Pub Date : 2018-07-13DOI: 10.1344/GEOLOGICAACTA2018.16.3.3
A. Arasa-Tuliesa, L. Cabrera
The lower Ebro is a bedrock-alluvial mixed incised valley with a persistent degradational stacking architecture developed from latest Serravallian(?) to Holocene. This degradational pattern was probably controlled by isostatic rebound in NE Iberia and punctuated by major relative sea level changes that temporally accentuated or attenuated the palaeovalley entrenchment and sediment retention. Six allostratigraphic units in the palaeovalley constitute the onshore record of its evolution and the opening and connection of the Ebro Basin with the Mediterranean. This paper deals with the analysis and reinterpretation of these units in order to precise the sequence of events that took place on the onshore part of the Catalan continental margin during the Ebro River drainage entrenchment. Plausible chronology and palaeogeographic evolution of the Neogene-Quaternary drainage incision in the lower Ebro are also proposed. The early evolutionary stages of the incised palaeovalley (Latest Serravallian?-Tortonian-Early Messinian, from 11.63–9? to near 5.6Ma) were dominated by entrenchment and intense sediment transfer from the onshore to the offshore zones (erosion surface S2). These processes were only punctuated by the sedimentation of the alluvial palaeovalley unit M2 (late Messinian). The polygenetic onshore erosion surfaces S2 and S3 are linked here with the onshore erosive processes that fed the sedimentation of the terrigenous shelf-slope system of the offshore Castellon group and considered coeval with the offshore Messinian erosion surfaces (reflectors M and m). During a further evolutionary stage (Pliocene to Early Pleistocene from 5.3 to approximately 2Ma) the Early Pliocene major Mediterranean reflooding caused some sediment retention in the incised palaeovalley (sedimentation of unit P) but sediment transfer into the offshore remained very effective. In the last evolutionary stage (Early Pleistocene-Holocene, from 2Ma to present) the palaeovalley became again mainly degradational (generation of erosion surfaces S4 to S6 and sedimentation of stepped alluvial terraces Q1-2 to Q4). The onshore stratigraphic record, including the allostratigraphic units P and Q1-2 to Q4 and the related bounding surfaces S3 to S6, is correlated with the sedimentation of the terrigenous shelf-slope system of the offshore Ebro group.
{"title":"Neogene-Quaternary onshore record in the lower Ebro river incised palaeovalley (Ebro margin, Catalan Coastal Range, NE Iberia)","authors":"A. Arasa-Tuliesa, L. Cabrera","doi":"10.1344/GEOLOGICAACTA2018.16.3.3","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.3.3","url":null,"abstract":"The lower Ebro is a bedrock-alluvial mixed incised valley with a persistent degradational stacking architecture developed from latest Serravallian(?) to Holocene. This degradational pattern was probably controlled by isostatic rebound in NE Iberia and punctuated by major relative sea level changes that temporally accentuated or attenuated the palaeovalley entrenchment and sediment retention. Six allostratigraphic units in the palaeovalley constitute the onshore record of its evolution and the opening and connection of the Ebro Basin with the Mediterranean. This paper deals with the analysis and reinterpretation of these units in order to precise the sequence of events that took place on the onshore part of the Catalan continental margin during the Ebro River drainage entrenchment. Plausible chronology and palaeogeographic evolution of the Neogene-Quaternary drainage incision in the lower Ebro are also proposed. The early evolutionary stages of the incised palaeovalley (Latest Serravallian?-Tortonian-Early Messinian, from 11.63–9? to near 5.6Ma) were dominated by entrenchment and intense sediment transfer from the onshore to the offshore zones (erosion surface S2). These processes were only punctuated by the sedimentation of the alluvial palaeovalley unit M2 (late Messinian). The polygenetic onshore erosion surfaces S2 and S3 are linked here with the onshore erosive processes that fed the sedimentation of the terrigenous shelf-slope system of the offshore Castellon group and considered coeval with the offshore Messinian erosion surfaces (reflectors M and m). During a further evolutionary stage (Pliocene to Early Pleistocene from 5.3 to approximately 2Ma) the Early Pliocene major Mediterranean reflooding caused some sediment retention in the incised palaeovalley (sedimentation of unit P) but sediment transfer into the offshore remained very effective. In the last evolutionary stage (Early Pleistocene-Holocene, from 2Ma to present) the palaeovalley became again mainly degradational (generation of erosion surfaces S4 to S6 and sedimentation of stepped alluvial terraces Q1-2 to Q4). The onshore stratigraphic record, including the allostratigraphic units P and Q1-2 to Q4 and the related bounding surfaces S3 to S6, is correlated with the sedimentation of the terrigenous shelf-slope system of the offshore Ebro group.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"0265-292"},"PeriodicalIF":1.5,"publicationDate":"2018-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41770282","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}
Pub Date : 2018-06-25DOI: 10.1344/GEOLOGICAACTA2018.16.3.2
T. Boschetti, B. Angulo, F. Quintero, J. Volcan, A. Casalins
In this short note, we present the first data on stable isotope composition of the oilfield waters from Carabobo area of the Faja Petrolifera del Orinoco “Hugo Chavez” (Orinoco Oil Belt). From a chemical point of view, the formation waters show a main Na-Cl level (TDS up to 30g/l) with a dilution trend toward Na-HCO3 composition (down to 1g/l). Until now, such a clear net chemical compositional trend was ascribed to a meteoric dilution (fresh/ brackish bicarbonate) of the seawater endmember (the saltiest chloride). The isotope results of this study reveal that the seawater mother water was modified during a high-temperature thrusting event (120–125°C), forming 18O-enriched diagenetic water (up to +4‰), which was diluted in recent times by glacial meltwater and presentday meteoric water. The hypothetical presence of flood by a meteoric paleo-water also offers new hints to explain the low API gravity (<10°API biodegraded, extra heavy oil) and composition of the local crude.
在这篇简短的文章中，我们首次介绍了Faja Petrolifera del Orinoco“Hugo Chavez”(Orinoco油带)Carabobo地区油田水的稳定同位素组成数据。从化学角度看，地层水以Na-Cl为主(TDS达30g/l)， Na-HCO3组分有稀释趋势(降至1g/l)。到目前为止，如此明确的净化学成分趋势被归因于海水末端成员(最咸的氯化物)的大气稀释(新鲜/微咸碳酸氢盐)。同位素结果表明，海水母水在高温逆冲事件(120 ~ 125℃)中发生了变质，形成了富18o的成岩水(高达+4‰)，并在近代被冰川融水和现代大气水稀释。大气古水洪水的假设存在也为解释当地原油的低API重力(<10°API生物降解，超重油)和成分提供了新的线索。
{"title":"Chemical and stable isotope composition (18O/16O, 2H/1H) of formation waters from the Carabobo Oilfield, Venezuela","authors":"T. Boschetti, B. Angulo, F. Quintero, J. Volcan, A. Casalins","doi":"10.1344/GEOLOGICAACTA2018.16.3.2","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.3.2","url":null,"abstract":"In this short note, we present the first data on stable isotope composition of the oilfield waters from Carabobo area of the Faja Petrolifera del Orinoco “Hugo Chavez” (Orinoco Oil Belt). From a chemical point of view, the formation waters show a main Na-Cl level (TDS up to 30g/l) with a dilution trend toward Na-HCO3 composition (down to 1g/l). Until now, such a clear net chemical compositional trend was ascribed to a meteoric dilution (fresh/ brackish bicarbonate) of the seawater endmember (the saltiest chloride). The isotope results of this study reveal that the seawater mother water was modified during a high-temperature thrusting event (120–125°C), forming 18O-enriched diagenetic water (up to +4‰), which was diluted in recent times by glacial meltwater and presentday meteoric water. The hypothetical presence of flood by a meteoric paleo-water also offers new hints to explain the low API gravity (<10°API biodegraded, extra heavy oil) and composition of the local crude.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"0257-264"},"PeriodicalIF":1.5,"publicationDate":"2018-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66404820","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}
Pub Date : 2018-06-21DOI: 10.1344/GEOLOGICAACTA2018.16.2.6
I. Canales-García, J. Urrutia‐Fucugauchi, E. Aguayo-Camargo
Chicxulub Crater, formed ~66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post- and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of ~300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change.
{"title":"Seismic imaging and attribute analysis of Chicxulub Crater central sector, Yucatán Platform, Gulf of Mexico","authors":"I. Canales-García, J. Urrutia‐Fucugauchi, E. Aguayo-Camargo","doi":"10.1344/GEOLOGICAACTA2018.16.2.6","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.2.6","url":null,"abstract":"Chicxulub Crater, formed ~66Ma ago by an asteroid impact on the southern Gulf of Mexico, is the best preserved of the three large multi-ring basins in the terrestrial record. The crater structure is characterized by a semi-circular concentric ring pattern, marking the crater basin, peak ring, terrace zone and basement uplift. Analysis of a grid of 19 seismic reflection profiles using seismic attributes, marker horizons, contour surfaces and 3-D views is used to investigate the stratigraphy of the central zone. We used interactive software and routine applications to map the impact breccias, breccia-carbonate contact and post-impact carbonates. Four horizons marked by high-amplitude reflectors representing high-impedance contrasts were identified and laterally correlated in the seismic images. Complex trace attribute analysis was applied for petrophysical characterization. Surface contour maps of base and top of stratigraphic packages were constructed, which mapped the impactites and post- and pre-impact carbonate stratigraphy. Basin floor, marked by the contact between the impact breccias and overlying carbonates is shown by laterally discontinuous high-amplitude reflectors. Discontinuous scattered reflectors interpreted as the upper breccias beneath the crater floor, have an average thickness of ~300msm. The Paleogene sedimentary units are characterized by multiple reflectors with lateral continuity, which contrast with the seismic response of underlying breccias. The basal Paleocene sediments follow the basin floor relief. Upwards in the section, the carbonate strata are characterized by horizontal reflectors, which are interrupted by a regional unconformity. Onlap/downlap packages over the unconformity record a period of sea level change.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"215-235"},"PeriodicalIF":1.5,"publicationDate":"2018-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48842241","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}
Pub Date : 2018-06-21DOI: 10.1344/GEOLOGICAACTA2018.16.2.1
C. Martín‐Closas, S. Trias, Josep María Casas Tuset
The pre-Variscan rocks of the Pyrenees exhibit a polyphase deformation linked to the Variscan crustal shortening and a low-pressure–high-temperature metamorphism. However, there is scarce chronostratigraphic evidence of this Variscan deformation. In the Pyrenean low-grade metamorphic domains, maximum ages have been provided by the synorogenic Carboniferous Culm deposits. In medium- to high-grade metamorphic areas, the Variscan regional metamorphism or intrusive magmatic bodies constrain the age of the main Variscan deformation structures. However, these data usually provide a minimum age. Here, we present new palaeobotanical records that assign a Namurian age to the base of the Culm deposits of la Cerdanya in the eastern Pyrenees. This dating is based on the co-occurrence of the sphenopsids Archaeocalamites radiatus , Mesocalamites cistiiformis and the seed of Cardiocarpus sp. The plant remains were found in sandstone facies produced by high-density turbidity flows of a deep-sea fan system. The new biostratigraphic information constrains the age of the Carboniferous Culm succession in the eastern Pyrenees.
{"title":"New palaeobotanical data from Carboniferous Culm deposits constrain the age of the Variscan deformation in the eastern Pyrenees","authors":"C. Martín‐Closas, S. Trias, Josep María Casas Tuset","doi":"10.1344/GEOLOGICAACTA2018.16.2.1","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.2.1","url":null,"abstract":"The pre-Variscan rocks of the Pyrenees exhibit a polyphase deformation linked to the Variscan crustal shortening and a low-pressure–high-temperature metamorphism. However, there is scarce chronostratigraphic evidence of this Variscan deformation. In the Pyrenean low-grade metamorphic domains, maximum ages have been provided by the synorogenic Carboniferous Culm deposits. In medium- to high-grade metamorphic areas, the Variscan regional metamorphism or intrusive magmatic bodies constrain the age of the main Variscan deformation structures. However, these data usually provide a minimum age. Here, we present new palaeobotanical records that assign a Namurian age to the base of the Culm deposits of la Cerdanya in the eastern Pyrenees. This dating is based on the co-occurrence of the sphenopsids Archaeocalamites radiatus , Mesocalamites cistiiformis and the seed of Cardiocarpus sp. The plant remains were found in sandstone facies produced by high-density turbidity flows of a deep-sea fan system. The new biostratigraphic information constrains the age of the Carboniferous Culm succession in the eastern Pyrenees.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"107-123"},"PeriodicalIF":1.5,"publicationDate":"2018-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48085675","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}
Pub Date : 2018-06-21DOI: 10.1344/GEOLOGICAACTA2018.16.2.5
S. Wedmann, D. Uhl, T. Lehmann, R. Garrouste, A. Nel, B. Gomez, Krister T. Smith, Stephan F. K. Schaal
The Konservat-Lagerstatte Menat (Puy-de-Dome, France) is an outstanding archive of a Paleocene ecosystem, which was deposited in a former maar lake. Excavations during the last century have yielded an extensive flora and fauna record, therefore an overview of the current state of paleontological investigations is given in this paper. Additionally, new results based on excavations from the years 2012 to 2014 are presented. The preservation of organic matter differed strongly between excavation sites, probably influenced by weathering processes. The stratigraphic succession consists mostly of organic-rich clays, intercalated with hard, silicified claystones. In 2013 and 2014 both impression and compression fossils were collected from different outcrops. Compression fossils from organic-rich clays were exceptionally well-preserved and included three-dimensional plant remains. A new database on insect paleobiodiversity was compiled. The occurrence of charcoal in almost all horizons investigated suggests that paleowildfires were frequent during the Paleocene in the vicinity of the paleolake. The results confirm the high potential of the Konservat-Lagerstatte Menat for future paleontological research.
Konservat Lagerstatte Menat（法国Puy de Dome）是古新世生态系统的杰出档案，该生态系统沉积在前马尔湖。上个世纪的发掘已经产生了广泛的动植物记录，因此本文概述了古生物学研究的现状。此外，还介绍了基于2012年至2014年挖掘的新结果。有机物的保存在不同的挖掘地点有很大的差异，可能受到风化过程的影响。地层序列主要由富含有机物的粘土组成，夹有坚硬的硅化粘土岩。2013年和2014年，从不同的露头采集了印模化石和挤压化石。富含有机质粘土的压缩化石保存得非常完好，其中包括三维植物遗骸。编制了一个关于昆虫古生物多样性的新数据库。几乎在所有调查的层位中都有木炭的存在，这表明古湖附近的古新世古野火很频繁。这一结果证实了湖螈在未来古生物学研究中的巨大潜力。
{"title":"The Konservat-Lagerstätte Menat (Paleocene; France) – an overview and new insights","authors":"S. Wedmann, D. Uhl, T. Lehmann, R. Garrouste, A. Nel, B. Gomez, Krister T. Smith, Stephan F. K. Schaal","doi":"10.1344/GEOLOGICAACTA2018.16.2.5","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.2.5","url":null,"abstract":"The Konservat-Lagerstatte Menat (Puy-de-Dome, France) is an outstanding archive of a Paleocene ecosystem, which was deposited in a former maar lake. Excavations during the last century have yielded an extensive flora and fauna record, therefore an overview of the current state of paleontological investigations is given in this paper. Additionally, new results based on excavations from the years 2012 to 2014 are presented. The preservation of organic matter differed strongly between excavation sites, probably influenced by weathering processes. The stratigraphic succession consists mostly of organic-rich clays, intercalated with hard, silicified claystones. In 2013 and 2014 both impression and compression fossils were collected from different outcrops. Compression fossils from organic-rich clays were exceptionally well-preserved and included three-dimensional plant remains. A new database on insect paleobiodiversity was compiled. The occurrence of charcoal in almost all horizons investigated suggests that paleowildfires were frequent during the Paleocene in the vicinity of the paleolake. The results confirm the high potential of the Konservat-Lagerstatte Menat for future paleontological research.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"189-213"},"PeriodicalIF":1.5,"publicationDate":"2018-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49172501","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}
Pub Date : 2018-06-21DOI: 10.1344/GEOLOGICAACTA2018.16.2.4
E. Özcan, A. Okay, K. A. Bürkan, A. O. Yücel, Z. Özcan
The Eocene shallow marine deposits marking the first marine incursion in the Biga Peninsula (NW Turkey) after the collision of the Sakarya and Anatolide-Tauride plates were investigated based on paleontological, litho- and chrono-stratigraphic data. Larger Benthic Foraminifera (LBF) from patchily distributed outcrops were studied in order to i) revise the stratigraphy of Eocene shallow marine units, and ii) establish a modern biostratigraphic setting and a correlation scheme. The Şevketiye Formation (Fm.) is herein defined as a predominantly shallow marine clastic deposit with subordinate carbonates overlying the Camlica metamorphic rocks, and passing laterally to the Sogucak Fm., a carbonate unit that is widely represented in the Thrace Basin. The record of alveolinids, primitive developmental stages of heterosteginids, and orthophragminids in the Şevketiye Fm. suggests that this formation is part of the Shallow Benthic Zones (SBZ) 16?/17 (Late Lutetian?/Early Bartonian), SBZ17?/18 and SBZ19A (Early Bartonian/earliest Priabonian). The Sogucak Fm., which overlies the Eocene volcanics, on the other hand, yielded advanced developmental stages of heterosteginids, Spiroclypeus sp. and Nummulites fabianii lineages, implying a younger marine incursion during the Late Eocene (earliest Priabonian; SBZ19A). A drastic shift in the depositional regime is marked amid Priabonian by the deposition of deep-marine clastics and volcanoclastics of the Ceylan Fm. In conclusion, the Eocene Sea transgressed first Gokceada (in the Aegean Sea) during the Late Lutetian, then reached the Biga and Gelibolu peninsulas in the Bartonian, and finally led to the widespread deposition of carbonate and siliciclastic rocks in the Biga Peninsula and the Thrace Basin during the Late Bartonian and Priabonian.
{"title":"Middle-Late Eocene marine record of the Biga Peninsula, NW Anatolia, Turkey","authors":"E. Özcan, A. Okay, K. A. Bürkan, A. O. Yücel, Z. Özcan","doi":"10.1344/GEOLOGICAACTA2018.16.2.4","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.2.4","url":null,"abstract":"The Eocene shallow marine deposits marking the first marine incursion in the Biga Peninsula (NW Turkey) after the collision of the Sakarya and Anatolide-Tauride plates were investigated based on paleontological, litho- and chrono-stratigraphic data. Larger Benthic Foraminifera (LBF) from patchily distributed outcrops were studied in order to i) revise the stratigraphy of Eocene shallow marine units, and ii) establish a modern biostratigraphic setting and a correlation scheme. The Şevketiye Formation (Fm.) is herein defined as a predominantly shallow marine clastic deposit with subordinate carbonates overlying the Camlica metamorphic rocks, and passing laterally to the Sogucak Fm., a carbonate unit that is widely represented in the Thrace Basin. The record of alveolinids, primitive developmental stages of heterosteginids, and orthophragminids in the Şevketiye Fm. suggests that this formation is part of the Shallow Benthic Zones (SBZ) 16?/17 (Late Lutetian?/Early Bartonian), SBZ17?/18 and SBZ19A (Early Bartonian/earliest Priabonian). The Sogucak Fm., which overlies the Eocene volcanics, on the other hand, yielded advanced developmental stages of heterosteginids, Spiroclypeus sp. and Nummulites fabianii lineages, implying a younger marine incursion during the Late Eocene (earliest Priabonian; SBZ19A). A drastic shift in the depositional regime is marked amid Priabonian by the deposition of deep-marine clastics and volcanoclastics of the Ceylan Fm. In conclusion, the Eocene Sea transgressed first Gokceada (in the Aegean Sea) during the Late Lutetian, then reached the Biga and Gelibolu peninsulas in the Bartonian, and finally led to the widespread deposition of carbonate and siliciclastic rocks in the Biga Peninsula and the Thrace Basin during the Late Bartonian and Priabonian.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"163-187"},"PeriodicalIF":1.5,"publicationDate":"2018-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49197569","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}
Pub Date : 2018-06-21DOI: 10.1344/GEOLOGICAACTA2018.16.2.2
P. N. Tehrani, A. A. Calagari, F. V. Roldan, V. Simmonds, Kamal Siahcheshm
The Pivehzhan iron deposit is located at about 80km southwest of Mashhad, NE Iran. They occur within the Devonian carbonates as lenticular and massive bodies, as well as veinlets of magnetite and iron sulphides, transformed to goethite and haematite by weathering process. The hydrothermal calcite is the most important gangue mineral, which is observed in the form of veins/veinlets and open-space filling. The iron ores are accompanied by some minor elements such as Mn, Ti, Cr, and V and negligible amounts of Co and Ni. The distribution pattern of Rare Earth Elements (REEs) normalized to Post Archean Australian Shale (PAAS), which is characterized by the upward convex, as well as the positive Eu anomalies indicate the activity of reduced and acidic hydrothermal fluids. The negative Ce anomalies of host carbonates, although slight, point to the dominance of anoxic conditions during interaction with hydrothermal fluids. The hydrothermal calcite and quartz coexisting with the iron minerals contain principally fluid, which were homogenized into liquid phase. The homogenization temperature (TH (L-V) ) and the salinity of the analysed fluid inclusions range from 129°C to 270°C and from 0.4wt.% to 9.41wt.% NaCl eq., respectively. The δ 13 C PDB and δ 18 O SMOW values ranges from -2.15‰ to -5.77‰ (PeeDee Belemnite standard, PDB) and from +19.87‰ to +21.64‰ (Standard Mean Ocean Water standard, SMOW) in hydrothermal calcite veinlets occurring with iron minerals and -0.66‰ to -4.37‰ (PDB) and +15.55‰ to +20.14‰ (SMOW) within the host carbonates, respectively. The field relations and petrographic examination along with geochemical and isotopic considerations indicate that the Pivehzhan iron deposit was formed through replacement processes by reducing and acid fluids containing light carbon and oxygen isotopes. Variations in the physico-chemical conditions of hydrothermal fluids and their interaction with carbonates were the most effective mechanisms in the formation of this iron deposit. The potential source of iron was probably the basement magmatic rocks from which iron was leached by hydrothermal solutions.
{"title":"C and O stable isotopes and rare earth elements in the Devonian carbonate host rock of the Pivehzhan iron deposit, NE Iran","authors":"P. N. Tehrani, A. A. Calagari, F. V. Roldan, V. Simmonds, Kamal Siahcheshm","doi":"10.1344/GEOLOGICAACTA2018.16.2.2","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.2.2","url":null,"abstract":"The Pivehzhan iron deposit is located at about 80km southwest of Mashhad, NE Iran. They occur within the Devonian carbonates as lenticular and massive bodies, as well as veinlets of magnetite and iron sulphides, transformed to goethite and haematite by weathering process. The hydrothermal calcite is the most important gangue mineral, which is observed in the form of veins/veinlets and open-space filling. The iron ores are accompanied by some minor elements such as Mn, Ti, Cr, and V and negligible amounts of Co and Ni. The distribution pattern of Rare Earth Elements (REEs) normalized to Post Archean Australian Shale (PAAS), which is characterized by the upward convex, as well as the positive Eu anomalies indicate the activity of reduced and acidic hydrothermal fluids. The negative Ce anomalies of host carbonates, although slight, point to the dominance of anoxic conditions during interaction with hydrothermal fluids. The hydrothermal calcite and quartz coexisting with the iron minerals contain principally fluid, which were homogenized into liquid phase. The homogenization temperature (TH (L-V) ) and the salinity of the analysed fluid inclusions range from 129°C to 270°C and from 0.4wt.% to 9.41wt.% NaCl eq., respectively. The δ 13 C PDB and δ 18 O SMOW values ranges from -2.15‰ to -5.77‰ (PeeDee Belemnite standard, PDB) and from +19.87‰ to +21.64‰ (Standard Mean Ocean Water standard, SMOW) in hydrothermal calcite veinlets occurring with iron minerals and -0.66‰ to -4.37‰ (PDB) and +15.55‰ to +20.14‰ (SMOW) within the host carbonates, respectively. The field relations and petrographic examination along with geochemical and isotopic considerations indicate that the Pivehzhan iron deposit was formed through replacement processes by reducing and acid fluids containing light carbon and oxygen isotopes. Variations in the physico-chemical conditions of hydrothermal fluids and their interaction with carbonates were the most effective mechanisms in the formation of this iron deposit. The potential source of iron was probably the basement magmatic rocks from which iron was leached by hydrothermal solutions.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"125-148"},"PeriodicalIF":1.5,"publicationDate":"2018-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44156630","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}
Pub Date : 2018-06-21DOI: 10.1344/GEOLOGICAACTA2018.16.2.3
M. Freudenthal, E. Martín-Suárez
In a recent study of van der Meulen and coauthors, the fossil rodents Fahlbuschia , Pseudofahlbuschia and Renzimys from the Aragonian type area (Calatayud Basin, Spain) were synonimized with Democricetodon . On the basis of the relative chronology provided by Daams and coauthors in an earlier study, these authors construed two evolutionary lineages, distinguished by size. One of these lineages contains Fahlbuschia koenigswaldi (Freudenthal, 1963) and the other one Democricetodon moralesi van der Meulen et al. (2004) but, in view of their great similarity, we consider D. moralesi to be a synonym of F. koenigswaldi . The relative stratigraphic position of some fossil mammal localities is difficult to establish in the Aragonian type area because it is affected by folds and faults. Early studies of Daams and Freudenthal subdivided the local zone D into D1, D2, D3 and gave a scheme of the stratigraphy in which the fossiliferous locality Valdemoros 1A is considered to be older than Valdemoros 3B. But Daams and coauthors came to the opposite interpretation in a later study, and divided zone D in Da, Db, Dc, Dd. But, new field data presented here enforce the original interpretation in which Valdemoros 1A is older than Valdemoros 3B. This leads to the conclusion that the division of local zone D into Da to Dd has to be discarded, and substituted by the formerly proposed zonation D1-D3.
在van der Meulen及其合著者最近的一项研究中，来自Aragonian类型地区（西班牙卡拉塔尤德盆地）的啮齿类化石Fahlbuschia、Pseudofahlbushia和Renzimys与Democricetodon同义。根据Daams和合著者在早期研究中提供的相对年表，这些作者解释了两个按大小区分的进化谱系。其中一个谱系包含Fahlbuschia koenigswaldi（Freudenthal，1963）和另一个谱系Democricetodon moralesi van der Meulen等人（2004），但鉴于它们的巨大相似性，我们认为D.moralesi是F.koenigswalldi的同义词。由于受到褶皱和断层的影响，在Aragonian型地区很难确定一些哺乳动物化石所在地的相对地层位置。Daams和Freudenthal的早期研究将当地的D带细分为D1、D2和D3，并给出了一个地层学方案，其中化石产地Valdemoros 1A被认为比Valdemoros 3B更古老。但Daams和合著者在后来的一项研究中得出了相反的解释，并将D区划分为Da、Db、Dc、Dd。但是，这里提供的新现场数据加强了最初的解释，即瓦尔迪摩罗斯1A比瓦尔迪摩洛斯3B更古老。这导致了这样的结论，即必须放弃将局部区域D划分为Da到Dd，并由先前提出的分区D1-D3代替。
{"title":"The Aragonian type area revisited; comments on paleontology and stratigraphy","authors":"M. Freudenthal, E. Martín-Suárez","doi":"10.1344/GEOLOGICAACTA2018.16.2.3","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.2.3","url":null,"abstract":"In a recent study of van der Meulen and coauthors, the fossil rodents Fahlbuschia , Pseudofahlbuschia and Renzimys from the Aragonian type area (Calatayud Basin, Spain) were synonimized with Democricetodon . On the basis of the relative chronology provided by Daams and coauthors in an earlier study, these authors construed two evolutionary lineages, distinguished by size. One of these lineages contains Fahlbuschia koenigswaldi (Freudenthal, 1963) and the other one Democricetodon moralesi van der Meulen et al. (2004) but, in view of their great similarity, we consider D. moralesi to be a synonym of F. koenigswaldi . The relative stratigraphic position of some fossil mammal localities is difficult to establish in the Aragonian type area because it is affected by folds and faults. Early studies of Daams and Freudenthal subdivided the local zone D into D1, D2, D3 and gave a scheme of the stratigraphy in which the fossiliferous locality Valdemoros 1A is considered to be older than Valdemoros 3B. But Daams and coauthors came to the opposite interpretation in a later study, and divided zone D in Da, Db, Dc, Dd. But, new field data presented here enforce the original interpretation in which Valdemoros 1A is older than Valdemoros 3B. This leads to the conclusion that the division of local zone D into Da to Dd has to be discarded, and substituted by the formerly proposed zonation D1-D3.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"149-162"},"PeriodicalIF":1.5,"publicationDate":"2018-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45264491","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}
Pub Date : 2018-06-08DOI: 10.1344/GEOLOGICAACTA2018.16.3.1
J. Errandonea-Martin, F. Sarrionandia, M. Carracedo-Sánchez, J. G. Ibarguchi, L. Eguiluz
The Sierra Bermeja Pluton (southern Central Iberian Zone, Iberian Massif) is a late-Variscan intrusive constituted by cordierite-bearing peraluminous monzogranites. Detailed field mapping has allowed to disclose the presence of several NE–SW trending longitudinal composite bodies, formed by either aphanitic or phaneritic mesocratic rocks. According to their petrography and geochemistry these rocks are categorised as calc-alkaline lamprophyres and vaugnerite series rocks. Their primary mineralogy is characterised by variable amounts of plagioclase, amphibole, clinopyroxene, biotite, K-feldspar, quartz and apatite. Broadly, they show low SiO2 content (49–56wt.%), and high MgO+FeOt (10–17wt.%), K2O (3–5wt.%), Ba (963–2095ppm), Sr (401–1149ppm) and Cr (87–330ppm) contents. Field scale observations suggest that vaugneritic rocks and lamprophyres would constitute two independent magma pulses. Vaugneritic dioritoids intruded as syn-plutonic dykes, whereas lamprophyres were emplaced after the almost complete consolidation of the host monzogranites. In this way, vaugnerite series rocks would be an evidence for the contemporaneity of crustal- and mantle-melting processes during a late-Variscan stage, while lamprophyres would represent the ending of this stage.
{"title":"Petrography and geochemistry of late- to post-Variscan vaugnerite series rocks and calc-alkaline lamprophyres within a cordierite-bearing monzogranite (the Sierra Bermeja Pluton, southern Iberian Massif).","authors":"J. Errandonea-Martin, F. Sarrionandia, M. Carracedo-Sánchez, J. G. Ibarguchi, L. Eguiluz","doi":"10.1344/GEOLOGICAACTA2018.16.3.1","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.3.1","url":null,"abstract":"The Sierra Bermeja Pluton (southern Central Iberian Zone, Iberian Massif) is a late-Variscan intrusive constituted by cordierite-bearing peraluminous monzogranites. Detailed field mapping has allowed to disclose the presence of several NE–SW trending longitudinal composite bodies, formed by either aphanitic or phaneritic mesocratic rocks. According to their petrography and geochemistry these rocks are categorised as calc-alkaline lamprophyres and vaugnerite series rocks. Their primary mineralogy is characterised by variable amounts of plagioclase, amphibole, clinopyroxene, biotite, K-feldspar, quartz and apatite. Broadly, they show low SiO2 content (49–56wt.%), and high MgO+FeOt (10–17wt.%), K2O (3–5wt.%), Ba (963–2095ppm), Sr (401–1149ppm) and Cr (87–330ppm) contents. Field scale observations suggest that vaugneritic rocks and lamprophyres would constitute two independent magma pulses. Vaugneritic dioritoids intruded as syn-plutonic dykes, whereas lamprophyres were emplaced after the almost complete consolidation of the host monzogranites. In this way, vaugnerite series rocks would be an evidence for the contemporaneity of crustal- and mantle-melting processes during a late-Variscan stage, while lamprophyres would represent the ending of this stage.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"237-255"},"PeriodicalIF":1.5,"publicationDate":"2018-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41481532","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}
Pub Date : 2018-03-26DOI: 10.1344/GEOLOGICAACTA2018.16.1.5
M. Bieńkowska-Wasiluk, M. Pałdyna
Small perch-like fishes from the Oligocene of the Paratethys were traditionally assigned to Serranus budensis (Heckel, 1856). A new morphological study of the holotype and specimens from the Outer Carpathians, Poland, is provided herein. Oligoserranoides budensis (Heckel, 1856), Percoidei incertae sedis, is revised and compared with other small perch-like fishes from the Oligocene Paratethys. Caucasoserranoides morozkiensis, Carpathoserranoides brnoensis, Carpathoserranoides polonicus and Oligoserranoides comparabilis are very similar to O. budensis and further studies are necessary to clarify the validity of those species. O. budensis is compared with the Oligocene-Lower Miocene Pirsagatia sytchevskayae, the Eocene Jimtylerius temnopterus, Ottaviania mariae,O. leptacanthus, Veranichthys ventralis and the Palaeocene Proserranus lundensis. O. budensis shares many characters with the Lutjanoidea, and differs in a toothless palatine. The palaeobiogeography of Oligocene small perch-like fishes in the Paratethys is presented.
Paratethys渐新世的小型类似鲈鱼的鱼类传统上被分配给布氏Serranus budensis（Heckel，1856）。本文对波兰外喀尔巴阡山脉的正模标本和标本进行了新的形态学研究。对布氏寡serranoides budensis（Heckel，1856），incertae sedis Percoidei进行了修订，并与渐新世副特提斯的其他类似鲈鱼的小型鱼类进行了比较。morozkiensis、brnoensis、polonicus和comparabilis的Carpathoseranoides与O.budensis非常相似，需要进一步的研究来澄清这些物种的有效性。布氏O.budensis与渐新世-下中新世Pirsagatia sytchevskaye、始新世Jimtylerius temnopterus、Ottaviania mariae、O。Leptitacnthus、Veranichthys ventralis和古新世Proseranus lundensis。布氏O.budensis与木犀总科有许多共同的特征，不同之处在于没有牙齿的腭。介绍了副特提斯渐新世小型鲈鱼的古生物地理学。
{"title":"Taxonomic revision of the Oligocene percoid fish Oligoserranoides budensis (Heckel, 1856), from the Paratethys and paleobiogeographic comments","authors":"M. Bieńkowska-Wasiluk, M. Pałdyna","doi":"10.1344/GEOLOGICAACTA2018.16.1.5","DOIUrl":"https://doi.org/10.1344/GEOLOGICAACTA2018.16.1.5","url":null,"abstract":"Small perch-like fishes from the Oligocene of the Paratethys were traditionally assigned to Serranus budensis (Heckel, 1856). A new morphological study of the holotype and specimens from the Outer Carpathians, Poland, is provided herein. Oligoserranoides budensis (Heckel, 1856), Percoidei incertae sedis, is revised and compared with other small perch-like fishes from the Oligocene Paratethys. Caucasoserranoides morozkiensis, Carpathoserranoides brnoensis, Carpathoserranoides polonicus and Oligoserranoides comparabilis are very similar to O. budensis and further studies are necessary to clarify the validity of those species. O. budensis is compared with the Oligocene-Lower Miocene Pirsagatia sytchevskayae, the Eocene Jimtylerius temnopterus, Ottaviania mariae,O. leptacanthus, Veranichthys ventralis and the Palaeocene Proserranus lundensis. O. budensis shares many characters with the Lutjanoidea, and differs in a toothless palatine. The palaeobiogeography of Oligocene small perch-like fishes in the Paratethys is presented.","PeriodicalId":55107,"journal":{"name":"Geologica Acta","volume":"16 1","pages":"75-92"},"PeriodicalIF":1.5,"publicationDate":"2018-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47894251","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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