Micromorphology of basalt alterite and its implications on the geological processes during quiescence period of the Deccan volcanism, Kharghar hill, Maharashtra, India
Year: 2024
Type: article
Abstract: Palaeoweathering unearths hidden mysteries of the previously weathered (paleo) surfaces. Researchers have shown that each mineral weathers/alters in a particular manner and is process-specific. Micromorphology is the most reliable and well-established technique to identify process-specific features imparted in an alterite under a given set of conditions. The Indian Deccan traps form one of the world’s largest flood basalt volcanic provinces and has numerous exposures. Notwithstanding, systematic micromorphological studies of Deccan flood basalts are lacking compared to such flood basalts of global occurrences. The episodic nature of Deccan volcanism provided subsequent phases of interaction with the Earth’s surface processes, thereby making the basalt alterites an ideal repository of surficial conditions and subsequent duration. Deccan basalt alterite exposed in the Kharghar hill of Mumbai (Maharashtra) has been selected for detailed micromorphology. Micromorphological results from the top to bottom of >70 cm thick, buried basalt alterite show changes in specific pattern of primary mineral alteration, formation of secondary minerals, development and patterns of secondary porosity. For example, the top of studied alterite (i.e. top 30 cm) has irregular, speckled and patchy patterns of mineral alteration, intramineral secondary pores, dominance of secondary products and only isolated alteromorphs that too with large elongate patches. Whereas towards the bottom (i.e. below 30 cm), the alterite shows planar patterns of mineral alteration, which is preceded at places by a linear/speckled pattern and most distinct is the dominance of intermineral pore system connected with transmineral fractures. Therefore, the basalt alterite can be subdivided from top to bottom into two distinct layers namely, alloterite and isalterite. This distinction significantly indicates a change in process with time as well as duration of basalt interaction with then prevailing surficial conditions. Thus, it can be concluded that alteroplasmation was progressively and gradually replaced with pedoplasmation resulting in dominance of supergene processes over hypogene processes.
Author: Anshul Dhiman
Institution: Panjab University
Language: English
Subfield: Soil Science
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W4405814907