ORIGIN OF HEMATITE CARRYING A LATE PALEOZOIC REMAGNETIZATION IN A QUARTZ SANDSTONE BED FROM THE SILURIAN ROSE HILL FORMATION, VIRGINIA, USA

Paleomagnetic and petrographic studies of a quartz sandstone bed from the Silurian Rose Hill Formation of the Central Appalachians show that hematite carrying a Late Paleozoic remagnetization is authigenic. Comparison of paleopole positions from the Rose Hill Formation with Late Paleozoic poles for North America suggests a synfolding remagnetization. The sandstone cement is characterized by pore-lining hematite, pore-filling berthierine and intergrowths of hematite, berthierine and quartz. These cements postdate pressure solution of detrital quartz grains. Late Paleozoic cementation is a consequence of diagenesis associated with Alleghanian deformation. Detrital Fe-Mg silicate grains art believed to have been a local source of Fe for some authigenic hematite and berthierine, although mass balance calculations suggest that an external source is also required. Some berthierine aggregates are pseudomorphic after detrital Fe-bearing silicate grains. Trace amounts of detrital tourmaline are the only remnants of the detrital Fe-Mg silicates.