Storm‐influenced siliciclastic and carbonate ramp deposits, the Lower Ordovician Dumugol Formation, South Korea

Abstract

The Dumugol Formation (Lower Ordovician) in the southern part of the Baegunsan syncline, South Korea, contains mixed siliciclastic and carbonate ramp deposits. The ramp sediments were frequently influenced by storm events resulting in tempestites of sandstone‐mudstone couplets, bioclastic grainstones to packstones, flat‐pebble conglomerates, a skeletal lag layer and laminated calcisiltites. All tempestites are characterized by an erosive to sharp base, poor grading and a transitional upper boundary. The difference in lithology of tempestites appears to have been controlled by the nature of substrates and by proximality. For example, laminated calcisiltites have developed on the shallow carbonate ramp, flat‐pebble conglomerates are closely associated with nodular limestones on shallow and deep ramps, and thin skeletal lag layers from fossiliferous argillaceous sediments formed in a basinal setting. The stratigraphic succession of the Dumugol Formation represents an initial transgression followed by a regression. The vertical facies change records the transition from a shallow siliciclastic ramp to a deep carbonate ramp, to a basin, shallowing to a deep carbonate ramp, and to a shallow carbonate ramp. Storm effects are mostly well preserved in shallow to deep ramp deposits.

Cenomanian rocks in the Sinai Peninsula, Northeast Egypt: Facies analysis and sequence stratigraphy

“…This can take place during storm influence on deposition in the shallow subtidal zone (Lee and Kim, 1992). In addition, nodular nature of the characteristic limestones may refer and support an occasional period of storm activity (Bàdenas and Aurell, 2001).…”

Storm deposition on a Silurian prograding carbonate ramp, Slite Beds, Gotland

“…Storms have frequently been referred to as the main agent in the generation of bioclastic sheets similar to those in the Filehajdar area (cf. Markello & Read 1981;Kreisa 1981;Aigner 1982Aigner , 1985Brett 1983;Wright 1986;Sami & Desrochers 1992;Lee & Kim 1992). Storm deposition on Gotland has previously been discussed by Sundquist (1982a) for the Slite Beds at Haganäs, by Sundquist (1982&) for the Hemse Beds at Grogarnshuvud, by Frykman (1989) for the Klinteberg Beds and by Long (1993) for the Burgsvik Beds.…”

“…As no such sediments have been found and no evidence of a slope break, reefal margin, slope or deep basin sediments has been reported in the area, the Slite beds are interpreted as being deposited on a low angle or homoclinal carbonate ramp (cf. Aigner 1982;Brett 1983;Lee & Kim 1992;Sami & Desrochers 1992;Anastas & Coniglio 1993). The carbonate ramp model has previously been suggested for the Silurian of Gotland by Sundquist (1982a) for beds at Haganäs (Slite Beds), and by Frykman (1989) for the Klinteberg Beds.…”

Untangling intricate microbial–sponge frameworks: The contributions of sponges to Early Ordovician reefs

“…The Taebaek Group is a subunit of the Joseon Supergroup consisting of 10 lithostratigraphic units (Choi, 1998;Choi and Chough, 2005). The 150-to 250-m-thick Dumugol Formation of the Taebaek Group consists of a sequence of alternating calcareous shale and limestone, which is interpreted to represent inner to outer ramp deposits (Lee and Choi, 1987;Lee and Kim, 1992;Kim and Lee, 1998;Kwon et al, 2003Kwon et al, , 2006Choi et al, 2004;Kwon and Chough, 2005). Trilobite and conodont biozones indicate that the formation is of middle Tremadocian to middle Floian (Early Ordovician) age (Kim et al, 1991;Seo et al, 1994).…”