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Ammonite specimens (re-figured), first illustrated and identified as Blanfordiceras curvatum Uhlig (left) and Aulacosphinctes hollandi Uhlig by Yi et al. (2005, pl. 1, Figs. 9 and 11) (right).
Source publication
The age of the Suowa Formation, the latest Jurassic marine deposit in the Qiangtang Block, is important not only because of its great hydrocarbon potential, but also because it defines the termination of the Jurassic ocean in the area. New ammonite evidence from the upper part of the Suowa Formation in the northwestern Qiangtang region allows us to...
Contexts in source publication
Context 1
... Jurassic strata are widely distributed in the region. To date, the present specimens number the largest macrocephalitid collection from Qiangtang (North Tibet), consisting of the madagascariensis- group and compressus-group, whereby the former is dominant and best matches Macrocephalites madagascariensis Lemoine (Spath, 1928, p. 181, pl. 22, Fig. 3) in having more inflated whorls, a wider umbilicus and somewhat coarse ribs. In addition, there are specimens whose measurements are transitional between the two groups, which also are referred to Macrocephalites madagas- cariensis rather than the compressus group based on their costation and the number of ribs (Fig. ...
Context 2
... with a diameter of about 90 mm. This is nearly as large as the phragmocones of three other well-preserved specimens in the collection, indicating that the specimen with the body-chamber preserved is an adult. The Tibetan specimens preserved as phragmocones agree well with Macrocephalites madagascariensis from Kachchh (Spath, 1928, p. 181, pl. 22, Fig. 3a, b). Superficially, the present madagascar- iensis-group resembles also Macrocephalites verus Buckman from Ehningen (Wü rttemberg), Germany (Buckman, 1922, pl. 334A, Figs. 1 and 2), but differs mainly in the position of the maximum thickness on the whorl flank. The maximum thickness of Macrocephalites verus is near the umbilicus, which ...
Context 4
... strong, primary ribs rectiradiate, regularly interspaced, bifurcating at around two-thirds of flank height. Secondary ribs with intercalated simple ribs, identical in strength. Height of last whorl increasing rapidly, whorl section oval in outline. Outer whorl of specimen (Fig. 10, a1) 89 mm in diameter, outer whorl apparently smooth. Specimen (Fig. 10, c3) fairly evolute, 74 mm in diameter, the whorl following a constriction smooth. Specimen (Fig. 10, a) consists of inner whorl with two or three constrictions per whorl, whorl section subquadrate, suture not seen. [M]. a1, cross-section, shaded area: body-chamber, a2, lateral view with outer whorls, the black arrow possibly denotes the ...
Context 5
... ( Pandey and Callomon, 1995;Roy et al., 2007;Jain, 2014) and Europe (Westermann, 1958;Schlegelmilch, 1985), except Gracilisphinctes suprapana- tinus Arkell, 1951b, is not as wide as that in the Tibetan specimens. Collignon (1958) erected three new species of Gracilisphinctes from Madagascar: Gracilisphinctes arkelli (Col- lignon, 1958, pl. 6, Figs. 31-33), Gracilisphinctes lemoinei (pl. 7, Fig. 35) and Gracilisphinctes andranomantsyensis (pl. 7, Fig. ...
Context 6
... 2014) and Europe (Westermann, 1958;Schlegelmilch, 1985), except Gracilisphinctes suprapana- tinus Arkell, 1951b, is not as wide as that in the Tibetan specimens. Collignon (1958) erected three new species of Gracilisphinctes from Madagascar: Gracilisphinctes arkelli (Col- lignon, 1958, pl. 6, Figs. 31-33), Gracilisphinctes lemoinei (pl. 7, Fig. 35) and Gracilisphinctes andranomantsyensis (pl. 7, Fig. ...
Context 7
... 1985), except Gracilisphinctes suprapana- tinus Arkell, 1951b, is not as wide as that in the Tibetan specimens. Collignon (1958) erected three new species of Gracilisphinctes from Madagascar: Gracilisphinctes arkelli (Col- lignon, 1958, pl. 6, Figs. 31-33), Gracilisphinctes lemoinei (pl. 7, Fig. 35) and Gracilisphinctes andranomantsyensis (pl. 7, Fig. ...
Context 8
... response to changes of depositional environment during Middle Jurassic times, and that the bivalve succession adds little to the biostratigraphical framework, supposed from the Middle to Upper Jurassic of the region. The faunal succession in the Yanshiping section reflects facies changes rather than any major biostratigraphical differences (Fig. ...
Context 9
... Xueshan Formation overlying the Suowa Formation in the northern Qiangtang is known to yield Early Cretaceous palynofloras, Fig. 13. Jurassic bivalve succession in the Yangshiping section and ammonite levels in the Cuoriju and Changhonghe sections in northern Qiangtang. Choffatia recuperoi 118 60 50 22/24 18/20 24/32 20/27 26 1030, pl.7-1 85 40 47 26 30 29 34 25 1033, pl.7-4 85 43 50 22 25 23 27 ? 1032, pl.8-1; pl. 7-3 88 37 42 17 19 20 22 - 1034, pl.8-2 98 - 26 26 ...
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Citations
... Later, Yin (2016) shed doubts on this 'so-called' Tithonian assemblage, which is now impossible to revise. Yin (2016) infers that the only two specimens figured present a very poor preservation. ...
... Later, Yin (2016) shed doubts on this 'so-called' Tithonian assemblage, which is now impossible to revise. Yin (2016) infers that the only two specimens figured present a very poor preservation. Yin (2016) analyzed a second ammonite collection from the 114 Daoban section from the top of the Suowa Formation. ...
... Yin (2016) infers that the only two specimens figured present a very poor preservation. Yin (2016) analyzed a second ammonite collection from the 114 Daoban section from the top of the Suowa Formation. Such further study demonstrates that the Suowa Formation in southern Qiangtang is Middle rather than Late Jurassic in age (Yin 2005, Yin 2016) and, more precisely, Bathonian-Callovian in the Amdo area, northern Tibet. ...
... Fig. 8). Regardless of that these 'so-called' Tithonian and early Cretaceous ammonites have been reviewed with alternative conclusions (Yin 2005(Yin , 2010(Yin , 2016a, and Cope (2016) point out that the work on ammonites (Yin 2016a) is of great significance as it already demonstrates how important it is to examine ammonite faunas in any attempt to identify the age of the Bailongbinghe Formation. These misidentified fossils remain to be used to date the Bailongbinghe and Suowa Formations. ...
... Fig. 8). Regardless of that these 'so-called' Tithonian and early Cretaceous ammonites have been reviewed with alternative conclusions (Yin 2005(Yin , 2010(Yin , 2016a, and Cope (2016) point out that the work on ammonites (Yin 2016a) is of great significance as it already demonstrates how important it is to examine ammonite faunas in any attempt to identify the age of the Bailongbinghe Formation. These misidentified fossils remain to be used to date the Bailongbinghe and Suowa Formations. ...
... M. madagascariensis has been discussed at length by Callomon (1971). This species is recorded from the Bailongbinghe Formation of the Changhonghe section (Yin 2016a Arkell, 1950 Genus Planisphinctes Buckman, 1922 Type species Planisphinctes planilobus Buckman, 1922. Buckman, 1922Figure 4, c1-3, d1-3 1922 Planisphinctes planilobus nov. ...
Since oil shales in northern Qiangtang were found, the determination of the age of the Bailongbinghe Formation bearing the oil shales becomes particularly important economically. In general, the Jurassic rocks and fossils of northern Qiangtang demonstrate a vast shallow marine environment. Three sedimentary facies have been recognized, they are subtidal–lagoonal facies in the eastern area (e.g., the Yanshiping area), represented by siliciclastic depositional sequences, intercalated by two sets of calcareous deposition. The Jurassic rocks and fossils in the Bailongbinghe area demonstrate the shallow-water carbonate platform facies, in which ammonites, bivalves, brachiopods, corals and calcareous sponges, and patch reefs of oyster, are widely distributed, thus an open marine environment is implied. The oil shales, outcropping in a depression band near the northern margin of the middle rising ridge in the Bandaohu area, are considered as the restrict lagoonal facies. The Bailongbinghe Formation is subdivided into the Lower and Upper parts, the Lower Bailongbinghe Formation is capped by the oil shales of Bathonian to lower Oxfordian age, confirmed by brachiopods and bivalves. The Upper Bailongbinghe Formation has been regarded as upper Jurassic to lower Cretaceous age, consisting of evaporitic rocks with a considerable thickness. Two Jurassic marine–faunal dispersals are, respectively, recorded in lower Bathonian and lower Oxfordian strata. Occurrences of western Tethyan components such as Planisphinctes planilobus, Lobosphinctes intersertus, Procerites subprocerus, and P. cf. aurigera indicate a Bathonian eastward-dispersal. In the meanwhile, various species of Burmirhynchia attain a wide distribution over the northern Qiangtang region. The early Oxfordian transgressive in scale is considered smaller than the Bathonian one, represented only by bivalves, such as Radulopecten scarburgensis, R. variants, and Capillimya striata. Early Bathonian sea-level rise plays a significant role in the development of oil shales in the Bandaohu area. A depositional model of irregular-bottom topography is applicable to interpretation of the oil shales formation. The Himalayan Spiti shale fauna, utilized for age-evidence of the Bailongbinghe Formation, are mistaken and misunderstood. Cretaceous age of the Bailongbinghe Formation, derived from palynofossils and Re–Os dating is challenged by the present biostratigraphical succession in the light of facilitate accurate identification of Bailongbinghe fossils. Furthermore, so-called Barremian–Aptian negative excursions of carbon isotopes in the Bailongbinghe Formation is thereby questionable.
... These features suggest a carbonate platform-lagoon facies. Based on many bivalves, ammonites and dinoflagellates, the unit was proposed to be Callovian-Kimmeridgian (Middle-Late Jurassic) in age (Yang and Yin, 1988;Cheng and He, 2006;Yao et al., 2011;Yin, 2016). ...
The Jurassic subduction of the Bangong-Nujiang Tethys Ocean is recognized as a significant event in the geotectonic evolution of Tibetan Plateau. This study focuses on the Mesozoic ophiolites, magmatic rocks, sedimentary strata, and metamorphic features, and discusses their relationship with the evolution of the Bangong-Nujiang Ocean. Two stages of Jurassic northward subduction are identified. The first stage is represented by the Early Jurassic subduction of the Amdo-Jiayuqiao subterrane. Slab break-off triggered the Middle-Late Jurassic exhumation of the subducted subterrane as well as the eclogite and high-pressure granulite. This process promoted the initiation of the second stage subduction at the southern margin of the South Qiangtang and Amdo-Jiayuqiao subterranes. For the western-central Bangong-Nujiang Ocean, we interpret the second stage as flat or shallow angle subduction and suggested that it was triggered by break-off of the subducted slab. The Bangong-Nujiang Tethys Ocean experienced southward ocean-continent and intra-oceanic subduction in the eastern and central-western segments, respectively, which are represented by the Shiquanhe-Yongzhu-Jiali mélange zone. The western and central-eastern segments of the Shiquanhe-Yongzhu-Jiali oceanic basin represented an immature to mature back-arc basin. The Bangong-Nujiang Ocean experienced a complex subduction evolution during Jurassic. Both northward and southward subduction zones were initiated during Late Triassic perhaps in response to the closure of the Paleo-Tethys oceans to the south and north.
... A deep neritic depth has been considered as the habitat of Paraboliceras (Hasibuan 2010). The basins of eastern Gondwana, which record Para boli ceras, mainly show deeper water facies (e.g., Énay & Cariou 1997;Énay 2009;Hasibuan 2010), whereas from adjacent shallow epicontinental basins in Turkey, Iraq, Pakistan, Kachchh, Jaisalmer and Tibet (Énay & Mangold 1994;Cecca et al. 2005;Fürsich et al. 2013;Fürsich et al. 2020;Yin 2016;Pandey et al. 2014), with some exception of coarse-grained sediments in New Zealand and Antarctica (Enay & Cariou 1997), the genus is absent. Similarly, the dispersal of Paraboliceras towards the central and NW Tethys was terminated since the Central Tethys was a very shallow shelf occupied by Mediterranean ammonite taxa (Énay & Mangold 1994;Cecca 1999). ...
Paraboliceras is a widely distributed ammonite genus of the Indo-Pacific Realm recorded from the Spiti Himalaya to New Zealand. It has been recorded as an index fossil of Kimmeridgian strata in the Nepal Himalaya, but has also been recorded in the Tithonian strata of the Indian Himalaya. Paraboliceras evolved apparently in New Zealand from the Late Oxfordian Sulaites (Perisphinctinae). There are no records of Paraboliceras in the Central Tethys (Turkey and Iraq) and in the marginal seas of the southern Tethys, such as Pakistan, the Kachchh Rift Basin, the Jaisalmer Shelf Basin, and the East-African and Madagascan basins. The environmental factor, which restricted the migration of Paraboliceras, would have been depth. However, other endemic ammonites of the Indo-East African Faunal Province, such as Torquatisphinctes, Pachysphinctes, Katroliceras or Virgatosphinctes, were able to migrate within the faunal province. In the Spiti Shale Formation of the Spiti Valley, Paraboliceras ranges from Early to Late Tithonian. Paraboliceras jubar is the most common and widespread species, followed in terms of abundance by P. fascicostatum. Three more taxa, Paraboliceras sp. A, Paraboliceras sp. B, and Paraboliceras sp. C have been recorded from the Middle to Upper member of the formation (Early Tithonian) of the Demul section, which is the most promising locality for Paraboliceras.
... In the Gerze area, the Mesozoic sedimentary rock units on the southern Qiangtang subterrane include the Upper Triassic Riganpeico Formation, the Jurassic Sewa, Shaoqiaomu and Jiebuqu formations, and the Lower Cretaceous Meiriqieco Formation (Figs. 4 and 5) (Zeng et al., 2006). Regionally, some other units, such as the Lower Jurassic Quse Formation, Upper Jurassic Xiali and Suowa formations, Lower Cretaceous Xueshan Formation and Upper Cretaceous Abushan Formation, have also been reported on the southern Qiangtang subterrane (e.g., Wang et al., 2008b;Yin, 2016;Ma et al., 2017). However, these units are not exposed in the Gerze area (Zeng et al., 2006;Li et al., 2017bLi et al., , 2017d. ...
... Tethys (in Europe, Iran and Tibet; Mönnig, 2015;Seyed-Emami et al., 2015;Yin, 2016;respectively). 3. The association of Indonesian Macrocephalites cf. etheridgei (Spath) [m] with Kachchh Sivajiceras congener (Waagen) [M] is also noted in definite Middle Bathonian strata of the Kachchh basin (Western India). ...
The alleged Callovian–Kimmeridgian (Middle–Late Jurassic) ammonite–bearing strata of the Anole marl (Anole Formation) exposed in South Western Somalia are appraised and found to be of Middle Bathonian age. Of them, Macrocephalites cf. etheridgei (Spath) [m] is a typical Indonesian Middle Bathonian form, also reported in coeval strata from other Jurassic localities of Kachchh (Western India), Madagascar and Sula Island (Indonesia). The other ammonite, Sivajiceras congener (Waagen) [M], which also co–occurs with M. cf. etheridgei (Spath) and is restricted to the Bathonian, and also occurs in the Kachchh basin, thus, strengthening the present Bathonian age assignment. This new assigned age has a profound bearing not only on the stratigraphy of Somalia but also on the age implications of equivalent strata exposed in East Africa (particularly in Kenya, Ethiopia, and Yemen). Hence, a re–look at the East African biostratigraphy is urgently needed.
... We fully agree with Chen et al. (2018) that marine sedimentation in the Lhasa block extended to the early Cenomanian (~99 Ma), as indicated by foraminifera from the Langshan shallow-marine limestone (Boudagher-Fadel et al., 2017). However, there seem to be no marine strata younger than the Late Jurassic in the southern Qiangtang basin, where the Suowa Formation, representing the youngest marine lithostratigraphic unit in the southern Qiangtang basin, is Callovian in age (~164 Ma) according to ammonites Yin, 2016). In the Bangong-Nujiang suture zone, the Mugagangri Group mélange is overlain by the shallow-marine limestones and sandstones of the Shamuluo Formation, which were deposited during Late Jurassic time , as constrained by coral and foraminifera biostratigraphy and the U-Pb zircon age of porphyritic granitoid intrusions . ...
The Qiangtang Basin, located in the Tibetan Plateau, is an appropriate area to verify the Lhasa–Qiangtang collision, which was recorded by the middle-upper part of the Yanshiping Group (the Xiali and Suowa Fms) in the basin. However, the chronology of the Xiali and Suowa Fms is HYPERLINK “javascript:;” controversial, which limits comprehending the timing of the Lhasa–Qiangtang collision. More importantly, HYPERLINK “javascript:;” oil HYPERLINK “javascript:;” shale and salt springs were exposed in the Xiali and Suowa Fms in the basin. 544 paleomagnetic samples were collected from the Yanshiping section in the basin in order to reveal the timing of the Lhasa–Qiangtang collision from the view of paleomagnetic ages of the two formations. However, we did not give credible magnetostratigraphic ages of the two formations because of ammonite fossils, a global primary standard for the Jurassic strata correlation, without being found in the last study. Yin (2016) revised the long-term HYPERLINK “javascript:;” controversial paleontological age of the Suowa Fm. from a Tithonian age of the Late Jurassic or a Berriasian age of the Early Cretaceous, to a Middle Bathonian–Middle Callovian age of the Middle Jurassic based on new ammonite fossils. Considering ammonite fossils as a powerful tool and a global primary standard for the Jurassic strata correlation, we attempted to correlate the last magnetostratigraphy with the GPTS 2012 again. Magnetostratigraphic ages of 164.0–160.2 Ma and 160.2–156.8 Ma for the Xiali and Suowa Fms are suggested, respectively. The timing of the Lhasa–Qiangtang collision (156.8–154.9 Ma) is revealed from the magnetostratigraphic ages and the zircon U–Pb age of the Xueshan Fm, 154.9 (+6.8/−1.6) Ma, overlying the Suowa Fm in the Yanshiping section.
The timing of the Lhasa—Qiangtang collision is a major concern for the academic community. The Qiangtang Basin, located in the Tibetan Plateau, is an appropriate area to verify the Lhasa—Qiangtang collision, which was recorded by the middle-upper part of the Yanshiping Group (the Xiali and Suowa Fms) in the basin. However, the chronology of the Xiali and Suowa Fms is controversial, which limits comprehending the timing of the Lhasa—Qiangtang collision. In total, 544 paleomagnetic samples were collected from the Yanshiping section in the basin to draw the two formations’ paleomagnetic ages. Paleomagnetic and rock magnetic measurements were performed, including isothermal remanent magnetization (IRM) analysis, three-component IRM thermal demagnetization, M—T analysis, thermal demagnetizations, and alternating field demagnetizations, to recognize the primary magnetic minerals and their grain sizes and concentrations. Finally, the leading magnetization carriers (magnetite and hematite) are extracted in the Xiali and Suowa Fms. The shallow bias in paleomagnetic inclinations is revised using elongation/inclination, yielding 13.7° and 15.9° of inclination shallowing of the Xiali and Suowa Fms, respectively. This study used 299 clear characteristic remanent magnetization directions to construct magnetostratigraphy. However, we did not give credible magnetostratigraphic ages of the two formations because of ammonite fossils, a global primary standard for the Jurassic strata correlation, without being found in the last study. Recently, Yin (2016) revised the long-term controversial paleontological age of the Suowa Fm. from a Tithonian age of the Late Jurassic or a Berriasian age of the Early Cretaceous, to a Middle Bathonian—Middle Callovian age of the Middle Jurassic based on new ammonite fossils. Considering ammonite fossils as a powerful tool and a global primary standard for the Jurassic strata correlation, we attempted to correlate the last magnetostratigraphy with the GPTS 2012 again. Magnetostratigraphic ages of 164.0–160.2 Ma and 160.2–156.8 Ma for the Xiali and Suowa Fms are suggested, respectively. The timing of the Lhasa—Qiangtang collision (156.8–154.9 Ma) is revealed from the magnetostratigraphic ages and the zircon U—Pb age of the Xueshan Fm, 154.9 (+6.8/−1.6) Ma, overlying the Suowa Fm in the Yanshiping section.
An integrated approach based on organic petrographic and geochemical proxies along with palynological and palynofacies analysis were employed using 24 rock samples representing the upper part of the Quse and Sewa formations in the southern Qiangtang Basin, Tibetan Plateau, SW China. This interval was deposited during the Early Jurassic Toarcian Oceanic Anoxic Event (T-OAE) and is investigated to assess the biostratigraphic age control based on palynomorphs composition. The current approach allows for the interpretation of the local paleoenvironmental response to T-OAE climate variability that still unraveled based on palynofacies analysis of the Bilong co succession. Visual palynofacies analysis, vitrinite reflectance (VRo), and total organic carbon (TOC)/Rock-Eval pyrolysis parameters enables a detailed assessment of probable source rock characterization.
The palynomorph content comprises mainly terrestrially-derived land-plants, mostly sphaeromorphs pollen grains, with minor content of marine dinoflagellate cysts (dinocysts). Marker dinocysts and pollen taxa allow the subdivision of the studied succession into two age-distinctive units of early Toarcian and late Bajocian-Bathonian. Additionally, carbon isotope profile of the studied succession observed a large negative carbon isotope excursion (CIE) within the lower Toarcian oil shale interval, which is compatible with regional δ13Corg records from adjacent basins at this time. The regional TOC contents of lower Toarcian reached up to 21 wt% in areas of the eastern Tethys compared to lower values in the western Tethys and Boreal (ca. 3 wt%). Two palynofacies assemblages revealed deposition of these deposits in distal inner neritic to fluvio-deltaic environment and to some extent in brackish marginal marine setting. Geochemical screening indicated that most samples were dominated by very good to excellent organic matter richness of kerogen Type II and mixed Type II/III with very good to excellent hydrocarbon generation. The calculated VRo-eq from Rock-Eval Tmax and measured VRo values are in good agreement and showed that the organic matter of the studied interval is in the early to middle stages of the oil window.
