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1. High-latitude ice and climate control on sediment supply across SW Gondwana during the late Carboniferous and early Permian

   https://doi.org/10.1130/B35852.1  

   Griffis, N.; Montañez, I.; Mundil, R.; Heron, D. Le; Dietrich, P.; Kettler, C.; Linol, B.; Mottin, T.; Vesely, F.; Iannuzzi, R.; et al (February 2021, GSA Bulletin)

   null (Ed.)

   Abstract The response of sediment routing to climatic changes across icehouse-to-greenhouse turnovers is not well documented in Earth's pre-Cenozoic sedimentary record. Southwest Gondwana hosts one of the thickest and most laterally extensive records of Earth's penultimate icehouse, the late Paleozoic ice age. We present the first high-resolution U-Pb zircon chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) analysis of late Paleozoic ice age deposits in the Kalahari Basin of southern Africa, which, coupled with existing CA-ID-TIMS zircon records from the Paraná and Karoo Basins, we used to refine the late Paleozoic ice age glacial history of SW Gondwana. Key findings from this work suggest that subglacial evidence in the Kalahari region is restricted to the Carboniferous (older than 300 Ma), with glacially influenced deposits culminating in this region by the earliest Permian (296 Ma). The U-Pb detrital zircon geochronologic records from the Paraná Basin of South America, which was located downstream of the Kalahari Basin in the latest Carboniferous and Permian, indicate that large-scale changes in sediment supplied to the Paraná were contemporaneous with shifts in the SW Gondwana ice record. Gondwanan deglaciation events were associated with the delivery of far-field, African-sourced sediments into the Paraná Basin. In contrast, Gondwanan glacial periods were associated with the restriction of African-sourced sediments into the basin. We interpret the influx of far-field sediments into the Paraná Basin as an expansion of the catchment area for the Paraná Basin during the deglaciation events, which occurred in the latest Carboniferous (300–299 Ma), early Permian (296 Ma), and late early Permian (<284 Ma). The coupled ice and detrital zircon records for this region of Gondwana present opportunities to investigate climate feedbacks associated with changes in freshwater and nutrient delivery to late Paleozoic ocean basins across the turnover from icehouse to greenhouse conditions. 

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2. Late Jurassic paleogeography of the U.S. Cordillera from detrital zircon age and hafnium analysis of the Galice Formation, Klamath Mountains, Oregon and California, USA

   https://doi.org/10.1130/B36810.1  

   Surpless, Kathleen D.; Alford, Ryan W.; Barnes, Calvin; Yoshinobu, Aaron; Weis, Natalee E. (August 2023, Geological Society of America Bulletin)

   The Upper Jurassic Galice Formation, a metasedimentary unit in the Western Klamath Mountains, formed within an intra-arc basin prior to and during the Nevadan orogeny. New detrital zircon U-Pb age analyses (N = 11; n = 2792) yield maximum depositional ages (MDA) ranging from ca. 160 Ma to 151 Ma, which span Oxfordian to Kimmeridgian time and overlap Nevadan contractional deformation that began by ca. 157 Ma. Zircon ages indicate a significant North American continental provenance component that is consistent with tectonic models placing the Western Klamath terrane on the continental margin in Late Jurassic time. Hf isotopic analysis of Mesozoic detrital zircon (n = 603) from Galice samples reveals wide-ranging εHf values for Jurassic and Triassic grains, many of which cannot be explained by a proximal source in the Klamath Mountains, thus indicating a complex provenance. New U-Pb ages and Hf data from Jurassic plutons within the Klamath Mountains match some of the Galice Formation detrital zircon, but these data cannot account for the most non-radiogenic Jurassic detrital grains. In fact, the in situ Cordilleran arc record does not provide a clear match for the wide-ranging isotopic signature of Triassic and Jurassic grains. When compiled, Galice samples indicate sources in the Sierra Nevada pre-batholithic framework and retroarc region, older Klamath terranes, and possibly overlap strata from the Blue Mountains and the Insular superterrane. Detrital zircon age spectra from strata of the Upper Jurassic Great Valley Group and Mariposa Formation contain similar age modes, which suggests shared sediment sources. Inferred Galice provenance within the Klamath Mountains and more distal sources suggest that the Galice basin received siliciclastic turbidites fed by rivers that traversed the Klamath-Sierran arc from headwaters in the retroarc region. Thus, the Galice Formation contains a record of active Jurassic magmatism in the continental arc, with significant detrital input from continental sediment sources within and east of the active arc. These westward-flowing river systems remained active throughout the shift in Cordilleran arc tectonics from a transtensional system to the Nevadan contractional system, which is characterized by sediment sourced in uplifts within and east of the arc and the thrusting of older Galice sediments beneath older Klamath terranes to the east. 

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3. Provenance of uppermost Carboniferous–Lower Triassic sandstones, Bogda Mountains, NW China: implication on late Paleozoic tectonic history of southern Central Asian Orogenic Belt

   Wu, S X; Yang, W (August 2025, International Meeting for Applied Geoscience and Energy)

   Provenance of uppermost Carboniferous–Lower Triassic sandstones, Bogda Mountains, NW China: implication on late Paleozoic tectonic history of southern Central Asian Orogenic Belt The Permian-Triassic time is a critical stage in the Paleozoic continental amalgamation and Cenozoic orogenic reactivation of southern Central Asian Orogenic Belt (CAOB). Field, petrographic and detrital zircon U-Pb geochronological data of the uppermost Carboniferous– Lower Triassic sandstones from 3 sections in Bogda Mountains, greater Turpan-Junggar basin, NW China, are used to decipher the tectonic history. They are Tarlong- Taodonggou (TT) and Zhaobishan (ZBS) in the south and Dalongkou (DLK) in the north, 100 km apart and ~7,000 m in total thickness. Four petrofacies of 229 sandstones are defined using the abundance of volcanic, sedimentary, and metamorphic (with polycrystalline quartz) lithics. Petrofacies A (Lv73Ls21(Qp+Lm)6) contains mainly volcanic lithics, indicating a volcanic arc as the main source. Petrofacies B (Lv14Ls41(Qp+Lm)45) and Petrofacies C (Lv38Ls14(Qp+Lm)48) contain mixed sedimentary, metamorphic, and volcanic lithics, indicating multiple sources. Petrofacies D (Lv11Ls82(Qp+Lm)7) contains mainly sedimentary lithics with a trace amount of volcanic and metamorphic lithics, indicating local rift-shoulder sedimentary sources. Additionally, the U-Pb dates of 3505 detrital zircon grains of 35 sandstones were analyzed. The predominant Paleozoic zircon grains yield major age populations at ca. 360–280 Ma and 485–385 Ma. Precambrian dates are present, ranging from 542 Ma to 3329 Ma. During Gzhelian–Asselian, andesite and basalt are the major source lithologies in TT. Zircon ages peak at ~300 Ma. During Sakmarian–Kungurian, basalt and andesite are the main source rocks in TT and ZBS; and zircon ages of both areas peak at ~300 Ma. The Roadian–Wordian is probably represented by a regional unconformity. The Guadalupian source lithology and zircon date show a major change. Andesite is the common and rhyolite and basalt minor source lithologies for TT and DLK; but rhyolite significant for ZBS. A unimodal peak at ~305 Ma occurs in TT; two peaks at 305 and 455 Ma with common Precambrian dates in ZBS; and peaks of 310–295 Ma in DLK. During Wuchiapingian–mid Olenekian, andesite and rhyolite are the common source lithologies for TT and DLK, and rhyolite as the primary volcanic lithology for ZBS. In TT, Wuchiapingian-Induan samples have a major age peak at ~300 Ma, and an Olenekian sample has two peaks at ~300 and ~450 Ma. In ZBS, the age pattern is similar to that of the Guadalupian sample. In DLK, samples have a major age peak at ~310 Ma and a minor peak at ~450 Ma. The comparable age clusters identified by multi-dimensional scaling indicate that North Tianshan is the source for TT and ZBS during the latest Carboniferous–early Permian. But south Central Tianshan became the main source solely to ZBS. During late Permian–Early Triassic, both north and central Tianshan became the common sources to the three areas due to enhanced denudation. The source change in mid-Permian across a regional unconformity is synchronous with Paleo-Asian Ocean closure and arc-continent and continent-continent collisions, which occurred no later than Guadalupian. 

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4. The amalgamation of Gondwana: calcite twinning and finite strains from the early–late Paleozoic Buzios, Ross, Kurgiakh and Gondwanide orogens

   https://doi.org/10.1144/SP531-2022-165  

   Craddock, John; Paulsen, Timothy; da Silva Schmitt, Renata; Johnston, Stephen T.; Myrow, Paul M.; Hughes, Nigel C. (October 2022, Geological Society, London, Special Publications)

   Abstract Orientated carbonate (calcite twinning strains; n = 78 with 2414 twin measurements) and quartzites (finite strains; n = 15) were collected around Gondwana to study the deformational history associated with the amalgamation of the supercontinent. The Buzios orogen (545–500 Ma), within interior Gondwana, records the high-grade collisional orogen between the São Francisco Craton (Brazil) and the Congo–Angola Craton (Angola and Namibia), and twinning strains in calc-silicates record a SE–NW shortening fabric parallel to the thrust transport. Along Gondwana's southern margin, the Saldanian–Ross–Delamerian orogen (590–480 Ma) is marked by a regional unconformity that cuts into deformed Neoproterozoic–Ordovician sedimentary rocks and associated intrusions. Cambrian carbonate is preserved in the central part of the southern Gondwana margin, namely in the Kango Inlier of the Cape Fold Belt and the Ellsworth, Pensacola and Transantarctic mountains. Paleozoic carbonate is not preserved in the Ventana Mountains in Argentina, in the Falkland Islands/Islas Malvinas or in Tasmania. Twinning strains in these Cambrian carbonate strata and synorogenic veins record a complex, overprinted deformation history with no stable foreland strain reference. The Kurgiakh orogen (490 Ma) along Gondwana's northern margin is also defined by a regional Ordovician unconformity throughout the Himalaya; these rocks record a mix of layer-parallel and layer-normal twinning strains with a likely Himalayan (40 Ma) strain overprint and no autochthonous foreland strain site. Conversely, the Gondwanide orogen (250 Ma) along Gondwana's southern margin has three foreland (autochthonous) sites for comparison with 59 allochthonous thrust-belt strain analyses. From west to east, these include: finite strains from Devonian quartzite preserve a layer-parallel shortening (LPS) strain rotated clockwise in the Ventana Mountains of Argentina; frontal (calcite twins) and internal (quartzite strains) samples in the Cape Fold Belt preserve a LPS fabric that is rotated clockwise from the autochthonous north–south horizontal shortening in the foreland strain site; Falkland Devonian quartzite shows the same clockwise rotation of the LPS fabric; and Permian limestone and veins in Tasmania record a thrust transport-parallel LPS fabric. Early amalgamation of Gondwana (Ordovician) is preserved by local layer-parallel and layer-normal strain without evidence of far-field deformation, whereas the Gondwanide orogen (Permian) is dominated by layer-parallel shortening, locally rotated by dextral shear along the margin, that propagated across the supercontinent. 

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5. The amalgamation of Gondwana: calcite twinning and finite strains from the early–late Paleozoic Buzios, Ross, Kurgiakh and Gondwanide orogens

   https://doi.org/10.1144/sp531  

   Craddock, JP; Paulsen, T; Schmitt, R_de-S; Johnston, ST; Myrow, PM; Hughes, NC (October 2022, Geological Society, London, Special Publications)

   Orientated carbonate (calcite twinning strains; n = 78 with 2414 twin measurements) and quartzites (finite strains; n = 15) were collected around Gondwana to study the deformational history associated with the amalgamation of the supercontinent. The Buzios orogen (545–500 Ma), within interior Gondwana, records the high-grade collisional orogen between the São Francisco Craton (Brazil) and the Congo–Angola Craton (Angola and Namibia), and twinning strains in calc-silicates record a SE–NW shortening fabric parallel to the thrust transport. Along Gondwana’s southern margin, the Saldanian–Ross–Delamerian orogen (590– 480 Ma) is marked by a regional unconformity that cuts into deformed Neoproterozoic–Ordovician sedimentary rocks and associated intrusions. Cambrian carbonate is preserved in the central part of the southern Gondwana margin, namely in the Kango Inlier of the Cape Fold Belt and the Ellsworth, Pensacola and Transantarctic mountains. Paleozoic carbonate is not preserved in the Ventana Mountains in Argentina, in the Falkland Islands/Islas Malvinas or in Tasmania. Twinning strains in these Cambrian carbonate strata and synorogenic veins record a complex, overprinted deformation history with no stable foreland strain reference. The Kurgiakh orogen (490 Ma) along Gondwana’s northern margin is also defined by a regional Ordovician unconformity throughout the Himalaya; these rocks record a mix of layer-parallel and layer-normal twinning strains with a likely Himalayan (40 Ma) strain overprint and no autochthonous foreland strain site. Conversely, the Gondwanide orogen (250 Ma) along Gondwana’s southern margin has three foreland (autochthonous) sites for comparison with 59 allochthonous thrust-belt strain analyses. From west to east, these include: finite strains from Devonian quartzite preserve a layer-parallel shortening (LPS) strain rotated clockwise in the Ventana Mountains of Argentina; frontal (calcite twins) and internal (quartzite strains) samples in the Cape Fold Belt preserve a LPS fabric that is rotated clockwise from the autochthonous north–south horizontal shortening in the foreland strain site; Falkland Devonian quartzite shows the same clockwise rotation of the LPS fabric; and Permian limestone and veins in Tasmania record a thrust transport-parallel LPS fabric. Early amalgamation of Gondwana (Ordovician) is preserved by local layer-parallel and layer-normal strain without evidence of far-field deformation, whereas the Gondwanide orogen (Permian) is dominated by layer-parallel shortening, locally rotated by dextral shear along the margin, that propagated across the supercontinent. 

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