Pub Date : 2022-02-25DOI: 10.1146/annurev-earth-100821-081832
D. Drucker
The Mammoth Steppe was the dominant terrestrial biome of the Northern Hemisphere during the late Pleistocene. It encompassed a nonanalog community of animals living in a cold and treeless steppe-tundra landscape. The high diversity of species, including megafauna, could be supported by a productive environment. The carbon-13 and nitrogen-15 abundances in bone collagen confirmed that the coexistence of the large herbivores was facilitated by a pronounced dietary niche partitioning, with some species relatively flexible in the exploitation of browse and graze, while others were more specialized. The isotopic abundances of carbon and nitrogen in carnivores confirm a dietary partitioning, probably based on the size of prey, with an increasingly generalist behavior emerging after the Last Glacial Maximum with notable exceptions. Isotopic investigation reveals dynamic processes of ecological displacement and replacement, shedding new light on the potential niche spectrum of extant species that are now present as relic populations. ▪ The Mammoth Steppe is an extinct nonanalog ecosystem with high productivity and biodiversity despite the cold and dry conditions of the Last Glacial Period. ▪ Stable isotopes reveal that niche partitioning among herbivores and carnivores is a dominant trait of the Mammoth Steppe. ▪ Switches in preferred prey and ecological replacement are observed among carnivores over time, with the few highly specialized predators going extinct. ▪ Warmer and more humid conditions preceding the Holocene impacted large herbivores in most regions of the Mammoth Steppe, driving some of the largest ones to extinction. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"The Isotopic Ecology of the Mammoth Steppe","authors":"D. Drucker","doi":"10.1146/annurev-earth-100821-081832","DOIUrl":"https://doi.org/10.1146/annurev-earth-100821-081832","url":null,"abstract":"The Mammoth Steppe was the dominant terrestrial biome of the Northern Hemisphere during the late Pleistocene. It encompassed a nonanalog community of animals living in a cold and treeless steppe-tundra landscape. The high diversity of species, including megafauna, could be supported by a productive environment. The carbon-13 and nitrogen-15 abundances in bone collagen confirmed that the coexistence of the large herbivores was facilitated by a pronounced dietary niche partitioning, with some species relatively flexible in the exploitation of browse and graze, while others were more specialized. The isotopic abundances of carbon and nitrogen in carnivores confirm a dietary partitioning, probably based on the size of prey, with an increasingly generalist behavior emerging after the Last Glacial Maximum with notable exceptions. Isotopic investigation reveals dynamic processes of ecological displacement and replacement, shedding new light on the potential niche spectrum of extant species that are now present as relic populations. ▪ The Mammoth Steppe is an extinct nonanalog ecosystem with high productivity and biodiversity despite the cold and dry conditions of the Last Glacial Period. ▪ Stable isotopes reveal that niche partitioning among herbivores and carnivores is a dominant trait of the Mammoth Steppe. ▪ Switches in preferred prey and ecological replacement are observed among carnivores over time, with the few highly specialized predators going extinct. ▪ Warmer and more humid conditions preceding the Holocene impacted large herbivores in most regions of the Mammoth Steppe, driving some of the largest ones to extinction. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"114 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2022-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86794615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-02-07DOI: 10.1146/annurev-earth-032320-111432
K. Karlstrom, J. Wilgus, Jacob O. Thacker, B. Schmandt, D. Coblentz, M. Albonico
The Cenozoic Colorado Plateau physiographic province overlies multiple Precambrian provinces. Its ∼2-km elevation rim surrounds an ∼1.6-km elevation core that is underlain by thicker crust and lithospheric mantle, with a sharp structural transition ∼100 km concentrically inboard of the physiographic boundary on all but its northeastern margin. The region was uplifted in three episodes: ∼70–50 Ma uplift above sea level driven by flat-slab subduction; ∼38–23 Ma uplift associated with voluminous regional magmatism and slab removal, and less than 20 Ma uplift associated with inboard propagation of basaltic magmatism that tracked convective erosion of the lithospheric core. Neogene uplift helped integrate the Colorado River from the Rockies at 11 Ma to the Gulf of California by ∼5 Ma. The sharp rim-to-core transition defined by geological and geophysical data sets suggests a young transient plateau that is uplifting as it shrinks to merge with surrounding regions of postorogenic extension. ▪ The Colorado Plateau's iconic landscapes were shaped during its 70-million-year, still-enigmatic, tectonic evolution characterized by uplift and erosion. ▪ Uplift of the Colorado Plateau from sea level took place in three episodes, the youngest of which has been ongoing for the past 20 million years. ▪ Tectonism across the Colorado Plateau's nearest plate margin (the base of the plate!) is driving uplift and volcanism and enhancing its rugged landscapes. ▪ The bowl-shaped Colorado Plateau province is defined by ongoing uplift and an inboard sweep of magmatism around its margins. ▪ The keel of the Colorado Plateau is being thinned as the North American plate moves southwest through the underlying mantle. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Tectonics of the Colorado Plateau and Its Margins","authors":"K. Karlstrom, J. Wilgus, Jacob O. Thacker, B. Schmandt, D. Coblentz, M. Albonico","doi":"10.1146/annurev-earth-032320-111432","DOIUrl":"https://doi.org/10.1146/annurev-earth-032320-111432","url":null,"abstract":"The Cenozoic Colorado Plateau physiographic province overlies multiple Precambrian provinces. Its ∼2-km elevation rim surrounds an ∼1.6-km elevation core that is underlain by thicker crust and lithospheric mantle, with a sharp structural transition ∼100 km concentrically inboard of the physiographic boundary on all but its northeastern margin. The region was uplifted in three episodes: ∼70–50 Ma uplift above sea level driven by flat-slab subduction; ∼38–23 Ma uplift associated with voluminous regional magmatism and slab removal, and less than 20 Ma uplift associated with inboard propagation of basaltic magmatism that tracked convective erosion of the lithospheric core. Neogene uplift helped integrate the Colorado River from the Rockies at 11 Ma to the Gulf of California by ∼5 Ma. The sharp rim-to-core transition defined by geological and geophysical data sets suggests a young transient plateau that is uplifting as it shrinks to merge with surrounding regions of postorogenic extension. ▪ The Colorado Plateau's iconic landscapes were shaped during its 70-million-year, still-enigmatic, tectonic evolution characterized by uplift and erosion. ▪ Uplift of the Colorado Plateau from sea level took place in three episodes, the youngest of which has been ongoing for the past 20 million years. ▪ Tectonism across the Colorado Plateau's nearest plate margin (the base of the plate!) is driving uplift and volcanism and enhancing its rugged landscapes. ▪ The bowl-shaped Colorado Plateau province is defined by ongoing uplift and an inboard sweep of magmatism around its margins. ▪ The keel of the Colorado Plateau is being thinned as the North American plate moves southwest through the underlying mantle. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"48 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2022-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75097817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-21DOI: 10.1146/annurev-earth-032320-084733
G. Giordano, L. Caricchi
Polygenetic volcanoes and calderas produce eruptions of a wide variety of magnitudes, chemistries, and recurrence times. Understanding the interplay between long- and short-term and deep and shallow processes associated with accumulation and transfer of eruptible magma is essential for assessing the potential for future eruptions to occur and estimating their magnitude, which remains one of the foremost challenges in the Earth sciences. We review literature and use existing data for emblematic volcanic systems to identify the essential data sets required to define the state of activity of volcanoes and their plumbing systems. We explore global eruptive records in combination with heat flux and other geological and geophysical data to determine the evolutionary stage of plumbing systems. We define a Volcanic Activity Index applicable to any volcano that provides an estimate of the potential of a system to erupt in the future, which is especially important for long-quiescent volcanoes. ▪ Magmatic plumbing systems that feed volcanic activity extend across Earth's crust and are long-lived at depth and ephemeral in their shallowest portions. ▪ We revise and update the definitions of active, quiescent, and extinct volcanoes based on physical proxies for the architecture, longevity, amount, and distribution of eruptible magma in the crust. ▪ We propose a Volcanic Activity Index, which provides a relative measure of the state of activity of a volcano with respect to all other volcanoes in the world. ▪ New imaging and monitoring strategies are required to improve our ability to detect lower and middle crust magmatic processes and forecast eruptions and their potential size. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Determining the State of Activity of Transcrustal Magmatic Systems and Their Volcanoes","authors":"G. Giordano, L. Caricchi","doi":"10.1146/annurev-earth-032320-084733","DOIUrl":"https://doi.org/10.1146/annurev-earth-032320-084733","url":null,"abstract":"Polygenetic volcanoes and calderas produce eruptions of a wide variety of magnitudes, chemistries, and recurrence times. Understanding the interplay between long- and short-term and deep and shallow processes associated with accumulation and transfer of eruptible magma is essential for assessing the potential for future eruptions to occur and estimating their magnitude, which remains one of the foremost challenges in the Earth sciences. We review literature and use existing data for emblematic volcanic systems to identify the essential data sets required to define the state of activity of volcanoes and their plumbing systems. We explore global eruptive records in combination with heat flux and other geological and geophysical data to determine the evolutionary stage of plumbing systems. We define a Volcanic Activity Index applicable to any volcano that provides an estimate of the potential of a system to erupt in the future, which is especially important for long-quiescent volcanoes. ▪ Magmatic plumbing systems that feed volcanic activity extend across Earth's crust and are long-lived at depth and ephemeral in their shallowest portions. ▪ We revise and update the definitions of active, quiescent, and extinct volcanoes based on physical proxies for the architecture, longevity, amount, and distribution of eruptible magma in the crust. ▪ We propose a Volcanic Activity Index, which provides a relative measure of the state of activity of a volcano with respect to all other volcanoes in the world. ▪ New imaging and monitoring strategies are required to improve our ability to detect lower and middle crust magmatic processes and forecast eruptions and their potential size. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"9 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2022-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88626247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-21DOI: 10.1146/annurev-earth-031621-080804
Agustín Kriscautzky, L. Kah, J. Bartley
Molar-tooth structure (MTS) is an unusual carbonate fabric that is composed of variously shaped cracks and voids filled with calcite microspar. Despite a century of study, MTS remains enigmatic because it juxtaposes void formation within a cohesive yet unlithified substrate with the penecontemporaneous precipitation and lithification of void-filling carbonate microspar. MTS is broadly restricted to shallow marine carbonate strata of the Mesoproterozoic and Neoproterozoic, suggesting a fundamental link between the formation of MTS and the biogeochemical evolution of marine environments. Despite uncertainties in the origin of MTS, molar-tooth (MT) microspar remains a popular target for geochemical analysis and the reconstruction of Precambrian marine chemistry. Here we review models for the formation of MTS and show how detailed petrographic analysis of MT microspar permits identification of a complex process of precipitation and diagenesis that must be considered when the microspar phase is used as a geochemical proxy. ▪ Molar-tooth fabric is an enigmatic structure in Precambrian sedimentary rocks that is composed of variously shaped cracks and voids filled with carbonate microspar. ▪ Time restriction of this fabric suggests a link between this unusual structure and the biogeochemical evolution of marine environments. ▪ Petrographic analysis of molar-tooth fabric provides insight into fundamental processes of crystallization. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Molar-Tooth Structure as a Window into the Deposition and Diagenesis of Precambrian Carbonate","authors":"Agustín Kriscautzky, L. Kah, J. Bartley","doi":"10.1146/annurev-earth-031621-080804","DOIUrl":"https://doi.org/10.1146/annurev-earth-031621-080804","url":null,"abstract":"Molar-tooth structure (MTS) is an unusual carbonate fabric that is composed of variously shaped cracks and voids filled with calcite microspar. Despite a century of study, MTS remains enigmatic because it juxtaposes void formation within a cohesive yet unlithified substrate with the penecontemporaneous precipitation and lithification of void-filling carbonate microspar. MTS is broadly restricted to shallow marine carbonate strata of the Mesoproterozoic and Neoproterozoic, suggesting a fundamental link between the formation of MTS and the biogeochemical evolution of marine environments. Despite uncertainties in the origin of MTS, molar-tooth (MT) microspar remains a popular target for geochemical analysis and the reconstruction of Precambrian marine chemistry. Here we review models for the formation of MTS and show how detailed petrographic analysis of MT microspar permits identification of a complex process of precipitation and diagenesis that must be considered when the microspar phase is used as a geochemical proxy. ▪ Molar-tooth fabric is an enigmatic structure in Precambrian sedimentary rocks that is composed of variously shaped cracks and voids filled with carbonate microspar. ▪ Time restriction of this fabric suggests a link between this unusual structure and the biogeochemical evolution of marine environments. ▪ Petrographic analysis of molar-tooth fabric provides insight into fundamental processes of crystallization. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"42 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2022-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73635873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-21DOI: 10.1146/annurev-earth-032320-104243
G. Yaxley, Michael Anenburg, S. Tappe, S. Decrée, T. Guzmics
Carbonatites are igneous rocks formed in the crust by fractional crystallization of carbonate-rich parental melts that are mostly mantle derived. They dominantly consist of carbonate minerals such as calcite, dolomite, and ankerite, as well as minor phosphates, oxides, and silicates. They are emplaced in continental intraplate settings such as cratonic interiors and margins, as well as rift zones, and rarely on oceanic islands. Carbonatites are cumulate rocks, which are formed by physical separation and accumulation of crystals that crystallize from a melt, and their parental melts form by either ( a) direct partial melting of carbonate-bearing, metasomatized, lithospheric mantle producing alkali-bearing calciodolomitic melts or ( b) silicate-carbonate liquid immiscibility following fractional crystallization of carbonate-bearing, silica-undersaturated magmas such as nephelinites, melilitites, or lamprophyres. Their emplacement into the crust is usually accompanied by fenitization, alkali metasomatism of wallrock caused by fluids expelled from the crystallizing carbonatite. Carbonatites are major hosts of deposits of the rare earth elements and niobium, and the vast majority of the global production of these commodities is from carbonatites. ▪ Carbonatites are igneous rocks formed from carbonate-rich magmas, which ultimately formed in Earth's upper mantle. ▪ Carbonatites are associated with economic deposits of metals such as the rare earth elements and niobium, which are essential in high-tech applications. ▪ There are more than 500 carbonatites in the geological record but only one currently active carbonatite volcano, Oldoinyo Lengai in Tanzania. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Carbonatites: Classification, Sources, Evolution, and Emplacement","authors":"G. Yaxley, Michael Anenburg, S. Tappe, S. Decrée, T. Guzmics","doi":"10.1146/annurev-earth-032320-104243","DOIUrl":"https://doi.org/10.1146/annurev-earth-032320-104243","url":null,"abstract":"Carbonatites are igneous rocks formed in the crust by fractional crystallization of carbonate-rich parental melts that are mostly mantle derived. They dominantly consist of carbonate minerals such as calcite, dolomite, and ankerite, as well as minor phosphates, oxides, and silicates. They are emplaced in continental intraplate settings such as cratonic interiors and margins, as well as rift zones, and rarely on oceanic islands. Carbonatites are cumulate rocks, which are formed by physical separation and accumulation of crystals that crystallize from a melt, and their parental melts form by either ( a) direct partial melting of carbonate-bearing, metasomatized, lithospheric mantle producing alkali-bearing calciodolomitic melts or ( b) silicate-carbonate liquid immiscibility following fractional crystallization of carbonate-bearing, silica-undersaturated magmas such as nephelinites, melilitites, or lamprophyres. Their emplacement into the crust is usually accompanied by fenitization, alkali metasomatism of wallrock caused by fluids expelled from the crystallizing carbonatite. Carbonatites are major hosts of deposits of the rare earth elements and niobium, and the vast majority of the global production of these commodities is from carbonatites. ▪ Carbonatites are igneous rocks formed from carbonate-rich magmas, which ultimately formed in Earth's upper mantle. ▪ Carbonatites are associated with economic deposits of metals such as the rare earth elements and niobium, which are essential in high-tech applications. ▪ There are more than 500 carbonatites in the geological record but only one currently active carbonatite volcano, Oldoinyo Lengai in Tanzania. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"14 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2022-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88943074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-01-06DOI: 10.1146/annurev-earth-032320-085133
Kristen L. Cook, Michael Dietze
One of the pillars of geomorphology is the study of geomorphic processes and their drivers, dynamics, and impacts. Like all activity that transfers energy to Earth's surface, a wide range of geomorphic process types create seismic waves that can be measured with standard seismic instruments. Seismic signals provide continuous high-resolution coverage with a spatial footprint that can vary from local to global, and in recent years, efforts to exploit these signals for information about surface processes have increased dramatically, coalescing into the emerging field of environmental seismology. The application of seismic methods has the potential to drive advances in our understanding of the occurrence, timing, and triggering of geomorphic events, the dynamics of geomorphic processes, fluvial bedload transport, and integrative geomorphic system monitoring. As new seismic applications move from development to proof of concept to routine application, integration between geomorphologists and seismologists is key for continued progress. ▪ Geomorphic activity on Earth's surface produces seismic signals that can be measured with standard seismic instruments. ▪ Seismic methods are driving advances in our understanding of the occurrence, triggering, and internal dynamics of a range of geomorphic processes. ▪ Dedicated seismic-based observatories offer the potential to comprehensively characterize geomorphic activity and its impacts across a landscape. ▪ Collaboration between seismologists and geomorphologists is fostering the development of new applications, models, and analysis techniques for geomorphic seismology.
{"title":"Seismic Advances in Process Geomorphology","authors":"Kristen L. Cook, Michael Dietze","doi":"10.1146/annurev-earth-032320-085133","DOIUrl":"https://doi.org/10.1146/annurev-earth-032320-085133","url":null,"abstract":"One of the pillars of geomorphology is the study of geomorphic processes and their drivers, dynamics, and impacts. Like all activity that transfers energy to Earth's surface, a wide range of geomorphic process types create seismic waves that can be measured with standard seismic instruments. Seismic signals provide continuous high-resolution coverage with a spatial footprint that can vary from local to global, and in recent years, efforts to exploit these signals for information about surface processes have increased dramatically, coalescing into the emerging field of environmental seismology. The application of seismic methods has the potential to drive advances in our understanding of the occurrence, timing, and triggering of geomorphic events, the dynamics of geomorphic processes, fluvial bedload transport, and integrative geomorphic system monitoring. As new seismic applications move from development to proof of concept to routine application, integration between geomorphologists and seismologists is key for continued progress. ▪ Geomorphic activity on Earth's surface produces seismic signals that can be measured with standard seismic instruments. ▪ Seismic methods are driving advances in our understanding of the occurrence, triggering, and internal dynamics of a range of geomorphic processes. ▪ Dedicated seismic-based observatories offer the potential to comprehensively characterize geomorphic activity and its impacts across a landscape. ▪ Collaboration between seismologists and geomorphologists is fostering the development of new applications, models, and analysis techniques for geomorphic seismology.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"13 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2022-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138533934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-10DOI: 10.1146/annurev-earth-071521-063942
H. Tkalčić, Sheng Wang, Thanh‐Son Phạm
Understanding how Earth's inner core (IC) develops and evolves, including fine details of its structure and energy exchange across the boundary with the liquid outer core, helps us constrain its age, relationship with the planetary differentiation, and other significant global events throughout Earth's history, as well as the changing magnetic field. Since its discovery in 1936 and the solidity hypothesis in 1940, Earth's IC has never ceased to inspire geoscientists. However, while there are many seismological observations of compressional waves and normal modes sensitive to the IC's compressional and shear structure, the shear waves that provide direct evidence for the IC's solidity have remained elusive and have been reported in only a few publications. Further advances in the emerging correlation-wavefield paradigm, which explores waveform similarities, may hold the keys to refined measurements of all inner-core shear properties, informing dynamical models and strengthening interpretations of the IC's anisotropic structure and viscosity. ▪ What are the shear properties of the inner core, such as the shear-wave speed, shear modulus, shear attenuation, and shear-wave anisotropy? Can the shear properties be measured seismologically and confirmed experimentally? Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Shear Properties of Earth's Inner Core","authors":"H. Tkalčić, Sheng Wang, Thanh‐Son Phạm","doi":"10.1146/annurev-earth-071521-063942","DOIUrl":"https://doi.org/10.1146/annurev-earth-071521-063942","url":null,"abstract":"Understanding how Earth's inner core (IC) develops and evolves, including fine details of its structure and energy exchange across the boundary with the liquid outer core, helps us constrain its age, relationship with the planetary differentiation, and other significant global events throughout Earth's history, as well as the changing magnetic field. Since its discovery in 1936 and the solidity hypothesis in 1940, Earth's IC has never ceased to inspire geoscientists. However, while there are many seismological observations of compressional waves and normal modes sensitive to the IC's compressional and shear structure, the shear waves that provide direct evidence for the IC's solidity have remained elusive and have been reported in only a few publications. Further advances in the emerging correlation-wavefield paradigm, which explores waveform similarities, may hold the keys to refined measurements of all inner-core shear properties, informing dynamical models and strengthening interpretations of the IC's anisotropic structure and viscosity. ▪ What are the shear properties of the inner core, such as the shear-wave speed, shear modulus, shear attenuation, and shear-wave anisotropy? Can the shear properties be measured seismologically and confirmed experimentally? Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"7 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2021-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78360784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-09DOI: 10.1146/annurev-earth-032320-095156
L. Ivany, E. Judd
Ongoing global warming due to anthropogenic climate change has long been recognized, yet uncertainties regarding how seasonal extremes will change in the future persist. Paleoseasonal proxy data from intervals when global climate differed from today can help constrain how and why the annual temperature cycle has varied through space and time. Records of past seasonal variation in marine temperatures are available in the oxygen isotope values of serially sampled accretionary organisms. The most useful data sets come from carefully designed and computationally robust studies that enable characterization of paleoseasonal parameters and seamless integration with mean annual temperature data sets and climate models. Seasonal data sharpen interpretations of—and quantify overlooked or unconstrained seasonal biases in—the more voluminous mean temperature data and aid in the evaluation of climate model performance. Methodologies to rigorously analyze seasonal data are now available, and the promise of paleoseasonal proxy data for the next generation of paleoclimate research is significant. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Deciphering Temperature Seasonality in Earth's Ancient Oceans","authors":"L. Ivany, E. Judd","doi":"10.1146/annurev-earth-032320-095156","DOIUrl":"https://doi.org/10.1146/annurev-earth-032320-095156","url":null,"abstract":"Ongoing global warming due to anthropogenic climate change has long been recognized, yet uncertainties regarding how seasonal extremes will change in the future persist. Paleoseasonal proxy data from intervals when global climate differed from today can help constrain how and why the annual temperature cycle has varied through space and time. Records of past seasonal variation in marine temperatures are available in the oxygen isotope values of serially sampled accretionary organisms. The most useful data sets come from carefully designed and computationally robust studies that enable characterization of paleoseasonal parameters and seamless integration with mean annual temperature data sets and climate models. Seasonal data sharpen interpretations of—and quantify overlooked or unconstrained seasonal biases in—the more voluminous mean temperature data and aid in the evaluation of climate model performance. Methodologies to rigorously analyze seasonal data are now available, and the promise of paleoseasonal proxy data for the next generation of paleoclimate research is significant. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"3367 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2021-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86619786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-09DOI: 10.1146/annurev-earth-032320-102418
S. Tikoo, A. Evans
Dynamo magnetic fields are primarily generated by thermochemical convection of electrically conductive liquid metal within planetary cores. Convection can be sustained by secular cooling and may be bolstered by compositional buoyancy associated with core solidification. Additionally, mechanical stirring of core fluids and external perturbations by large impact events, tidal effects, and orbital precession can also contribute to sustaining dynamo fields. Convective dynamos cease when the core-mantle heat flux becomes subadiabatic or if specific crystallization regimes inhibit core fluid flows. Therefore, exploring the histories of magnetic fields across the Solar System provides a window into the thermal and chemical evolution of planetary interiors. Here we review how recent spacecraft-based studies of remanent crustal magnetism, paleomagnetic studies of rock samples, and planetary interior models have revealed the magnetic and evolutionary histories of Mercury, Earth, Mars, the Moon, and several planetesimals, as well as discuss avenues for future exploration and discovery. ▪ Paleomagnetism and remanent crustal magnetism studies elucidate the magnetic histories of rocky planetary bodies. ▪ Records of ancient dynamo fields have been obtained from 3 out of 4 terrestrial planets, the Moon, and several planetesimals. ▪ The geometries, intensities, and longevities of dynamo fields can provide information on core processes and planetary thermal evolution. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Dynamos in the Inner Solar System","authors":"S. Tikoo, A. Evans","doi":"10.1146/annurev-earth-032320-102418","DOIUrl":"https://doi.org/10.1146/annurev-earth-032320-102418","url":null,"abstract":"Dynamo magnetic fields are primarily generated by thermochemical convection of electrically conductive liquid metal within planetary cores. Convection can be sustained by secular cooling and may be bolstered by compositional buoyancy associated with core solidification. Additionally, mechanical stirring of core fluids and external perturbations by large impact events, tidal effects, and orbital precession can also contribute to sustaining dynamo fields. Convective dynamos cease when the core-mantle heat flux becomes subadiabatic or if specific crystallization regimes inhibit core fluid flows. Therefore, exploring the histories of magnetic fields across the Solar System provides a window into the thermal and chemical evolution of planetary interiors. Here we review how recent spacecraft-based studies of remanent crustal magnetism, paleomagnetic studies of rock samples, and planetary interior models have revealed the magnetic and evolutionary histories of Mercury, Earth, Mars, the Moon, and several planetesimals, as well as discuss avenues for future exploration and discovery. ▪ Paleomagnetism and remanent crustal magnetism studies elucidate the magnetic histories of rocky planetary bodies. ▪ Records of ancient dynamo fields have been obtained from 3 out of 4 terrestrial planets, the Moon, and several planetesimals. ▪ The geometries, intensities, and longevities of dynamo fields can provide information on core processes and planetary thermal evolution. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"83 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2021-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90252526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Light hydrocarbons (LHs) are an important component of natural gas whose chemical and isotopic compositions play a vital role in identifying gas genetic type, thermal maturity, gas–gas correlation, gas–source correlation, migration direction and phase, and secondary alterations (such as evaporative fractionation, biodegradation, and thermochemical sulfate reduction) experienced by the gas pool. Through review of geochemical research into LHs over recent decades, and analysis of chemical and isotopic compositions of LHs of gases and condensates from more than 40 gas fields in China, we present an overview of the genetic mechanisms of LHs and the impacts of various factors on their geochemical compositions. The primary objectives of this review are to demonstrate the application of LH chemical and isotopic composition characteristics to gas geochemistry research and to assess the applicability and reliability of geochemical identification diagrams and parameters for determining gas genetic types, maturity, source, secondary alteration, and migration direction and phase. ▪ Three main genetic mechanisms are proposed for the formation of light hydrocarbons: thermal decomposition, catalytic decomposition of organic matter, and microbial action. ▪ Chemical and isotopic compositions of light hydrocarbons with different carbon numbers and/or structures can be used to identify the genetic types and maturity of natural gas. ▪ Content ratios and carbon isotopes of characteristic light hydrocarbons are good indicators for gas–gas and gas–source correlations. ▪ Secondary alterations (evaporative fractionation, biodegradation, thermochemical sulfate reduction) and migration of gas can be indicated by chemical and isotopic compositions of light hydrocarbons. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
{"title":"Application of Light Hydrocarbons in Natural Gas Geochemistry of Gas Fields in China","authors":"Shipeng Huang, Jianzhong Li, Tongshan Wang, Q. Jiang, Hua Jiang, X. Tao, Bin Bai, Ziqi Feng","doi":"10.1146/annurev-earth-070921-054917","DOIUrl":"https://doi.org/10.1146/annurev-earth-070921-054917","url":null,"abstract":"Light hydrocarbons (LHs) are an important component of natural gas whose chemical and isotopic compositions play a vital role in identifying gas genetic type, thermal maturity, gas–gas correlation, gas–source correlation, migration direction and phase, and secondary alterations (such as evaporative fractionation, biodegradation, and thermochemical sulfate reduction) experienced by the gas pool. Through review of geochemical research into LHs over recent decades, and analysis of chemical and isotopic compositions of LHs of gases and condensates from more than 40 gas fields in China, we present an overview of the genetic mechanisms of LHs and the impacts of various factors on their geochemical compositions. The primary objectives of this review are to demonstrate the application of LH chemical and isotopic composition characteristics to gas geochemistry research and to assess the applicability and reliability of geochemical identification diagrams and parameters for determining gas genetic types, maturity, source, secondary alteration, and migration direction and phase. ▪ Three main genetic mechanisms are proposed for the formation of light hydrocarbons: thermal decomposition, catalytic decomposition of organic matter, and microbial action. ▪ Chemical and isotopic compositions of light hydrocarbons with different carbon numbers and/or structures can be used to identify the genetic types and maturity of natural gas. ▪ Content ratios and carbon isotopes of characteristic light hydrocarbons are good indicators for gas–gas and gas–source correlations. ▪ Secondary alterations (evaporative fractionation, biodegradation, thermochemical sulfate reduction) and migration of gas can be indicated by chemical and isotopic compositions of light hydrocarbons. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.","PeriodicalId":8034,"journal":{"name":"Annual Review of Earth and Planetary Sciences","volume":"68 1","pages":""},"PeriodicalIF":14.9,"publicationDate":"2021-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89694520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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