Micromorphology of the Paleosols to Reconstruct Late Quaternary Paleoclimatic Record, Alluvial Cyclicity, and Stratigraphy of the Ganga Basin

Micromorphology has been utilized as one of the most useful tools to record the paleopedological details of the paleosols archived in the geological records of the Earth. In this chapter, we describe the presence of paleosols, their paleopedofeatures, and the ~100 ka paleopedogenic history from four pedosedimentary successions of the Ganga–Yamuna interfluve (GYI) of the Ganga Basin (GB). Micromorphological features such as microstructures, b-fabrics, rhizocretions, Fe-Mn features, pedogenic CaCO3, and illuvial clay pedofeatures were utilized to describe the pedogenic processes for the last 100 ka archived in 13 paleosols of the Indian Institute of Technology, Kanpur (IITK), drill core and 10 paleosols in the Bhognipur core (BH) succession of the GYI. The paleopedofeatures preserved in paleosols of the GYI range in characteristics from simple and weakly developed to one having strongly developed pedofeatures and that are similar to modern Entisols, Inceptisols, Alfisols, and Vertisols. The IITK succession in the northern part of the GYI is defined by a very well-developed mature paleosol with the Bt horizons at 41–55 m depth and the remaining part of the succession is dominated by only weakly developed paleosols. This mature paleosol at a 41–55 m depth interval defines a prolonged duration of discontinuity at 8000–10,000 years ago in the interfluve when regional scale degradation and paleopedogenic activity took place in the Ganga Basin in response to climate change and landscape stability. On the other hand, the Bhognipur succession in the southern part of the GYI is defined by thin-thick cumulative but weakly developed paleosols defining rapid aggradation over this part of the GYI over the last 100 ka. In addition to micromorphology of the two pedosedimentary successions in the marginal parts of the GYI, two more successions from middle parts, that is, Mawar and Rania, were also investigated to provide an important information regarding alluvial cyclicity and sequence stratigraphy of the GYI and Ganga Basin for the last 100 ka.