Early Jurassic carbon-isotope excursion in the Qiangtang Basin (Tibet), the eastern Tethys: Implications for the Toarcian Oceanic anoxic event

Fu, Xiugen; Wang, Jian; Feng, Xinglei; Wang, Dong; Chen, Wenbin; Song, Chao; Zeng, Shengqiang

doi:10.1016/j.chemgeo.2016.09.007

Cited by 48 publications

(28 citation statements)

References 70 publications

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“… The Upper Triassic Riganpeico Group [ Institute of Tibetan Geological Survey , ] consists of limestone interbedded with minor clastic rocks south of Biluoco, whereas north of Biluoco, voluminous sandstones contain pebbles, plant fragments, and brachiopod and bivalve fragments. The conformably overlying Quse Formation consists mainly of shale and limestone [ Liu and Lü , ]. The black shale intervals containing Toarcian (183–174 Ma) ammonites [ Chen et al , ; Su et al , ; Yi et al , ] were related to the widespread Toarcian oceanic anoxic event [ Fu et al , ]. Our new ammonite data suggest that the unit may extend into the Aalenian (174–170 Ma) (Figure S2 in the supporting information).…”

Section: Geological Settingmentioning

confidence: 99%

Sedimentary and tectonic evolution of the southern Qiangtang basin: Implications for the Lhasa‐Qiangtang collision timing

et al. 2017

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The Mesozoic stratigraphic record of the southern Qiangtang basin in central Tibet records the evolution and closure of the Bangong‐Nujiang ocean to the south. The Jurassic succession includes Toarcian‐Aalenian shallow‐marine limestones (Quse Formation), Aalenian‐Bajocian feldspatho‐litho‐quartzose to feldspatho‐quartzo‐lithic sandstones (shallow‐marine Sewa Formation and deep‐sea Gaaco Formation), and Bathonian outer platform to shoal limestones (Buqu Formation). This succession is truncated by an angular unconformity, overlain by upper Bathonian to lower Callovian fan‐delta conglomerates and litho‐quartzose to quartzo‐lithic sandstones (Biluoco Formation) and Callovian shoal to outer platform limestones (Suowa Formation). Sandstone petrography coupled with detrital‐zircon U‐Pb and Hf isotope analysis indicate that the Sewa and Gaaco formations contain intermediate to felsic volcanic detritus and youngest detrital zircons (183–170 Ma) with εHf(t) ranging widely from +13 to −25, pointing to continental‐arc provenance from igneous rocks with mixed mantle and continental‐crust contributions. An arc‐trench system thus developed toward the end of the Early Jurassic, with the southern Qiangtang basin representing the fore‐arc basin. Above the angular unconformity, the Biluoco Formation documents a change to dominant sedimentary detritus including old detrital zircons (mainly >500 Ma ages in the lower part of the unit) with age spectra similar to those from Paleozoic strata in the central Qiangtang area. A major tectonic event with intense folding and thrusting thus took place in late Bathonian time (166 ± 1 Ma), when the Qiangtang block collided with another microcontinental block possibly the Lhasa block.

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Section: Geological Settingmentioning

confidence: 99%

Sedimentary and tectonic evolution of the southern Qiangtang basin: Implications for the Lhasa‐Qiangtang collision timing

et al. 2017

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“…Although some studies have challenged the global nature of the Toarcian carbon cycle perturbations (e.g., Wignall et al, 2006), new geochemical records from outside European Boreal and Tethyan regions support the global extent of the T-OAE CIE; it has now been documented in Argentina (Al-Suwaidi et al, 2011), the Arctic (Suan et al, 2011), British Columbia (Caruthers et al, 2011(Caruthers et al, , 2014, Japan (Gröcke et al, 2011;Kemp and Izumi, 2014), and more recently China (Fu et al, 2016) (Fig. 1).…”

Section: Introductionmentioning

confidence: 97%

High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle

Them

Gill

Caruthers

et al. 2017

Earth and Planetary Science Letters

163

117

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The Mesozoic Era experienced several instances of abrupt environmental change that are associated with instabilities in the climate, reorganizations of the global carbon cycle, and elevated extinction rates. Often during these perturbations, oxygen-deficient conditions developed in the oceans resulting in the widespread deposition of organic-rich sedimentsthese events are referred to as Oceanic Anoxic Events or OAEs. Such events have been linked to massive injections of greenhouse gases into the ocean-atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments. Nevertheless, uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the OAEs that caused perturbations in the carbon cycle; this is particularly true of the Early Jurassic Toarcian OAE (~183.1 Ma). Here, we present biostratigraphically constrained carbon isotope data from western North America (Alberta and British Columbia, Canada) to better assess the global extent of the carbon cycle perturbations. We identify the large negative carbon isotope excursion associated with the OAE along with high-frequency oscillations and steps within the onset of this excursion. We propose that these high-frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales. Furthermore, increased terrestrial methanogenesis should be considered an important climatic feedback during Ocean Anoxic Events and other similar events in Earth history after the proliferation of land plants.

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“…The Early Jurassic Toarcian stage was characterized by the deposition of mudrocks enriched in organic matter in many marine sedimentary successions worldwide. The wide distribution of age‐equivalent lower Toarcian black shales from northern and southern Europe [ Jenkyns , ; Jenkyns et al , ], South America [ Al‐Suwaidi et al , , ], Japan [ Gröcke et al , ; Kemp and Izumi , ], western Canada and Siberia [ Caruthers et al , ; Suan et al , ], Tibet [ Fu et al , ], and elsewhere suggests that enhanced organic matter burial was principally controlled by a global set of environmental drivers and therefore constitutes a global Oceanic Anoxic Event (commonly termed the “T‐OAE” [ Jenkyns , ; van der Schootbrugge et al , ]). The T‐OAE can be chemostratigraphically defined not only by the stratigraphic extent of organic‐rich sediments but also by a broad positive carbon‐isotope excursion that was primarily caused by enhanced global deposition of organic matter.…”

Section: Introductionmentioning

confidence: 99%

Molybdenum‐isotope chemostratigraphy and paleoceanography of the Toarcian Oceanic Anoxic Event (Early Jurassic)

et al. 2017

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Molybdenum (Mo)‐isotope chemostratigraphy of organic‐rich mudrocks has been a valuable tool for testing the hypothesis that the Toarcian Oceanic Anoxic Event (T‐OAE, Early Jurassic, ~183 Ma) was characterized by the spread of marine euxinia (and organic matter burial) at a global scale. However, the interpretation of existing Mo‐isotope data for the T‐OAE (from Yorkshire, Cleveland Basin, U.K.) is equivocal. In this study, three new Mo‐isotope profiles are presented: from Dotternhausen Quarry (South German Basin, Germany), the Rijswijk core (West Netherlands Basin, Netherlands), and the Dogna core (Belluno Basin, northern Italy). Precise biostratigraphic and chemostratigraphic correlation between the three sites allows a direct comparison of the data, enabling some key conclusions to be reached: (i) The Mo‐isotope composition of seawater during the peak of the T‐OAE was probably close to ~1.45‰, implicating a greater removal flux of sulphides from seawater, and a larger extent of global seafloor euxinia compared to the present day; (ii) Mo‐isotope cycles previously identified in the Yorkshire sedimentary succession are attributed to changes in the degree of local Mo drawdown from overlying Cleveland Basin seawater; (iii) The consistency of the new multisite Mo‐isotope data set indicates a secular reduction in the burial of Mo globally in the late stages of the T‐OAE, implying a contraction in the extent of global marine euxinia; (iv) Subtle differences in the Mo‐isotope composition of deposits formed in different euxinic subbasins of the European epicontinental shelf were probably governed by local variations in basin hydrography and rates of water renewal.

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Early Jurassic carbon-isotope excursion in the Qiangtang Basin (Tibet), the eastern Tethys: Implications for the Toarcian Oceanic anoxic event

Cited by 48 publications

References 70 publications

Sedimentary and tectonic evolution of the southern Qiangtang basin: Implications for the Lhasa‐Qiangtang collision timing

Sedimentary and tectonic evolution of the southern Qiangtang basin: Implications for the Lhasa‐Qiangtang collision timing

High-resolution carbon isotope records of the Toarcian Oceanic Anoxic Event (Early Jurassic) from North America and implications for the global drivers of the Toarcian carbon cycle

Molybdenum‐isotope chemostratigraphy and paleoceanography of the Toarcian Oceanic Anoxic Event (Early Jurassic)

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