Magnetostratigraphy, fence diagrams and basin analysis
Maodu Yan, Rob Van Der Voo, Xiao-Min Fang, Chunhui Song, 2013. "Magnetostratigraphy, fence diagrams and basin analysis", Magnetic Methods and the Timing of Geological Processes, L. Jovane, E. Herrero-Bervera, L.A. Hinnov, B. Housen
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Correlation of lithostratigraphic sections is widely used to examine the nature of lateral facies changes within or between basins. It can provide significant clues for regional environmental and palaeogeographic reconstructions. There are problems associated with lithostratigraphic correlation; diachronous deposition of similar lithological units may not be recognized. We report here an attempt to determine lateral facies changes in coeval sedimentary sections, through three-dimensional magnetostratigraphic correlations in the Guide Basin, an intramontane basin in the northeastern part of the Tibetan Plateau. The method is successful for correlating lateral facies and helps to identify sediment sources in the basin.
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Magnetostratigraphy is best known as a technique that employs correlation among different stratigraphic sections using the magnetic directions defining geomagnetic polarity reversals as marker horizons. The ages of the polarity reversals provide common tie points among the sections, allowing accurate time correlation. Recently, studies of magnetic methods and the timing of geological processes have acquired a broader meaning, now referring to many types of magnetic measurements within a stratigraphic sequence. Many of these measurements provide correlation and age control not only for the older and younger boundaries of a polarity interval, but also within intervals. Thus, magnetostratigraphy no longer represents a dating tool based only on geomagnetic polarity reversals, but comprises a set of techniques that includes measurements of geomagnetic field parameters, environmental magnetism, rock-magnetic properties, radiometric dating and astronomically forced palaeoclimatic change recorded in sedimentary rocks, and key corrections to magnetic directions related to geodynamics, palaeocurrents, tectonics and diagenetic processes.