Cala di Labra area, Cala di Labra Fm, upper part (Miocene of France)

Where: France (41.4° N, 9.2° E: paleocoordinates 42.7° N, 5.0° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Cala di Labra Formation, Burdigalian (20.4 - 16.0 Ma)

• 18.6 Ma, thus assigning an early–middle Burdigalian age.

• formation-level stratigraphic resolution

Environment/lithology: reef, buildup or bioherm; wackestone and packstone

• Coral bioconstruction. As a result of the extremely irregular and articulated substrate, the coral buildup appears as an organized lens-shaped structure, and its core is constituted by a relatively dense coral domestone with a moderate

•increase of platy corals in the upper part. A coral rubble associated with granitic cobbles and pebbles is locally present at the base. The inter-coral sediment consists of poorly sorted bioclastic wackestone to packstone. Results

•from this study clearly show evidence for the occurrence of a former submerged granitic substrate that, as very rarely documented in the geological record, is here interpreted as the subtidal substrate for growth of a small bioconstruction

•under relatively high energy and clear water conditions. The Cala di Labra bioconstruction is overlain by a finingupward quartzose conglomerate and sandstone succession interpreted as deposited in a coastal setting near fluvial

•point sources. The demise of coral growth was caused by a regressive event and by the consequent quite-sudden burial and related changes of trophic conditions. The inter-coral sediment consists of silt-size bioclastic debris dominated by benthic foraminifera, red algae and bryozoans.

•The terrigenous fraction generally does not exceed 30 % and is dominated by lithic fragments (granite) and by quartz and feldspar grains. The coral unit is overlain by a 10-m-thick unit of finingupward, dominantly quartzose to bioclastic sediment. The first 5 m are represented by a fine conglomeratecharacterized by 1 to 2-m-thick amalgamated beds with massive to crude stratification, and moderately sorted, subangular to subrounded pebbles. The conglomerate contains highly fragmented and abraded bivalves, echinoderms, barnacle fragments, and minor encrusting bryozoans and larger benthic foraminifera (Heterostegina). The upper portion of the unit (6 m thick) consists of coarse bioclastic quartz sandstone. The bioclastic sandstone is low-angle tabular–planar and trough cross-stratified, and contains fragmented and abraded oysters, pectinids and echinoids (clypeasteroids). Amalgamated hummocky cross-stratification, with both convex-up and convex-down internal beds up to 10 cm thick, is also locally present.

Size classes: macrofossils, mesofossils

Primary reference: L. Tomassetti, F. R. Bosellini, and M. Brandano. 2013. Growth and demise of a Burdigalian coral bioconstruction on a granite rocky substrate (Bonifacio Basin, southeastern Corsica). Facies 59(4):703-716 [W. Kiessling/M. Krause]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 151415: authorized by Wolfgang Kiessling, entered by Mihaela Krause on 30.09.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

unclassified
  -
Florideophyceae
 Hapalidiales - Corallinophycidae
Mesophyllum sp. Lemoine 1930
Lithothamnion sp. Heydrich 1897
 Sporolithales - Corallinophycidae
Sporolithon sp. Rothpletz 1891
Foraminifera
 Nummulitacea - Nummulitidae
Heterostegina sp. d'Orbigny 1826
 Asterigerinacea - Amphisteginidae
Amphistegina sp. d'Orbigny 1826
Globothalamea
 Rotaliida - Miogypsinidae
Anthozoa
 Scleractinia - Heliastraeidae
"Heliastraea "sp. 1"" = Heliastrea, "Heliastraea "sp. 2"" = Heliastrea
"Heliastraea "sp. 1"" = Heliastrea Milne Edwards and Haime 1857 stony coral
"Heliastraea "sp. 2"" = Heliastrea Milne Edwards and Haime 1857 stony coral
 Scleractinia - Faviidae
Favia sp. Oken 1815 stony coral
Favia cf. valceppii stony coral
 Scleractinia - Merulinidae
Favites sp. Link 1807 stony coral
Favites detecta Michelotti 1871 stony coral
Favites cf. neglecta Michelotti 1868 stony coral
Favites neglecta Michelotti 1868 stony coral
Tarbellastraea sp. Alloiteau 1950 stony coral
Tarbellastraea carryensis d'Orbigny 1852 stony coral
major
Tarbellastraea reussiana Milne-Edwards and Haime 1850 stony coral
ss
 Scleractinia - Poritidae
Porites sp. Link 1807 stony coral
Porites arenosa Esper 1797 stony coral
 Scleractinia - Pocilloporidae
Stylophora affinis Duncan 1863 stony coral
 Scleractinia - Acroporidae
Astreopora sp. Blainville 1830 stony coral
 Scleractinia - Diploastraeidae
"Thegioastraea speciosa" = Diploastrea speciosa, "Thegioastraea burdigalensis" = Diploastrea burdigalensis, "Thegioastraea diversiformis" = Diploastrea diversiformis, "Thegioastraea sp." = Diploastrea, "Thegioastraea corsica" = Diploastrea, "Thegioastraea indet." = Diploastrea
"Thegioastraea speciosa" = Diploastrea speciosa Sismonda 1871 stony coral
"Thegioastraea burdigalensis" = Diploastrea burdigalensis Chevalier 1961 stony coral
"Thegioastraea diversiformis" = Diploastrea diversiformis Michelin 1842 stony coral
"Thegioastraea sp." = Diploastrea Matthai 1914 stony coral
"Thegioastraea corsica" = Diploastrea stony coral
"Thegioastraea indet." = Diploastrea Matthai 1914 stony coral
unclassified
  -
Mollusca indet. Linnaeus 1758
Bivalvia
  -
Bivalvia indet. Linnaeus 1758 clam
Echinoidea
  -
Echinoidea indet. Leske 1778 sea urchin