The lower–middle Cambrian transition and the Sauk I-II unconformable boundary in Iran, a record of late early Cambrian global Hawke Bay regression

Lasemi, Yaghoob; Amin-Rasouli, Hadi

doi:10.1130/2016.2525(10)

Cited by 6 publications

(10 citation statements)

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“…from a distal compared to proximal source within the Arabian shield) cannot readily account for the up‐section increase in rounding of zircon, rutile, and tourmaline (Figure 10). Considering that the quartz‐rich unit was deposited in a high‐energy shallow marine setting (Geyer et al, 2014; Lasemi & Amin‐Rasouli, 2016), it is plausible that the increase in roundness of detrital zircon, rutile, and tourmaline grains in this unit relative to underlying strata reflects protracted reworking in a higher energy depositional environment. However, the predominance of angular apatite grains–the most mechanically labile mineral analysed in this study–within the quartz‐rich unit is inconsistent with this scenario.…”

Section: Discussionmentioning

confidence: 99%

“…Sedimentary structures, bedform geometry, and trace fossils have been interpreted to indicate a fluvial to the shallow marine depositional environment for the Lalun Formation (Geyer et al, 2014; Lasemi & Amin‐Rasouli, 2016). The arkose unit is interpreted to have been deposited in fluvial and estuarine environments, followed by marine transgression during the deposition of the shale unit, and subsequent regression and deposition of the quartz‐rich unit in a shoreface environment (Bayet‐Goll & Daraei, 2020; Bayet‐Goll et al, 2018; Geyer et al, 2014; Lasemi & Amin‐Rasouli, 2016). The increase in grain size toward the Zagros zone, and W–SW to E–NE directed paleocurrents (Bayet‐Goll et al, 2018; Poursoltani, 2020) indicates sediment transport from the Gondwanan hinterland (Arabian Plate) toward Iran.…”

Section: Geological Settingmentioning

confidence: 99%

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Evaluating sediment recycling through combining inherited petrogenic and acquired sedimentary features of multiple detrital minerals

2022

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An implicit assumption of most sedimentary provenance analyses is a direct link between source and sink. However, recycling of sedimentary detritus from pre‐existing strata interrupts the direct source‐to‐sink link and can result in incorrect interpretations of paleogeography and paleodrainage. Detrital zircon is the favoured proxy of contemporary provenance studies, but its physiochemical resilience makes it particularly prone to recycling. In this study, we integrate geochemical (age, isotope, and trace elements) and grain roundness data of multiple detrital minerals with different physiochemical stabilities (zircon, tourmaline, rutile, and apatite) to evaluate the importance of recycling in an ancient sedimentary basin. We focus on the early Cambrian Lalun Formation of Iran, which forms part of a laterally extensive sandstone‐rich succession deposited along the northern margin of Gondwana. The Lalun Formation preserves a distinct change of compositional maturity between lower arkose and shale units and an upper unit of quartz‐rich sandstone. Detrital zircon, rutile, and apatite data demonstrate that all units of the Lalun Formation share a common source in the Arabian‐Nubian Shield. Whole‐rock geochemical data further indicate that all units have similar chemical alteration indices, suggesting the change in compositional maturity is not a product of differential weathering of the source region. Analysis of grain roundness reveals that detrital zircon, rutile, and tourmaline in the upper quartz‐rich unit are typically more rounded than those in the underlying arkose and shale units. In contrast, detrital apatite grains are nearly all angular in the quartz‐rich unit but mostly rounded in the lower arkose and shale. Together, the detrital mineral provenance, whole‐rock geochemistry, and morphological data are consistent with recycling of the lower arkose and shale units of the Lalun Formation into the uppermost quartz‐rich unit, with the latter also receiving a component of first‐cycle detritus represented by angular detrital apatite. Our findings demonstrate that integrating the features of detrital minerals acquired during a sedimentary cycle (grain rounding and diversity of mineral assemblages) with features inherited from their ultimate source rocks (age, isotopic, and geochemical proxies) can assist in recognising sediment recycling in ancient strata.

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Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Evaluating sediment recycling through combining inherited petrogenic and acquired sedimentary features of multiple detrital minerals

2022

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“…During the Ediacaran–Cambrian transition, the Iranian blocks were originally part of a series of peri‐Gondwanan terranes that bordered the north‐western margin of Gondwana (the so‐called Proto‐Palaeotethyan margin sensu Lasemi 2001 and Proto‐Tethyan margin sensu Stampfli & Borel 2002). This part of the peri‐Gondwanan margin is interpreted either as a thermally subsiding passive margin of the Afro‐Arabian platform that was formed after the late Proterozoic rifting of the north‐western Gondwana supercontinent (Stöcklin, 1968; Berberian & King 1981; Husseini 1989; Talbot & Alavi 1996; Lasemi 2001, 2007, 2017) or alternatively as an active continental margin with Cadomian arc plutonism and volcanism resulting from the southwards subduction of the Proto‐Tethys ocean along the northern margin of Gondwana (Ramezani & Tucker 2003; Hassanzadeh et al . 2008; Horton et al .…”

Section: Geological Settingmentioning

confidence: 99%

New and revised small shelly fossil record from the lower Cambrian of northern Iran

Devaere

Korn

Ghaderi

et al. 2021

Papers in Palaeontology

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Small shelly fossils (SSFs) are highly informative of the ‘Cambrian explosion’. Their palaeobiodiversity has been documented from lower Cambrian deposits worldwide but it remains elusive in areas such as Iran, despite this region occupying a critical position on the north‐western Gondwana margin during the early Cambrian. This new study of the SSFs of the lower Cambrian of northern Iran provides a large new dataset from this understudied area. We revise the micropalaeontological signal of the Soltanieh Formation of the Alborz Mountains and introduce novel data from the Soltanieh and overlying Barut Formations of the Soltanieh Mountains. The new, solid taxonomic and stratigraphic SSF data enable us to distinguish two successive microfaunal assemblages. The first occurs in the Soltanieh Formation of the Soltanieh and Alborz Mountains and is dominated by anabaritids (Anabarites trisulcatus, A. ex gr. trisulcatus, A. tristichus, A. dalirense sp. nov., Cambrotubulus decurvatus) along with protoconodonts (Protohertzina anabarica and P. unguliformis), maikhanellids (Maikhanella multa, Purella squamulosa and Purella sp.), Aetholicopalla adnata, indeterminate cones and irregular tubes. The second assemblage, from the Barut Formation, is dominated by a diverse assemblage of molluscs (Oelandiella korobkovi and cap‐shaped morphotypes). Siphogonuchitid sclerites also occur in both assemblages. The two SSF assemblages are characteristic of the Terreneuvian. Our dataset enables us to assess the sequence of faunal change of the Ediacaran–Cambrian transition; in contrast to the tube–sclerite–brachiopod succession presented in the literature, the Iranian fauna changes from one dominated by tubes and sclerites, to one dominated by molluscs and sclerites.

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“…During Ediacaran and Cambrian, Iran was part of a thermally subsiding passive margin that was formed through late Proterozoic rifting of northwestern Gondwana (Berberian and King 1981;Lasemi 2001;Lasemi and Amin-Rasouli 2016). Shallow-marine (mostly carbonates) and fluviodeltaic sediments were deposited over a vast area, from northern Arabia in the southeast to the Alborz region in northern Iran, forming the northern passive paleocontinental margin of Gondwana (Berberian and King 1981;Lasemi 2001;Berberian 2014, Lasemi andAmin-Rasouli 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Shallow-marine (mostly carbonates) and fluviodeltaic sediments were deposited over a vast area, from northern Arabia in the southeast to the Alborz region in northern Iran, forming the northern passive paleocontinental margin of Gondwana (Berberian and King 1981;Lasemi 2001;Berberian 2014, Lasemi andAmin-Rasouli 2016). Facies and sequence stratigraphic studies of the upper Neoproterozoic through Paleozoic successions in the region (Lasemi 2001) suggest that Iran and northern Arabia were connected until their breakup in the early Permian (Lasemi and Amin-Rasouli 2016).…”

Section: Introductionmentioning

confidence: 99%

Lithostratigraphy and sedimentary environment of the Precambrian Kushk Series of central Iran

Vaziri

Laflamme

2018

Can. J. Earth Sci.

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The Kushk Series is a distinctive late Ediacaran succession occurring in the Bafq and Behabad regions of central Iran that has yielded an extensive community of diverse Ediacara biota, including several Precambrian (Chuaria) and Ediacaran (Cloudina, Corumbella) index fossils.The Kushk Series reaches a thickness of up to 518 m and consists of shallow to deep subtidal deposits along a homoclinal carbonate ramp during a transgression/regression cycle. These deposits accumulated as part of an extensional rift basin complex resulting from the opening of the Proto-Paleotethys Ocean in northeastern Gondwana. Latest Ediacaran fossils occur in the deep-water calcareous marine shales, and represent a thriving community at the dawn of animal life.

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The lower–middle Cambrian transition and the Sauk I-II unconformable boundary in Iran, a record of late early Cambrian global Hawke Bay regression

Cited by 6 publications

References 0 publications

Evaluating sediment recycling through combining inherited petrogenic and acquired sedimentary features of multiple detrital minerals

Evaluating sediment recycling through combining inherited petrogenic and acquired sedimentary features of multiple detrital minerals

New and revised small shelly fossil record from the lower Cambrian of northern Iran

Lithostratigraphy and sedimentary environment of the Precambrian Kushk Series of central Iran

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