Joaquín Bastías

Trinity College Dublin

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i-10 index

Research Trends

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Co-Authors

David Chew

Trinity College Dublin

Richard Spikings

University of Geneva

Teal R. Riley

British Antarctic Survey

Alex Burton‐Johnson

British Antarctic Survey

Massimo Chiaradia

University of Geneva

Fernando Poblete

University of Chile

Anne Grunow

The Ohio State University

Alexey Ulianov

University of Lausanne

Francisco Hervé

University of Chile

Foteini Drakou

Trinity College Dublin

Cooperative Institutions

University of Chile

National University of Patagonia San Juan Bosco

Consejo Nacional de Investigaciones Científicas y Técnicas

British Antarctic Survey

Ministry of Natural Resources

Universidad Andrés Bello

Chinese Academy of Geological Sciences

Centre National de la Recherche Scientifique

China Geological Survey

Ministry of Civil Affairs

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A Precambrian basement beneath the King George Island (Antarctica Peninsula) revealed by zircon xenocrystals from Eocene to Miocene volcanic rocks

Lithos (2024)

Hao Xing Junling Pei Liang Gao Jinfeng Wen Joaquín Bastías

Peninsula

Basement

George (robot)

10.1016/j.lithos.2024.107899

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Citations (0)

New Chondrichthyans from the Upper Cretaceous (Campanian–Maastrichtian) of Seymour and James Ross Islands, Antarctica

Journal of Paleontology (2014)

Rodrigo A. Otero Carolina S. Gutstein Alexander O. Vargas David Rubilar-Rogers Roberto E. Yury-Yáñez

We present new records of chondrichthyans recovered from strata of Maastrichtian age of the López de Bertodano Formation, Seymour (=Marambio) Island, and from levels of latest Campanian age of the Santa Marta Formation, James Ross Island, both located in the eastern Antarctic Peninsula. The material from Marambio Island comprises an associated assemblage with the first records of an indeterminate odontaspidid different from Odontaspis , as well as the genera Pristiophorus , Squatina , Paraorthacodus , and the species Chlamydoselachus tatere from the López de Bertodano Formation. Also, the studied section provides a well-constrained age for several taxa already recognized in the López de Bertodano Formation only by scattered samples of Maastrichtian age for the first time. The assemblage from Marambio Island is representative of one of the latest environmental conditions during the end of the Cretaceous in the coastal seas of the Larsen Basin before major changes that began after the K/P boundary. In addition, the finds from James Ross Island comprise the southernmost records of the neoselachians Cretalamna sp., Centrophoroides sp., as well as the holocephalans Callorhinchus sp. and an indeterminate rhinochimaerid, extending the occurrence of some of these taxa into the late Campanian, being their oldest record of the Weddellian Biogeographic Province.

Assemblage (archaeology)

Peninsula

Paleoecology

10.1666/13-041

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Citations (19)

Cretaceous magmatism in the Antarctic Peninsula and its tectonic implications

Figshare (2022)

Joaquín Bastías Richard Spikings Teal R. Riley David Chew Anne Grunow

SM Table 5_Raw data apatites

Peninsula

10.6084/m9.figshare.20286393

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Citations (0)

Breaking the Ring of Fire: How Ridge Collision, Slab Age, and Convergence Rate Narrowed and Terminated the Antarctic Continental Arc

Tectonics (2023)

Alex Burton‐Johnson Joaquín Bastías Stefan Kraus

Abstract The geometry of the Antarctic‐Phoenix Plate system, with the Antarctic Plate forming both the overriding plate and the conjugate to the subducting oceanic plate, allows quantification of slab age and convergence rate back to the Paleocene and direct comparison with the associated magmatic arc. New Ar‐Ar data from Cape Melville (South Shetland Islands, SSI) and collated geochronology shows Antarctic arc magmatism ceased at ∼19 Ma. Since the Cretaceous, the arc front remained ∼100 km from the trench whilst its rear migrated trenchward at 6 km/Myr. South of the SSI, arc magmatism ceased ∼8–5 Myr prior to each ridge‐trench collision, whilst on the SSI (where no collision occurred) the end of arc magmatism predates the end of subduction by ∼16 Myr. Despite the narrowing and successive cessation of the arc, geochemical and dyke orientation data shows the arc remained in a consistently transitional state of compressional continental arc and extensional backarc tectonics. Numerically relating slab age, convergence rate, and slab dip to the Antarctic‐Phoenix Plate system, we conclude that the narrowing of the arc and the cessation of magmatism south of the SSI was primarily in response to the subduction of progressively younger oceanic crust, and secondarily to the decreasing convergence rate. Increased slab dip beneath the SSI migrated the final magmatism offshore. Comparable changes in the geometry and composition are observed on the Andean arc, suggesting slab age and convergence rate may affect magmatic arc geometry and composition in settings currently attributed to slab dip variation.

Back-arc basin

Slab

Slab window

Volcanic arc

Eclogitization

Underplating

Continental arc

10.1029/2022tc007634

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Citations (1)

Uplift and denudation history of the Ellsworth Mountains: insights from low-temperature thermochronology

Solid Earth (2024)

Joaquín Bastías David Chew Fernando Poblete Paula Castillo William R. Guenthner

Abstract. While thermochronological studies have constrained the landscape evolution of several of the crustal blocks of West and East Antarctica, the tectono-thermal evolution of the Ellsworth Mountains remains relatively poorly constrained. These mountains are among the crustal blocks that comprise West Antarctica and exhibit an exceptionally well-preserved Palaeozoic sedimentary sequence. Despite the seminal contribution of Fitzgerald and Stump (1991), who suggested an Early Cretaceous uplift event for the Ellsworth Mountains, further thermochronological studies are required to improve the current understanding of the landscape evolution of this mountain chain. We present new zircon (U–Th) / He (ZHe) ages, which provide insights into the landscape evolution of the Ellsworth Mountains. The ZHe ages collected from near the base and the top of the sequence suggest that these rocks underwent burial reheating after deposition. A cooling event is recorded during the Jurassic–Early Cretaceous, which we interpret as representing exhumation in response to rock uplift of the Ellsworth Mountains. Moreover, our results show that while ZHe ages at the base of the sequence are fully reset, towards the top ZHe ages are partially reset. Uplift and exhumation of the Ellsworth Mountains during the Jurassic–Early Cretaceous was contemporaneous with the rotation and translation of this crustal block with respect to East Antarctica and possibly the Antarctic Peninsula. Furthermore, this period is characterized by widespread extension associated with the disassembly and breakup of Gondwana, with the Ellsworth Mountains playing a key role in the opening of the far southern Atlantic. Based on these results, we suggest that uplift of the Ellsworth Mountains during the disassembly of Gondwana provides additional evidence for major rearrangement of the crustal blocks between the South American, African, Australian and Antarctic plates. Finally, uplift of the Ellsworth Mountains commenced during the Jurassic, which predates the Early Cretaceous uplift of the Transantarctic Mountains. We suggest that the rift-related exhumation of the Ellsworth Mountains occurred throughout two events: (i) a Jurassic uplift associated with the disassembly of southwestern Gondwana and (ii) an Early Cretaceous uplift related with the separation between Antarctica and Australia, which is also recorded in the Transantarctic Mountains.

Thermochronology

Denudation

10.5194/se-15-555-2024

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Citations (0)

A revised interpretation of the Chon Aike magmatic province: Active margin origin and implications for the opening of the Weddell Sea

Lithos (2021)

Joaquín Bastías Richard Spikings Teal R. Riley Alexey Ulianov Anne Grunow

Late Triassic – Jurassic igneous rocks of the Antarctic Peninsula and Patagonia provide evidence for the evolution of the margin of southwestern Gondwana. We present new geochronological (LA-ICP-MS zircon UPb dates) analyses of 12 intrusive and volcanic rocks, which are complemented by geochemical and zircon isotopic (Hf) as well as whole rock isotopic (Nd, Sr) data. These are combined with similar analyses of 73 other igneous rocks by previous studies, to constrain the magmatic evolution and Late Triassic – Jurassic tectonic setting. The distribution of crystallisation ages reveals four main magmatic pulses that collectively span ~225–145 Ma, all of which have compositions that are consistent with a continental arc setting. The first episode occurred between ~223–200 Ma, and records active margin magmatism within the Antarctic Peninsula and northern Patagonia, and reveals the presence of a flat-slab that gave rise to magmatism in eastern Patagonia. After a period of magmatic quiescence (~200–188 Ma), the second episode occurred between ~188 and 178 Ma, with a continuation of arc magmatism above a flattened slab. The third episode spanned ~173–160 Ma, and its geographic distribution suggests the slab was steepening, driving magmatism towards the south and west in Patagonia. Finally, the fourth period occurred between ~157 and ~ 145 Ma, during which time magmas were emplaced along the Antarctic Peninsula and western Patagonia, with no evidence for flat-slab subduction. The analysed rocks include the Chon Aike magmatic province, which has been considered to have been influenced by the break-up of Gondwana, via heating associated with the Karoo plume in southern Africa and the active margin in western Patagonia and the Antarctic Peninsula. Our new data and revised compilation now suggest that the Early - Middle Chon Aike Jurassic silicic magmatic province in Patagonia and the Antarctic Peninsula can be entirely accounted by active margin processes. We also show that the final stage of Jurassic magmatism (~157–145 Ma) was coincident with rifting that formed oceanic lithosphere of the Weddell Sea and back-arc extension of the Rocas Verdes Basin, potentially revealing the presence of a triple junction located between southern Patagonia and the northern Antarctic Peninsula that led to the disassembly of southern Gondwana.

Continental arc

Peninsula

Back-arc basin

10.1016/j.lithos.2021.106013

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Citations (39)

A temporal control on the isotopic compositions of the Antarctic Peninsula arc

Communications Earth & Environment (2024)

Joaquín Bastías Alex Burton‐Johnson David Chew Teal R. Riley Wuidad Jara

Abstract Radiogenic isotopic compositions of arc magmas are a key tool for studying active margin evolution. They have two isotopic end-members: melts formed mostly from juvenile asthenosphere and melts sourced from evolved continental crust/continental lithospheric mantle. Cordilleran-margins are typically more isotopically juvenile near the trench, and conversely, increasingly evolved landward. However, this model has not been tested on the ~1,500 km long Mesozoic-Cenozoic arc of the Antarctic Peninsula. Here we show that while geochemical compositions remain largely constant, radiogenic isotopes become increasingly juvenile with time. Unlike other continental arcs, there is no association between isotopic composition and spatial distribution. This is attributed to: (i) slow subduction of young oceanic lithosphere, resulting in narrowing of the arc and reduced capacity to incorporate continental crust into melts, and (ii) the Cenozoic decrease in convergence rate, which reduced the friction in the slab-overriding plate interface, allowing the arc melts to increasingly source from young juvenile asthenosphere.

Peninsula

10.1038/s43247-024-01301-1

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Citations (1)

Magmatic arc evolution during the tectonic closure of the Rocas Verdes basin: insights from Cretaceous-earliest Paleocene intrusive rocks of Navarino Island (55°S), Fuegian Andes

Figshare (2023)

Ricardo Velásquez Joaquín Bastías Esteban Salazar Fernando Poblete Mauricio González Guillot

U-Pb_INS-10d

Back-arc basin

10.6084/m9.figshare.23277458

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Citations (0)

Magmatic arc evolution during the tectonic closure of the Rocas Verdes basin: insights from Cretaceous-earliest Paleocene intrusive rocks of Navarino Island (55°S), Fuegian Andes

Figshare (2023)

Ricardo Velásquez Joaquín Bastías Esteban Salazar Fernando Poblete Mauricio González Guillot

U-Pb_INS-45d

Back-arc basin

10.6084/m9.figshare.23277437

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Citations (0)

Uplift and denudation history of the Ellsworth Mountains: insights from low temperature thermochronology

Joaquín Bastías David Chew Fernando Poblete Paula Castillo William R. Guenthner

Abstract. While thermochronological studies have constrained the landscape evolution of several of the crustal blocks of West and East Antarctica, the tectono-thermal evolution of the Ellsworth Mountains remains relatively poorly constrained. These mountains are among the crustal blocks that comprise West Antarctica and exhibit an exceptionally well-preserved Palaeozoic sedimentary sequence. Despite the seminal contribution of Fitzgerald and Stump (1991), who suggested an Early Cretaceous uplift event for the Ellsworth Mountains, further thermochronological studies are required to improve the current understanding of the landscape evolution of this mountain chain. We present new zircon (U-Th)/He (ZHe) ages, which provide insights into the landscape evolution of the Ellsworth Mountains. The ZHe ages collected from near the base and the top of the sequence suggest that these rocks underwent burial reheating after deposition. A cooling event is recorded during the Jurassic–Early Cretaceous, which we interpret as representing exhumation in response to rock uplift of the Ellsworth Mountains. Moreover, our results show that, while ZHe ages at the base of the sequence are fully reset, towards the top ZHe are partially reset. Uplift and exhumation of the Ellsworth Mountains during the Jurassic–Early Cretaceous was contemporaneous with the rotation and translation of this crustal block with respect to East Antarctica and possibly the Antarctic Peninsula. Furthermore, this period is characterised by widespread extension associated with the disassembly and breakup of Gondwana, with the Ellsworth Mountains playing a key role in the opening of the far South Atlantic. Based on these results, we suggest that uplift of the Ellsworth Mountains during the disassembly of Gondwana provides additional evidence for major rearrangement of the crustal blocks between the South American, African, Australian and Antarctic plates. Finally, uplift of the Ellsworth Mountains commenced during the Jurassic, which predates the Early Cretaceous uplift of the Transantarctic Mountains. This may indicate that continental scale, rift-related exhumation was diachronous, initiating in the Ellsworth Mountains in the Jurassic and then propagating southwards into the Transantarctic Mountains during the Early Cretaceous.

Thermochronology

Denudation

Sequence (biology)

Peninsula

10.5194/egusphere-2023-1769

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Citations (1)