Geochronology of the Tectonic, Stratigraphic, and Magmatic Evolution of Neoproterozoic to Early Paleozoic, North American Cordillera and Cryogenian Glaciation

Isakson, Vincent H.

doi:10.18122/b2p42z

Cited by 9 publications

(45 citation statements)

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“…These field observations indicate that a relatively structurally intact stratigraphic section exists west from Daugherty Gulch (Figure 4). This section consists of the 667 Ma tuff of Daugherty Gulch (Isakson, 2017; Lund et al, 2010), which is overlain by ~1.5 km of dolostone and argillite that coarsen upward into the ~1 km thick Clayton Mine Quartzite. Small (<100 m) gabbroic sill‐like bodies (hereby referred to as the Ramshorn gabbro; Brennan et al, 2020) intruded into the Ramshorn Slate within this gradational contact.…”

Section: Resultsmentioning

confidence: 99%

“…During this interval, conglomeratic channels within quartzites (above sequence boundary S2; Figure 5; Link et al, 1987) represent Marinoan glacial drawdown (Levy et al, 1994). Final rifting is recorded by unconformably overlying (sequence The Daugherty Gulch borehole containing the Cryogenian 667.8 ± 0.22 Ma (Isakson, 2017) tuff in the northeastern corner of the field area, as well as detrital zircon sample locations, are denoted. Approximately 2.5 km of strata proposed to be Ordovician in age by prior workers (Hobbs et al, 1990) have been reassigned to the Neoproterozoic within this area.…”

Section: Tectonicsmentioning

confidence: 99%

“…Neoproterozoic to Ordovician stratigraphy of (a) central Idaho at Bayhorse and Stibnite and (b) southeastern Idaho. U-Pb radiometric zircon ages are from Fanning and Link (2004) and Isakson (2017). Southeastern Idaho unit thicknesses are from Trimble (1976) and Link et al (1987).…”

Section: 1029/2020tc006145mentioning

confidence: 99%

“…Southeastern Idaho unit thicknesses are from Trimble (1976) and Link et al (1987). Stibnite stratigraphy is adapted from Stewart et al (2016) and Isakson (2017). Bayhorse mapped unit abbreviations ( Figure 3) are labeled.…”

Section: 1029/2020tc006145mentioning

confidence: 99%

“…Simplified geologic map (adapted from 1:24,000 scale mapping of Brennan et al, 2020) of the northern portion of the Bayhorse anticline, central Idaho. The Daugherty Gulch borehole containing the Cryogenian 667.8 ± 0.22 Ma (Isakson, 2017) tuff in the northeastern corner of the field area, as well as detrital zircon sample locations, are denoted. Approximately 2.5 km of strata proposed to be Ordovician in age by prior workers (Hobbs et al, 1990) have been reassigned to the Neoproterozoic within this area.…”

Section: Introductionmentioning

confidence: 99%

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Neoproterozoic Windermere Supergroup Near Bayhorse, Idaho: Late‐Stage Rodinian Rifting Was Deflected West Around the Belt Basin

et al. 2020

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Conflicting models of Rodinian rifting have been proposed to explain the recognized variation in the Neoproterozoic and early Cambrian tectonostratigraphic architecture of the western Laurentian margin. However, discrimination among rift models is hampered by limited exposure and metamorphism of the rocks. Southeastern Idaho preserves more than 6 km of Neoproterozoic and Cambrian strata. In contrast, along the inferred continuation of the margin in east central Idaho, correlative rocks are missing across the Lemhi arch. Our field mapping and U‐Pb dating studies, located approximately 50 km west of the Lemhi arch unconformity, focused on a succession of regionally extensive rocks that were previously assigned an Ordovician age. We show that ~1.5 km of strata here overlies a ~667 Ma reworked felsic tuff and was intruded by a 601 ± 27 Ma gabbro sill; we thus redesignate these rocks as Cryogenian and Ediacaran in age. These rocks are overlain by a ~1 km thick Ediacaran to middle Cambrian quartzite. Middle Ordovician quartzites overlie these middle Cambrian strata, indicating that though Neoproterozoic and lower Cambrian rocks are present west of the Lemhi arch, upper Cambrian and Lower Ordovician rocks are thin or absent. Comparison of this redesignated section to the closest correlative sections suggests an initial stage of symmetric rifting followed by later asymmetric rifting. We suggest that prerifting ~1,370 Ma magmatism within the Belt basin produced lithospheric rigidity that influenced the final stage of rifting and produced heterogeneity in the geometries of structural domains similar to those documented in other well‐defined, modern rift margins.

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Section: Resultsmentioning

confidence: 99%

Section: Tectonicsmentioning

confidence: 99%

Section: 1029/2020tc006145mentioning

confidence: 99%

Section: 1029/2020tc006145mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Neoproterozoic Windermere Supergroup Near Bayhorse, Idaho: Late‐Stage Rodinian Rifting Was Deflected West Around the Belt Basin

et al. 2020

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Zircon U–Pb ages and Hf isotope compositions of the Neoproterozoic magmatic rocks in the Helan Mountains, North China

et al. 2019

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The periodic dispersal and assembly of continental fragments has been an inherent feature of the continental crust. Based on the discovery of large-scale supercontinent cycle and the theory of plate tectonics, several supercontinents have been identified, such as Columbia/Nuna, Rodinia, Gondwana and Pangaea. Neoproterozoic magmatic events related to the break-up of Rodinia are globally well preserved. Although Neoproterozoic magmatic events were very weak in the North China Craton (NCC), they are crucial in reconstructing the geometries of the NCC and could facilitate the completion of the Neoproterozoic configuration of the supercontinent. In this study, c. 853–835 Ma magmatic rocks are identified in the western margin of the NCC. Precise zircon U–Pb age determination yields 206Pb/238U average ages of 835.5 ± 5.3 Ma (HL-39) and 853.7 ± 4.5 Ma (HL-30). In situ zircon Hf isotope compositions of the samples reveal that their parental magma was formed by the reworking of ancient crust evolved from Mesoproterozoic mantle. In summary, the discovery of Neoproterozoic magmatic rocks in the western margin of the NCC, and reported synchronous rocks in other parts of the NCC indicate that the NCC might be conjoined with the supercontinent Rodinia during the Neoproterozoic. This discovery is of significant help in unravelling the early Neoproterozoic history of the NCC and the evolution of the supercontinent Rodinia.

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Geochronology and formal stratigraphy of the Sturtian Glaciation in the Adelaide Superbasin

et al. 2023

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The glaciogenic nature of the Yudnamutana Subgroup was first recognized over a century ago, and its global significance was recognized shortly after, with the eventual postulation of a global Sturtian Glaciation and Snowball Earth theory. Much debate on the origin and timing of these rocks, locally and globally, has ensued in the years since. A significant corpus of research on the lithology, sedimentology, geochronology and formal lithostratigraphy of these sequences globally has attempted to resolve many of these debates. In the type area for the Sturtian Glaciation, South Australia’s Adelaide Superbasin, the lithostratigraphy and sedimentology are well understood; however, formal stratigraphic nomenclature has remained complicated and contested. Absolute dates on the stratigraphy are also extremely sparse in this area. The result of these longstanding issues has been disagreement as to whether the sedimentary rocks of the Yudnamutana Subgroup are truly correlative throughout South Australia, and if they were deposited in the same time span recently defined for Sturtian glacial rocks globally, c. 717 Ma to c. 660 Ma. This study presents a large detrital zircon study, summarizes and compiles existing global geochronology for the Sturtian Glaciation and revises the formal lithostratigraphic framework of the Yudnamutana Subgroup. We show equivalence of the rocks that comprise the revised Sturt Formation, the main glaciogenic unit of the Yudnamutana Subgroup, and that it was deposited within the time span globally defined for the Sturtian Glaciation.

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Geochronology of the Tectonic, Stratigraphic, and Magmatic Evolution of Neoproterozoic to Early Paleozoic, North American Cordillera and Cryogenian Glaciation

Cited by 9 publications

References 0 publications

Neoproterozoic Windermere Supergroup Near Bayhorse, Idaho: Late‐Stage Rodinian Rifting Was Deflected West Around the Belt Basin

Neoproterozoic Windermere Supergroup Near Bayhorse, Idaho: Late‐Stage Rodinian Rifting Was Deflected West Around the Belt Basin

Zircon U–Pb ages and Hf isotope compositions of the Neoproterozoic magmatic rocks in the Helan Mountains, North China

Geochronology and formal stratigraphy of the Sturtian Glaciation in the Adelaide Superbasin

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