Evolving Earth最新文献

{"title":"Evolutionary history, biogeography, and extinction of the Cretaceous cheirolepidiaceous conifer, Frenelopsis","authors":"Josep Marmi ,&nbsp;Aixa Tosal ,&nbsp;Carles Martín-Closas","doi":"10.1016/j.eve.2023.100017","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100017","url":null,"abstract":"<div><p><em>Frenelopsis</em> Schenk (family Cheirolepidiaceae†) was among the most widespread conifer genera and a dominant element of wetland ecosystems in low to mid-palaeolatitudes in the the Northern Hemisphere. It was also one of the more important peat-forming shrubs and trees generating extensive deposits of Cretaceous lignite. The genus became extinct at the end of the Cretaceous. Studies of the presence/absence and diversity of <em>Frenelopsis</em> allow us to analyse its evolutionary history, biogeography, and the consider the possible causes of its extinction. During the Early Cretaceous, the genus diversified, triggered by the rise of short-lived species and the constraint of endemism. The maximum diversity and species richness were attained in Barremian and Aptian times while the maximum number of global occurrences is documented during the Albian. In the Late Cretaceous, <em>Frenelopsis</em> species richness declined and the genus became progressively more restricted to the Tethyan archipelago in the context of the rise to dominance of angiosperms. In the Maastrichtian, the last representatives of <em>Frenelopsis</em> survived in the coastal wetlands of Iberia as a relictual plant. In northeast Iberia (present-day Pyrenees) the last occurrences from this genus are early to middle Maastrichtian in age and show an intriguing contrast between the abundance of vegetative remains and the lack of <em>Classopollis</em> pollen grains. These data suggest that at the end of its lineage, the plant was reproducing only vegetatively and that male sterility may have contributed to extinction.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100017"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000171/pdfft?md5=9d7b608b2f34dac9129d5df883924ee7&pid=1-s2.0-S2950117223000171-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136571798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is there a link between carbon isotopes and sea level in epicontinental carbonate settings?","authors":"Page C. Quinton,&nbsp;Michael C. Rygel","doi":"10.1016/j.eve.2023.100016","DOIUrl":"10.1016/j.eve.2023.100016","url":null,"abstract":"<div><p>A presumed link between carbon isotopic trends and sea level change features prominently in many studies of epicontinental carbonates. In these shallow marine environments, a combination of basin restriction, burial/oxidation of organic carbon, proximity to terrestrial carbon sources, carbonate mineralogy, and/or meteoric influence can result in δ¹³C_carb records that are distinct from that of the open ocean. Because many of these processes are linked to sea level change, it has been argued that sea level might exert a significant and systematic control on the δ¹³C_carb records from epicontinental settings. Multiple studies have attempted to document sea level's influence on carbon isotopic trends, but they do so with only limited constraints on sea level change and without objective evaluations of interpreted trends and relationships. We argue that the complex and complicated set of processes influencing carbon isotopic values in epicontinental settings requires a systematic approach to truly address the question of sea level's influence on δ¹³C_carb. Only by integrating carbon isotopic records with a detailed sedimentological and sequence stratigraphic framework can we properly track changes in depositional environments and reconstruct the transgressive-regressive history of the rocks. Trends and relationships in these robust datasets can be evaluated with rank correlation tests specifically designed and empirically tested to deal with noisy datasets. In short, we map a possible path forward for systematic testing of the relationship between sea level and δ¹³C_carb.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100016"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S295011722300016X/pdfft?md5=c783a7e8b990a68ebb4f19ca0cbd22f8&pid=1-s2.0-S295011722300016X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135809637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Response of the Patagonian floras to climatic cooling during Oligocene−Miocene transition and the expansion of Antarctic glaciation","authors":"Mariano J. Tapia ,&nbsp;Carolina Panti ,&nbsp;Damián A. Fernández ,&nbsp;Roberto R. Pujana ,&nbsp;Viviana D. Barreda ,&nbsp;Luis Palazzesi","doi":"10.1016/j.eve.2023.100015","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100015","url":null,"abstract":"<div><p>Pulses of Antarctic ice sheet expansion and associated climatic deterioration are thought to have driven major shifts in the world's flora during the Cenozoic Era. However, the rarity of fossils from well-constrained sedimentary strata in high palaeolatitudes makes it difficult to explore to these vegetation shifts directly. In this study, we infer changing patterns of floristic richness through the Oligocene−Miocene cooling event (∼23 Ma), based on analysis of terrestrial palynological samples in the radiometrically-constrained sediments of the Río Guillermo Formation of southern Patagonia. Our fossil assemblages include plant families typical of modern Magellanic subpolar forests such as Nothofagaceae, Podocarpaceae, Araucariaceae, and Myrtaceae. Adjusted for sample completeness (or coverage), our floristic richness estimates are, on average, higher than those from modern subpolar forests yet considerably lower than any other Paleogene or Neogene palynological records published elsewhere from the continent. The transient Oligocene−Miocene cooling episode, whose effects were probably intensified in southern Patagonia due to its close proximity to the glaciated Antarctic Peninsula, may have contributed to the steep decline in floristic richness. We infer that most Gondwanan plant relicts that survived across the Oligocene−Miocene transition endured through subsequent Neogene climatic fluctuations and contribute to present-day Magellanic subpolar forests. Our study highlights how precisely-dated fossil assemblages and robust diversity methods can be used to track biodiversity shifts in response to past climate change.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100015"},"PeriodicalIF":0.0,"publicationDate":"2023-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000158/pdfft?md5=9e1af49cc9f8e769306a656d4aa2c76c&pid=1-s2.0-S2950117223000158-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136570895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The link between lithospheric scale deformations and deep fluid emanations: Inferences from the Southeastern Carpathians, Romania","authors":"T.P. Lange ,&nbsp;L. Palcsu ,&nbsp;A. Szakács ,&nbsp;Á. Kővágó ,&nbsp;O. Gelencsér ,&nbsp;Á. Gál ,&nbsp;S. Gyila ,&nbsp;T. M. Tóth ,&nbsp;L. Mațenco ,&nbsp;Cs. Krézsek ,&nbsp;L. Lenkey ,&nbsp;Cs. Szabó ,&nbsp;I.J. Kovács","doi":"10.1016/j.eve.2023.100013","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100013","url":null,"abstract":"<div><p>Understanding the formation, migration and emanation of deep CO₂, H₂O and noble gases (He–Ne) in deep-seated deformation settings is crucial to know the complex relationship between deep-originated fluids and lithospheric deformation. To gain a better insight into these phenomena, we studied the origin of H₂O, CO₂ and noble gases of gas-rich springs found in the Târgu Secuiesc Basin located in the southeasternmost part of the Carpathian-Pannonian region of Europe. This study area is one of the best natural examples to understand the connection between the deep sources of gas emanations and deep-seated deformation zones, providing an excellent analogue for regions with similar tectonic settings and fluid emanation properties. We studied the δ²H and δ¹⁸O stable isotopic ratios of the spring waters, and the δ¹³C, He and Ne stable isotopic ratio of the emanating CO₂-rich gases dissolved in the mineral spring waters in Covasna town and its vicinity. Based on the δ²H, δ¹³C, δ¹⁸O stable isotopic ratios, the spring waters and the majority of the gases are released through two consecutive fluid infiltration events. The preservation of the metamorphic signal of the upwelling H₂O is linked to the local groundwater flow and fault abundancy. Furthermore, the noble gas isotopic ratios show a high degree of atmospheric contamination in the dissolved water gasses that is most likely related to the local hydrogeology. Nevertheless, the elevated corrected helium stable isotopic ratios (R_c/Ra) of our filtered data suggest that part of the emanating gases have a potential upper mantle source component. Beneath the Southeastern Carpathians, mantle fluids can have multiple origin including the dehydration of the sinking slab hosting the Vrancea seismogenic zone, the local asthenospheric upwelling and the lithospheric mantle. The flux of the mantle fluids is enhanced by lithospheric scale deformation zones that also support the fluid inflow from the upper mantle into the lower crust. The upwelling CO₂–H₂O mantle fluids may induce the release of crustal fluids by shifting X(CO₂) composition of the pore fluid and, consequently, initiating decarbonisation and devolatilization metamorphic reactions as a result of carbonate and hydrous mineral destabilisation in the crust. Based on the p-T-X(CO₂) conditions of calc-silicates and the local low geotherm, we emphasise the importance of the upwelling fluids in the release and upward migration of further H₂O and CO₂ in the shallower lower and upper crust. We infer that migration of deep fluids may also play an important role in addition to temperature control on the generation of crustal fluids in deep-seated deformation zones.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100013"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000134/pdfft?md5=760562bb09cda23425114f08388c1c93&pid=1-s2.0-S2950117223000134-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136571797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Imprecision and instability of the Phanerozoic chronostratigraphic scale: A solution","authors":"Spencer G. Lucas","doi":"10.1016/j.eve.2023.100011","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100011","url":null,"abstract":"<div><p>The use of the GSSP (Global Stratotype Section and Point) method to define a Phanerozoic chronostratigraphic timescale has resulted in imprecision and instability because most of the primary signals for correlation of the GSSPs are single taxon biotic events that are inherently diachronous and restricted in their paleogeographic distributions by the limitations of sampling, facies and provincialism. Greater precision and stability can be achieved by using non-biotic criteria as the primary signals of GSSPs-numerical ages, magnetostratigraphy, isotope excursions and others. If correlation is aided by close association of the non-biotic primary signal with secondary signals of geographically widespread, ergo global, extent, such non-biotic primary signals of GSSPs will produce a more precise and more stable chronostratigraphic timescale.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100011"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000110/pdfft?md5=752531362dee9947549a7a3edab5417f&pid=1-s2.0-S2950117223000110-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136570935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A multidisciplinary approach to resolving the end-Guadalupian extinction","authors":"Christopher R. Fielding ,&nbsp;Scott E. Bryan ,&nbsp;James L. Crowley ,&nbsp;Tracy D. Frank ,&nbsp;Michael T. Hren ,&nbsp;Chris Mays ,&nbsp;Stephen McLoughlin ,&nbsp;Jun Shen ,&nbsp;Peter J. Wagner ,&nbsp;Arne Winguth ,&nbsp;Cornelia Winguth","doi":"10.1016/j.eve.2023.100014","DOIUrl":"10.1016/j.eve.2023.100014","url":null,"abstract":"<div><p>The transition from the middle to late Permian (Guadalupian–Lopingian) is claimed to record one or more extinction events that rival the ‘Big Five’ in terms of depletion of biological diversity and reorganization of ecosystem structure. Yet many questions remain as to whether the events recorded in separate regions were synchronous, causally related, or were of a magnitude rivaling other major crises in Earth's history. In this paper, we survey some major unresolved issues related to the Guadalupian–Lopingian transition and offer a multidisciplinary approach to advance understanding of this under-appreciated biotic crisis by utilizing records in Southern Hemisphere high-palaeolatitude settings. We focus on the Bowen-Gunnedah-Sydney Basin System (BGSBS) as a prime site for analyses of biotic and physical environmental change at high palaeolatitudes in the middle and terminal Capitanian. Preliminary data suggest the likely position of the mid-Capitanian event is recorded in regressive deposits at the base of the Tomago Coal Measures (northern Sydney Basin) and around the contact between the Broughton Formation and the disconformably overlying Pheasants Nest Formation (southern Sydney Basin). Initial data suggest that the end-Capitanian event roughly correlates to the transgressive “Kulnura Marine Tongue” in the middle of the Tomago Coal Measures (northern Sydney Basin) and strata bearing dispersed, ice-rafted gravel in the Erins Vale Formation (southern Sydney Basin). Preliminary observations suggest that few plant genera or species disappeared in the transition from the Guadalupian to Lopingian, and the latter interval saw an increase in floristic diversity.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100014"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000146/pdfft?md5=8569f08c174efb88859cf5e3f5d5d424&pid=1-s2.0-S2950117223000146-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135707383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstruction of annual and seasonal variations in water temperature in the Haute-Dronne River of southwest France based on δ18O records of freshwater pearl mussel shells (M. margaritifera), and its palaeoenvironmental implications","authors":"Emma Samin ,&nbsp;Bruno Malaizé ,&nbsp;Émilie P. Dassié ,&nbsp;Karine Charlier ,&nbsp;Dominique Genty ,&nbsp;Patricia Richard ,&nbsp;Johan Vieira ,&nbsp;Magalie Baudrimont","doi":"10.1016/j.eve.2023.100012","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100012","url":null,"abstract":"<div><p>The aragonitic shells of freshwater pearl mussels (<em>Margaritifera margaritifera</em>) contain annual growth increments, whose composition reflect the geochemistry of the river water and bivalve metabolism. The wide geographic distribution and the long lifespan of <em>M. margaritifera</em> coupled with a previously established relationship between the δ¹⁸O values of their shells and river temperature means this taxon is a potentially important environmental archive; such freshwater proxies are currently limited in both space and time. In this paper, we investigate the relationship between δ¹⁸O values and both <em>in situ</em> and modeled river temperature (2007–2015) for a population of <em>M. margaritifera</em> living in the Haute-Dronne River (southwest France). Our δ¹⁸O data permit the reconstruction of seasonal temperature variations in the river. Sclerochronology reveals that shells also record seasonal patterns and produce winter growth increments, contrary to other investigations carried out on the same mussel species from northern Europe where low winter temperatures (below 5 °C) interrupt shell growth. The presented calibration for <em>M. margaritifera</em> and host river temperature offers the potential for reconstructing palaeoenvironmental conditions based on fossil specimens of the same species. Such reconstructions may improve our understanding of past continental climate and help calibrate regional palaeoclimate models.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100012"},"PeriodicalIF":0.0,"publicationDate":"2023-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2950117223000122/pdfft?md5=9ae993f1bf87b3423c4853bf4663eac0&pid=1-s2.0-S2950117223000122-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136572132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Watershed resilience to climate change: From hillslopes to rivers and coasts","authors":"Paolo Tarolli ,&nbsp;Giulia Zuecco ,&nbsp;Lorenzo Picco","doi":"10.1016/j.eve.2023.100010","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100010","url":null,"abstract":"<div><p>Climate is changing rapidly, resulting in more frequent and extreme weather events, such as megadroughts or flash droughts, intense rainfall events causing floods and landslides, heavy snowfalls, and windstorms. With a rising global population and increased levels of urbanization, the socio-economic consequences of these changes to Earth's surface processes are severe and have a more significant impact than in the past. A critical need is to improve understanding of physical processes at the watershed scale by integrating modern technologies. This will help define change hotspots and detect cascade effects from hillslopes through rivers to coastal areas. In this watershed approach to resilience management, adaptative strategies need to be re-balanced in terms of structural and non-structural measures. On the one hand, sustainable structural solutions may be the only choice for some densely populated urban areas. On the other hand, Nature-Based Solutions (NBS) may offer an unparalleled approach to combining sustainability and resilience while preserving ecosystems. The lack of a sustainable response to climate change will have only one result: land abandonment with related migration and conflicts.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100010"},"PeriodicalIF":0.0,"publicationDate":"2023-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203456","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":"Ontogeny of islands associated with mantle-plume hotspots and its implications for biogeographical models","authors":"Jason R. Ali ,&nbsp;Shai Meiri","doi":"10.1016/j.eve.2023.100007","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100007","url":null,"abstract":"<div><p>Mantle-plume hotspot islands are a common focus of biogeographical studies, and models for the growth of their biodiversity often incorporate aspects of their physical evolution. The ontogenetic pathways of such islands have generally been perceived as simple, comprising successive episodes of emergence, growth, peak size, reduction and elimination. In this paper, we improve knowledge of island development by examining key physical data from 60 islands at eight archipelagoes in equatorial to mid-latitude regions of the Atlantic, Indian and Pacific oceans. Such landmasses achieve their maximum sizes within 200–500 kyrs. However, island longevity varies by up to a factor of 5 and is strongly controlled by the speed of the associated tectonic plate as it moves over the narrow, thermally-elevated conduit where volcanism is focused. At moderate to high speeds (40–90 ​mm/year; e.g., Galápagos, Hawaii), lifetimes are no more than 4–6 Myrs. In contrast, the oldest landmasses (in the Cabo Verde, Canary, and Mascarene archipelagoes) are built upon slow-travelling plates (&lt;20 ​mm/year) and date from the Miocene. Notably, Fuerteventura in the Canary Islands, where the rate is <em>c</em>. 2.5 ​mm/year, has existed since 23 ​Ma. Two processes likely sustain the sub-aerial elevation of these massifs: heat from the plume expands the underlying lithosphere thus increasing its buoyancy, which in turn inhibits cooling-contraction subsidence; protracted magmatic activity counteracts denudation. Furthermore, the Cabo Verde and the Canary archipelagoes sit within dry climatic regions, which likely reduced erosion and mass-wasting. Consequently, two ontogenetic models are presented, one for the edifices on the intermediate- and fast-moving plates, and a second for the constructions on the slow-moving plates. The development path for the former is similar to the schema that is commonly envisaged (see above) and takes place over <em>c</em>. 5 Myrs, whereas the one for the latter is rather different and involves quasi-continuous surface renewal plus the maintenance of elevation that lasts for <em>c</em>. 10–25 Myrs. The new information should permit a fuller understanding of how a hotspot island's physical development shapes its biota and inform the formulation of related theoretical models.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100007"},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203454","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":"Ultra-slow transverse waves during continental breakup","authors":"Antonio Schettino ,&nbsp;Giorgio Ranalli","doi":"10.1016/j.eve.2023.100009","DOIUrl":"https://doi.org/10.1016/j.eve.2023.100009","url":null,"abstract":"<div><p>Continental rifting is one of the four fundamental geological processes of the Wilson cycle. Rifting results from the continuous stretching of continental lithosphere and involves mechanical, thermodynamic, and rheological processes. It may be followed by a catastrophic breakup stage, which determines cessation of extensional deformation and the final separation of a continent into two distinct tectonic plates that grow by accretion of oceanic lithosphere. To date, the transition to sea−floor spreading and the conditions for the development of a new ocean have not been fully understood. We propose that a consistent description of this process must consider the existence of long−term retarded elasticity in the mantle lithosphere, the superadiabatic conditions of this layer, and the combined action of such elastic forces with the localized buoyancy arising from thermal anomalies. We present a solution of the rheological equation for a nonlinear viscoelastic model of the lithosphere mantle and numerical experiments showing that transient thermal anomalies are generated during the extension, which lead to the formation of transverse waves having wavelengths of the order of hundreds to thousands km and periods of several tens kyrs. These waves induce oscillating topography and influence the relief. Therefore, they could be responsible for eustatic cycles both in the axial rift lacustrine system and in off−axis (dendritic) lakes placed in areas of reversed drainage. At sufficiently high extension rates, deformation localizes and these ultra-slow waves determine cyclic shear failure, with formation of X−shaped cross structures through the lithosphere that prelude to the final rupture.</p></div>","PeriodicalId":100516,"journal":{"name":"Evolving Earth","volume":"1 ","pages":"Article 100009"},"PeriodicalIF":0.0,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50203455","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}