Chemical remagnetization and burial diagenesis: Testing the hypothesis in the Pennsylvanian Belden Formation, Colorado

摘要: Lower Pennsylvanian Belden Formation carbonate rocks from Colorado were subjected to paleomagnetic, rock magnetic and geochemical studies test whether there is a connection between widespread chemical remanent magnetization (CRM), carried by authigenic magnetite, burial diagenesis. Thermal demagnetization results indicate the presence of two components natural (NRM) after removal low unblocking temperature (NRM-250°C) remanence that interpreted be modern, viscous magnetization. An intermediate (250–400°C) component with normal reversed polarity Tertiary directions thermoviscous Many limestones also contain high (400–570°C) which CRM. Fold tests different parts basin CRM was acquired either before or during Laramide folding. This magnetite formed replacement pyrite. Hysteresis ratios are consistent those reported for other remagnetized carbonates single-domain/pseudo single-domain magnetite. Although elevated 87Sr/86Sr values passage radiogenic fluids through limestones, contact vein do not support hypothesis these responsible The time acquisition, varies late Paleozoic Cretaceous, coincides modeled organic matter maturation in basin. suggests diagenetic reactions, triggered moderate temperatures, may have caused authigenesis probably gave rise