The most recent Giant Gaussian Process (GGP) model, based on the last 5 Ma, has been used as a reference for directional distribution of paleomagnetic record of older rocks as Cenozoic and Proterozoic. However, for Paleozoic times, its validity has not yet been tested. Here we evaluate the validity of this recent GGP model for the Kiaman superchron. We present new paleomagnetic results from a late Pennsylvanian section of glacial rhythmites (Mafra Formation) from southern Brazil. The 5-m section sampled spans more than 800 kyr, as evaluated by cyclostratigraphic analysis. Thermal demagnetization revealed a reversed characteristic component carried by single domain magnetite. Anisotropy of anhysteretic remanent magnetization indicated a small shallowing correction of f = 0.97. The final paleomagnetic pole position is located at 51.9°S, 344.3°E (N = 111, R = 109.0, K = 55.9, A95 = 1.8°), with a mean direction of Dec = 144.2°, Inc = 69.5° (N = 111, R = 110.2, k = 134.4, α95 = 1.2°, Paleolat = 53.2°S). The shape of the distribution of magnetization directions (elongation E = (Formula presented.) and the dispersion of virtual geomagnetic poles ((Formula presented.) are incompatible with the recent model. The reduced dispersion, also found in other studies, implies a different shape in directional distributions for any GGP model describing the Kiaman interval. This result alerts us that we should abandon the use of the recent GGP model as a reference for inclination shallowing correction of Carboniferous sedimentary data.
Bibliographical noteFunding Information:
Comments from two anonymous reviewers improved the paper. This study was supported by the Brazilian funding agency CNPq (308475/2015-1) and in part by the Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior-Brasil (CAPES)-Finance Code 88881.186997/2018-01. The data can be found at https://earthref.org/ERDA/2391/ (demagnetization data), https://earthref.org/ERDA/2392/ (rock magnetism data), and in the Tables?S1, S2, S3, S4, S5, and S6 of supporting information.
- Giant Gaussian Process
- Kiaman superchron
- Mafra Formation