Abstract: The continental crust is the archive of the geological history of the Earth. Only 7% of the crust is older than 2.5 Ga, and yet significantly more crust was generated before 2.5 Ga than subsequently. Zircons offer robust records of the magmatic and crust-forming events preserved in the continental crust. They yield marked peaks of ages of crystallization and of crust formation. The latter might reflect periods of high rates of crust generation, and as such be due to magmatism associated with deep-seated mantle plumes. Alternatively the peaks are artefacts of preservation, they mark the times of supercontinent formation, and magmas generated in some tectonic settings may be preferentially preserved. There is increasing evidence that depletion of the upper mantle was in response to early planetary differentiation events. Arguments in favour of large volumes of continental crust before the end of the Archaean, and the thickness of felsic and mafic crust, therefore rely on thermal models for the progressively cooling Earth. They are consistent with recent estimates that the rates of crust generation and destruction along modern subduction zones are strikingly similar. The implication is that the present volume of continental crust was established 2–3 Ga ago. The generation and evolution of the continental crust The generation and evolution of the continental crust Publication Journal of the Geological Society Record type Journal article Published March 2010 Authors C.J. Hawkesworth | B. Dhuime | A.B. Pietranik | P.A. Cawood | A.I.S. Kemp | C.D. Storey DOI https://doi.org/10.1144/0016-76492009-072 The publisher of this work supports multiple resolution . The work is available from the following locations: lyellcollection.org geoscienceworld.org debug {'doi': '10.1144/0016-76492009-072', 'member_id': '1881', 'member': 'Geological Society of London', 'container-title': 'Journal of the Geological Society', 'primary-resource': 'https://www.lyellcollection.org/doi/10.1144/0016-76492009-072', 'tld': 'lyellcollection.org', 'clearbit-logo': '/static/no_logo.svg', 'coaccess': [], 'multiple-resolution': [{'url': 'https://geoscienceworld.org/jgs/article-lookup?doi=10.1144/0016-76492009-072', 'tld': 'geoscienceworld.org', 'clearbit-logo': '/static/no_logo.svg'}], 'type': 'JOURNAL ARTICLE', 'published_date': 'March 2010', 'publication': 'Journal of the Geological Society', 'title': 'The generation and evolution of the continental crust', 'name': None, 'id': None, 'location': None, 'display_doi': 'https://doi.org/10.1144/0016-76492009-072', 'grant_info': None, 'grant_info_funders': None, 'grant_info_funder_ids': '', 'grant_info_type': None, 'multiple_lead_investigators': [], 'multiple_co_lead_investigators': [], 'multiple_investigators': [], 'finances': [], 'project_description': None, 'award_amount': None, 'award_start': None, 'funding_scheme': None, 'internal_award_number': None, 'editors': None, 'authors': 'C.J.

Phanerozoic addition rates to the continental crust are calculated by using seismic profiles through magmatic arcs to measure the crustal volumes added during the active lifespans of the arcs. Data for 17 arcs give addition rates per kilometer of arc in the range 20 to 40 km³ km−1 Ma−1. From these data we deduce a world‐wide addition rate of 1.65 km³ a−1 after adding other contributions to the formation of the continental crust, e.g., from hot spot volcanism. We infer a subtraction rate, mainly by subducting sediments, of 0.6 km³ a−1 and arrive at a net crustal growth rate of about 1 km³ a−1. Growth of the continental crust is necessary to maintain approximately constant freeboard, because the secular decline in the heat production of the mantle causes the ocean basins to deepen. An equation for the growth of the continents as a function of the decline in terrestrial heat flow yields approximately constant growth rate since the Archean of 0.9 km³ a−1, in good agreement with the above estimate. On the average, Archean growth rates must have been 3 to 4 times the present rate. Island arc growth rates are inadequate to explain the formation of the Arabian‐Nubian Shield and the Archean granite‐greenstone terrain of the Superior Province, and a captured island chain in Oregon. We confirm the oceanic island origin of the Oregon terrain on the basis of the large growth rates of hotspot islands.

From the extraterrestrial telescopic, space probe, meteorite and returned sample studies of planetary evolution, and terrestrial evidence for early differentiation of core and fluid spheres and continental crust, I feel the conclusion is inescapable that large terrestrial planets of our solar system underwent essentially immediate differentiation into relatively constant‐volume core, depleted mantle, enriched crust and fluid reservoirs. Differentiation was an early event, carried rapidly to completion. It is a false premise to have the formation of sialic crust on Earth dragged out over billions of years after hot accretion. The uniqueness of the Earth arises from its size, retention of water and dynamic surface‐renewal processes, which have effectively erased all vestiges of the first several hundred million years of its crustal history. A large volume of depleted mantle always existed and an isotopically nearly homogeneous character for mantle and crust in early times was only sustained by rapid convective stirring of the silicate Earth. The sigmoidal continental crust age curve that is recorded in whole rock Nd and zircon U‐Pb dates is a predictable consequence of the highly exponential decline in stirring rates. It represents survival, not the original extent of crustal domains. Positive εNd(T) values for Archaean mantle‐derived magmas are quantitatively predicted by this model, as are the observed depleted‐mantle model ages of clastic sedimentary rocks. Current rates of crustal accretion and loss of crust by sediment subduction and tectonic erosion are approximately in balance and compatible with negligible crustal growth at present. Claims that current growth is approximately 1 km3 per year are based on incorrect and selectively cited data and incomplete analyses of the freeboard argument. The idea that the Earth's crust has grown is a myth dating from the 19th century and was established as geochemical dogma in the 1950s and 1960s. It has survived by inertia and repetition and endless self‐citation. The alternative no‐growth view has been sometimes ignored, frequently questioned and downplayed, often cited only as an end member hypothesis (on the presumption that the truth must lie between extremes), and sometimes acclaimed and supported. Evidence in its favour has been accumulating. The growth myth has survived, however, as the consensus. In science, conventional wisdom is difficult to overturn. After more than 20 years some implications of plate tectonics have yet to be fully appreciated by isotope geochemists who advocate crustal growth, and by geologists and geophysicsts who have followed their lead.

The evolution of Earth's continental crust is crucial for understanding geodynamics, climate regulation, and the origins of life. The Paleoproterozoic, marked by the Great Oxidation Event and the consolidation of plate tectonics, was a critical interval for continental growth. While arc magmatism dominates crust formation in the Phanerozoic, its role in earlier Earth history remains uncertain. Three silicic LIPs in the Amazon Craton were emplaced at regular ~90-100 million-year intervals (1980 Ma, 1880 Ma, and 1790 Ma), producing high-temperature (>750 °C) silicic magmas derived from lower crust ( ~ 45 km thick). Our findings demonstrate that LIPs contributed significantly to continental crustal growth through deep-crustal partial melting of Archean-Rhyacian crust. We highlight that silicic LIP magmatism was a fundamental driver of continental differentiation and long-term stability during the Paleoproterozoic. The Paleoproterozoic, marked by the Great Oxidation Event and the consolidation of plate tectonics, was a critical interval for continental growth. While arc magmatism dominates crust formation in the Phanerozoic, its role in earlier Earth history remains uncertain. Three silicic LIPs in the Amazon Craton were emplaced at regular ~90-100 million-year intervals (1980 Ma, 1880 Ma, and 1790 Ma), producing high-temperature (>750 °C) silicic magmas derived from lower crust ( ~ 45 km thick). Our findings demonstrate that LIPs contributed significantly to continental crustal growth through deep-crustal partial melting of Archean-Rhyacian crust. To understand this evolution, we must assess both when and how plate tectonics took place and the processes responsible for the creation of continental crust. The onset of plate tectonics as a local or global system, powered by the negative buoyancy of old dense oceanic lithosphere sinking into weaker ductile asthenosphere in subduction zones 2 , dates back to Hadean 3 or the end of Archean 4 . In addition, there are two divergent hypotheses regarding the compositional evolution of the continental crust through time. A uniformitarian view based on geochemical and Hadean zircon data suggests that silicic continental crust was already formed in the Hadean, and nearly constant crustal silica compositions prevailed since the early Archean 1 . An alternative view, based on tectonic/metamorphic asymmetry, magmatic associations, and geochemistry, proposes that the early Earth was composed of a mafic crust, evolving towards more intermediate compositions from 3.1 Ga to 2.5 Ga 4 . The extensive silicic magmatism from the Orosirian to the Statherian is defined by bimodal compositions, the coexistence of A- and I-type magmas, contemporaneity with basaltic radial dyke swarms and sill complexes, short-lived times of duration, and evidence of coeval crustal anatexis. These features suggest an intraplate tectonic setting for this period of significant continental crust growth and differentiation 12 – 14 . Hot silicic magmas (>750 °C) formed through partial melting of the lower crust in response to repeated emplacement of mantle-derived tholeiitic basaltic magmas. These features are considered hallmark indicators of arc magmas 56 . Consequently, models of crustal growth that emphasize arc magmatism inherently assume a major role for plate tectonics and subduction processes. As 56 aptly summarized: “No water, no oceans, no plate tectonics, no granites, no continents.” Nonetheless, the mantle transition zone is a major H 2 O reservoir 58 , and hydrous upwellings from this region may generate intraplate volcanism 59 . Large volumes of silicic magmas, however, can only be produced predominantly through partial melting of fertile, hydrous lower-crustal material previously generated by subduction 60 . Such processes not only facilitate the generation of extensive silicic magmatism but also account for mantle-normalized negative Nb and Ta anomalies, together with elevated Pb concentrations. Such crustal partial melting often results from anomalous heat supplied by voluminous mafic underplating, leading to the formation of silicic LIPs 60 . LIPs are well-documented from the Paleoarchean to the present 61 and may have overlapped with subduction episodes in early Earth. Even during times when plate tectonics was inactive or poorly developed, LIP magmatism likely played a critical role in crust-building processes. These features provided positive evidence for more stagnant tectonic regimes, such as single-lid tectonics 70 . UHT metamorphism and granulite belt formation were likely driven by heat supplied through basaltic underplating 68 . Collectively, such features reflected elevated thermal regimes 62 and represented unique phenomena restricted to specific intervals in Earth’s geological history. After 1740 Ma, the Mesoproterozoic crustal evolution of the Amazon Craton was dominated by bursts of juvenile magmatism, including gabbroic and AMCG suites, which exhibited minimal contributions from pre-existing crust. This magmatic activity continued from 1600 Ma to 1500 Ma 22 . Plate tectonic indicators, such as ophiolites, appear at 1460 Ma 24 , suggesting that subduction processes became active after this period. Prior to this, from the Orosirian to the Statherian, no clear evidence of subduction events exists within the Amazon Craton following the Rhyacian Transamazon-Eburnean-Birimian orogenies. Along with negative evidence of plate tectonics, positive evidence of a more stagnant A potential exception is the proposed Statherian arc magmatism in the Rio Negro Province 16 , 69 , which lacks definitive plate tectonic indicators and lacks positive evidence for the absence of plate tectonics. This highlights the critical role of intraplate magmatism as a key driver of continental crust differentiation. It functioned as a mechanism to generate crustal strength and stability, facilitating the preservation of large, undeformed, and unmetamorphosed cratonic regions.

The evolution of continents involves modification of the lithosphere through time, including changes in crustal thickness and composition that create a dynamic crust-mantle boundary (Moho). The geological history of the southern Rocky Mountain region is relatively well understood and recent additions of modern seismic data provide an ideal opportunity to investigate the evolution of the crust. The results presented in this volume show that crust in the southern Rocky Mountains is relatively thick compared to the global average for the continents. The mafic lower crust and crust-mantle boundary of the Proterozoic provinces of the southwestern U.S. likely formed, and reformed, in several stages. Initial formation of juvenile continental crust took place by development and assembly of magmatic arcs between 1.8 and 1.6 Ga. Volcanic and plutonic rocks of this age record whole-crust differentiation and probably resulted in a mafic lower crustal residue. From 1.45 to 1.35 Ga, the crust underwent another period of differentiation leading to emplacement of A-type granites in the middle crust across southern Laurentia. Voluminous granitoid emplacement ca. 1.4 Ga, petrology of granitoids, widespread metamorphism, and 1.4 Ga lower crustal xenoliths are best explained by mafic underplating. Subsequent mafic additions to the lower crust likely took place at each of the times when basalts were emplaced in the Rocky Mountain region (1.1 Ga Grenville orogeny, Laramide orogeny, Oligocene ignim

The oldest decipherable rock complexes within continents (more than 2.5 billion years old) are largely basaltic volcanics and graywacke. Recent and modern analogs are the island arcs formed along and adjacent to the unstable interface of continental and oceanic crusts. The major interfacial reactions (orogenies) incorporate pre-existing sial, oceanic crust, and mantle into crust of a more continental type. Incipient stages of continental evolution, more than 3 billion years ago, remain obscure. They may involve either a cataclysmic granite-forming event or a succession of volcanic-sedimentary and granite-forming cycles. Intermediate and recent stages of continental evolution, as indicated by data for North America, involve accretion of numerous crustal interfaces with fragments of adjacent continental crust and their partial melting, reinjection, elevation, unroofing, and stabilization. Areas of relict provinces defined by ages of granites suggest that continental growth is approximately linear. But the advanced differentiation found in many provinces and the known overlaps permit wide deviation from linearity in the direction of a more explosive early or intermediate growth.

The interaction between erosion and tectonics has been a topic of debate since the early 1990s. While the tectonic effects on surface processes such as The interaction between erosion and tectonics has been a topic of debate since the early 1990s. While the tectonic effects on surface processes such as erosion have long been recognized (for example, river formation as a result of tectonic uplift), the opposite (erosional effects on tectonic activity) has only recently been addressed. The primary questions surrounding this topic are what types of Continental shields – Generally large areas of low relief (<100 m) in Earth's crust where Precambrian crystalline igneous and high-grade metamorphic rocks are exposed. Shields are considered tectonically stable areas in comparison to the activity occurring at their margins and the boundaries between plates, but their formation required large amounts of tectonic activity and erosion. Shields, along with stable platforms, are the basic tectonic components of continents, therefore understanding their development is critical to understanding the development of other surface features on Earth. Initially, a mountain belt is formed at a convergent plate margin. Transformation of a mountain belt to a shield is majorly dependent on two factors: (1) erosion of the mountain belt by running water and (2) isostatic adjustment resulting from the removal of surface rock due to erosion. This process of erosion followed by isostatic adjustment continues until the system is at isostatic equilibrium. At this point large-scale erosion can no longer occur because the surface has eroded down to nearly sea-level and uplift ceases due to the system's state of equilibrium. River anticlines – Geologic structures formed through the focused uplift of rock underlying confined areas of high erosion (i.e., rivers). Isostatic rebound resulting from the rapid removal of overlying rock, via erosion, causes the weakened areas of crustal rock to uplift from the apex of the river. In order for the development of these structures to occur the erosion rate of the river must exceed both the average erosional rate of the area, and the rate of uplift of the orogen. The two factors influencing the development of these structures are stream power of the associated river and the flexural rigidity of the crust in the area. The combination of increased stream power with decreased flexural rigidity results in the system's progression from a transverse anticline to a river anticline.

impact. None of Earth's primary crust has survived to today; all was destroyed by erosion, impacts, and plate tectonics over the past several billion years Earth's crust is its thick outer shell of rock, comprising less than one percent of the planet's radius and volume. It is the top component of the lithosphere, a solidified division of Earth's layers that includes the crust and the upper part of the mantle. The lithosphere is broken into tectonic plates whose motion allows heat to escape the interior of Earth into space. The crust lies on top of t Earth formed approximately 4.6 billion years ago from a disk of dust and gas orbiting the newly formed Sun. It formed via accretion, where planetesimals and other smaller rocky bodies collided and stuck, gradually growing into a…

‘Tectonics of continents’ shows that the much greater thickness of continental than oceanic crust makes continental and oceanic lithosphere behave differently. First, because crust is less dense and therefore buoyant, compared with the mantle, thick continental crust resists subduction into the asthenosphere. Slices of the upper part of the crust detach from underlying parts and become stacked atop one another to form a mountain range, like the Alps or Himalaya. Second, continental lithosphere is weaker than oceanic lithosphere and when put under stress it deforms. When the horizontal dimension of a region of continental crust is shortened, the crust thickens. Because of isostasy, thick buoyant crust stands higher than thin crust, creating mountain ranges. Various mountain ranges around the world are used to illustrate these principles.