Remagnetization and orogenic fluids: testing the hypothesis in the centralAppalachians

Palaeomagnetic and geochemical studies on Devonian sedimentary rocks in the Valley and Ridge province in West Virginia indicate that the hypothesized relationship between orogenic fluids and remagnetization is not straightfor ward. The Helderberg Group, an aquitard, and the Oriskany Formation, a pala eoaquifer, both contain similar, synfolding late Palaeozoic chemical remane nt magnetizations (CRMs) residing in magnetite. The results from the Oriska ny Formation are consistent with remagnetization by orogenic fluids because the unit contains geochemical evidence for the migration of such fluids. I n contrast, there is no geochemical evidence for the widespread migration o f orogenic fluids into the Helderberg Group and thus the CRM cannot be rela ted to such fluids. Another remagnetization mechanism, which remains elusiv e, must be responsible for the CRM in the Helderberg Group.