Cold-water Carbonates at high palaeolatitudes from the Palaeozoic to the Recent - Combining outcrops studies with core studies and geophysical imaging: Field seminar guidebook

Bodil Wesenberg Lauridsen (Redaktør), Morten Bjerager (Redaktør), Ane Elise Schrøder (Redaktør)

Publikation: Bog/rapportBogForskning

Abstrakt

Cold-water carbonates from Denmark, the North Sea and the Arctic region have been a main research area for many years in Denmark. Today the carbonates form excellent reservoirs of both hydrocarbons and groundwater.

Cenomanian to Danian cold-water carbonates, consisting almost exclusively of the remains of planktonic coccolithophorod algae and characterized as chalk, are widely distributed in northwest Europe, where they reach a general thickness of up to 0,5–1,5 km (Surlyk et al., 2003). The chalk was deposited over a period of 35 million years in an extensive, relatively deep, epicontinental sea during one of the largest transgressions known in Earth history (Surlyk 1997). The palaeolatitude of the Danish Basin were between 44° to 46°N (Smith et al., 1994). The faunas are characteristic of the Late Cretaceous Boreal Realm, and tropical forms such as reef corals, large foraminifera and rudists are generally absent (Lauridsen and Surlyk, 2008). Campanian to Danian carbonates outcrop several places onshore Sweden and Denmark (Surlyk et al., 2006, Bjerager and Surlyk, 2007ab; Lauridsen and Surlyk, 2008; Surlyk and Sørensen, 2010).

Biogenic mounds are known sporadically in the Cretaceous chalk sea of northwest Europe. Possible sponge baffling thickets of the Arnager Limestone are known from the Coniacian on Bornholm (Noe-Nygaard and Surlyk, 1985). Chalk mounds of Maastrichtian age are known from the Sigerslev Mb and small bryozoan mounds from the Højerup Member all of latest Maastrichtian age (Anderskouv et al., 2007). The most prominent mounds occur after the mass-extinction at the K/T boundary. The impressive asymmetrical bryozoan mounds on Stevns Klint started to form in early Danian concurrently with the increase in
accommodation space. The mounds show migration direction towards the SSW and they are typically 50 – 100m long and had a seafloor relief of 5 – 9m. Studies have shown that the mounds are mainly of biogenic
origin but bottom currents played an important role in their formation (Bjerager and Surlyk, 2007a).

In middle Danian, the azooxanthellate scleractinian species Dendrophyllia candelabrum (Hennig, 1899) started to form coral mound complexes on the outer shelf and at submarine structural highs in the Danish Basin, NW Europe (Floris 1980; Bernecker and Weidlich 1990, 2005; Willumsen 1995; Bjerager et al., 2010; Lauridsen et al., 2012). Other framebuilding scleractinian species such as Faksephyllia faxoensis (Lyell, 1837) and Oculina becki (Nielsen, 1922) have more patchy occurrences within the Danish Basin. Only these three framebuilding coral species are known from the Faxe Fm (Lauridsen and Bjerager, 2014). The presence of a diverse and abundant stylasterine fauna suggests a stable palaeoenvironment, probably in a bathymetric depth range of 200– 400 meters (Lauridsen and Bjerager, 2014). The coral mounds are
intercalated with bryozoan mounds of various sizes and together they form the Faxe Formation (Lauridsen et al. 2012). Significantly, bryozoan mounds were present in the area both before and after the coral mounds started to grow. Later the corals developed to be the most efficient framework producers in the
Cenozoic and the Danian mounds in the Danish Basin show strong similarities to the coral mounds ecosystems encountered at high latitudes in the North Atlantic today. The Danian cold-water coral mound complex at Faxe is possibly the oldest and best developed mound complex of its kind.

The main focus of the field seminar will be the Cretaceous cold-water carbonates reservoir analogues and the Paleocene coral and bryozoan mounds in the Danish Basin.
OriginalsprogEngelsk
ForlagGEUS
Antal sider51
StatusUdgivet - 2014
BegivenhedCOCARDE Workshop and Field Seminar 2014 - , Danmark
Varighed: 10 jun. 201413 jun. 2014

Programområde

  • Programområde 3: Energiressourcer

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