TITLE:
The Influence of Variable (Monsoon) Rainfall on Sedimentation in the Roaches Grit and Other Upper Carboniferous Delta Sequences in the UK Pennine Basin
AUTHORS:
Colin Michael Jones
KEYWORDS:
Carboniferous, Delta, Climate, Monsoon, Rainfall, ITCZ, Precession
JOURNAL NAME:
International Journal of Geosciences,
Vol.15 No.8,
August
30,
2024
ABSTRACT: The Roaches Grit in the UK Pennine Basin was a complex deep water deltaic sequence deposited during the Late Carboniferous glacial period. The channels of the upper part of the Roaches Grit, deposited towards the end of the cyclothem after the eustatic minimum, contain evidence for very high seasonal discharges related to strong monsoon rainfall in the catchment areas. In some channels, intense turbulence near the delta front, led to knick point recession and deep incision. These channels were filled with sediments during reduced discharge, including very large sets of cross-bedding up to 16 m thick. Channels were short-lived with frequent avulsions. Over time slightly lower discharges formed laterally migrating channels dominated by bar forms. Different discharge-controlled processes operated on the reactivated delta slope. Incised channels generated turbidity currents during floods which transported sediments directly into the basin far from the delta. Migrating channels built mouth bars; resedimentation during floods formed density currents which then deposited sediment on the lower parts of the slope.