Paleomagnetic investigation of the basal Maieberg Formation (Namibia) cap carbonate sequence (635 Ma): Implications for Snowball Earth postglacial dynamics

• DOI: 10.1130/b37378.1
• Publication Date: 2024-04-23T16:55:31Z
• Authors: Thales Pescarini; Ricardo I.F. Trin...; Paul F. Hoffman; Lucy Gomes Sant’Anna
• Keywords: Sequence (biology)

Abstract In this study, we investigate the paleomagnetism of basal Maieberg Formation (Namibia) cap carbonate sequence to elucidate its magnetic properties and paleolatitude deposition, establish global correlations, contribute understanding Snowball Earth postglacial dynamics. Two distinct magnetization components, C1 C2, were identified. is interpreted as a depositional or post-depositional remanent carried by detrital pseudo-single domain (PSD) magnetite, while C2 component thermochemical fine authigenic single (SD)–PSD magnetite. The deposition provided 33.3° ± 3.2°, which gives an initial quantitative approximation for underlying Marinoan Ghaub diamictites. thickness Keilberg Member dolostone anomalously high calculated with C1, suggests that other factors besides influence on oversaturation may have influenced sedimentary production dolostones overall flooding sequence. Possible explanations could include alkalinity input combined local tectonic subsidence during long glacial period unusually low sedimentation rates, appear be in favorable configuration substantial Member. Paleomagnetic field reversals at analogous units globally suggest longer duration marine transgression than energy-balance deglaciation models sedimentological-geochemical observations constrained. Factors such ocean warming, thermal expansion, glacio-isostatic adjustments imply extended transgressions beyond period. Still, magnetostratigraphic estimates transgressive sequences require time scales factor five more. Thus, conflict arising between derived from paleomagnetic data constraints imposed climate physics underscores uncertainties regarding unconventional state remanence acquisition mechanism within these carbonates not fully understood. Importantly, if phenomenon proves primary global, widespread occurrence stratigraphically compressed would support precise temporal correlation dolostones. pole correlates Cambrian remagnetization poles observed West Gondwana, now extend Congo craton. likely stems diagenesis-related low-temperature magnetite formation after conversion iron-rich smectite iron-poor illite. Cooling associated Kaoko orogen’s exhumation uplift possibly locked system ca. 520 Ma, supported position Gondwana apparent polar wander path, although remain valid.