Causes and implications of Mid- to Late Holocene relative sea-level change in the Gulf of Kachchh, western India

Abstract

The relict intertidal deposits from the Kharod River Estuary, Gulf of Kachchh, and the distal end of Kori Creek are used to infer the Mid- to Late Holocene relative sea-level (RSL) change in western India. Employing sedimentology, geochemistry, palynology, ichnology, and optical and radiocarbon dating, the study suggests the dominance of fluvial activity between 16.5 ± 1.6 and 9.9 ± 0.7 ka. After ~7 ka (7.3 ± 0.4, 6.8 ± 0.5 ka), the sea level showed a positive tendency until 4.7 ± 0.2 ka. The tectonically corrected Mid-Holocene RSL change is estimated as 1.45 ± 0.33 m between ~7 and ~5 ka. The study suggests that the Mid-Holocene RSL high was due to the meltwater contribution from the Himalayan cryosphere, with subordinate contribution from glacio-isostatic adjustment and crustal subsidence. The Late Holocene tectonically corrected RSL change at ~1 ka (1.1 ± 0.1 ka and 1045 ± 175 cal yr BP) is estimated as 0.53 ± 0.43 m. This is ascribed to monsoon wind-driven tidal ingression that might have affected the tidal amplitude positively. The study suggests that the Mid-Holocene RSL change did not play a deterministic role in the abandonment of the Harappan coastal settlements.

Introduction to Geology of the Kachchh (Kutch) Basin, Western India

“…At places, the relict intertidal flats are preserved in the spit-sheltered location. Such sheltered locations with low tidal amplitudes and restricted wave activity have deposited fine, cohesive deposits in low energy environments (weakest current) occur at various elevations from the present-day tidal amplitude (Sharma et al 2020). Thakkar et al (1999Thakkar et al ( , 2001 reported the Quaternary sequences within the rocky mainland in the form of three major episodes as alluvial and colluvial fan deposits as Early Pleistocene, sandy sheets of miliolites with boulders and pebbles as middle Pleistocene and fluvial sand silt and clay with some aeolian deposits of late Pleistocene and Recent age.…”

The Unique Geoheritage of the Kachchh (Kutch) Basin, Western India, and its Conservation

“…In places, relict intertidal flats are preserved in the spit-sheltered locations. Such locations have low tidal amplitudes and restricted wave activity and have deposited fine, cohesive deposits in a low energy environment but now occur at various elevations compared to the present-day tidal amplitude (Sharma et al 2020).…”

Middle to Late Holocene palaeoenvironmental evolution of the western Great Rann of Kachchh, India: Insights from ichnology, geochemistry, and sedimentology

“…Since then, the basin has recorded several episodes of transgression and regression, documenting the variety of palaeoenvironments. The most recent period of the geological history, that is, the Holocene period, has speculatively witnessed transgressive–regressive cycle in the western continental margin of India (Banerji, Pandey, Bhushan, & Juyal, 2015; Das, Prizomwala, Makwana, & Thakkar, 2017; Desai & Patel, 2008; Makwana, Prizomwala, Chauhan, Phartiyal, & Thakkar, 2019; Patel & Desai, 2009; Patel, Desai, & Bhatt, 2001; Sharma et al, 2021; Solanki, Prizomwala, Makwana, & Solanki, 2021; Tyagi et al, 2012). The spatio‐temporal evidences of these are sparsely documented, and for reconstructing a reliable relative sea level history, more data are warranted.…”

“…Previously, the Great Rann of Kachchh (GRK) has been investigated for its evolutionary history, stratigraphy, and shallow subsurface nature (Glennie & Evans, 1976; Khonde et al, 2011, 2017,b; Makwana et al, 2019; Maurya, Khonde, Das, Chowksey, & Chamyal, 2013; Merh, 2005; Ngangom, Thakkar, Bhushan, & Juyal, 2012; Sarkar et al, 2020; Sharma et al, 2021; Thakkar, Mamata, Thakkar, & Juyal, 2012; Tyagi et al, 2012). The Ranns are considered as depocentres of Holocene sedimentation and thus ideal sites for reconstructing palaeoenvironmental history (Maurya et al, 2013; Merh, 2005).…”