Marcela Restrepo

Thermobarometry of Jurassic and Early Cretaceous plutonic rocks from the Northern Andes: tracing magmatic and tectonic changes

L. Chavarría Camilo Bustamante A. Cardona Marcela Restrepo

Plutonic rocks in magmatic arcs record variations in composition, thermal flux, and dynamics of subduction through time. In the northern Andes, arc magmatism of Jurassic age registers a complex history, including the fragmentation of Pangea at the end of the Triassic as well as the beginning of a new subduction zone in the Jurassic located at the western margin of South America. Two contrasting models have been proposed by previous researches to explain the evolution of this arc: i) continuous subduction with a slab-roll back that produced a crustal thinning and ii) oblique subduction associated with a crustal thickening.We characterized the emplacement conditions and crustal thickness variations of the Jurassic and Early Cretaceous arc in the northern Andes from 170 to 130 Ma using a combination of thermobarometers and trace element signatures and reviewed the previously suggested evolution models. The zircon and apatite saturation temperatures indicate that the intermediate magma became Zr and P2O5 oversaturated at 695-739 &#176;C and 849-909 &#176;C, respectively. Pressures obtained with the Al-in-hornblende barometer shows that the magma emplacement pressures varied from 1.2 to 7.1 kbar, with two distinct trends. A low-pressure trend (<2 kbar) related to different stock size bodies emplaced through the arc formation and a high-pressure trend (>5 kbar), which is restricted to the southern segment of the arc at the end of the Jurassic. Low Sm/Yb and Dy/Yb ratios show that the magma interacted with an amphibole-rich crust, implying that the Northern Andes was characterized by a thin crust during the Jurassic.The shallow emplacement pressures and thin crust suggest that the Jurassic magmatic arc record a predominant extensional tectonic style that could be linked with the Pangea breakup and the beginning of the arc magmatism. However, the younger magmatic pulses are characterized by higher emplacement pressures associated with an increase in crustal thickness during convergence. Such variation indicates that the Jurassic magmatism in the Northern Andes experienced significant changes in their tectonic controls and not a single dominant mechanism, as has been proposed.

Hornblende

Back-arc basin

10.5194/egusphere-egu2020-921

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Magnetic fabric of the Parashi stock and related dyke swarm, Alta Guajira (Colombia): The Caribbean-South American plates oblique convergence

Andean geology (2021)

Camilo Bustamante Carlos José Archanjo A. Cardona Marcela Restrepo

Anisotropy of magnetic susceptibility (AMS) and anhysteretic remanence (AAR) were used to evaluate the emplacement history of the Parashi stock and related dyke swarm situated in NW Colombia. The average magnetic susceptibility of 4.5×10-2 SI, in conjunction with low-coercivity components provided by the isothermal remanence and thermomagnetic curves with net Verwey and Curie transitions, indicates that multidomain magnetite records the anisotropy directions. The similar orientation and shape of the AMS and AAR ellipsoids indicate the absence of very fine magnetite with an inverse fabric. The magnetic foliation is the best-defined fabric element in these rocks and outlines a concentric structure, elongated parallel to the NE-SW direction of the pluton. Crystallisation age of the stock and dykes (51-47 Ma), along with pressure of emplacement determination indicate that the stock and the dyke swarm probably formed simultaneously, and they were emplaced in the shallow crust (

Lineation

Rock magnetism

10.5027/andgeov48n2-3332

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Geochemistry and geochronology of Permian plutonic rocks at the north‐western margin of Gondwana

Geological Journal (2023)

Marcela Restrepo Camilo Bustamante A. Cardona Alejandro Beltrán‐Triviño V. Valencia

The occurrence of Permian magmatic rocks in the Colombian Andes is restricted to a few localities. Previous works have focused mainly on explaining its tectonic setting, whereas petrogenesis has received less attention. This study closes this gap by reporting whole‐rock geochemistry, zircon U–Pb geochronology, trace elements and Hf isotopes from massive and mylonitic granitoids along central Colombia to constrain their age, source and petrogenesis. Our results show that the granitoids have a calc‐alkaline character, are rich in light‐rare elements (LREEs) and large‐ion lithophile elements (LILEs), present negative Nb and Ti anomalies, crystallized between ca. 276–265 Ma and show variable εHf(i) values ranging from −1.5 to +1.7. Combining our results with published geochemical, geochronological and isotopic data from this region, we suggest that the Middle Permian granitoids from the Tolima region were formed in a continental magmatic arc installed at the western margin of Gondwana, where partial melting of the mantle wedge and further crustal assimilation of the magmas with an old radiogenic and heterogeneous crust were essential processes for the modification of the source of the magmas that generated the granitoids. The Middle Permian may have reached the peak magmatic conditions (ca. 280–270 Ma), according to the recurrence of ages in this time interval. This period of magmatic activity may have been interrupted by the Triassic extensional period related to the beginning of the Pangea breakup.

Petrogenesis

Geochronology

Continental arc

10.1002/gj.4743

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Tectonic implications of the jurassic magmatism and the metamorphic record at the southern Colombian Andes

Journal of South American Earth Sciences (2021)

Marcela Restrepo Camilo Bustamante A. Cardona Alejandro Beltrán‐Triviño Andrés Bustamante

Geochronology

Hornblende

Protolith

Continental arc

Diorite

Geothermobarometry

Lile

10.1016/j.jsames.2021.103439

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Middle Triassic to Jurassic convergence at the north-western margin of Gondwana: insights from the Central Cordillera of Colombia

Figshare (2023)

Camilo Bustamante A. Cardona Marcela Restrepo Daniela Zapata Alejandro Beltrán‐Triviño

The northern Andes are crucial for understanding the processes associated with the break-up of Pangea and its impact on the evolution of the Pacific margin of South America. Despite its importance, the origin and significance of mafic magmatism and its relationship with the Permian arc-related granitoids in the northern Andes remains controversial. To address this, we examined the Tierradentro gneisses and amphibolites, which comprise Permian-Triassic lithologies that may help resolve this controversy. Our study focuses on representative lithologies of the Central Cordillera of Colombia, including mylonitized granitoids, metabasites, metapelites, and serpentinites, to shed light on the history of the western margin of Gondwana during and after its break-up (~230 to 200 Ma). To investigate these lithologies, we conducted field observations, petrographic analyses, U-Pb dating of zircons, and whole-rock geochemical, Nd, Pb, and Hf isotopic analyses. Our results show that mylonitized mafic rocks with Triassic crystallization ages (ca. 236 Ma) intruded Permian granitoids. Furthermore, these mafic and felsic rocks were intruded by Jurassic calc-alkaline batholiths. The geochemical and isotopic signatures of these rocks indicate their subduction-related extension origin and further mylonitic deformation, possibly during the Jurassic strike-slip movement of the Farallón plate relative to western Gondwana. The Otú-Pericos fault bounds these rocks to the west, where Jurassic metabasic and metapelitic sequences with serpentinites interleaved and formed in a collisional setting. Our findings suggest that the Pacific margin of northern South America underwent subduction-related extension during the middle Triassic and evolved towards a more oblique convergence during the Jurassic.

Margin (machine learning)

10.6084/m9.figshare.22707399

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Middle Triassic to Jurassic convergence at the north-western margin of Gondwana: insights from the Central Cordillera of Colombia

International Geology Review (2023)

Camilo Bustamante A. Cardona Marcela Restrepo Daniela Zapata Alejandro Beltrán‐Triviño

The northern Andes are crucial for understanding the processes associated with the break-up of Pangea and its impact on the evolution of the Pacific margin of South America. Despite its importance, the origin and significance of mafic magmatism and its relationship with the Permian arc-related granitoids in the northern Andes remains controversial. To address this, we examined the Tierradentro gneisses and amphibolites, which comprise Permian-Triassic lithologies that may help resolve this controversy. Our study focuses on representative lithologies of the Central Cordillera of Colombia, including mylonitized granitoids, metabasites, metapelites, and serpentinites, to shed light on the history of the western margin of Gondwana during and after its break-up (~230 to 200 Ma). To investigate these lithologies, we conducted field observations, petrographic analyses, U-Pb dating of zircons, and whole-rock geochemical, Nd, Pb, and Hf isotopic analyses. Our results show that mylonitized mafic rocks with Triassic crystallization ages (ca. 236 Ma) intruded Permian granitoids. Furthermore, these mafic and felsic rocks were intruded by Jurassic calc-alkaline batholiths. The geochemical and isotopic signatures of these rocks indicate their subduction-related extension origin and further mylonitic deformation, possibly during the Jurassic strike-slip movement of the Farallón plate relative to western Gondwana. The Otú-Pericos fault bounds these rocks to the west, where Jurassic metabasic and metapelitic sequences with serpentinites interleaved and formed in a collisional setting. Our findings suggest that the Pacific margin of northern South America underwent subduction-related extension during the middle Triassic and evolved towards a more oblique convergence during the Jurassic.

Batholith

Lithology

Felsic

10.1080/00206814.2023.2195901

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Citations (6)

Papers

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H-Index

i-10 index

Papers

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i-10 index