late aptian and early albian regional emersion phase in
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Late Aptian and Early Albian regional emersion phasein Istria, Croatia
Mileusnić, Marta; Durn, Goran; Ottner, Franz; Fröschl, Heinz; Tišljar,Josip
Conference presentation / Izlaganje na skupu
Permanent link / Trajna poveznica: https://urn.nsk.hr/urn:nbn:hr:169:425391
Rights / Prava: In copyright
Download date / Datum preuzimanja: 2022-06-10
Repository / Repozitorij:
Faculty of Mining, Geology and Petroleum Engineering Repository, University of Zagreb
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7th International Symposium on the Cretaceous
5-9 September 2005
Scientific Program and Abstracts
Conveners: Karl B. Follmi and Thierry Adatte
Edited by Alexis Godet, Haydon Mort, Pascal Linder and Stephane Bodin
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7th International Symposium on the Cretaceous - NeuchCitel, 5ttl - 9th of September, 2005
during this important stage of their evolution.
LATE APTIAN AND EARLY ALBIANREGIONAL EMERSION PHASE IN ISTRIA,
CROATIA
Mileusnic Marta1, Durri Goran\Ottner Franz2,
Froschl Heinz3 and Tisljar Josip1
1Faculty of mining, geology and petroleumengineering, University of Zagreb, Zagreb, HR
10000, Croatia; department Jur Bautechnik undNaturgefahren, University of Natural Resources
and Applied Life Sciences, Vienna, A 1190,Austria; 3Austrian Research Centers GmbH — ARC,
Seibersdorf , A-2444, Austria
Emails: : [email protected]; [email protected];[email protected]; [email protected]
Istrian part of the Adriatic carbonate platformemerged in the Middle/Late Aptian for the secondtime and was exposed for 11-19 MY. Exposure relatedfeatures, which mark type 1 sequence boundary, arerepresented by greenish-grey clays, marls and limebreccias. Mineralogical, micromorphological andgeochemical analysis were performed on clay layers,ranging in thickness from several centimetres up to1 meter, and the insoluble residues of limestonessituated immediately bellow clay layers.
The main mineral components of claysare illitic material and illite/smectite mixed layerminerals. Occasionally, pyrite, gypsum and chloriteare present. In contrast, insoluble residue^ is dominatedby smectite and illitic material, and occasionallykaolinite. The clay mineral distribution of oneinvestigated profile show a dear trend indicating theinfluence of both pedogenic and diagenetic processes.Micromorphological data support consideration ofpedogenetic alteration. Distribution of vanadium,uranium, molibdenum and REE, as colour of clay andpresence of abundance of pyrite framboids indicateunoxic environment. The current investigation shouldgive answers to provenance of the material fromwhich this clays are formed.
We consider that the clays are remnants ofseasonally marshy soils to permanently watterlogedsoil, which formed from the erosional remains ofsurficial soils and sediments, which were accumulatedin palaeokarst pits following an oscillating marinetransgression that terminated emergence. TheLower Cretaceous shallow-marine depositionsporadically interrupted by periods of emersion aresedimentologically and palaeogeographically very
similar to Purbeckian sediments of NW Europe.
OCEAN ANOXIC EVENTS IN THEMID-CRETACEOUS SIMULATED BY3-D BIOGEOCHEMICAL GENERAL
CIRCULATION MODEL
Misumi Kazuhiro1, Yamanaka Yasuhiro1
1Graduate School of Environmental Earth Science,Hokkaido University, Sapporo, 060-0810, Japan
Emails: : [email protected], [email protected]
okudai.ac.jp
The mid-Cretaceous is well known by its OceanAnoxic Event (OAEs). Decreased supply or increasedconsumption of dissolved 02 in the deep water isregarded as a cause for the OAEs. But there is littleconsensus as to the overall forces behind the OAEs. Inthis study, we conducted a mid-Cretaceous simulationby an OGCM combined with the biogeochemicalcycle model to investigate causes of OAEs. Themodel results show that the thermohaline circulation(THC) oscillated between activity and inactivity. Astable enlargement of an anoxic region is only seenin the proto-Atlantic. This is due to the high exportproduction supported by the elevated concentrationof P04, which prevents the supplying of dissolved02 to the deep water even under the active THC.Mechanisms that enhance the P04 concentration areneeded to explain the large temporal and spatial scalesthat are associated with the OAEs.
AMMONITES FROM THE BASE OF THERYAZANIAN STAGE
AND BOREAL-TETHYAN CORRELATION
Mitta Vasily
Paleontological Institute ofRAS, Moscow, 117997Russia
Email: [email protected]
The Zone Riasanites rjasanensis is the lowestZone of the Ryazanian Stage and Cretaceous System.This Zone is presented in Russian platform by stronglycondensed phosphate sandstones by thickness up to1-2 m with numerous fossils. The Rjasanensis Zoneis characterized by two groups of ammonites whichare quite different in the origin. They are “ Boreal”Craspeditidae and “ Tethyan” Neocomitidae. The
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