Orogenic Andesites and Crustal Growth


Book Description

Orogenic andesites have long intrigued scientists because of their remarkable compositional similarities to the continental crust. The significance of orogenic andesites as proxies to continental crust formation has been recognized for over 30 years, but no consensus model of andesite genesis exists. Much of the controversy revolves around whether orogenic andesites are primary mantle melts of slab and mantle materials, or instead evolve from basaltic mantle melts at shallower crustal levels. In three sections, this book provides an overview of andesite genesis at convergent margins that focuses on the slab–mantle interaction, crustal processing and andesite evolution through the life of volcanic arcs. Without favouring a particular view, the books aims to engender cross-fertilization and discussion that will smooth the pathway towards a holistic communal model of andesite petrogenesis and its role within the broader geochemical cycles of the Earth.




Crust–Mantle Interactions and Granitoid Diversification


Book Description

This Special Publication sheds light on crust formation and tectonic processes in early Earth by focusing on Archaean granitoids and related rocks from West Greenland in the North Atlantic Craton, Karelia Province of the Fennoscandian Shield, Eastern Dharwar and Bundelkhand cratons in the Indian Shield and Bug Complex of the Ukrainian Shield. Resulting from the IGCP-SIDA 599 project `The Changing Early Earth’, this compilation of papers provides explanations on the nomenclature of Archaean granitoids and explores the petrology, element and isotope geochemistry, geochronology and metamorphism of granitoids and supracrustal rocks of variable metamorphic grade. This volume provides information on the increase and timing of crust-mantle interactions and granitoid diversification from early Archaean protoliths of island arc origin to the emergence of multi-source high-K calc-alkaline granitoid batholiths at convergent continental margins. The formation of abundant granitoid batholiths suggests a significant change in mantle dynamics and plate tectonics towards the end of the Archaean.




Dynamic Magma Evolution


Book Description

Explores the complex physico-chemical processes involved in active volcanism and dynamic magmatism Understanding the magmatic processes responsible for the chemical and textural signatures of volcanic products and igneous rocks is crucial for monitoring, forecasting, and mitigating the impacts of volcanic activity. Dynamic Magma Evolution is a compilation of recent geochemical, petrological, physical, and thermodynamic studies. It combines field research, experimental results, theoretical approaches, unconventional and novel techniques, and computational modeling to present the latest developments in the field. Volume highlights include: Crystallization and degassing processes in magmatic environments Bubble and mineral nucleation and growth induced by cooling and decompression Kinetic processes during magma ascent to the surface Magma mixing, mingling, and recharge dynamics Geo-speedometer measurement of volcanic events Changes in magma rheology induced by mineral and volatile content The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.




The Role of Volatiles in the Genesis, Evolution and Eruption of Arc Magmas


Book Description

The subduction zone volatile cycle is key to understanding the petrogenesis, transport, storage and eruption of arc magmas. Volatiles control the flux of slab components into the mantle wedge, are responsible for melt generation through lowering the solidi of mantle materials and influence the crystallizing phase assemblages in the overriding crust. Further, the rates and extents of degassing during magma storage and decompression affect magma rheology, ultimately control eruption style and have consequences for the environmental impact of explosive arc volcanism. This book highlights recent progress in constraining the role of volatiles in magmatic processes. Individual book sections are devoted to tracing volatiles from the subducting slab to the overriding crust, their role in subvolcanic processes and eruption triggering, as well as magmatic-hydrothermal systems and volcanic degassing. For the first time, all aspects of the overarching theme of volatile cycling are covered in detail within a single volume.




Orogenic Andesites and Plate Tectonics


Book Description

Students of a phenomenon as common but complex as andesite genesis often are overwhelmed by, or overlook, the volume and diversity of relevant information. Thus there is need for periodic overview even in the absence of a dramatic breakthrough which "solves the andesite problem" and even though new ideas and data keep the issues in a state of flux. Thus I have summarized the subject through mid·1980 from my perspective to help clarify the long-standing problem and to identify profitable areas for future research. Overviews are more easily justified than achieved and there are fundamental differences of opinion concerning how to go about them. It is professionally dangerous and therefore uncom mon for single authors, especially those under 35 such as I, to summarize a broad, active field of science in book-length thor oughness. Review articles in journals, multi-authored books, or symposia proceedings appear instead. The single-authored approach is intimidating in scale and can result in loss of thoroughness or authority on individual topics. The alternatives lack scope or integration or both.




Chemical, Physical and Temporal Evolution of Magmatic Systems


Book Description

Our understanding of the physical and chemical processes that regulate the evolution of magmatic systems has improved tremendously since the foundations were laid down 100 years ago by Bowen. The concept of crustal magma chambers has progressively evolved from molten-rock vats to thermally, chemically and physically heterogeneous reservoirs that are kept active by the periodic injection of magma. This new model, while more complex, provides a better framework to interpret volcanic activity and decipher the information contained in intrusive and extrusive rocks. Igneous and metamorphic petrology, geochemistry, geochronology, and numerical modelling, all contributed towards this new picture of crustal magmatic systems. This book provides an overview of the wide range of approaches that can nowadays be used to understand the chemical, physical and temporal evolution of magmatic and volcanic systems.




Field Volcanology: A Tribute to the Distinguished Career of Don Swanson


Book Description

Don Swanson, who received the GSA Mineralogy, Geochemistry, Petrology, and Volcanology Division's Distinguished Geologic Career award in 2016, has adopted a detailed, field-oriented approach to studying problems of great volcanologic importance across a range of compositions and spatio-temporal scales. Swanson's work has resulted in a series of fundamental contributions that have advanced understanding of the Columbia River flood basalts, Cascade volcanic arc, and Hawai'i, and his insights have been applied not only around the world, but across the solar system. This volume emphasizes the role of field volcanology as a window into better understanding volcanic processes past and present, and highlights, in particular, those places and processes where Swanson's insights have been particularly impactful.







The Tectonic Setting and Origin of Cretaceous Batholiths within the North American Cordillera


Book Description

In this Special Paper, Hildebrand and Whalen present a big-picture, paradigm-busting synthesis that examines the tectonic setting, temporal relations, and geochemistry of many plutons within Cretaceous batholithic terranes of the North American Cordillera. In addition to their compelling tectonic synthesis, they argue that most of the batholiths are not products of arc magmatism as commonly believed, but instead were formed by slab failure during and after collision. They show that slab window and Precambrian TTG suites share many geochemical similarities with Cretaceous slab failure rocks. Geochemical and isotopic data indicate that the slab failure magmas were derived dominantly from the mantle and thus have been one of the largest contributors to growth of continental crust. The authors also note that slab failure plutons emplaced into the epizone are commonly associated with Cu-Au porphyries, as well as Li-Cs-Ta pegmatites.




Tectonic Growth of a Collisional Continental Margin


Book Description

"The convergent margin of southern Alaska is considered one of the type areas for understanding the growth of continental margins through collisional tectonic processes. Collisional processes that formed this margin were responsible for multiple episodes of sedimentary basin development, subduction complex growth, magmatism, and deformation. Two main collisional episodes shaped this Mesozoic-Cenozoic continental margin. The first event was the Mesozoic collision of the allochthonous Wrangellia composite terrane. This event represents the largest addition of juvenile crust to western North America in the past 100 m.y. The second event is the ongoing collision of the Yakutat terrane along the southeastern margin of Alaska. This Cenozoic event has produced the highest coast mountain range on Earth (Saint Elias Mountains), the Wrangell continental arc, and sedimentary basins throughout southern Alaska. Active collisional processes continue to shape the southern margin of Alaska, mainly through crustal shortening and strike-slip deformation, large-magnitude earthquakes, and rapid uplift and exhumation of mountain belts and high sedimentation rates in adjacent sedimentary basins. This volume contains 24 articles that integrate new geophysical and geologic data, including many field-based studies, to better link the sedimentary, structural, geochemical, and magmatic processes that are important for understanding the development of collisional continental margins."--Publisher's website.