ

Artikel

Journal

Precambrian research

Band

406

ISSN

0301-9268

Publikationsdatum

15.06.2024

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Geologie, Geochemie und Petrologie

Ziele für nachhaltige Entwicklung

SDG 14 – Lebensraum Wasser

Elektronische Version(en)

https://doi.org/10.1016/j.precamres.2024.107384 (Zugang: Geschlossen)