Carbonate platforms in wedge-top basins: An example from the Gunung Mulu National Park, Northern Sarawak (Malaysia)

Unravelling the depositional origins and diagenetic alteration of carbonate breccias

“…Most authors comment on the significant hiatus between the upper Late Oligocene brecciated part of the Batu Gading Limestone and the underlying Late Eocene limestones, with localised evidence of karstification associated with the hiatal surface, but do not comment on breccia origins (Adams and Haak, 1962;Adams, 1965;Leichti et al, 1960;Abdullah and Yaw, 1993). Wannier (2009) inferred for the Batu Gading breccia that, consistent with the Melinau basin, differential loading by fresh sediments maintained rotation of the thrusted part of the wedge-top basin leading to local reworking down-dip as well as incorporation into the wedge-top basin. While the structural development of the Batu Gading Limestone is postulated in Wannier (2009) and the foraminiferal stratigraphy of the deposits also outlined (Adams andHaak, 1962, Adams, 1965;Abdullah and Yaw, 1993), this is the first detailed account of the sedimentology and diagenesis of these deposits.…”

“…Wannier (2009) inferred for the Batu Gading breccia that, consistent with the Melinau basin, differential loading by fresh sediments maintained rotation of the thrusted part of the wedge-top basin leading to local reworking down-dip as well as incorporation into the wedge-top basin. While the structural development of the Batu Gading Limestone is postulated in Wannier (2009) and the foraminiferal stratigraphy of the deposits also outlined (Adams andHaak, 1962, Adams, 1965;Abdullah and Yaw, 1993), this is the first detailed account of the sedimentology and diagenesis of these deposits.…”

“…), Heterostegina and Cycloclypeus (cf. Adams and Haak, 1962;Adams, 1965;Wannier, 2009). The biotic assemblage is stenohaline with good preservation of planktonic foraminifera indicative of an open oceanic influence.…”

“…(cf. Adams and Haak, 1962;Adams, 1965;Wannier, 2009). The abundance of micrite together with common planktonic foraminifera and small benthic foraminifera indicate a low energy, open oceanic, probably sub-photic depth depositional setting for the planktonic foraminifera facies group.…”

“…Limestones during the Mid to Late Eocene is interpreted to have been on rotating slices of the folded deep marine turbidites and hemipelagics of the Rajang accretionary prism (Hutchinson, 2005;Wannier, 2009). However, limited data points do not allow for spatial or structural constraints to be applied (Wannier, 2009).…”