Paleomagnetic stratigraphy and time in sediments: Studies in alluvial Siwalik rocks of Pakistan

Journal Article · Sun Jul 01 00:00:00 EDT 1990 · Journal of Geology; (USA)

DOI:https://doi.org/10.1086/629419· OSTI ID:6033623

Badgley, C ^[1]; Tauxe, L ^[2]

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1. Univ. of Michigan, Ann Arbor (USA)
2. Scripps Institution of Oceanography, La Jolla, CA (USA)

Sediments may acquire magnetic remanence upon deposition and shortly after deposition. Hence, the paleomagnetic record of sedimentary rocks may provide a chronostratigraphic framework for rates and patterns of depositional and post-depositional processes over time scales intermediate between those of modern observation and those of the dated geologic record. Two applications of high-resolution magneto-stratigraphy in Miocene, alluvial rocks of Pakistan illustrate this point. (1) Transition stratigraphy-the dense sampling of a magnetic reversal-of correlated sections in the Dhok Pathan Formation revealed high variability in sediment accumulation rates (over several thousand to 10,000 yr), time-transgressive strata representing a paleosol and a floodplain marsh, and a pervasive post-depositional record mainly from pedogenesis. (2) Lateral tracing of paleomagnetic reversal boundaries in the Chinji Formation revealed a secular change in sediment accumulation rate and evidence for increased accumulation rate associated with extensive sandstones and the time-transgressive nature of certain sandstone units. Both studies demonstrate the significant lateral component to accumulation of lithological units, indicating that individual strata may embody considerably greater time spans in their lateral extent than in any vertical transect. Hence, stratigraphic completeness should be evaluated in the lateral as well as the vertical dimension.

• OSTI ID: 6033623
• Journal Information: Journal of Geology; (USA), Vol. 98:4; ISSN 0022-1376
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
PAKISTAN
SEDIMENTARY BASINS
PALEOMAGNETISM
STRATIGRAPHY
AGE ESTIMATION
CORRELATIONS
DEPOSITION
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRATA
LITHOLOGY
MAGNETIC SURVEYS
MIOCENE EPOCH
SEDIMENTATION
SEDIMENTS
ASIA
CENOZOIC ERA
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
GEOPHYSICAL SURVEYS
MAGNETISM
SURVEYS
TERTIARY PERIOD
580000* - Geosciences