Biological memoirs最新文献

{"title":"Chapter 5.4b Marie Byrd Land and Ellsworth Land: petrology","authors":"K. Panter, T. Wilch, J. Smellie, P. Kyle, W. Mcintosh","doi":"10.1144/M55-2019-50","DOIUrl":"https://doi.org/10.1144/M55-2019-50","url":null,"abstract":"Abstract In Marie Byrd Land and Ellsworth Land 19 large polygenetic volcanoes and numerous smaller centres are exposed above the West Antarctic Ice Sheet along the northern flank of the West Antarctic Rift System. The Cenozoic (36.7 Ma to active) volcanism of the Marie Byrd Land Volcanic Group (MBLVG) encompasses the full spectrum of alkaline series compositions ranging from basalt to intermediate (e.g. mugearite, benmoreite) to phonolite, peralkaline trachyte, rhyolite and rare pantellerite. Differentiation from basalt is described by progressive fractional crystallization; however, to produce silica-oversaturated compositions two mechanisms are proposed: (1) polybaric fractionation with early-stage removal of amphibole at high pressures; and (2) assimilation–fractional crystallization to explain elevated 87Sr/86Sri ratios. Most basalts are silica-undersaturated and enriched in incompatible trace elements (e.g. La/YbN >10), indicating small degrees of partial melting of a garnet-bearing mantle. Mildly silica-undersaturated and rare silica-saturated basalts, including tholeiites, are less enriched (La/YbN <10), a result of higher degrees of melting. Trace elements and isotopes (Sr, Nd, Pb) reveal a regional gradient explained by mixing between two mantle components, subduction-modified lithosphere and HIMU-like plume (206Pb/204Pb >20) materials. Geophysical studies indicate a deep thermal anomaly beneath central Marie Byrd Land, suggesting a plume influence on volcanism and tectonism.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"75 1","pages":"577 - 614"},"PeriodicalIF":0.0,"publicationDate":"2021-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88957877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 5 Tectonic evolution of the Oman Mountains","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.5","DOIUrl":"https://doi.org/10.1144/M54.5","url":null,"abstract":"Abstract The tectonic evolution of the Oman Mountains as of the Neoproterozoic begins with a major extensional event, the Neoproterozoic Abu Mahara rifting. It was followed by the compressional Nabitah event, still during the Neoproterozoic, in Oman but possibly not in the study area. During the earliest Cambrian, the Jabal Akhdar area was affected by the Cadomian Orogeny, marked by NE--SW shortening. It is unclear, whether the Saih Hatat area was exposed to the Cadomian deformation, too. Still during the lower Cambrian, the Angudan Orogeny followed, characterized by NW--SE shortening. An episode of rifting affected the Saih Hatat area during the mid-Ordovician. During the mid-Carboniferous, both dome areas were deformed by tilting and large-scale open folding in the course of the ‘Hercynian’ event. As a consequence, a major unconformity formed. As another Late Paleozoic event, the Permian break-up of Pangaea and subsequent formation of the Hawasina ocean basin, are recorded in the Southeastern Oman Mountains. As a result, a passive margin formed which existed until the mid-Cretaceous, characterized by deposition of mostly shelfal carbonates. This interval of general tectonic quiescence was interrupted during the early Jurassic by uplift and tilting of the Arabian Platform. The platform collapsed during the late Cretaceous, related to the arrival of the obducted allochthonous nappes including the Semail Ophiolite, transforming the passive margin to an active margin. The Semail Ophiolite formed most likely above a subduction zone within the Neo-Tethys Ocean during the Cenomanian while parts of the Arabian Plate were subducted to the NE. Formation of oceanic lithosphere and SW-thrusting was broadly coeval, resulting in ophiolite obduction onto the Hawasina Basin. The Semail Ophiolite and the Hawasina rocks combined were thrust further onto the Arabian Plate. Their load created a foreland basin and forebulge within the Arabian Platform. Once the continental lithosphere of the Arabian Platform was forced into the subduction zone, a tear between the dense oceanic lithosphere and the buoyant continental lithosphere developed. This led to rapid uplift and exhumation of subducted continental lithosphere of the Saih Hatat area, while obduction was still going on, causing in multiple and intense folding/thrusting within the eastern Saih Hatat Dome. Exhumation of the Saih Hatat Dome was massive. The emplacement of the ophiolite was completed during the Campanian/Maastrichtian. For completeness, we also present alternative models for the developmental history of the Semail Ophiolite. Immediately after emplacement, the Arabian lithosphere underwent intense top-to-the-NE extensional shearing. Most of the Saih Hatat Dome was exhumed during the latest Cretaceous to Early Eocene, associated with major extensional shearing at its flanks. Further convergence during the late Eocene to Miocene resulted in exhumation of the Jabal Akhdar Dome and some gentle exhumation","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"1 1","pages":"67 - 103"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90507520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 4 Large-scale structure of the study area","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.4","DOIUrl":"https://doi.org/10.1144/M54.4","url":null,"abstract":"Abstract The Southeastern Oman Mountains are dominated by two major culminations: the Jabal Akhdar and Saih Hatat domes, surrounded by allochthonous and/or neo-autochthonous rocks. In the cores of both domes, folded autochthonous and par-autochthonous pre-Permian metasedimentary rocks are exposed, subjacent to the ‘Hercynian’ Unconformity. Above the unconformity are Permo--Mesozoic shelfal sedimentary rocks, characterized by carbonates. These sedimentary rocks were openly folded. The open folds are large-scale elongate structures that define the shapes of both domes. The main elongation direction is NW--SE. Doming is syn- to post-obductional. Most margins of the domes are marked by major post-obductional, extensional faults. Reactivated basement faults along the eastern margin of the Jabal Akhdar Dome may be responsible for the straight NNE-striking eastern margin which is perpendicular to the main elongation direction of the domes. The deep structure of both domes is poorly known. However, the Moho depth below the centre of the Jabal Akhdar Dome is at 50 km. We present a geological map of both domes, depicting the main faults and folds, and schematic cross-sections, parallel and perpendicular to the Oman Mountains.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"53 1","pages":"61 - 66"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91036699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 6 Conclusions, differences between the Jabal Akhdar and Saih Hatat domes and unanswered questions","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.6","DOIUrl":"https://doi.org/10.1144/M54.6","url":null,"abstract":"Abstract This chapter provides the conclusions/outlines of the tectonics, affecting the Southeastern Oman Mountains, including the Jabal Akhdar and Saih Hatat domes. The main tectonic events include amongst others (1) Neoproterozoic rifting, (2) two distinct early Paleozoic compressive events, (3) large-scale open ‘Hercynian’ folding and formation of a pronounced unconformity during the late Paleozoic, (4) rifting preceding the opening of the Neo-Tethys Ocean during the late Paleozoic, (5) late Cretaceous obduction of the Semail Ophiolite and the response of the Arabian lithosphere as well as (6) post-obductional tectonics. Also of major geological significance are the three major glaciations (Sturtian, Marinoan and Late Paleozoic Gondwana glaciation) which have been recorded in the rocks of northern Oman. Moreover, major lithological, structural and metamorphic differences exist between the Jabal Akhdar and Saih Hatat domes. It appears likely that a major fault, striking parallel to the eastern margin of the Jabal Akhdar Dome, probably originating during Neoproterozoic terrain accretion, acted as a divide between both domes until present. This fault was multiple times reactivated and could explain the differences between the two domes. A catalogue of unanswered questions is included in chronological order to express that many geological aspects need further investigation and future research projects.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"92 1","pages":"105 - 111"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74208297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 6.1 Marine record of Antarctic volcanism from drill cores","authors":"A. Di Roberto, P. Del Carlo, M. Pompilio","doi":"10.1144/M55-2018-49","DOIUrl":"https://doi.org/10.1144/M55-2018-49","url":null,"abstract":"Abstract We review here data and information on Antarctic volcanism resulting from recent tephrostratigraphic investigations on marine cores. Records include deep drill cores recovered during oceanographic expeditions: DSDP, ODP and IODP drill cores recovered during ice-based and land-based international cooperative drilling programmes DVDP 15, MSSTS-1, CIROS-1 and CIROS-2, DVDP 15, CRP-1, CRP-2/2A and CRP-3, ANDRILL-MIS and ANDRILL-SMS, and shallow gravity and piston cores recovered in the Antarctic and sub-Antarctic oceans. We report on the identification of visible volcaniclastic horizons and, in particular, of primary tephra within the marine sequences. Where available, the results of analyses carried out on these products are presented. The volcanic material identified differs in its nature, composition and emplacement mechanisms. It was derived from different sources on the Antarctic continent and was emplaced over a wide time span. Marine sediments contain a more complete record of the explosive activity from Antarctic volcanoes and are complementary to those obtained by land-based studies. This record provides important information for volcanological reconstructions including approximate intensities and magnitudes of eruptions, and their duration, age and recurrence, as well as their eruptive dynamics. In addition, characterized tephra layers represent an invaluable chronological tool essential in establishing correlations between different archives and in synchronizing climate records.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"1 1","pages":"631 - 647"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78386570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Appendices to: The Geology and Tectonics of the Jabal Akhdar and Saih Hatat Domes, Oman Mountains","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.7","DOIUrl":"https://doi.org/10.1144/M54.7","url":null,"abstract":"Andreas Scharf1*, Frank Mattern1, Mohammed Al-Wardi1, Gianluca Frijia2, Daniel Moraetis1,3, Bernhard Pracejus1, Wilfried Bauer4 and Ivan Callegari4 Department of Earth Sciences, College of Science, Sultan Qaboos University, P.O. Box: 36, PC 123, Al-Khod, Muscat, Sultanate of Oman Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, 44122, Ferrara, Italy Department of Applied Physics and Astronomy, College of Sciences, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates Department of Applied Geosciences, German University of Technology GUtech, P.O. Box: 1816, PC 130, Halban, Sultanate of Oman","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"5 1","pages":"113 - 115"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75485666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 1 Introduction and tectonic framework","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.1","DOIUrl":"https://doi.org/10.1144/M54.1","url":null,"abstract":"Abstract The extraordinary outcrop conditions provide a unique opportunity to study the geology and tectonics of the Oman Mountains, which record a geological history of more than 800 million years. We provide a summary of the geological evolution of the Oman Mountains with the emphasis on the Jabal Akhdar and Saih Hatat domes. This Memoir comprises seven chapters. This first chapter summarizes the former studies and the tectonic framework. This is followed by a comprehensive description of all geological formations/rock units (Scharf et al. 2021a, Chapter 2, this Memoir) including the famous Semail Ophiolite, the fault and fold pattern (Scharf et al. 2021b, Chapter 3, this Memoir) and the overall structure (Scharf et al. 2021c, Chapter 4, this Memoir). Chapter 5 (Scharf et al. 2021d) explains the varied tectonic evolution of the study area, ranging from the Neoproterozoic until present, while Chapter 6 (Scharf et al. 2021e) contains the conclusions and a catalogue of open questions. Finally, Chapter 7 (Scharf et al. 2021f) provides two over-sized geological maps (1 : 250 000 version available online) and a correlation chart, providing an overview of the geological units/formations. This volume is of interest for all geoscientists, geoscience students and professionals studying the Oman Mountains on the surface as well as in the subsurface because it represents a comprehensive and detailed reference.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"1 1","pages":"1 - 10"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90341858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"About this title - The Geology and Tectonics of the Jabal Akhdar and Saih Hatat Domes, Oman Mountains","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/m54","DOIUrl":"https://doi.org/10.1144/m54","url":null,"abstract":"The geology of the Oman Mountains, including the Jabal Akhdar and Saih Hatat domes, is extraordinarily well-exposed and diverse, spanning a geological record of more than 800 Ma. The area is blessed with first-class outcrops and is well known in the geological community for its ophiolite. The Oman Mountains have much more to offer; including, Neoproterozoic diamictites (“Snowball Earth”), fossil-rich Permo-Mesozoic carbonates and metamorphic rocks. The arid climate and deep incision of wadis allow for nearly complete rock exposure which can be investigated in all three dimensions. The diverse geology is also responsible for the breathtaking landscape. New roads and the nature of the friendly Omani people make fieldwork unforgettable. This Memoir provides a thorough state-of-the-art overview of the geology and tectonics of the Southeastern Oman Mountains, and is accompanied by an over-sized geological map and a correlation chart.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"29 1","pages":"NP - NP"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90484607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 2 Tectonostratigraphy of the eastern part of the Oman Mountains","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.2","DOIUrl":"https://doi.org/10.1144/M54.2","url":null,"abstract":"Abstract This chapter provides comprehensive descriptions of 52 numbered formations/rock units of the Southeastern Oman Mountains, based on available literature. The oldest eight siliciclastic and carbonate formations are positioned below the ‘Hercynian’ Unconformity. The overlying formation (9–16) mostly represent carbonates which accumulated in a passive margin platform setting during or after the opening of the Neo-Tethys Ocean. The passive margin slope and platform collapsed during the late Cretaceous because of the obduction of the Semail Ophiolite along with the deep marine Hawasina sedimentary rocks. The collapsing passive margin interval was recorded within the syn-obductional Aruma Group (17; Muti Formation). Above this formation are the allochthonous units (18–42) of the tectonically lower Hawasina deep-sea basin and the structurally overlying Semail Ophiolite. The former contains Permian to Upper Cretaceous formations, while the latter is Cenomanian in age. Above the allochthonous rocks, the Neo-autochthonous formations were deposited, starting with the post-obductional uppermost Cretaceous Aruma Group (43; Al-Khod Formation) until the Quaternary deposits (52). All these formations/rock units are depicted on an accompanying map and stratigraphic chart.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"35 1","pages":"11 - 47"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82184565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chapter 3 Thrusts, extensional faults and fold patterns of the major units","authors":"A. Scharf, F. Mattern, M. Al-Wardi, G. Frijia, D. Moraetis, B. Pracejus, W. Bauer, I. Callegari","doi":"10.1144/M54.3","DOIUrl":"https://doi.org/10.1144/M54.3","url":null,"abstract":"Abstract This chapter is concerned with the main faults and folds within the Southeastern Oman Mountains based on available literature. The main, best and most widely exposed thrusts are those related to the SW-directed late Cretaceous obduction of the allochthonous nappes onto the Arabian platform and margin. These thrusts are related to obduction of rocks, which had formed hundreds of kilometres offshore Oman. The thrusts were active from the Cenomanian to the Campanian. Obduction-related thrusts and folds are spectacularly exposed within the rocks of the Arabian platform in the eastern part of the Saih Hatat Dome, including large-scale recumbent cylindrical folds and sheath folds. At least six fold sets can be studied in the Southeastern Oman Mountains. At least two of them had formed prior to obduction and are exposed in the Pre-Permian formations of the Jabal Akhdar Dome. At least three fold sets formed in the course of obduction, while at least one fold set is postobductional in age. Besides the compressional structures, the Oman Mountains expose major post-obductional extensional faults, mostly at the margins of the Jabal Akhdar and Saih Hatat domes. The throw of these faults amounts to a few to several kilometres. Finally, this chapter provides an overview of the enigmatic Batinah Mélange which consists of slivers of Hawasina rocks, resting (unusually) structurally above the Semail Ophiolite.","PeriodicalId":84271,"journal":{"name":"Biological memoirs","volume":"17 1","pages":"49 - 60"},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83492719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}