Organic carbon content and carbon isotope variations across the Permo-Triassic boundary in the Gartnerkofe l-1borehole, Carnic Alps, Austria

AbstractTheGartnerkofelboreholeisoneofthemostthoroughlystudiedanddescribedPermo-Triassicsectionsintheworld.Detailedbulkorganiccarbonisotopestudiesshowanegativebaseshiftfrom-24%0to-28%0intheLatestPermianwhichlattervaluepersistsintotheEarliestTriassicafterwhichitdecreasesslightlyto-26‰.Twostronglynegativepeaksof〉-38‰intheLatestPermianandalesserpeakof-31‰intheEarlyTriassicaretoonegativetobeduetoagreaterproportionofmorenegativeorganicmatterandmustbeduetoverynegativemethaneeffects.TheoverallchangetomorenegativevaluesacrosstheBulla/Teseroboundaryfitstherelativeriseinsealevelforthistransitionbasedonthefacieschanges.ApositiveshiftinorganiccarbonisotopevaluesattheLatePermianEventHorizonmaybeduetoanincreaseinland-derivedorganicdetritusatthislevel-afeatureshownbyallTethyanPermo-Triassicboundarysectionsthoughtheseothersectionsdonothavethesamevalues.Carbonatecarbonisotopetrendsaresimilarinallsectionsdroppingby2-3unitsacrossthePermo-Triassicboundary.Gart-nerkofelcarbonateoxygenvaluesaresurprisingly,con-sideringtheubiquitousdolomitization,compatiblewithvalueselsewhereandindicatereasonabletropicaltemper-aturesof60~CintheLatestPermiansabkhasto20-40℃intheoverlyingmarinetransitionbeds.Increasedland-derivedinputattheLatePermianEventHorizonmaybeduetooffshoretransportbytsunamiswhosedepositshavebeenrecognizedinIndiaatthislevel.