Dolomite caves within the Seroe Domi Formation on Curacao, Netherland Antilles

Povzetek

Remnant caves formed within the dolomitized Seroe Domi Formation on Curaçao were documented in order to determine their origin. Petrographic thin sections and geochemical analyses of samples from outcrops and cave wall rock agree with previous interpretations of a mixing zone origin for the replacement dolomite. Further, stable isotope analysis suggests migration of fluids from the underlying basalts along fracture networks in the Seroe Domi Formation. Most of the caves represent remnant phreatic caves based on morphology; however, a number of pseudokarst features were identified. Minimum cliff retreat rates were estimated (5 mm/1000 yrs to 52 mm/1000 yrs) using cave morphologies and elevations. These remnant caves, many of which were previously overlooked, have been used as indicators of diagenetic events within the Seroe Domi Formation and contain significant information when placed in the proper geologic framework.
Key words: Flank Margin Cave, Dolomitization, Seroe Domi Formation, Curaçao.

Jame v dolomitiziranem profilu formacije Seroe Domin na otoku Curaçao, Nizozemski Antili
Dokumentirali smo ostanke jam v dolomitizirani formaciji Seroe Domi na otoku Curaçao in raziskovali njihov nastanek. Petrografske analize zbruskov ter geokemiče analize površinskih izdankov in vzorcev jamskih sten, potrjujejo predhodno domnevo o izvoru (replacement) dolomita v območju mešanja slane in sladke vode. Analiza stabilnih izotopov kaže na prenos tekočin iz bazaltne podlage vzdolž mreže razpok v formaciji Seroe Domi. Oblika večine jam kaže, da gre za dele freatičnih sistemov, odkrili pa smo tudi več psevdokraških pojavov. Morfološke značilnosti jam in njihova nadmorska višina sta nam omogočili oceno minimalne hitrosti umikanja otoških klifov, ki je med 5 m in 52 mm na tisoč let. Ostanki jam, ki so bili prej največkrat spregledani, so kazalci diagenetskih dogodkov v formaciji Seroe Domi in vsebujejo druge pomembne informacije, če jih le postavimo v ustrezen geološki okvir.
Ključne besede: Jame tipa “flank margin”, dolomitizacija, formacija Seroe Domi, Curaçao.