This work presents the results of a geological mapping project performed on the Narni-Amelia Ridge (Central Apennines, Italy). Fieldwork was aimed at defining the rift and post-rift architecture of the Jurassic to Cretaceous part of the Umbria-Marche-Sabina basin succession, which is characterised by Jurassic rift-related pelagic carbonate platform (PCP)/basin systems. While the effects of the Early Jurassic rifting are well documented in the regional literature, a phase of post-rift extensional tectonics in the late Early Cretaceous is a relatively under-investigated subject. This normal faulting was apparently widespread at a super-regional scale, and the Narni- Amelia Ridge carries direct and indirect evidence for this episode of revived deformation:(i) the occurrence of limestone megabreccias (Mt. Cosce Breccia) resting unconformably, through an erosional surface, on a Jurassic (and Cretaceous) horst-block. Stepped unconformities are associated with spur and groove geometries of the escarpment, suggesting topographic backstepping due to rock- fall processes;(ii) millimetre to decametre-scale neptunian dykes and sills made of Mt. Cosce Breccia and of Maiolica pelagites. These fractures cut the footwall-block of Cretaceous faults, made of Calcare Massiccio Fm (Hettangian), sub-orthogonal to its master- bedding. Dykes are associated with tension gashes filled with chert (silicification of fracture zones). The steep walls of those neptunian dykes filled with Maiolica-type deposits also exhibit a thin chert band;(iii) the onlap of Aptian-Albian Marne a Fucoidi Fm on the Hettangian Calcare Massiccio Fm. This is an unicum in the whole Umbria- Marche-Sabina Domain;(iv) the presence of mass-transport deposits (slumps and debris flows) in the uppermost part of the Maiolica Fm and lower part of the Marne a Fucoidi Fm.These stratigraphic anomalies are collectively interpreted as the products of normal faulting, which caused the retreat of the original Jurassic margins of the PCPs, rejuvenating the submarine palaeotopography. A middle Barremian age for this phase of syn- sedimentary extension is indicated by the nannofossil assemblage of Maiolica-type facies sampled from the Mt. Cosce Breccia and from the neptunian dykes.
这项工作展示了在Narni Amelia山脊（意大利亚平宁山脉中部）进行的地质测绘项目的结果。实地工作旨在确定翁布里亚-马尔凯-萨宾纳盆地序列侏罗纪至白垩纪部分的裂谷和裂谷后构造，其特征是侏罗纪裂谷相关的远洋碳酸盐岩平台（PCP）/盆地系统。虽然早侏罗世裂谷作用的影响在区域文献中有很好的记录，但早白垩世晚期的后裂谷伸展构造阶段是一个研究相对较少的主题。这种正断层作用显然在超区域范围内广泛存在，Narni-Amelia山脊为这种复活变形事件提供了直接和间接的证据：（i）石灰岩大角砾岩（Mt.Cosce角砾岩）的出现，通过侵蚀表面不整合地坐落在侏罗纪（和白垩纪）地垒块上。阶梯状不整合面与陡崖的丁坝和凹槽几何形状有关，表明由于落石过程导致的地形后退；（ii）由科斯角砾岩和迈奥利卡群岛建造的毫米至十米级海王星堤坝和岩床。这些裂缝切割了白垩系断层的下盘区块，该断层由Calcare Massiccio Fm（Hettaganian）组成，与主层理亚正交。堤坝与充满燧石的张力裂缝有关（断裂带硅化）。那些充满Maiolica型矿床的海王星脉的陡峭壁也显示出一条薄的燧石带；（iii）Hettaganian Calcare Massiccio Fm上的Aptian Albian Marne a Fucoidi Fm的上盖层。这是整个Umbria-Marche Sabina域中的一个单一层；（iv）在Maiolica Fm的上部和Marne a Fucoidi Fm的下部存在质量输送矿床（滑塌和泥石流）。这些地层异常被统称为正断层的产物，正断层导致PCP的原始侏罗纪边缘后退，使海底古地形恢复活力。从科斯角砾岩和海王星脉取样的Maiolica型相的超微化石组合表明，这一同沉积伸展阶段的中期Barremian年龄。
{"title":"Unconformities, neptunian dykes and mass-transport deposits as an evidence for Early Cretaceous syn-sedimentary tectonics: new insights from the Central Apennines","authors":"A. Cipriani, C. Bottini","doi":"10.3301/IJG.2019.09","DOIUrl":"https://doi.org/10.3301/IJG.2019.09","url":null,"abstract":"This work presents the results of a geological mapping project performed on the Narni-Amelia Ridge (Central Apennines, Italy). Fieldwork was aimed at defining the rift and post-rift architecture of the Jurassic to Cretaceous part of the Umbria-Marche-Sabina basin succession, which is characterised by Jurassic rift-related pelagic carbonate platform (PCP)/basin systems. While the effects of the Early Jurassic rifting are well documented in the regional literature, a phase of post-rift extensional tectonics in the late Early Cretaceous is a relatively under-investigated subject. This normal faulting was apparently widespread at a super-regional scale, and the Narni- Amelia Ridge carries direct and indirect evidence for this episode of revived deformation:(i) the occurrence of limestone megabreccias (Mt. Cosce Breccia) resting unconformably, through an erosional surface, on a Jurassic (and Cretaceous) horst-block. Stepped unconformities are associated with spur and groove geometries of the escarpment, suggesting topographic backstepping due to rock- fall processes;(ii) millimetre to decametre-scale neptunian dykes and sills made of Mt. Cosce Breccia and of Maiolica pelagites. These fractures cut the footwall-block of Cretaceous faults, made of Calcare Massiccio Fm (Hettangian), sub-orthogonal to its master- bedding. Dykes are associated with tension gashes filled with chert (silicification of fracture zones). The steep walls of those neptunian dykes filled with Maiolica-type deposits also exhibit a thin chert band;(iii) the onlap of Aptian-Albian Marne a Fucoidi Fm on the Hettangian Calcare Massiccio Fm. This is an unicum in the whole Umbria- Marche-Sabina Domain;(iv) the presence of mass-transport deposits (slumps and debris flows) in the uppermost part of the Maiolica Fm and lower part of the Marne a Fucoidi Fm.These stratigraphic anomalies are collectively interpreted as the products of normal faulting, which caused the retreat of the original Jurassic margins of the PCPs, rejuvenating the submarine palaeotopography. A middle Barremian age for this phase of syn- sedimentary extension is indicated by the nannofossil assemblage of Maiolica-type facies sampled from the Mt. Cosce Breccia and from the neptunian dykes.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":"1 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2019-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3301/IJG.2019.09","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41587229","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. Casalini, A. Heumann, Sara Marchionni, S. Conticelli, R. Avanzinelli, S. Tommasini
The active volcano of Ischia, the well-known island off-shore the city of Naples, has had a discontinuous volcanic activity characterised by caldera-forming paroxysmal eruptions, lava flows, and lava domes for >150 kyr. The overall geochemical composition of erupted magmas includes shoshonite, latite, and trachyte/ trachyphonolite. In a complementary study, we demonstrated that the evolution of Ischia trachytes with Sr
{"title":"Inverse modelling to unravel the radiogenic isotope signature of mantle sources from evolved magmas: the case-study of Ischia volcano","authors":"M. Casalini, A. Heumann, Sara Marchionni, S. Conticelli, R. Avanzinelli, S. Tommasini","doi":"10.3301/IJG.2018.05","DOIUrl":"https://doi.org/10.3301/IJG.2018.05","url":null,"abstract":"The active volcano of Ischia, the well-known island off-shore the city of Naples, has had a discontinuous volcanic activity characterised by caldera-forming paroxysmal eruptions, lava flows, and lava domes for >150 kyr. The overall geochemical composition of erupted magmas includes shoshonite, latite, and trachyte/ trachyphonolite. In a complementary study, we demonstrated that the evolution of Ischia trachytes with Sr","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3301/IJG.2018.05","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46915996","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 Pancherot-Cime Bianche-Bettaforca (PCB) is an ophiolite-free decollement cover unit with a greenschist facies imprint, continental affinity and problematic provenance. It is located in the ophiolitic Piemonte zone which marks the suture in the north-western Alps of the Mesozoic Liguria-Piemonte ocean (western Tethys). A new stratigraphic reconstruction of this unit is presented. It includes the following main lithofacies: Quartzitic Schists and metaconglomerates (Permian), Yellowish Quartzite (Early Triassic), Bedded Dolostone and Marbles (Middle Triassic), Tabular White Quartzite (Carnian), Massive Dolostone (Norian), Carnieules and Brown Marble (Rhaetian-Jurassic). Ages are hypothetical because no fossil has been found.Comparison with the Prepiemontese and Austroalpine sedimentary successions shows major affinity with the Austroalpine cover units.The continental basement of this exotic unit is unknown. Suitable candidates can be considered the Mt Emilius and other Lower Austroalpine eclogitic outliers, as these continental slices are missing of a sedimentary cover and are located inside the ophiolitic Piemonte zone, near the structural level of the PCB unit. In this view, thesebasement and cover units were decoupled during subduction due to their contrasting metamorphic features.
{"title":"The problematic origin of the Pancherot-Cime Bianche-Bettaforca unit (PCB) in the Piemonte zone (Western Alps)","authors":"L. Passeri, G. Ciarapica, G. D. Dal Piaz","doi":"10.3301/IJG.2018.21","DOIUrl":"https://doi.org/10.3301/IJG.2018.21","url":null,"abstract":"The Pancherot-Cime Bianche-Bettaforca (PCB) is an ophiolite-free decollement cover unit with a greenschist facies imprint, continental affinity and problematic provenance. It is located in the ophiolitic Piemonte zone which marks the suture in the north-western Alps of the Mesozoic Liguria-Piemonte ocean (western Tethys). A new stratigraphic reconstruction of this unit is presented. It includes the following main lithofacies: Quartzitic Schists and metaconglomerates (Permian), Yellowish Quartzite (Early Triassic), Bedded Dolostone and Marbles (Middle Triassic), Tabular White Quartzite (Carnian), Massive Dolostone (Norian), Carnieules and Brown Marble (Rhaetian-Jurassic). Ages are hypothetical because no fossil has been found.Comparison with the Prepiemontese and Austroalpine sedimentary successions shows major affinity with the Austroalpine cover units.The continental basement of this exotic unit is unknown. Suitable candidates can be considered the Mt Emilius and other Lower Austroalpine eclogitic outliers, as these continental slices are missing of a sedimentary cover and are located inside the ophiolitic Piemonte zone, near the structural level of the PCB unit. In this view, thesebasement and cover units were decoupled during subduction due to their contrasting metamorphic features.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43539528","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 Oligocene-Miocene turbidite successions of the Emilia-Tuscany Apennines are one of the most intriguing aspects of the geology of the Northern Apennines (NA) in Italy. To better understand the stratigraphic and tectonic evolution of this sector of the NA, we conducted a detailed field-mapping and stratigraphic study of turbidite successions of the most critical areas of this sector of the chain, which are composed of Mt. Modino Sandstone, Mt. Cervarola Sandstone, Gova Sandstone and associated marly units. Our contribution encompasses a review of the regional geology and fieldrelationships of arenaceous and marly formations, with a particular focus on new biostratigraphic data. This new biostratigraphic study is coupled with a compositional characterization of sandstone, with a view to producing a paleogeographic and evolutionary model of the thrust-foredeep system of the NA during the late Oligocene-early Miocene. This system was structured in a first stage during the Chattian-Aquitanian with the development of different inner turbidite systems (the Mt. Modino Sandstone in the frontal thrust-top basin, the Macigno, the Torre degli Amorotti System of the Mt. Cervarola Sandstone and the Gova Sandstone in the foredeep). The orogenic wedge was then affected by a later important deformation event during the earliest Burdigalian (Tuscan phase), developing the wider foredeep of the Mt. Cervarola Sandstone basin.
艾米利亚-托斯卡纳亚平宁山脉的渐新世-中新世浊积岩序列是意大利北亚平宁山脉（NA）地质中最有趣的方面之一。为了更好地了解该区块的地层和构造演化，我们对该区块链最关键区域的浊积岩序列进行了详细的野外测绘和地层研究，这些区域由莫迪诺山砂岩、塞瓦洛拉山砂岩、戈瓦砂岩和相关的泥灰岩单元组成。我们的贡献包括对砂质和泥灰岩地层的区域地质和野外关系的审查，特别关注新的生物地层学数据。这项新的生物地层学研究与砂岩的成分特征相结合，以期建立渐新世晚期-中新世早期北美逆冲前深系统的古地理和进化模型。该系统是在查特-阿基坦阶的第一阶段构造的，发育了不同的内部浊积岩系统（前缘逆冲顶盆地的莫迪诺山砂岩、Macigno、Cervarola山砂岩的Torre degli Amorotti系统和前深部的Gova砂岩）。造山楔随后在最早的布尔迪加利安（托斯卡纳阶段）受到后来的一次重要变形事件的影响，形成了塞瓦罗拉山砂岩盆地更宽的前深部。
{"title":"The Late Oligocene to Early Miocene foredeep basin system evolution of the Northern Apennines (Emilia-Tuscany, Italy): review and new litho- biostratigraphic data","authors":"G. Cornamusini, P. Conti, A. M. Bambini","doi":"10.3301/IJG.2018.06","DOIUrl":"https://doi.org/10.3301/IJG.2018.06","url":null,"abstract":"The Oligocene-Miocene turbidite successions of the Emilia-Tuscany Apennines are one of the most intriguing aspects of the geology of the Northern Apennines (NA) in Italy. To better understand the stratigraphic and tectonic evolution of this sector of the NA, we conducted a detailed field-mapping and stratigraphic study of turbidite successions of the most critical areas of this sector of the chain, which are composed of Mt. Modino Sandstone, Mt. Cervarola Sandstone, Gova Sandstone and associated marly units. Our contribution encompasses a review of the regional geology and fieldrelationships of arenaceous and marly formations, with a particular focus on new biostratigraphic data. This new biostratigraphic study is coupled with a compositional characterization of sandstone, with a view to producing a paleogeographic and evolutionary model of the thrust-foredeep system of the NA during the late Oligocene-early Miocene. This system was structured in a first stage during the Chattian-Aquitanian with the development of different inner turbidite systems (the Mt. Modino Sandstone in the frontal thrust-top basin, the Macigno, the Torre degli Amorotti System of the Mt. Cervarola Sandstone and the Gova Sandstone in the foredeep). The orogenic wedge was then affected by a later important deformation event during the earliest Burdigalian (Tuscan phase), developing the wider foredeep of the Mt. Cervarola Sandstone basin.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45266750","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}
Oligocene ultrapotassic and associated potassic rocks from Western Alps derived from the crystallisation of magmas originated from partial melting of mantle sources extremely enriched in recycled crustal components. These rocks are well suited for studying the effects of subduction-related, sediment-derived metasomatism on Molybdenum and Uranium isotopes. This paper reports the first 98Mo/95Mo and 238U/235U data on potassic and ultrapotassic rocks at destructive plate margins. Both 98Mo/95Mo and 238U/235U ratios show large variations in the samples from Western Alps. U isotope compositions are consistent with an increasing role of metasomatising melts from recycled sediments, which explains the variable enrichment in potassium and incompatible trace elements passing from high-K calc-alkaline to lamproitic magmas through shoshonitic ones. The variation of Mo isotope compositions is more complex due to the extreme depletion in Mo observed and since their values exceed the range observed for volcanic arcs. These features were investigated considering several possible processes such as secondary weathering, hosting of Mo related to residual mineral phases during sediment melting or physical removal during subduction. The results were also discussed in the framework of the complex processes responsible for the genesis and geochemical characteristics of the Tethyan Realm Lamproites, particularly in relationship with the exotic SALATHO geochemical component.
{"title":"98Mo/95Mo and 238U/235U in lamproites, shoshonites, and high-K calc-alkaline rocks from Western Alps: inferences on their genesis","authors":"M. Casalini","doi":"10.3301/IJG.2018.20","DOIUrl":"https://doi.org/10.3301/IJG.2018.20","url":null,"abstract":"Oligocene ultrapotassic and associated potassic rocks from Western Alps derived from the crystallisation of magmas originated from partial melting of mantle sources extremely enriched in recycled crustal components. These rocks are well suited for studying the effects of subduction-related, sediment-derived metasomatism on Molybdenum and Uranium isotopes. This paper reports the first 98Mo/95Mo and 238U/235U data on potassic and ultrapotassic rocks at destructive plate margins. Both 98Mo/95Mo and 238U/235U ratios show large variations in the samples from Western Alps. U isotope compositions are consistent with an increasing role of metasomatising melts from recycled sediments, which explains the variable enrichment in potassium and incompatible trace elements passing from high-K calc-alkaline to lamproitic magmas through shoshonitic ones. The variation of Mo isotope compositions is more complex due to the extreme depletion in Mo observed and since their values exceed the range observed for volcanic arcs. These features were investigated considering several possible processes such as secondary weathering, hosting of Mo related to residual mineral phases during sediment melting or physical removal during subduction. The results were also discussed in the framework of the complex processes responsible for the genesis and geochemical characteristics of the Tethyan Realm Lamproites, particularly in relationship with the exotic SALATHO geochemical component.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44325176","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 paper aims to study the geomaterials of the most important Romanesque-style monument of Sardinia, the Santissima Trinita di Saccargia Basilica (Codrongianos, north Sardinia). The monument was built up on ruins of a pre-existing monastery, and completed in 1116 A.D. Over time, the aspect of the monument is quite changed due to two series of restoration works. The stone materials consist of both grey-black basalts and whitish limestones and marls, intentionally used to give a bichromy effect of the construction. The volcanic rocks belong to the Miocene-Pleistocene volcanic Sardinian activity, while limestones and marls belong to the sedimentary marine Miocene Formation of Meilogu (Logudoro).To define both the origin and the alteration processes of materials, geochemical, petrographic and physical-mechanical investigations of volcanic and sedimentary rocks were carried out on samples collected from monument and possible source outcrops.The integrated chemical (ICP-MS) and petrographic data allowed to ascertain the sourcing sites of raw materials. Moreover, physical-mechanical tests along with X-Ray Diffraction (XRPD) analysis, highlighted the main weathering processes responsible of the chemical-physical alteration affecting the geomaterials, and the newly-formed mineral phases formed on stone surface.
本文旨在研究撒丁岛最重要的罗马式纪念碑Santissima Trinita di Saccargia Basilica（Codronianos，北撒丁岛）的地质材料。这座纪念碑建在一座先前存在的修道院的废墟上，于公元1116年竣工。随着时间的推移，由于两系列的修复工程，纪念碑的面貌发生了很大的变化。石材包括灰黑色玄武岩、白色石灰石和泥灰岩，有意用于营造双色效果。火山岩属于中新世-更新世的撒丁岛火山活动，石灰岩和泥灰岩属于Meilogu（Logudoro）的沉积海相中新世组，火山岩和沉积岩的岩相和物理力学研究是在从纪念碑和可能的来源露头采集的样本上进行的。综合化学（ICP-MS）和岩相数据可以确定原材料的来源地。此外，物理力学测试以及X射线衍射（XRPD）分析强调了影响岩土材料的化学物理蚀变的主要风化过程，以及在岩石表面形成的新形成的矿物相。
{"title":"Geochemical, mineral-petrographic and physical-mechanical characterization of stones and mortars from the Romanesque Saccargia Basilica (Sardinia, Italy) to define their origin and alteration","authors":"S. Columbu, M. Palomba, F. Sitzia, M. Murgia","doi":"10.3301/IJG.2018.04","DOIUrl":"https://doi.org/10.3301/IJG.2018.04","url":null,"abstract":"This paper aims to study the geomaterials of the most important Romanesque-style monument of Sardinia, the Santissima Trinita di Saccargia Basilica (Codrongianos, north Sardinia). The monument was built up on ruins of a pre-existing monastery, and completed in 1116 A.D. Over time, the aspect of the monument is quite changed due to two series of restoration works. The stone materials consist of both grey-black basalts and whitish limestones and marls, intentionally used to give a bichromy effect of the construction. The volcanic rocks belong to the Miocene-Pleistocene volcanic Sardinian activity, while limestones and marls belong to the sedimentary marine Miocene Formation of Meilogu (Logudoro).To define both the origin and the alteration processes of materials, geochemical, petrographic and physical-mechanical investigations of volcanic and sedimentary rocks were carried out on samples collected from monument and possible source outcrops.The integrated chemical (ICP-MS) and petrographic data allowed to ascertain the sourcing sites of raw materials. Moreover, physical-mechanical tests along with X-Ray Diffraction (XRPD) analysis, highlighted the main weathering processes responsible of the chemical-physical alteration affecting the geomaterials, and the newly-formed mineral phases formed on stone surface.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3301/IJG.2018.04","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44833557","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. Öğretmen, V. Frezza, N. Hudáčková, E. Gliozzi, P. Cipollari, C. Faranda, Giuditta Radeff, D. Cosentino
The Mediterranean Basin is a semi-enclosed basin highly sensitive to climate changes such as evaporation-precipitation processes and glacial-interglacial transitions. It is composed by two main basins, the Western Mediterranean and the Eastern Mediterranean, which are differently sensitive to the high latitude and low latitude climate interactions. Such differences could translate in different reactionsto climate changes recorded in the bottom sediments, i.e. the enhanced effects of the freshwater inputs on the bottom oxygenation in the Eastern Mediterranean. In this paper we investigate the palaeoenvironment and palaeoclimate derived from the study of Early Pleistocene (Calabrian) deep marine deposits cropping out along the southern margin of the Central Anatolian Plateau at the Gulnar East section (southern Turkey). Using benthic and planktonic foraminifers the bottom oxygenation and the sea surface temperature (SST) were evaluated through the calculation of the benthic foraminifera oxygen index (BFOI) and palaeoclimate curve. The results show that the marine epibathyal palaeonvironment in this Eastern Mediterranean area reacted to the palaeoclimate changes with the water mass stratification (warm periods) and/or with enhanced primary productivity (cool/cold periods) leading to the deposition of sapropel layers with different degrees of bottom oxygenation.
{"title":"Early Pleistocene (Calabrian) marine bottom oxygenation and palaeoclimate at the southern margin of the Central Anatolian Plateau","authors":"N. Öğretmen, V. Frezza, N. Hudáčková, E. Gliozzi, P. Cipollari, C. Faranda, Giuditta Radeff, D. Cosentino","doi":"10.3301/IJG.2018.19","DOIUrl":"https://doi.org/10.3301/IJG.2018.19","url":null,"abstract":"The Mediterranean Basin is a semi-enclosed basin highly sensitive to climate changes such as evaporation-precipitation processes and glacial-interglacial transitions. It is composed by two main basins, the Western Mediterranean and the Eastern Mediterranean, which are differently sensitive to the high latitude and low latitude climate interactions. Such differences could translate in different reactionsto climate changes recorded in the bottom sediments, i.e. the enhanced effects of the freshwater inputs on the bottom oxygenation in the Eastern Mediterranean. In this paper we investigate the palaeoenvironment and palaeoclimate derived from the study of Early Pleistocene (Calabrian) deep marine deposits cropping out along the southern margin of the Central Anatolian Plateau at the Gulnar East section (southern Turkey). Using benthic and planktonic foraminifers the bottom oxygenation and the sea surface temperature (SST) were evaluated through the calculation of the benthic foraminifera oxygen index (BFOI) and palaeoclimate curve. The results show that the marine epibathyal palaeonvironment in this Eastern Mediterranean area reacted to the palaeoclimate changes with the water mass stratification (warm periods) and/or with enhanced primary productivity (cool/cold periods) leading to the deposition of sapropel layers with different degrees of bottom oxygenation.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44044659","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}
V. Santis, M. Caldara, Trinidad Torres, J. Ortiz, Y. Sánchez-Palencia
We performed detailed geological and geomorphological analyses on a well-exposed series of marine terrace deposits located along a coastal area from the city of Taranto to the Bradano River in the northern Gulf of Taranto (southern Italy). Absolute dating was performed by applying amino acid racemisation (AAR) to ostracod shells and isoleucine epimerisation (D-aIle/L-Ile) to Glycymeris sp. shells. The combination of field geological surveys, remote sensing,digital terrain model analysis, and absolute dating allowed us to study a large number of stratigraphic sections as well as recognise and map three terrace deposits in the Apulian sector of the Gulf of Taranto that date to MIS 7.3, MIS 7.1 and MIS 5. A peculiar feature of the MIS 7.1terrace deposit is the presence of biohermal and biostromal limestones rich in Cladocora caespitosa, calcareous algae and bryozoans; this feature contrasts with general context of the prevailing siliciclastic deposits.Based on currently available data, we propose two hypotheses regarding the MIS 5 terrace deposit: 1) the MIS 5 terrace formed entirely during MIS 5.5; and 2) the MIS 5 terrace is a set of terraces that correlates to MIS 5.5, 5.3 and 5.1, in which the scarps and abrasion platforms have been partially masked by the superimposition of the so-called givoni, ridges that are elongated sub-parallel to the coastline.Our data, combined with an extensive critical review of age dates in the literature, allow us to exclude the presence of an emerged marine terrace deposit of MIS 3.We calculate the uplift rates of the MIS 7.3, 7.1, 5.5 and 5.3 palaeoshorelines. In the west sector, the mean uplift rates calculated for the recognised inner edges are MIS 7.3 = 0.65 mm/a, MIS 5.5 = 0.39 mm/a, MIS 5.3 = 0.31 mm/a; in the central sector the rates are MIS 7.3 = 0.485 mm/a, MIS 7.1 = 0.37 mm/a, MIS 5.5 = 0.35 mm/a, MIS 5.3 = 0.26 mm/a; in the east sector the rates are MIS 7.3 = 0.39 mm/a, MIS 5.5 = 0.25 mm/a, MIS 5.3 = 0.21 mm/a. These uplift ratesshow a uniform decreasing trend in time and space, proceeding from the western to the eastern sector, which allows us to hypothesise a slowing of the uplift phase characterising the foredeep, which began in the middle Pleistocene.
{"title":"A review of MIS 7 and MIS 5 terrace deposits along the Gulf of Taranto based on new stratigraphic and chronological data","authors":"V. Santis, M. Caldara, Trinidad Torres, J. Ortiz, Y. Sánchez-Palencia","doi":"10.3301/IJG.2018.02","DOIUrl":"https://doi.org/10.3301/IJG.2018.02","url":null,"abstract":"We performed detailed geological and geomorphological analyses on a well-exposed series of marine terrace deposits located along a coastal area from the city of Taranto to the Bradano River in the northern Gulf of Taranto (southern Italy). Absolute dating was performed by applying amino acid racemisation (AAR) to ostracod shells and isoleucine epimerisation (D-aIle/L-Ile) to Glycymeris sp. shells. The combination of field geological surveys, remote sensing,digital terrain model analysis, and absolute dating allowed us to study a large number of stratigraphic sections as well as recognise and map three terrace deposits in the Apulian sector of the Gulf of Taranto that date to MIS 7.3, MIS 7.1 and MIS 5. A peculiar feature of the MIS 7.1terrace deposit is the presence of biohermal and biostromal limestones rich in Cladocora caespitosa, calcareous algae and bryozoans; this feature contrasts with general context of the prevailing siliciclastic deposits.Based on currently available data, we propose two hypotheses regarding the MIS 5 terrace deposit: 1) the MIS 5 terrace formed entirely during MIS 5.5; and 2) the MIS 5 terrace is a set of terraces that correlates to MIS 5.5, 5.3 and 5.1, in which the scarps and abrasion platforms have been partially masked by the superimposition of the so-called givoni, ridges that are elongated sub-parallel to the coastline.Our data, combined with an extensive critical review of age dates in the literature, allow us to exclude the presence of an emerged marine terrace deposit of MIS 3.We calculate the uplift rates of the MIS 7.3, 7.1, 5.5 and 5.3 palaeoshorelines. In the west sector, the mean uplift rates calculated for the recognised inner edges are MIS 7.3 = 0.65 mm/a, MIS 5.5 = 0.39 mm/a, MIS 5.3 = 0.31 mm/a; in the central sector the rates are MIS 7.3 = 0.485 mm/a, MIS 7.1 = 0.37 mm/a, MIS 5.5 = 0.35 mm/a, MIS 5.3 = 0.26 mm/a; in the east sector the rates are MIS 7.3 = 0.39 mm/a, MIS 5.5 = 0.25 mm/a, MIS 5.3 = 0.21 mm/a. These uplift ratesshow a uniform decreasing trend in time and space, proceeding from the western to the eastern sector, which allows us to hypothesise a slowing of the uplift phase characterising the foredeep, which began in the middle Pleistocene.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43362321","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 Sesia-Lanzo Zone (SLZ), the subunit Rocca Canavese Thrust Sheet (RCT) is characterised by a mixture of mantle- and crust-derived lithologies and can be a good candidate to be a former subduction-related melange of the Austroalpine domain. The unit consists of metapelites, metagranitoids, metabasics, metagabbro and serpentinised lherzolite lenses from metre to hundred-metre size.According to the literature, PT peak conditions for all lithologies are 0.8-1 GPa at 300-400°C, in lawsonite-blueschist facies conditions recorded during the Alpine subduction. However recent work describes different mineral assemblages for the metamorphic peak, separating rocks with lawsonite from those with jadeite. Therefore, we refined the meso and microstructural analysis of the tectonic slices of RCT and we performed a detailed thermo-barometry of different metamorphicstages in order to quantify Alpine peak conditions and P-T-d-t paths, and to test whether the RCT represents a subduction-related melange. We focus on metagabbros, Jd-bearing and Lws-bearing glaucophanites since they have the most suitable chemistry allowing to reconstruct the complex evolution of the mixing. Metagabbros and Jd-bearing glaucophanites experienced a D1a metamorphic stage characterised by a pressure of 1.3-1.8 GPa and temperature of 450-550°C, in eclogite facies condition. Lws-bearing glaucophanites experienced a D1b metamorphic stage at a temperature
{"title":"Structural and metamorphic evolution during tectonic mixing: is the Rocca Canavese Thrust Sheet (Italian Western Alps) a subduction-related mélange?","authors":"M. Roda, F. D. Salvo, M. Zucali, M. Spalla","doi":"10.3301/IJG.2018.17","DOIUrl":"https://doi.org/10.3301/IJG.2018.17","url":null,"abstract":"In the Sesia-Lanzo Zone (SLZ), the subunit Rocca Canavese Thrust Sheet (RCT) is characterised by a mixture of mantle- and crust-derived lithologies and can be a good candidate to be a former subduction-related melange of the Austroalpine domain. The unit consists of metapelites, metagranitoids, metabasics, metagabbro and serpentinised lherzolite lenses from metre to hundred-metre size.According to the literature, PT peak conditions for all lithologies are 0.8-1 GPa at 300-400°C, in lawsonite-blueschist facies conditions recorded during the Alpine subduction. However recent work describes different mineral assemblages for the metamorphic peak, separating rocks with lawsonite from those with jadeite. Therefore, we refined the meso and microstructural analysis of the tectonic slices of RCT and we performed a detailed thermo-barometry of different metamorphicstages in order to quantify Alpine peak conditions and P-T-d-t paths, and to test whether the RCT represents a subduction-related melange. We focus on metagabbros, Jd-bearing and Lws-bearing glaucophanites since they have the most suitable chemistry allowing to reconstruct the complex evolution of the mixing. Metagabbros and Jd-bearing glaucophanites experienced a D1a metamorphic stage characterised by a pressure of 1.3-1.8 GPa and temperature of 450-550°C, in eclogite facies condition. Lws-bearing glaucophanites experienced a D1b metamorphic stage at a temperature","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44215378","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}
C. Montemagni, S. Iaccarino, C. Montomoli, R. Carosi, A. Jain, I. Villa
In the Garhwal Himalaya, the Malari granite, a small pluton, intrudes the upper portion of the Greater Himalayan Sequence (GHS) and is deformed in the South Tibetan Detachment System (STDS) shearing. In the present work, we undertook a multidisciplinary approach involving microstructural, chemical and geochronological analyses of the samples in order to constrain the timing of shearing along the STDS. Microstructural observations of samples suggest a switch in deformation features with structural position from the structurally upper samples to the structurally lower one. X-ray maps and electron microprobe analyses reveal a quite uniform chemical composition of muscovite in the three selected samples. 40Ar/39Ar muscovite ages constrain the waning stages of ductile deformation: in rocks ductilely deformed by the STDS activity, they record recrystallization at 16.0-16.5 Ma; the age of static muscovite grown after sillimanite at 14.3 Ma post-dates cessation of movement on the STDS and pre-dates the main activity of the Main Central Thrust in the Western Himalaya.
{"title":"Age constraints on the deformation style of the South Tibetan Detachment System in Garhwal Himalaya","authors":"C. Montemagni, S. Iaccarino, C. Montomoli, R. Carosi, A. Jain, I. Villa","doi":"10.3301/IJG.2018.07","DOIUrl":"https://doi.org/10.3301/IJG.2018.07","url":null,"abstract":"In the Garhwal Himalaya, the Malari granite, a small pluton, intrudes the upper portion of the Greater Himalayan Sequence (GHS) and is deformed in the South Tibetan Detachment System (STDS) shearing. In the present work, we undertook a multidisciplinary approach involving microstructural, chemical and geochronological analyses of the samples in order to constrain the timing of shearing along the STDS. Microstructural observations of samples suggest a switch in deformation features with structural position from the structurally upper samples to the structurally lower one. X-ray maps and electron microprobe analyses reveal a quite uniform chemical composition of muscovite in the three selected samples. 40Ar/39Ar muscovite ages constrain the waning stages of ductile deformation: in rocks ductilely deformed by the STDS activity, they record recrystallization at 16.0-16.5 Ma; the age of static muscovite grown after sillimanite at 14.3 Ma post-dates cessation of movement on the STDS and pre-dates the main activity of the Main Central Thrust in the Western Himalaya.","PeriodicalId":49317,"journal":{"name":"Italian Journal of Geosciences","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2018-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3301/IJG.2018.07","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49506429","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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