Geology Reference
In-Depth Information
displays some of the microfacies types of the limestone
boulders. Fig. 16.14 presents a reconstruction of a lost
platform that was attached to the Alboran Block, rep-
resenting a sedimentary realm before the Variscan orog-
eny. The paleogeographic relationships of that realm
were preserved in the Mesozoic A
LKAPECA
microplate.
The break-up and the dispersal of parts of this micro-
plate led to the formation of isolated Paleozoic terranes
(now distributed in Spain, Italy and North Africa) whose
paleogegraphic relations become more transparent from
microfacies-based clast analyses.
• the superposition of the oolites by micritized skel-
etal grainstones and wackestones, and by wackestones
with radiolarians and sponge spicules indicating the
decrease of platform carbonate productivity, recording
a dissection of the platform and the subsequent isola-
tion of a submarine topographic high;
• the deposition of crinoidal packstones (encrinites)
in times of increasing synsedimentary tectonics re-
flected by neptunian dikes exhibiting infillings of dif-
ferent microfacies types pointing to a stepped slope.
Basics: Reconstructing lost platforms
Belka, Z., Skompski, S., Sobon-Podgorska, J. (1996): Re-
construction of a lost carbonate platform on the shelf of
Fennosarmatia: evidence from Viséan polymictic debris,
Holy Cross Mountains, Poland. - In: Strogon, P., Sommer-
ville I.D., Jones, L.L. (eds.): Recent advances in Lower
Carboniferous geology. - Geological Society of London,
Special Publications,
107
, 305-329
Di Stefano, P., Galacz, A., Mallarino, G., Mindszenty, A.,
Vörös, A. (2002): Birth and early evolution of a Jurassic
escarpment: Monte Kumeta, Western Sicily. - Facies,
46
,
273-298
Flügel, E., Herbig, H.-G. (1988): Mikrofazies karbonischer
Kalkgerölle aus dem Paläozoikum des Rif (Marokko): Ein
Beitrag zur Paläogeographie der westmediterranen Paläo-
tethys im Karbon. - Facies,
19
, 271-299
16.3.2.2 Case Study: Reconstruction of Paleo
Escarpments from Microfacies Data
Di Stefano et al. (2002) gave an example demon-
strating how microfacies analysis can be used in re-
constructing the conversion of a Bahamian-type car-
bonate platform into a pelagic escarpment that is not
recorded by outcrop data.
Diagnostic criteria used are
• the change from tidalites to oolites, i.e. from re-
stricted, interior lagoonal to a more open marine sandy
depositional environment;
