Date of Award
Doctor of Philosophy
In this research, paleomagnetic methods are used to study the magnetization characteristics of both ores and host rocks of several major Mississippi Valley-type (MVT) districts, to date their genesis, and thereby to provide paleomagnetic constraints for models of their genesis. In this thesis, research on three major MVT deposits and on a red bed unit has been undertaken. All four of the study areas are situated in or adjacent to the Ouachita-Appalachian orogenic belt in Paleozoic strata.;The Gays River MVT lead-zinc deposit in Nova Scotia is hosted in the Mississippian Windsor Group. A coeval regional hydrothermal event in the area, high mineralization temperatures and geochemical evidence indicate that the mineralization and magnetization events are coeval. Genesis of this deposit is related to the initial tectonic faulting and uplift of the Alleghenian orogeny.;The northern Arkansas (NAD) and Tri-State (TSD) MVT districts are on the craton of midcontinental U.S.A. Stepwise alternating field (AF) and thermal demagnetization first removed a steep viscous remanence component, leaving an underlying stable ChRM component with very low intensity. For the northern Arkansas, paleomagnetic analysis reveals a Late Devonian (A) component from unmineralized secondary dolomite and a Permian (C) component from mineralized host rocks and silicified rocks. The unaltered Mississippian host rocks of Tri-State retain a primary (B) remanence component.;Paleomagnetic results for the MVT deposits at the Newfoundland Zinc Mines of the northern Appalachians revealed that both ore and host rocks carry a Middle-Late Devonian remanence. Paleomagnetic stability tests constrain the age of both magnetization and mineralization to be post-Taconic or post-Late Ordovician.;Thermal demagnetization reveals that the Pennsylvanian red beds of the lower Pictou Group on Prince Edward Island retain a stable remanence in fine-grained hematite. Positive conglomerate and contact tests along with dual polarity evidence indicate that the remanence is primary and of Stephanian age. In addition, Bingham statistical analysis indicates that poles from the Appalachian orogeny and interior craton segments of North America are significantly different from the Pennsylvanian to Late Triassic. (Abstract shortened by UMI.)
Pan, Hairu, "Paleomagnetism Of Mississippi Valley-type Ores And Their Paleozoic Host Rocks In Eastern North America" (1993). Digitized Theses. 2211.