M. Rodríguez-Martínez, A. Perejón, E. Moreno-Eiris, S. Menéndez, W. Buggisch
The carbonate clasts from the Mount Wegener Formation provide sedimentological, diagenetic and palaeontological evidences of the destruction and resedimentation of a hidden/unknown Cambrian carbonate shallow-water record at the Coats Land region of Antarctica. This incomplete mosaic could play a key role in comparisons and biostratigraphic correlations between the Cambrian record of the Transantarctic Mountains, Ellsworth-Whitmore block and Antarctic Peninsula at the Antarctica continent. Moreover, it represents a key record in future palaeobiogeographic reconstructions of South Gondwana based on archaeocyathan assemblages.
{"title":"Clastos con calcimicrobios y arqueociatos procedentes de depósitos marinos del talud de la Formación cámbrica del Monte Wegener, Coats Land, Cordillera de Shackleton Antártida","authors":"M. Rodríguez-Martínez, A. Perejón, E. Moreno-Eiris, S. Menéndez, W. Buggisch","doi":"10.3989/egeol.43586.567","DOIUrl":"https://doi.org/10.3989/egeol.43586.567","url":null,"abstract":"The carbonate clasts from the Mount Wegener Formation provide sedimentological, diagenetic and palaeontological evidences of the destruction and resedimentation of a hidden/unknown Cambrian carbonate shallow-water record at the Coats Land region of Antarctica. This incomplete mosaic could play a key role in comparisons and biostratigraphic correlations between the Cambrian record of the Transantarctic Mountains, Ellsworth-Whitmore block and Antarctic Peninsula at the Antarctica continent. Moreover, it represents a key record in future palaeobiogeographic reconstructions of South Gondwana based on archaeocyathan assemblages.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"24 1","pages":"112"},"PeriodicalIF":0.7,"publicationDate":"2019-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81881883","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}
One of the corners of the geographical maps that link the provinces of Badajoz, Caceres and Toledo contains some key outcrops necessary to understand the Ediacaran-Cambrian transition in the Central-Iberian Zone. In the cores of the Extremenian Anticlinorium and the Ibor and Valdelacasa anticlines, the Lower Alcudian-Domo Extremeno Supergroup (including the diamictites of the Orellana Formation), the most spectacular microbial reefs with Cloudina of the Villarta Formation, and the palaeoichnological base of the Cambrian in the Arrocampo Formation (both the Villarta and Arrocampo formations belong to the Ibor Group) stand out. The exposures that were traditionally considered as representatives of the Precambrian-Cambrian boundary and base of the Cordubian regional Stage are located in the lower member of the Pusa Formation, unconformably overlying the Ibor Group, and are considered at present as intra-Terreneuvian in age.
{"title":"Guía de campo post-congreso, 21-24 de Octubre de 2019: Ediacárico y Terreneuviense en los alrededores del Geoparque de la UNESCO Villuercas-Ibores-Jara","authors":"J. Álvaro, S. Jensen, T. Palacios","doi":"10.3989/egeol.43726.576","DOIUrl":"https://doi.org/10.3989/egeol.43726.576","url":null,"abstract":"One of the corners of the geographical maps that link the provinces of Badajoz, Caceres and Toledo contains some key outcrops necessary to understand the Ediacaran-Cambrian transition in the Central-Iberian Zone. In the cores of the Extremenian Anticlinorium and the Ibor and Valdelacasa anticlines, the Lower Alcudian-Domo Extremeno Supergroup (including the diamictites of the Orellana Formation), the most spectacular microbial reefs with Cloudina of the Villarta Formation, and the palaeoichnological base of the Cambrian in the Arrocampo Formation (both the Villarta and Arrocampo formations belong to the Ibor Group) stand out. The exposures that were traditionally considered as representatives of the Precambrian-Cambrian boundary and base of the Cordubian regional Stage are located in the lower member of the Pusa Formation, unconformably overlying the Ibor Group, and are considered at present as intra-Terreneuvian in age.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"29 3 1","pages":"121"},"PeriodicalIF":0.7,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81056006","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}
Y. Zhao, S. Peng, J. Yuan, J. Esteve, X. Yang, M. Wu, Z. Chen
Ongoing work is carrying out in the Balang and “Tsinghsutung” formations to aim a suitable candidate for the base of the Cambrian Series 2, Stage 4. The revision of the trilobite systematics and zonation shed light about the stratigraphic distribution and the geographical distribution of the new trilobite-based zones in the Balang area (South China). Our results suggest that either Oryctocarella duyunensis or Arthricocephalus chauveaui could be good candidates since they also occur in the Eoaagnostus roddyi-Arthricocephalus chauveaui Zone of the Henson Gletscher Formation, North Greenland.
{"title":"Bioestratigrafía a partir de trilobites de las Formaciones de Balang y “Tsinghsutung” (Serie Cámbrica 2, Piso 4) en el área de Balang, Jianhe, Guizhou, China meridional","authors":"Y. Zhao, S. Peng, J. Yuan, J. Esteve, X. Yang, M. Wu, Z. Chen","doi":"10.3989/egeol.43595.574","DOIUrl":"https://doi.org/10.3989/egeol.43595.574","url":null,"abstract":"Ongoing work is carrying out in the Balang and “Tsinghsutung” formations to aim a suitable candidate for the base of the Cambrian Series 2, Stage 4. The revision of the trilobite systematics and zonation shed light about the stratigraphic distribution and the geographical distribution of the new trilobite-based zones in the Balang area (South China). Our results suggest that either Oryctocarella duyunensis or Arthricocephalus chauveaui could be good candidates since they also occur in the Eoaagnostus roddyi-Arthricocephalus chauveaui Zone of the Henson Gletscher Formation, North Greenland.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"48 1","pages":"119"},"PeriodicalIF":0.7,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81455402","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}
L. Warren, E. Tohver, L. Inglez, J. Okubo, C. Riccomini, S. Xiao
The paleontological, isotopic and geochronological data summarized below support the paleogeographic and temporal correlation between Itapucumi (Paraguay) and Corumba (Brazil) groups, suggesting a coeval sedimentary evolution of these units in the margins of the Amazon Craton and the Rio Apa Block.
{"title":"Calibrando la transición ediacárico-cámbrica en Gondwana suddoccidental","authors":"L. Warren, E. Tohver, L. Inglez, J. Okubo, C. Riccomini, S. Xiao","doi":"10.3989/egeol.43593.573","DOIUrl":"https://doi.org/10.3989/egeol.43593.573","url":null,"abstract":"The paleontological, isotopic and geochronological data summarized below support the paleogeographic and temporal correlation between Itapucumi (Paraguay) and Corumba (Brazil) groups, suggesting a coeval sedimentary evolution of these units in the margins of the Amazon Craton and the Rio Apa Block.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"39 1","pages":"118"},"PeriodicalIF":0.7,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85791854","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}
Several stratigraphic units characteristic of the Ediacaran-Cambrian transition between Guadalupe and Castanar de Ibor, north of the Villuercas-Ibores-Jara Geopark (Caceres), are described and illustrated here. The outcrops of (i) the Castanar and Villarta formations (Ibor Group, terminal Ediacaran and Terreneuvian), together with their content in vendotaenids, sabelliditids and microbial reefs with Cloudina ; and (ii) the San Lorenzo Formation (Terreneuvian) and its palaeoichnological content, are detailed. Finally, the palaeoichnological record of the Armorican Quartzite (Lower Ordovician), mainly of Cruziana and Daedalus , which characterize some sites of geological interest (geosites) in the Geopark, are highlighted.
{"title":"Guía de campo pre-congreso, 17-18 de Octubre de 2019: Ediacárico, Paleozoico Inferior y panorámicas en el Geoparque de la UNESCO Villuercas-Ibores-Jara","authors":"S. Jensen, J. Álvaro, T. Palacios","doi":"10.3989/egeol.43725.575","DOIUrl":"https://doi.org/10.3989/egeol.43725.575","url":null,"abstract":"Several stratigraphic units characteristic of the Ediacaran-Cambrian transition between Guadalupe and Castanar de Ibor, north of the Villuercas-Ibores-Jara Geopark (Caceres), are described and illustrated here. The outcrops of (i) the Castanar and Villarta formations (Ibor Group, terminal Ediacaran and Terreneuvian), together with their content in vendotaenids, sabelliditids and microbial reefs with Cloudina ; and (ii) the San Lorenzo Formation (Terreneuvian) and its palaeoichnological content, are detailed. Finally, the palaeoichnological record of the Armorican Quartzite (Lower Ordovician), mainly of Cruziana and Daedalus , which characterize some sites of geological interest (geosites) in the Geopark, are highlighted.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"1 1","pages":"120"},"PeriodicalIF":0.7,"publicationDate":"2019-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75766483","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}
N. G. Sozonov, N. I. Bobkov, E. G. Mitchell, A. Kolesnikov, D. Grazhdankin
Specimens of Dickinsonia from the Central Urals are characterised by clear bilateral symmetry. Taking into account observations from Australian specimens, we consider that the so called ‘glide reflection symmetry’ in these fossils is a taphonomic phenomenon. The size frequency distribution plot shows the predominance of smaller individuals in the studied population of Dickinsonia from the Central Urals. Assuming that the age of an individual is manifested in the body size, there is a significant predominance of juvenile individuals in the population. Three possible scenarios can be envisaged: (i) the population has a large number of juvenile individuals as the result of high survivorship rate in the intertidal zone; (ii) the population teems with juvenile forms because it is buried immediately after hatching; (iii) assuming that Dickinsonia was an actively motile organisms, that abundance of juvenile individuals could be explained by their inability to escape burial (although it is difficult to imagine that some of the mature individuals are buried with signs of escape behaviour); and (iv) the population could be interpreted as a fossilised ‘nesting ground’ for Dickinsonia in the intertidal zone where juvenile forms underwent maturation before migrating back to the subtidal zone. The study population can be characterised as expanding or stable; therefore, the intertidal setting can be described as favourable for these organisms.
{"title":"Ecología de Dickinsonia en llanuras mareales","authors":"N. G. Sozonov, N. I. Bobkov, E. G. Mitchell, A. Kolesnikov, D. Grazhdankin","doi":"10.3989/egeol.43587.571","DOIUrl":"https://doi.org/10.3989/egeol.43587.571","url":null,"abstract":"Specimens of Dickinsonia from the Central Urals are characterised by clear bilateral symmetry. Taking into account observations from Australian specimens, we consider that the so called ‘glide reflection symmetry’ in these fossils is a taphonomic phenomenon. The size frequency distribution plot shows the predominance of smaller individuals in the studied population of Dickinsonia from the Central Urals. Assuming that the age of an individual is manifested in the body size, there is a significant predominance of juvenile individuals in the population. Three possible scenarios can be envisaged: (i) the population has a large number of juvenile individuals as the result of high survivorship rate in the intertidal zone; (ii) the population teems with juvenile forms because it is buried immediately after hatching; (iii) assuming that Dickinsonia was an actively motile organisms, that abundance of juvenile individuals could be explained by their inability to escape burial (although it is difficult to imagine that some of the mature individuals are buried with signs of escape behaviour); and (iv) the population could be interpreted as a fossilised ‘nesting ground’ for Dickinsonia in the intertidal zone where juvenile forms underwent maturation before migrating back to the subtidal zone. The study population can be characterised as expanding or stable; therefore, the intertidal setting can be described as favourable for these organisms.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"110 1","pages":"116"},"PeriodicalIF":0.7,"publicationDate":"2019-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80539042","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 stratigraphic revision of the latest Cryogenian, Ediacaran and earliest Cambrian of the southwestern Siberian Platform is proposed here. All late Neoproterozoic stratigraphic units fill the Sayan foredeep. The sedimentary record is adscribed to the upper Cryogenian and Ediacaran Oselok Group and the lower Cambrian Ust’-Tagul Formation. They can be subdivided into members with a characteristic fossiliferous content ecology of Dickinsonia.
{"title":"El Criogénico terminal, el Ediacárico y el Cámbrico temprano en la Plataforma Siberiana sudoccidental: estratotipos y limitotipos","authors":"J. K. Sovetov, L. V. Solovetskaya","doi":"10.3989/egeol.43595.570","DOIUrl":"https://doi.org/10.3989/egeol.43595.570","url":null,"abstract":"A stratigraphic revision of the latest Cryogenian, Ediacaran and earliest Cambrian of the southwestern Siberian Platform is proposed here. All late Neoproterozoic stratigraphic units fill the Sayan foredeep. The sedimentary record is adscribed to the upper Cryogenian and Ediacaran Oselok Group and the lower Cambrian Ust’-Tagul Formation. They can be subdivided into members with a characteristic fossiliferous content ecology of Dickinsonia.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"123 1","pages":"115"},"PeriodicalIF":0.7,"publicationDate":"2019-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77039978","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}
The basal Cambrian Stage 2 strata of the Olenek Uplift host diverse assemblages of macroscopic fossils, which closely resemble certain small skeletal taxa early reported from this section and typical for the Terreneuvian Epoch. Herein studied macroscopic assemblage includes helcionellid, stenothecid and kharkhaniid molluscs, and anabaritids and circothecid hyoliths. Among the assemblage, only anabaritids and some citrcothecid hyoliths exhibit relics of calcite shell, whereas most of the fossils reveal no evidence of rigid biomineralized exoskeleton. Hence, at least these problematic Cambrian organisms had reached macroscopic sizes (up to 35 mm long) and were covered with calcite shells at the very beginning of the Cambrian Age 2.
{"title":"Grandes hitos de la Explosión Cámbrica: asociación bentónica macrobioclástica en el Piso cámbrico inferior 2 del Olenek Uplift, Siberia ártica","authors":"Z. Sarsembaev, V. V. Marusin","doi":"10.3989/egeol.43595.568","DOIUrl":"https://doi.org/10.3989/egeol.43595.568","url":null,"abstract":"The basal Cambrian Stage 2 strata of the Olenek Uplift host diverse assemblages of macroscopic fossils, which closely resemble certain small skeletal taxa early reported from this section and typical for the Terreneuvian Epoch. Herein studied macroscopic assemblage includes helcionellid, stenothecid and kharkhaniid molluscs, and anabaritids and circothecid hyoliths. Among the assemblage, only anabaritids and some citrcothecid hyoliths exhibit relics of calcite shell, whereas most of the fossils reveal no evidence of rigid biomineralized exoskeleton. Hence, at least these problematic Cambrian organisms had reached macroscopic sizes (up to 35 mm long) and were covered with calcite shells at the very beginning of the Cambrian Age 2.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"15 1","pages":"113"},"PeriodicalIF":0.7,"publicationDate":"2019-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91089531","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}
In the southern Central Iberian Zone, unconformably lying on the Cadomian folded Lower Alcudian-Domo Extremeno Supergroup the most complete succession of late Ediacaran rocks crops out at the Sierra de la Zarzuela syncline. The purpose of this contribution is to study and redefine a regional lithostratigraphic framework for the “Upper Alcudian” rocks of this area related to the Ibor Group.
{"title":"Revisión de la sucesión de la Sierra de la Zarzuela: último registro del Ediacárico-¿Fortuniense inferior? del Gran Anticlinorio Extremeño central, Zona Centroibérica meridional, Macizo Ibérico, España","authors":"A. Pieren, M. Rodríguez-Martínez","doi":"10.3989/egeol.43591.565","DOIUrl":"https://doi.org/10.3989/egeol.43591.565","url":null,"abstract":"In the southern Central Iberian Zone, unconformably lying on the Cadomian folded Lower Alcudian-Domo Extremeno Supergroup the most complete succession of late Ediacaran rocks crops out at the Sierra de la Zarzuela syncline. The purpose of this contribution is to study and redefine a regional lithostratigraphic framework for the \u0000“Upper Alcudian” rocks of this area related to the Ibor Group.","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"10 1","pages":"110"},"PeriodicalIF":0.7,"publicationDate":"2019-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75136951","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}
M. Ramos, M. Giorgioni, D. D. Do Carmo, D. Walde, E. Guimarães, G. Fazio, L. C. Vieira, M. Denezine, R. Santos, R. Adôrno
This study presents updates and upgrades concerning the stable isotopic register of the Tamengo Formation, upper part of the Corumba Group, which crops out in the meridional portion of the Paraguay Belt. This work includes detailed stratigraphic sections paired with high-resolution δ 13 C and δ 18 O geochemistry from two mining sites near Corumba (Mato Grosso do Sul, Brazil).
本文对位于巴拉圭带经向部分的Corumba群上部Tamengo组稳定同位素记录进行了更新和升级。在巴西南马托格罗索州(Mato Grosso do Sul) Corumba附近的两个矿区进行了详细的地层剖面和高分辨率的δ 13c和δ 18o地球化学对比研究。
{"title":"Caracterización quimioestratigráfica y facies carbonatadas de una plataforma ediacárica, Formación de Tamengo, Grupo de Corumbá: resultados preliminares","authors":"M. Ramos, M. Giorgioni, D. D. Do Carmo, D. Walde, E. Guimarães, G. Fazio, L. C. Vieira, M. Denezine, R. Santos, R. Adôrno","doi":"10.3989/egeol.43589.566","DOIUrl":"https://doi.org/10.3989/egeol.43589.566","url":null,"abstract":"This study presents updates and upgrades concerning the stable isotopic register of the Tamengo Formation, upper part of the Corumba Group, which crops out in the meridional portion of the Paraguay Belt. This work includes detailed stratigraphic sections paired with high-resolution δ 13 C and δ 18 O geochemistry from two mining sites near Corumba (Mato Grosso do Sul, Brazil).","PeriodicalId":50496,"journal":{"name":"Estudios Geologicos-Madrid","volume":"32 4 1","pages":"111"},"PeriodicalIF":0.7,"publicationDate":"2019-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74061317","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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