Discussion of Li et al. (2021) – On the origin and significance of composite particles in mudstones: Examples from the Cenomanian Dunvegan Formation, Sedimentology, 68, 737–754

Reply to the Discussion by Al‐Mufti on “On the origin and significance of composite particles in mudstones: Examples from the Cenomanian Dunvegan Formation” by Li et al. (2021), Sedimentology, 68, 737–754

“…Consider that, at the beginning of their journey, muddy intraclasts are water‐rich (upward of 70% by volume; Schieber, 2011) and fragile, and that upon compaction the water is lost, and the particles should yield to gravity and get flattened in bedding‐normal view. In contrast to that expectation, most aggregates outlined by Al‐Mufti (2022) are equidimensional in the bedding‐normal view. There is no evidence of particles flattened by compaction, implying that they were hard‐enough (solid particles) to resist compaction.…”

“…The best way to avoid textural ambiguity in mudstone studies is the study of ion milled surfaces instead of mechanical polishes. We do this routinely and employed this methodology in the Li et al (2021) study that is being critiqued by Al-Mufti (2022).…”

“…No specific criteria are provided to support the designation of the face‐to‐face (FF) aggregates outlined in fig. 1 (Al‐Mufti, 2022) as intraclastic aggregates. Different types of allochthonous MCPs identified in the Dunvegan Formation are characterized by distinct suites of characteristics (for example, grain size, mineral composition, texture; Li et al ., 2021), which allows them to be distinguished from their surroundings.…”

“…Yet, none of the aggregates outlined in fig. 1 (Al‐Mufti, 2022) contain discernible early diagenetic minerals. Because, in the absence of early cementation, argillaceous intraclasts are destined to suffer significant compaction, the equidimensional shape of most aggregates outlined in fig.…”

“…We thank Dr Al‐Mufti for the interest he has taken in our paper (Li et al ., 2021) concerning the types of mud‐dominated composite particles (MCPs) or clay‐particle aggregates ( sensu Al‐Mufti, 2022) in the prodelta mudstones of the Cenomanian Dunvegan Formation. It is our hope to contribute to advancing the field of mudstone sedimentology by taking this opportunity to reiterate some of our key points.…”