ISSN:
1365-246X
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
The Late Carboniferous and Permo-Triassic red beds of the Pyeongan Supergroup in the Okcheon zone, southern part of the Korean Peninsula, were found to contain three components of remanence. These components, which are resolved by thermal demagnetization, are characterized by high (Hhc for Late Carboniferous and Hhpc for Permo-Triassic), intermediate (Hm) and low (HI) unblocking temperatures. As the maximum unblocking temperature spectra of the Hhc (Hhpt) component often overlapped the Hm spectra above 680° C, 3° to 5° C steps were needed above 670° C to resolve the Hhc-(Hhpt-) component magnetization.The tilt-corrected mean direction of the Hhc component red beds is D = 255.5°, 1 = -2.4° (α95= 20.8°), and that of the Hhpt component is D = 271.9°, 1= -33.4° (α95= 16.5°). the precisions of mean directions of Hhc and Hhpt components improve after tilt correction and allow the directions to be distinguished from each another. This indicates that both Hhc and Hhpt component magnetizations were acquired during or shortly after the deposition of the red beds.According to micropetrographic observations, the haematite in the red beds can be divided into three types: detrital specularite (A), non-detrital specularite (B), and pigmental haematite (C). Type A grains are tens of micrometres in size, and many of them are martite. the remanent magnetization of type A is possibly depositional remanent magnetization (DRM), post-DRM or chemical remanent magnetization (CRM) acquired close to the deposition time, whereas that of types B and C is of CRM origin acquired during and after folding, respectively. the time of folding is well established as a Triassic to Jurassic event. We believe that the remanent magnetization carried by type A grains is primary, and is correlated to Hhc-(or Hhpt-) component magnetization.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-246X.1996.tb06550.x
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