Distinct sources of bacterial branched GMGTs in the Godavari River basin (India) and Bay of Bengal sediments

•H-shaped brGDGTs/brGMGTs were investigated along a soil-river-sea continuum.•On land, brGMGTs mainly occur at sites with high nutrient and/or low oxygen levels.•BrGMGT composition shifts from basin to marine realm, indicating marine production.•Transport of land-derived brGMGTs to Holocene marine sediments is negligible.•Marine brGMGTs may be produced in the deep water column and/or sediments.