scholarly journals Detrital zircon record of Phanerozoic magmatism in the southern Central Andes

Geosphere ◽  
2021 ◽  
Author(s):  
T.N. Capaldi ◽  
N.R. McKenzie ◽  
B.K. Horton ◽  
C. Mackaman-Lofland ◽  
C.L. Colleps ◽  
...  
Keyword(s):  
South America ◽  
Detrital Zircon ◽  
Temporal Distribution ◽  
Arc Magmatism ◽  
Clear Trend ◽  
Isotopic Signatures ◽  
Magmatic Arc ◽  
Rough Approximation ◽  
Southern Central ◽  
Continental Magmatic Arc

The spatial and temporal distribution of arc magmatism and associated isotopic variations provide insights into the Phanerozoic history of the western margin of South America during major shifts in Andean and pre-Andean plate interactions. We integrated detrital zircon U-Th-Pb and Hf isotopic results across continental magmatic arc systems of Chile and western Argentina (28°S–33°S) with igneous bedrock geochronologic and zircon Hf isotope results to define isotopic signatures linked to changes in continental margin processes. Key tectonic phases included: Paleozoic terrane accretion and Carboniferous subduction initiation during Gondwanide orogenesis, Permian–Triassic extensional collapse, Jurassic–Paleogene continental arc magmatism, and Neogene flat slab subduction during Andean shortening. The ~550 m.y. record of magmatic activity records spatial trends in magma composition associated with terrane boundaries. East of 69°W, radiogenic isotopic signatures indicate reworked continental lithosphere with enriched (evolved) εHf values and low (<0.65) zircon Th/U ratios during phases of early Paleozoic and Miocene shortening and lithospheric thickening. In contrast, the magmatic record west of 69°W displays depleted (juvenile) εHf values and high (>0.7) zircon Th/U values consistent with increased asthenospheric contributions during lithospheric thinning. Spatial constraints on Mesozoic to Cenozoic arc width provide a rough approximation of relative subduction angle, such that an increase in arc width reflects shallower slab dip. Comparisons among slab dip calculations with time-averaged εHf and Th/U zircon results exhibit a clear trend of decreasing (enriched) magma compositions with increasing arc width and decreasing slab dip. Collectively, these data sets demonstrate the influence of subduction angle on the position of upper-plate magmatism (including inboard arc advance and outboard arc retreat), changes in isotopic signatures, and overall composition of crustal and mantle material along the western edge of South America.

Jurassic Arc: Reconstructing the Lost World of eastern Gondwana

Geology ◽  
2021 ◽  
Author(s):  
Elliot K. Foley ◽  
R.A. Henderson ◽  
E.M. Roberts ◽  
A.I.S. Kemp ◽  
C.N. Todd ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Tectonic Setting ◽  
Magmatic Arc ◽  
Continental Arc ◽  
Key Factor ◽  
Igneous Activity ◽  
Competing Models ◽  
Juvenile Crust ◽  
Sedimentary Fill ◽  
Continental Magmatic Arc

The tectonic setting of the Australian sector of the eastern Gondwanan margin during the Jurassic and Cretaceous is enigmatic. Whether this involved convergent tectonism and a long-lived continental magmatic arc or rift-related extension unrelated to subduction is debated. The paucity of Australian Jurassic–Cretaceous igneous outcrops makes resolving these competing models difficult. We used the detrital zircon record of the Jurassic–Cretaceous Great Australian Superbasin (GAS) as a proxy for igneous activity. We attribute the persistent magmatism recorded in GAS sedimentary fill throughout the Mesozoic to ca. 95 Ma to continuation of the established Paleozoic continental arc system. The detrital zircon record signals short (~10 m.y.) pulses of elevated Jurassic and Cretaceous magmatic activity and strongly positive εHf values, indicating juvenile crust or mantle-derived magmatism. Margin reconstruction indicates sustained continental growth at rates of at least ~55 km3 km–1 m.y.–1, mainly to the tract now represented by submerged northern Zealandia, due to the retreat of this arc system. We posit that arc retreat was a key factor in rapid crust generation and preservation, and that continental sedimentary systems globally may host cryptic records of juvenile crustal addition that must be considered in estimating crustal growth rates along convergent plate margins.

scholarly journals Interplay of Cretaceous transpressional deformation and continental arc magmatism in a long-lived crustal boundary, central Fiordland, New Zealand

Geosphere ◽  
2020 ◽  
Vol 16 (5) ◽  
pp. 1225-1248
Author(s):  
Hannah J. Blatchford ◽  
Keith A. Klepeis ◽  
Joshua J. Schwartz ◽  
Richard Jongens ◽  
Rose E. Turnbull ◽  
...  
Keyword(s):  
New Zealand ◽  
Thermal Structure ◽  
Shear Zones ◽  
Arc Magmatism ◽  
Magmatic Arc ◽  
Continental Arcs ◽  
Metasedimentary Rocks ◽  
Spatio Temporal ◽  
Continental Magmatic Arc ◽  
Lower Crustal

Abstract Recovering the time-evolving relationship between arc magmatism and deformation, and the influence of anisotropies (inherited foliations, crustal-scale features, and thermal gradients), is critical for interpreting the location, timing, and geometry of transpressional structures in continental arcs. We investigated these themes of magma-deformation interactions and preexisting anisotropies within a middle- and lower-crustal section of Cretaceous arc crust coinciding with a Paleozoic boundary in central Fiordland, New Zealand. We present new structural mapping and results of Zr-in-titanite thermometry and U-Pb zircon and titanite geochronology from an Early Cretaceous batholith and its host rock. The data reveal how the expression of transpression in the middle and lower crust of a continental magmatic arc evolved during emplacement and crystallization of the ∼2300 km2 lower-crustal Western Fiordland Orthogneiss (WFO) batholith. Two structures within Fiordland’s architecture of transpressional shear zones are identified. The gently dipping Misty shear zone records syn-magmatic oblique-sinistral thrust motion between ca. 123 and ca. 118 Ma, along the lower-crustal WFO Misty Pluton margin. The subhorizontal South Adams Burn thrust records mid-crustal arc-normal shortening between ca. 114 and ca. 111 Ma. Both structures are localized within and reactivate a recently described >10 km-wide Paleozoic crustal boundary, and show that deformation migrated upwards between ca. 118 and ca. 114 Ma. WFO emplacement and crystallization (mainly 118–115 Ma) coincided with elevated (>750 °C) middle- and lower-crustal Zr-in-titanite temperatures and the onset of mid-crustal cooling at 5.9 ± 2.0 °C Ma−1 between ca. 118 and ca. 95 Ma. We suggest that reduced strength contrasts across lower-crustal pluton margins during crystallization caused deformation to migrate upwards into thermally weakened rocks of the mid-crust. The migration was accompanied by partitioning of deformation into domains of arc-normal shortening in Paleozoic metasedimentary rocks and domains that combined shortening and strike-slip deformation in crustal-scale subvertical, transpressional shear zones previously documented in Fiordland. U-Pb titanite dates indicate Carboniferous–Cretaceous (re)crystallization, consistent with reactivation of the inherited boundary. Our results show that spatio-temporal patterns of transpression are influenced by magma emplacement and crystallization and by the thermal structure of a reactivated boundary.

scholarly journals Reviewing the Antioquia batholith and satellite bodies: a record of Late Cretaceous to Eocene syn- to post-collisional arc magmatism in the Central Cordillera of Colombia

2018 ◽  
Vol 46 (1) ◽  
pp. 82 ◽  
Author(s):  
José Duque-Trujillo ◽  
Camilo Bustamante ◽  
Luigi Solari ◽  
Álvaro Gómez-Mafla ◽  
Gloria Toro-Villegas ◽  
...  
Keyword(s):  
South America ◽  
Arc Magmatism ◽  
South American ◽  
South American Plate ◽  
Magmatic Arc ◽  
History Of ◽  
Formation Conditions ◽  
Early Interaction ◽  
Central Cordillera ◽  
Existing Data

The Antioquia batholith represents the magmatic record of the interaction between the Farallón and Caribbean plates with the NW part of the South American Plate during the Meso-Cenozoic. Several authors have reported zircon U-Pb ages and whole rock geochemistry in order to constrain the crystallization history of this batholith and its formation conditions. The present work aims to gather the existing data with new data obtained from the Ovejas batholith and La Unión stock, both genetically related to the main intrusion. Gathering our new data with information obtained in previous works, we conclude that the Antioquia batholith was constructed by successive pulses from ca. 97 to 58 Ma in an arc-related setting. The initial pulses are related to syn-collisional tectonics, during the early interaction between the Farallón plate and NW South America. The final pulses, that record Eocene ages, are related to a post-collisional setting, similar to that recorded in other plutons of the Paleogene magmatic arc of the Central Cordillera.

Geochemistry of the Coastal Sonora batholith, Northwestern Mexico

2003 ◽  
Vol 40 (6) ◽  
pp. 819-831 ◽  
Author(s):  
M Valencia-Moreno ◽  
J Ruiz ◽  
L Ochoa-Landín ◽  
R Martínez-Serrano ◽  
P Vargas-Navarro
Keyword(s):  
Granitic Rocks ◽  
Magma Source ◽  
Arc Magmatism ◽  
American Continent ◽  
Geochemical Composition ◽  
Isotopic Signatures ◽  
Magmatic Arc ◽  
North American Continent ◽  
The North ◽  
Northwestern Mexico

New major- and trace-element and radiogenic Sr and Nd data from granitic rocks help to characterize the geochemical composition of the Coastal Sonora batholith, which represents the westernmost portion of the Laramide Magmatic arc (~80–40 Ma) in Mexico. Compared with more inland-located regions of the arc in central and eastern Sonora (Inner Granites), the plutons within the coastal batholith have higher MgO, FeO, and CaO and lower K2O contents, and tend to be more depleted in Nb, U, and to a lesser extent Rb, but relatively enriched in Sr. These rocks display flatter slopes of rare-earth elements, with La abundances around 80 to 200 times chondrite values and smaller but well-developed negative Eu anomalies. Initial 87Sr/86Sr ratios and εNd values from a few studied samples of the Coastal Sonora batholith range from 0.70586 to 0.70679 and from –2.3 to –4.7, respectively. These isotopic signatures allow recognition of a more mantle-related magma source for this batholith as compared with the Inner Granites, which have higher Sr and lower Nd ratios. In a more regional context, the compositions of the Coastal Sonora batholith rocks resemble those of the eastern portion of the Peninsular Ranges batholith to the northwest. Based on our observations, we propose that partial melting of a crust thickened by overlapping periods of Jurassic through Cretaceous arc magmatism along the southwestern edge of the North American continent may account for the geochemical and isotopic characteristics displayed by the Coastal Sonora batholith granitic rocks.

Quantifying the growth of continental crust through crustal thickness and zircon Hf-O isotopic signatures: A case study from the southern Central Asian Orogenic Belt

2021 ◽  
Author(s):  
Yujian Wang ◽  
Dicheng Zhu ◽  
Chengfa Lin ◽  
Fangyang Hu ◽  
Jingao Liu
Keyword(s):  
Continental Crust ◽  
Crustal Thickness ◽  
Orogenic Belt ◽  
Central Asian Orogenic Belt ◽  
Crustal Thickening ◽  
Crustal Growth ◽  
Isotopic Signatures ◽  
Central Asian ◽  
Southern Central ◽  
Juvenile Crust

Accretionary orogens function as major sites for the generation of continental crust, but the growth model of continental crust remains poorly constrained. The Central Asian Orogenic Belt, as one of the most important Phanerozoic accretionary orogens on Earth, has been the focus of debates regarding the proportion of juvenile crust present. Using published geochemical and zircon Hf-O isotopic data sets for three belts in the Eastern Tianshan terrane of the southern Central Asian Orogenic Belt, we first explore the variations in crustal thickness and isotopic composition in response to tectono-magmatic activity over time. Steady progression to radiogenic zircon Hf isotopic signatures associated with syn-collisional crustal thickening indicates enhanced input of mantle-derived material, which greatly contributes to the growth of the continental crust. Using the surface areas and relative increases in crustal thickness as the proxies for magma volumes, in conjunction with the calculated mantle fraction of the mixing flux, we then are able to determine that a volume of ∼14−22% of juvenile crust formed in the southern Central Asian Orogenic Belt during the Phanerozoic. This study highlights the validity of using crustal thickness and zircon isotopic signatures of magmatic rocks to quantify the volume of juvenile crust in complex accretionary orogens. With reference to the crustal growth pattern in other accretionary orogens and the Nd-Hf isotopic record at the global scale, our work reconciles the rapid crustal growth in the accretionary orogens with its episodic generation pattern in the formation of global continental crust.

scholarly journals U–Pb age and Lu–Hf signatures of detrital zircon from Palaeozoic sandstones in the Oslo Rift, Norway

2013 ◽  
Vol 151 (5) ◽  
pp. 816-829 ◽  
Author(s):  
MAGNUS KRISTOFFERSEN ◽  
TOM ANDERSEN ◽  
ARILD ANDRESEN
Keyword(s):  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Late Carboniferous ◽  
Isotopic Signatures ◽  
Inductively Coupled ◽  
Source To Sink ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Isotope Analyses ◽  
Multiple Episodes

AbstractU–Pb and Lu–Hf isotope analyses of detrital zircon from the latest Ordovician (Hirnantian) Langøyene Formation, the Late Silurian Ringerike Group and the Late Carboniferous Asker Group in the Oslo Rift were obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Overall the U–Pb dating yielded ages within the range 2861–313 Ma. The U–Pb age and Lu–Hf isotopic signatures correspond to virtually all known events of crustal evolution in Fennoscandia, as well as synorogenic intrusions from the Norwegian Caledonides. Such temporally and geographically diverse source areas likely reflect multiple episodes of sediment recycling in Fennoscandia, and highlights the intrinsic problem of using zircon as a tracer-mineral in ‘source to sink’ sedimentary provenance studies. In addition to its mostly Fennoscandia-derived detritus, the Asker Group also have zircon grains of Late Devonian – Late Carboniferous age. Since no rocks of these ages are known in Fennoscandia, these zircons are inferred to be derived from the Variscan Orogen of central Europe.

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