Late Paleozoic remagnetization of shallow-water limestones in the Cordillera: Results of micro'-fold tests from stylolitic compaction around chert nodules

Conference · Thu Feb 28 23:00:00 EST 1991 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:5617890

Gillett, S L ^[1]; Geissman, J W ^[2]

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1. Univ. of Nevada, Reno (United States)
2. Univ. of New Mexico, Albuquerque (United States)

In the Desert Range (southern Nevada), the Egan Range (central Nevada), and the southern House Range (western Utah), heterogeneous, shallow-water, miogeoclinal limestones of the Pogonip Group (Early Ordovician) locally contain abundant replacive chert that preserves relict textures from the host limestones as well as clearly detrital grains (e.g. blue-luminescing feldspars). Differential compaction on major stylolites wrapping around chert masses has caused local deformation. The stylolites are a very late diagenetic feature as (1) they cut late cements; and (2) other studies suggest a threshold load is needed to initiate stylolite formation. All three sections yield a low-inclination, southerly characteristic magnetization, residing in magnetite, that must reflect remagnetization because directions from different samples are not dispersed by the compaction deformation. The uniform reversed polarity suggests late Paleozoic remagnetization. It is tentatively attributed to late diagenetic magnetite, such as is well-documented in the Appalachians, because (1) the cherts are almost nonmagnetic, as would be expected from their impermeability if the magnetite were precipitated from late fluids; and (2) abundant authigenic alkali feldspar also suggests late metasomatism. These results underscore the importance of integrating paleomagnetic observations with carbonate textures; both the timing of magnetization and of diagenetic events can be constrained.

• OSTI ID: 5617890
• Report Number(s): CONF-910403--
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 75:3; ISSN AABUD; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AGE ESTIMATION
CARBONATE ROCKS
CHERT
DEVELOPED COUNTRIES
DIAGENESIS
FEDERAL REGION IX
FEDERAL REGION VIII
FELDSPARS
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
IRON ORES
LIMESTONE
MAGNETIC PROPERTIES
MAGNETISM
MAGNETITE
MAGNETIZATION
MINERALOGY
MINERALS
NEVADA
NORTH AMERICA
ORDOVICIAN PERIOD
ORES
OXIDE MINERALS
PALEOMAGNETISM
PALEOZOIC ERA
PHYSICAL PROPERTIES
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
USA
UTAH