Čukaru Peki is a recently discovered copper-gold deposit in the Bor metallogenic zone in east Serbia. Three types of mineralization can be distinguished in this ore deposit: porphyry, high-sulphidation, and transitional epithermal type. This research was focused on fluid inclusion analysis of genetically different veins from the porphyry and the transitional zones of Čukaru Peki with an aim of better understanding the fluid evolution and mineralization processes in this system. Seven types of veins were identified in the porphyry zone of Čukaru Peki and four of these veins contained transparent minerals which were suitable for fluid inclusion analysis. Eight types of inclusion assemblages were distinguished in these veins: type 1 – primary inclusions with homogenization temperatures above 550°C and high salinity, type 2a- scattered polyphase inclusions two salt crystals, type 2b-polyphase inclusions with two salt crystals in crystal growth zones, type 3- brine inclusions with one salt crystal in crystal growth zones, type 4- vapour-rich inclusions, type 5- primary inclusions in anhydrite, and types 6 and 7- secondary low-temperature inclusions This research suggests that saline fluids (30-40% wt.% NaCl eq.) were the most important ones for the formation of porphyry-type mineralization and that the mineralization was formed at temperatures between 350 and 450°C and pressures between 100 and 500 bars. The epithermal stage was characterized by cooler low-salinity fluids with temperatures between 150-350°C, and salinity between 0 and 7 wt.% NaCl eq.
{"title":"Fluid Evolution of the Čukaru Peki Cu-Au Porphyry System (East Serbia) inferred from a fluid inclusion study","authors":"Milos Velojic, R. Jelenković, V. Cvetkovic","doi":"10.4154/gc.2020.14","DOIUrl":"https://doi.org/10.4154/gc.2020.14","url":null,"abstract":"Čukaru Peki is a recently discovered copper-gold deposit in the Bor metallogenic zone in east Serbia. Three types of mineralization can be distinguished in this ore deposit: porphyry, high-sulphidation, and transitional epithermal type. This research was focused on fluid inclusion analysis of genetically different veins from the porphyry and the transitional zones of Čukaru Peki with an aim of better understanding the fluid evolution and mineralization processes in this system. Seven types of veins were identified in the porphyry zone of Čukaru Peki and four of these veins contained transparent minerals which were suitable for fluid inclusion analysis. Eight types of inclusion assemblages were distinguished in these veins: type 1 – primary inclusions with homogenization temperatures above 550°C and high salinity, type 2a- scattered polyphase inclusions two salt crystals, type 2b-polyphase inclusions with two salt crystals in crystal growth zones, type 3- brine inclusions with one salt crystal in crystal growth zones, type 4- vapour-rich inclusions, type 5- primary inclusions in anhydrite, and types 6 and 7- secondary low-temperature inclusions This research suggests that saline fluids (30-40% wt.% NaCl eq.) were the most important ones for the formation of porphyry-type mineralization and that the mineralization was formed at temperatures between 350 and 450°C and pressures between 100 and 500 bars. The epithermal stage was characterized by cooler low-salinity fluids with temperatures between 150-350°C, and salinity between 0 and 7 wt.% NaCl eq.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"1 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45405901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents new discoveries of vascular plants and the trace fossil Dictyodora liebeana (GEINITZ) from the Devonian–Carboniferous Kucaj-Zvonce flysch of the Carpatho-Balkanides and the implications of this fossil association for its sedimentary setting. The occurrence of the described plant debris in a deep-marine environment indicates the presence of hyperpycnites within the siliciclastic turbidites exposed at the Kostadinovica locality. The sedimentological data and the characteristics of the fossil material support the proposed model in which the sediment was at least partially transported by hyperpycnite currents. Furthermore, based on the assessment to similar palaeofloras from comparable formations, the age of the fossil plants can be determined as Early Carboniferous. This can be used as an additional biostratigraphic criterion given the relative abundance of vascular plants in other localities of the Kucaj-Zvonce flysch described in previous studies. The age and the depositional setting of the succession is further better constrained by the first observation of Dictyodora liebeana (GEINITZ) in the Carpatho-Balkanides of Serbia.
{"title":"Hyperpycnites within the Devonian-Carboniferous flysch of the Carpatho-Balkanides (Kostadinovica, eastern Serbia)","authors":"M. Radonjić","doi":"10.4154/gc.2020.13","DOIUrl":"https://doi.org/10.4154/gc.2020.13","url":null,"abstract":"This study presents new discoveries of vascular plants and the trace fossil Dictyodora liebeana (GEINITZ) from the Devonian–Carboniferous Kucaj-Zvonce flysch of the Carpatho-Balkanides and the implications of this fossil association for its sedimentary setting. The occurrence of the described plant debris in a deep-marine environment indicates the presence of hyperpycnites within the siliciclastic turbidites exposed at the Kostadinovica locality. The sedimentological data and the characteristics of the fossil material support the proposed model in which the sediment was at least partially transported by hyperpycnite currents. Furthermore, based on the assessment to similar palaeofloras from comparable formations, the age of the fossil plants can be determined as Early Carboniferous. This can be used as an additional biostratigraphic criterion given the relative abundance of vascular plants in other localities of the Kucaj-Zvonce flysch described in previous studies. The age and the depositional setting of the succession is further better constrained by the first observation of Dictyodora liebeana (GEINITZ) in the Carpatho-Balkanides of Serbia.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46154410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Krisztina Sebe, M. Kovácic, I. Magyar, K. Krizmanić, M. Špelić, D. Bigunac, M. Sütő-Szentai, Á. Kovács, Andrea Szuromi-Korec, K. Bakrač, Valentina Hajek-Tadesse, T. Troskot-Čorbić, O. Sztanó
Upper Miocene to Pliocene (Pannonian) sediments of the Pannonian Basin System accumulated in the brackish Lake Pannon and the fluvial feeder systems, between 11.6-2.6 Ma. Their stratigraphic subdivision has been problematic for a long time due to the laterally prograding architecture of the basin fill and the historically independently evolving stratigraphic schemes of the neighbouring countries. We correlated the lithostratigraphic units of the Lake Pannon deposits between Hungary and Croatia in the Drava Basin, using lithological, sedimentological and palaeontological data from boreholes and outcrops, and seismic correlation. The Croatica and Medvedski breg formations in Croatia correspond to the Endrőd Fm. in Hungary, comprising shallow to deep water, open lacustrine, calcareous to argillaceous marls. The Andrasevec fm. in Croatia corresponds to the Szolnok and Algyő Fms. in Hungary, consisting of sandstones and siltstones of turbidite systems and of clay marls deposited on the shelf-break slope. The Nova Gradiska fm. in Croatia is an equivalent of the Ujfalu Fm. in Hungary, built up of a variety of lithologies, including sand, silt, clay and huminitic clay, deposited in deltaic environments. The Pluska fm. in Croatia corresponds to the Zagyva Fm. in Hungary, consisting of variegated clays, silts, sands and lignites, deposited in alluvial and fluvial environments. Coarse-grained (sand, gravel) basal layers are assigned to the Kalla and Bekes Fms. and the Sveti Matej member of the Croatica fm. Coarse-grained intercalations within the deep-water marls belong to the Dorozsma Member of the Endrőd Fm. in Hungary, and to the Bacun member of the Medvedski breg fm. in Croatia. Sediment transport and lateral accretion of the shelf edge in the Drava Basin took place from the N, NW, and W, to the S, SE, and E, respectively. According to the biostratigraphic and chronostratigraphic analyses, the oldest shelf-break slopes in the Mura Basin are more than 8 Ma old, whereas the youngest ones in the southeasternmost part of the Drava Basin may be Pliocene in age (younger than 5.3 Ma). Thus, the 180 km long and at least 700 m deep Drava Basin was transformed into a fluvial plain during the last 3.5 million years of the Miocene.
{"title":"Correlation of upper Miocene–Pliocene Lake Pannon deposits across the Drava Basin, Croatia and Hungary","authors":"Krisztina Sebe, M. Kovácic, I. Magyar, K. Krizmanić, M. Špelić, D. Bigunac, M. Sütő-Szentai, Á. Kovács, Andrea Szuromi-Korec, K. Bakrač, Valentina Hajek-Tadesse, T. Troskot-Čorbić, O. Sztanó","doi":"10.4154/gc.2020.12","DOIUrl":"https://doi.org/10.4154/gc.2020.12","url":null,"abstract":"Upper Miocene to Pliocene (Pannonian) sediments of the Pannonian Basin System accumulated in the brackish Lake Pannon and the fluvial feeder systems, between 11.6-2.6 Ma. Their stratigraphic subdivision has been problematic for a long time due to the laterally prograding architecture of the basin fill and the historically independently evolving stratigraphic schemes of the neighbouring countries. We correlated the lithostratigraphic units of the Lake Pannon deposits between Hungary and Croatia in the Drava Basin, using lithological, sedimentological and palaeontological data from boreholes and outcrops, and seismic correlation. The Croatica and Medvedski breg formations in Croatia correspond to the Endrőd Fm. in Hungary, comprising shallow to deep water, open lacustrine, calcareous to argillaceous marls. The Andrasevec fm. in Croatia corresponds to the Szolnok and Algyő Fms. in Hungary, consisting of sandstones and siltstones of turbidite systems and of clay marls deposited on the shelf-break slope. The Nova Gradiska fm. in Croatia is an equivalent of the Ujfalu Fm. in Hungary, built up of a variety of lithologies, including sand, silt, clay and huminitic clay, deposited in deltaic environments. The Pluska fm. in Croatia corresponds to the Zagyva Fm. in Hungary, consisting of variegated clays, silts, sands and lignites, deposited in alluvial and fluvial environments. Coarse-grained (sand, gravel) basal layers are assigned to the Kalla and Bekes Fms. and the Sveti Matej member of the Croatica fm. Coarse-grained intercalations within the deep-water marls belong to the Dorozsma Member of the Endrőd Fm. in Hungary, and to the Bacun member of the Medvedski breg fm. in Croatia. Sediment transport and lateral accretion of the shelf edge in the Drava Basin took place from the N, NW, and W, to the S, SE, and E, respectively. According to the biostratigraphic and chronostratigraphic analyses, the oldest shelf-break slopes in the Mura Basin are more than 8 Ma old, whereas the youngest ones in the southeasternmost part of the Drava Basin may be Pliocene in age (younger than 5.3 Ma). Thus, the 180 km long and at least 700 m deep Drava Basin was transformed into a fluvial plain during the last 3.5 million years of the Miocene.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"177-195"},"PeriodicalIF":1.3,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45320345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three main facies associations FA-3 to FA occur in the Oxfordian Argiles rouges de Kheneg Formation in northwestern Algeria. They correspond respectively to the deeper part of a mixed siliciclastic-carbonate shelf, upper shoreface and offshore transition-lower offshore. The trace fossil association of the Argiles rouges de Kheneg Formation contains fifteen ichnogenera and is moderately diverse for the Upper Jurassic. The formation contains diverse and abundant deep water or dominantly deep water trace fossils (i.e. Belorhaphe, Chondrites, Helminthopsis, Nereites, Megagrapton). They indicate that a part of the formation was deposited in offshore transition to lower offshore environments.
在阿尔及利亚西北部的Oxfordian Argiles rouge de Kheneg组中存在FA-3 ~ FA三种主要相组合。它们分别对应于硅塑料-碳酸盐混合陆架的深层、上滨面和近海过渡-下近海。胭脂Argiles rouge de Kheneg组的化石组合包括15个鱼属，上侏罗统具有中等多样性。地层中含有丰富多样的深水或以深水为主的痕迹化石(如Belorhaphe、Chondrites、Helminthopsis、Nereites、Megagrapton)。表明该组部分沉积于近海向下海环境过渡时期。
{"title":"First record of trace fossils from the Oxfordian Argiles rouges de Kheneg Formation (Tiaret, northwestern Algeria)","authors":"Mourad Belaid, Amine Cherif, O. Vinn, M. Naimi","doi":"10.4154/gc.2020.10","DOIUrl":"https://doi.org/10.4154/gc.2020.10","url":null,"abstract":"Three main facies associations FA-3 to FA occur in the Oxfordian Argiles rouges de Kheneg Formation in northwestern Algeria. They correspond respectively to the deeper part of a mixed siliciclastic-carbonate shelf, upper shoreface and offshore transition-lower offshore. The trace fossil association of the Argiles rouges de Kheneg Formation contains fifteen ichnogenera and is moderately diverse for the Upper Jurassic. The formation contains diverse and abundant deep water or dominantly deep water trace fossils (i.e. Belorhaphe, Chondrites, Helminthopsis, Nereites, Megagrapton). They indicate that a part of the formation was deposited in offshore transition to lower offshore environments.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"85-94"},"PeriodicalIF":1.3,"publicationDate":"2020-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43263969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A relatively novel and abridged methodology for assessing the quantity and quality status of groundwater bodies has been applied in the Dinaric karst of SE Europe. Validation of pressure on quantity is based on groundwater budgeting and the correlation of available groundwater reserves and projected water demands, while pressure on quality is estimated by GIS-created maps: vulnerability – hazard – risk. The results obtained from the studied groundwater bodies indicate mostly low pressure on water quantity, but increased risk from diffuse and point pollution sources. The application of methods is possible in many transboundary and inner aquifer systems even in geologically complex environments where there is insufficient monitoring dataon the groundwater regime.
{"title":"A methodology for assessing the pressures on transboundary groundwater quantity and quality – experiences from the Dinaric karst","authors":"Z. Stevanović, Veljko Marinović","doi":"10.4154/gc.2020.08","DOIUrl":"https://doi.org/10.4154/gc.2020.08","url":null,"abstract":"A relatively novel and abridged methodology for assessing the quantity and quality status of groundwater bodies has been applied in the Dinaric karst of SE Europe. Validation of pressure on quantity is based on groundwater budgeting and the correlation of available groundwater reserves and projected water demands, while pressure on quality is estimated by GIS-created maps: vulnerability – hazard – risk. The results obtained from the studied groundwater bodies indicate mostly low pressure on water quantity, but increased risk from diffuse and point pollution sources. The application of methods is possible in many transboundary and inner aquifer systems even in geologically complex environments where there is insufficient monitoring dataon the groundwater regime.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"107-118"},"PeriodicalIF":1.3,"publicationDate":"2020-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43567193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tvrtko Korbar, Ladislav Fuček, Vlasta Premec Fuček, Nenad Oštrić
Maastrichtian to Palaeocene pelagic carbonates on the central Adriatic island of Svetac (Sveti Andrija) are the only outcrops reported to date that document pelagic deposition during the Cretaceous–Palaeogene (K–Pg) transition within the Adriatic Basin. An approximately 3 m thick succession at the Smokvica locality contains a rich and diverse planktonic foraminiferal assemblage which allows dating of the succession and the recognition of some biostratigraphic zones. The lower part of the Smokvica section consists of 1.5 m thick pelagic biomicrite characterized by the abundance of late Maastrichtian planktonic foraminifera that indicate the Abathomphalus mayaroensis Zone. An intercalation of intraclastic floatstone <0.5 m in thickness occurring on top of Maastrichtian pelagic biomicrite is characterized by unsorted pelagic intraclasts floating within the pelagic matrix, and both components only contain Maastrichtian planktonic foraminifera.The floatstone is overlain by another <0.5 m thick intraclastic-bioclastic floatstone characterized by rounded pelagic intraclasts (plasticlasts) containing Maastrichtian planktonic foraminifera floating in the pelagic matrix. The matrix of the later floatstone contains Maastrichtian and Palaeocene planktonic foraminifera mixed together. Thus, the transition from the Maastrichtian to the Palaeocene is not continuous but is characterized by amalgamated debrites that are related to at least two separated re-depositional events within the basin. The overlying pure pelagic biomicrite is rich in planktonic foraminifera that indicates the Palaeocene P3 Zone. A few metres apart, after the covered interval, there are also Eocene pelagic biomicrites with planktonic foraminifera which indicate the Eocene E9 Zone, characterized by the co-appearance of benthic foraminifera (Discocyclina) floating within the pelagic matrix. It is assumed that a Maastrichtian opening of the deep-water environment connected to the Adriatic Basin within the former Adriatic Carbonate Platform west of the island of Vis could be related to a re-activation of an inherited transverse fault zone.
{"title":"Maastrichtian to Palaeocene and Eocene pelagic carbonates on the island of Svetac (central Adriatic, Croatia)","authors":"Tvrtko Korbar, Ladislav Fuček, Vlasta Premec Fuček, Nenad Oštrić","doi":"10.4154/gc.2020.07","DOIUrl":"https://doi.org/10.4154/gc.2020.07","url":null,"abstract":"Maastrichtian to Palaeocene pelagic carbonates on the central Adriatic island of Svetac (Sveti Andrija) are the only outcrops reported to date that document pelagic deposition during the Cretaceous–Palaeogene (K–Pg) transition within the Adriatic Basin. An approximately 3 m thick succession at the Smokvica locality contains a rich and diverse planktonic foraminiferal assemblage which allows dating of the succession and the recognition of some biostratigraphic zones. The lower part of the Smokvica section consists of 1.5 m thick pelagic biomicrite characterized by the abundance of late Maastrichtian planktonic foraminifera that indicate the Abathomphalus mayaroensis Zone. An intercalation of intraclastic floatstone <0.5 m in thickness occurring on top of Maastrichtian pelagic biomicrite is characterized by unsorted pelagic intraclasts floating within the pelagic matrix, and both components only contain Maastrichtian planktonic foraminifera.The floatstone is overlain by another <0.5 m thick intraclastic-bioclastic floatstone characterized by rounded pelagic intraclasts (plasticlasts) containing Maastrichtian planktonic foraminifera floating in the pelagic matrix. The matrix of the later floatstone contains Maastrichtian and Palaeocene planktonic foraminifera mixed together. Thus, the transition from the Maastrichtian to the Palaeocene is not continuous but is characterized by amalgamated debrites that are related to at least two separated re-depositional events within the basin. The overlying pure pelagic biomicrite is rich in planktonic foraminifera that indicates the Palaeocene P3 Zone. A few metres apart, after the covered interval, there are also Eocene pelagic biomicrites with planktonic foraminifera which indicate the Eocene E9 Zone, characterized by the co-appearance of benthic foraminifera (Discocyclina) floating within the pelagic matrix. It is assumed that a Maastrichtian opening of the deep-water environment connected to the Adriatic Basin within the former Adriatic Carbonate Platform west of the island of Vis could be related to a re-activation of an inherited transverse fault zone.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"95-106"},"PeriodicalIF":1.3,"publicationDate":"2020-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45139080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Šegvić, Damir Slovenec, R. Schuster, E. Babajić, L. Badurina, B. Lugović
The Dinaridic segment of Neotethys was affected by a widespread shortening and related subduction-accretion-obduction processes that commenced in the middle Jurassic. In the Dinarides, the Krivaja-Konjuh Ophiolite Complex (KKOC) stands as the largest ophiolite complex with a well-exposed metamorphic sole which is the key to understanding the dynamics of intraoceanic subduction initiation in this part of Neotethys. In this contribution we present Sm-Nd geochronology on a granulite facies amphibolite from the KKOC, as well as a detailed petrological description. A five-point isochrone age calculated from clinopyroxene, plagioclase, garnet, amphibole and whole rock is 162 ± 14 Ma (MSWD = 6.2), whereas garnet and whole rock yield 160 ± 7 Ma. Ages calculated from all data points except clinopyroxene are 162 ± 5 Ma (MSWD = 1.09). Petrographic investigations suggest that these ages date granulite facies metamorphic conditions (i.e. peak metamorphism of Grt-Cpx amphibolite) rather than post-peak exhumation or obduction processes. Phase textural relationships are in line with previous research, which indicated a peak metamorphism equilibration pressure and temperature of ~1 GPa and ~800 °C, respectively. Granulite facies conditions are elucidated for an igneous precursor, which underwent a multi-stage metamorphism that gave rise to recrystallization of igneous clinopyroxene and plagioclase, epitaxial growth of amphibole, and garnet blastosis. Taking into account the age of gabbronorite from the youngest segment of the KKOC oceanic crust (Taorcian to Bathonian) and ages of radiolarian assemblages from the KKOC melange (Bajocian to Bathonian), it may be inferred that within ~25 Ma the Dinaridic segment of Neotethys evolved rapidly from active ridge spreading through a stage of intraoceanic subduction and arc magmatism toward sub-ophioliteexhumation and further obduction along the Adria passive margin at the end of the Jurassic era.
{"title":"Sm-Nd geochronology and petrologic investigation of sub-ophiolite metamorphic sole from the Dinarides (Krivaja-Konjuh, Ophiolite Complex, Bosnia and Herzegovina)","authors":"B. Šegvić, Damir Slovenec, R. Schuster, E. Babajić, L. Badurina, B. Lugović","doi":"10.4154/gc.2020.09","DOIUrl":"https://doi.org/10.4154/gc.2020.09","url":null,"abstract":"The Dinaridic segment of Neotethys was affected by a widespread shortening and related subduction-accretion-obduction processes that commenced in the middle Jurassic. In the Dinarides, the Krivaja-Konjuh Ophiolite Complex (KKOC) stands as the largest ophiolite complex with a well-exposed metamorphic sole which is the key to understanding the dynamics of intraoceanic subduction initiation in this part of Neotethys. In this contribution we present Sm-Nd geochronology on a granulite facies amphibolite from the KKOC, as well as a detailed petrological description. A five-point isochrone age calculated from clinopyroxene, plagioclase, garnet, amphibole and whole rock is 162 ± 14 Ma (MSWD = 6.2), whereas garnet and whole rock yield 160 ± 7 Ma. Ages calculated from all data points except clinopyroxene are 162 ± 5 Ma (MSWD = 1.09). Petrographic investigations suggest that these ages date granulite facies metamorphic conditions (i.e. peak metamorphism of Grt-Cpx amphibolite) rather than post-peak exhumation or obduction processes. Phase textural relationships are in line with previous research, which indicated a peak metamorphism equilibration pressure and temperature of ~1 GPa and ~800 °C, respectively. Granulite facies conditions are elucidated for an igneous precursor, which underwent a multi-stage metamorphism that gave rise to recrystallization of igneous clinopyroxene and plagioclase, epitaxial growth of amphibole, and garnet blastosis. Taking into account the age of gabbronorite from the youngest segment of the KKOC oceanic crust (Taorcian to Bathonian) and ages of radiolarian assemblages from the KKOC melange (Bajocian to Bathonian), it may be inferred that within ~25 Ma the Dinaridic segment of Neotethys evolved rapidly from active ridge spreading through a stage of intraoceanic subduction and arc magmatism toward sub-ophioliteexhumation and further obduction along the Adria passive margin at the end of the Jurassic era.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"119-130"},"PeriodicalIF":1.3,"publicationDate":"2020-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48731822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Black carbonaceous shale of the Niutitang Formation in the Xixiang–Zhenba area was found to be well developed and abundant in high-quality shale gas. However, few studies have been conducted in this area, and its reservoir-forming conditions are not clear. This study aims to analyse source rocks, reservoir characteristics and storage conditions of the Niutitang Formation shale in the Xixiang–Zhenba area using field investigations, drilling and logging, supplemented with laboratory experiments. Results of this study shows that the Niutitang Formation shale is deeply buried at 1500–4500 m and is mainly 10-110 m thick. The shale is widely distributed, thicker in the west, thinner in the east and is a highly mature organic rich source rock with kerogen type I and II. The shale stratum features a high content of brittle minerals, many natural cracks, and a low content of clay minerals which are mainly illite, followed by a mixed layer of illite and smectite. The shale reservoir is characterized by low porosity and permeability. In addition, the lithology is dense and acts as a good seal in this area while it has a high adsorption capacity and high gas-bearing potential. Overall, within the study area, the western, central, and southern parts have good structural preservation conditions. The Niutitang Formation in the study area shows excellent organic matter characteristics for shale gas generation as well as good geological conditions for shale gas accumulation.
{"title":"Geological conditions and gas-bearing evaluation of the Niutitang Formation shale in the Xixiang–Zhenba area, China","authors":"Qinghui Xie, Feng Xu, Ning Wang, Zhenheng Yang","doi":"10.4154/gc.2020.05","DOIUrl":"https://doi.org/10.4154/gc.2020.05","url":null,"abstract":"Black carbonaceous shale of the Niutitang Formation in the Xixiang–Zhenba area was found to be well developed and abundant in high-quality shale gas. However, few studies have been conducted in this area, and its reservoir-forming conditions are not clear. This study aims to analyse source rocks, reservoir characteristics and storage conditions of the Niutitang Formation shale in the Xixiang–Zhenba area using field investigations, drilling and logging, supplemented with laboratory experiments. Results of this study shows that the Niutitang Formation shale is deeply buried at 1500–4500 m and is mainly 10-110 m thick. The shale is widely distributed, thicker in the west, thinner in the east and is a highly mature organic rich source rock with kerogen type I and II. The shale stratum features a high content of brittle minerals, many natural cracks, and a low content of clay minerals which are mainly illite, followed by a mixed layer of illite and smectite. The shale reservoir is characterized by low porosity and permeability. In addition, the lithology is dense and acts as a good seal in this area while it has a high adsorption capacity and high gas-bearing potential. Overall, within the study area, the western, central, and southern parts have good structural preservation conditions. The Niutitang Formation in the study area shows excellent organic matter characteristics for shale gas generation as well as good geological conditions for shale gas accumulation.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"49-58"},"PeriodicalIF":1.3,"publicationDate":"2020-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42282844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Khaled Lazzez, Marzouk Lazzez, M. B. Fadhel, Ramla ben Rabah, T. Zouaghi
The Aptian hydrocarbon-producing reservoirs, in the onshore Semmama and Douleb oil fields of west-central Tunisia are characterized by a heterogeneous flow with continuous decline. Petroleum exploration in this area requires detailed knowledge of the structural development of the basin and its relationship to the reservoir sequence and the source rock distribution. The structural configuration of west-central Tunisia is characterized by NE-SW, NW-SE and N-S deep-seated faults, which outline tectonic structures and it is influenced by Triassic salt intrusions. During the Aptian period, the basin was extensive and shallow at the center, though moderately deep to the North. The northeast-southwest dominated synsedimentary extensional tectonics induced high and subsiding zones and thus controlled sedimentary deposition. The Aptian reservoir is characterized by the lateral variation of sedimentary facies. The first zone, dominated by dolomitic lithofacies has been proven as a petroleum reservoir. The second zone corresponds to carbonate reef and para-reef facies. The third zone, trending north-south is characterized by shallow marine sedimentation, punctuated by episodes of detrital influx. The early Aptian is outlined by the emergence of Kairouan Island that took place in central Tunisia. This study facilitated mapping of the areas exhibiting hydrocarbon reservoir potential which resulted from the conjunction of extensional tectonics and salt ascension.
{"title":"Sedimentary and structural setting of the Aptian reservoir deposits in the Kasserine area, west-central Tunisia","authors":"Khaled Lazzez, Marzouk Lazzez, M. B. Fadhel, Ramla ben Rabah, T. Zouaghi","doi":"10.4154/gc.2020.06","DOIUrl":"https://doi.org/10.4154/gc.2020.06","url":null,"abstract":"The Aptian hydrocarbon-producing reservoirs, in the onshore Semmama and Douleb oil fields of west-central Tunisia are characterized by a heterogeneous flow with continuous decline. Petroleum exploration in this area requires detailed knowledge of the structural development of the basin and its relationship to the reservoir sequence and the source rock distribution. The structural configuration of west-central Tunisia is characterized by NE-SW, NW-SE and N-S deep-seated faults, which outline tectonic structures and it is influenced by Triassic salt intrusions. During the Aptian period, the basin was extensive and shallow at the center, though moderately deep to the North. The northeast-southwest dominated synsedimentary extensional tectonics induced high and subsiding zones and thus controlled sedimentary deposition. \u0000The Aptian reservoir is characterized by the lateral variation of sedimentary facies. The first zone, dominated by dolomitic lithofacies has been proven as a petroleum reservoir. The second zone corresponds to carbonate reef and para-reef facies. The third zone, trending north-south is characterized by shallow marine sedimentation, punctuated by episodes of detrital influx. The early Aptian is outlined by the emergence of Kairouan Island that took place in central Tunisia. This study facilitated mapping of the areas exhibiting hydrocarbon reservoir potential which resulted from the conjunction of extensional tectonics and salt ascension.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"59-67"},"PeriodicalIF":1.3,"publicationDate":"2020-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4154/gc.2020.06","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48006992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study is focused on cave bears from the Grotta del Bandito (Cuneo Province, Piedmont Region, Northern Italy), especially their teeth. The morphodynamic analyses have been elaborated and compared with other cave bears from Northern Italy, and other cave bear taxa from particular European sites. The Grotta del Bandito bears are similar in size to other cave bears from Italy, and no differences were observed with the other cave bear species or subspecies (e.g. U. ingressus, U. s. ladinicus, U. s. eremus). Thus their inclusion in the U. gr. spelaeus is the most appropriate classification, and they show a simpler dental surface than the “modern” cave bears (i.e. ingressus). The question of whether a single species of spelaeus lived in North Italy, is also introduced. In fact, the differences in size are probably the result of population variability, and no clear evidence of other spelaeoid species and/or subspecies, i.e. ingressus, s. ladinicus and s. eremus, was discovered.
本研究集中在Grotta del banditto (Cuneo省，Piedmont地区，意大利北部)的洞熊，特别是他们的牙齿。对其形态动力学分析进行了详细阐述，并与意大利北部的其他洞熊和欧洲特定地点的其他洞熊类群进行了比较。Grotta del banditto熊的体型与意大利的其他洞熊相似，与其他洞熊物种或亚种(如U. ingressus, U. ladinicus, U. eremus)没有观察到差异。因此，将它们归入洞穴熊是最合适的分类，它们的牙齿表面比“现代”洞穴熊(即侵入熊)更简单。是否单一种的spelaeus生活在意大利北部的问题，也被介绍。事实上，这种大小差异可能是种群变异的结果，没有发现其他spelaeoid物种和/或亚种(即ingressus, s. ladinicus和s. eremus)的明确证据。
{"title":"Ursus gr. spelaeus from Grotta del Bandito (Piedmont, Northern Italy). 1. Morphodynamics of teeth and indications of an evolutionary step","authors":"G. Santi, M. Rossi","doi":"10.4154/gc.2020.03","DOIUrl":"https://doi.org/10.4154/gc.2020.03","url":null,"abstract":"This study is focused on cave bears from the Grotta del Bandito (Cuneo Province, Piedmont Region, Northern Italy), especially their teeth. The morphodynamic analyses have been elaborated and compared with other cave bears from Northern Italy, and other cave bear taxa from particular European sites. The Grotta del Bandito bears are similar in size to other cave bears from Italy, and no differences were observed with the other cave bear species or subspecies (e.g. U. ingressus, U. s. ladinicus, U. s. eremus). Thus their inclusion in the U. gr. spelaeus is the most appropriate classification, and they show a simpler dental surface than the “modern” cave bears (i.e. ingressus). The question of whether a single species of spelaeus lived in North Italy, is also introduced. In fact, the differences in size are probably the result of population variability, and no clear evidence of other spelaeoid species and/or subspecies, i.e. ingressus, s. ladinicus and s. eremus, was discovered.","PeriodicalId":55108,"journal":{"name":"Geologia Croatica","volume":"73 1","pages":"1-12"},"PeriodicalIF":1.3,"publicationDate":"2020-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47536159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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