Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 2012 | public
Journal Article

Constraints on Neoproterozoic paleogeography and Paleozoic orogenesis from paleomagnetic records of the Bitter Springs Formation, Amadeus Basin, central Australia


The supercontinent Rodinia is hypothesized to have been assembled and positioned in tropical latitudes by the early Neoproterozoic Era. Paleomagnetic data from limestones of Svalbard and basaltic dikes of South China have been interpreted to record rapid changes in paleogeography driven by true polar wander that may have rotated the supercontinent in association with the ∼800 Ma Bitter Springs carbon isotope event. To further constrain early Neoproterozoic paleogeography and to test proposed rapid rotations, we have developed sequence- and chemo-stratigraphically constrained paleomagnetic data from the Bitter Springs Formation of the Amadeus Basin of central Australia. A new paleomagnetic pole for the post–Bitter Springs stage ∼770 Ma Johnny's Creek Member (Bitter Springs Formation) provides a positive test for a long-lived history of Australia and Laurentia in a single supercontinent as its similar position to late Mesoproterozoic north Australia poles reproduces the closure of the Laurentian "Grenville Loop." This new pole also provides support for the hypothesis that there was significant rotation between north and south+west Australia at the end of the Neoproterozoic as this rotation brings the south+west Australia ∼755 Ma Mundine Well pole into much closer proximity to the north Australia Johnny's Creek pole. Syn–Bitter Springs stage carbonates of the Love's Creek Member of the formation contain a well-behaved remanence held by magnetite. The direction of this remanent magnetization falls on the Cambrian portion of Australia's apparent polar wander path suggesting that the magnetite may have formed authigenically at that time. If primary, the Love's Creek direction is consistent with the true polar wander hypothesis for the Bitter Springs stage, is internally consistent with the relative sea level changes inferred from the formation, and can constrain Australia to a SouthWest North America East AnTarctica (SWEAT) fit. A remanence held by pyrrhotite in carbonates of the Bitter Springs Formation corresponds to the apparent polar wander path of Australia at ∼350 Ma. This component can be used to constrain the history of the Devonian-Carboniferous Alice Springs Orogeny as it demonstrates that regional folding of basinal sediments occurred prior to ∼350 Ma, but that the latest stages of tectonism in the hinterland drove fluids through the sediments that altered redox conditions to favor pyrrhotite precipitation.

Additional Information

© 2012 American Journal of Science. Seth Burgess, Ross Mitchell, Catherine Rose, Justin Strauss and Sarah Swanson- Hysell assisted with field work. We gratefully acknowledge assistance from the Northern Territory Geological Survey. In particular, Max Heckenberg at the Alice Springs core library and Christine Edgoose at the central office. We thank numerous pastoralists, the community of Areyonga, Ross River Tourist Resort and the Northern Territory Government for permission to conduct fieldwork on their lands. Steven Shonts and Jenn Kasbohm assisted with sample preparation. Hysteresis loops were acquired on an AGM instrument at Princeton Measurements Corporation Headquarters. We thank Anthony Cumbo for access to the instrument and his help with the experiments. Low-temperature rock magnetic experiments were conducted at the Institute for Rock Magnetism, which is funded by the Instruments and Facilities Division of NSF and by the University of Minnesota. We thank Mike Jackson for his help with the experiments and their interpretation. Tim Raub and Isaac Hilburn are thanked for their technical support during measurements at the Caltech Paleomagnetism Lab. Mike McElhinny of the ANU in Canberra made his lab available for the early work on the Heavitree Formation, with a superconducting magnetometer on loan from Eugene Shoemaker of Caltech. We gratefully acknowledge the following scientists for their freely available software: Lisa Tauxe for her PmagPy software package that was utilized for the bootstrap fold tests, Craig Jones for his Paleomag X paleomagnetic data analysis program, Jean-Pascal Cogné for his Paleomac plate reconstruction software program, and Bob Kopp for the matRockmag data analysis package. The manuscript benefitted from reviews from Rob Van der Voo, Phil Schmidt and anonymous referees. The research was supported financially by NSF-EAR0514657 to A.C.M., an NSF EAPSI fellowship to N.L.S.-H., a grant from the American Philosophical Society's Lewis and Clark Fund for Exploration and Field Research in Astrobiology to N.L.S.-H. and by Princeton University.

Additional details

August 19, 2023
October 23, 2023