An early, Synsedimentary, chemical remanent magnetization (CRM) is found in and below terra rosa paleosols with cap regressive carbonate cycles in the Pennsylvanian (Morrowan) Black Prince Limestone in southeastern Arizona. Authigenic hematite, occurring in fractures between soil nodules, in Liesegang bands, and replacing allochems, is abundant in specific horizons and is related to soil-forming processes. Paleomagnetic analysis of many specimens from the paleosol horizons reveals both northwesterly and shallow and southeasterly and shallow directions. These unidirectional, northwesterly and southeasterly magnetizations are interpreted to be antipodal equivalents and show a stratigraphic distribution with at least three reversals. The mean direction (declination 308¿, inclination 9¿) corresponds to a pole position at latitude 34¿N, longitude 143¿E similar to other pre-Kiaman, Carboniferous poles. Some specimens also contain multicomponent magnetizations (those with dual polarities or with curved thermal demagnetization trajectories) and are interpreted to be the result of remagnetization after a reversal in the Earth's field. Demagnetization and rock magnetic results for the reddened rocks confirm that hematite is the primary magnetic carrier. In contrast to the paleosol zones, the magnetization in the interbedded, gray marine limestones resides in magnetite and does not exhibit stable decay. Terra rosa paleosols are likely to have preserved the hematite and associated magnetizations that formed as a result of soil forming processes. These paleosols, therefore, may contain data that are useful in determining pole positions and validating polarity zonations. |