Search results for "South china"
showing 10 items of 13 documents
GIGJ: a crustal gravity model of the Guangdong Province for predicting the geoneutrino signal at the JUNO experiment
2019
Gravimetric methods are expected to play a decisive role in geophysical modeling of the regional crustal structure applied to geoneutrino studies. GIGJ (GOCE Inversion for Geoneutrinos at JUNO) is a 3D numerical model constituted by ~46 x 10$^{3}$ voxels of 50 x 50 x 0.1 km, built by inverting gravimetric data over the 6{\deg} x 4{\deg} area centered at the Jiangmen Underground Neutrino Observatory (JUNO) experiment, currently under construction in the Guangdong Province (China). The a-priori modeling is based on the adoption of deep seismic sounding profiles, receiver functions, teleseismic P-wave velocity models and Moho depth maps, according to their own accuracy and spatial resolution. …
Diagenesis of clay minerals and K-bentonites in Late Permian/Early Triassic sediments of the Sichuan Basin (Chaotian section, Central China).
2014
10 pages; International audience; Detailed clay mineralogical analyses were carried out on Late Permian/Early Triassic carbonate sediments exposed on the Chaotian section (Sichuan Basin, Central China). The clay assemblages are dominantly composed of illite in platform carbonates and clay seams, and illite-smectite mixed-layers (I/S) in tuff layers (K-bentonites) intercalated in the carbonate succession. Detrital and authigenic volcanogenic clay minerals have been partially replaced through illitisation processes during burial, raising questions about diagenetic effects. The precise determination of I/S occurring in K-bentonites shows that the sediments reached a temperature of about 180 °C…
Griesbachian and Dienerian (Early Triassic) ammonoid faunas from Northwestern Guangxi and Southern Guizhou (South China).
2008
30 pages; International audience; Intensive sampling of the Luolou (northwestern Guangxi) and the Daye (southern Guizhou) Formations in South China leads to the recognition of a regional Griesbachian and Dienerian ammonoid succession for this key palaeobiogeographical area. The new biostratigraphical sequence comprises the upper Griesbachian ‘Ophiceras beds' and the lower Dienerian ‘Proptychites candidus beds', which are separated from the uppermost Dienerian ‘Clypites beds' by an unfossiliferous interval. These faunas contain some taxa with wide geographic distribution (e.g. Ambites, Pleurambites, Pleurogyronites, Proptychites candidus), thus facilitating correlation with faunal succession…
Guodunites, a low-palaeolatitude and trans-panthalassic Smithian (Early Triassic) ammonoid genus
2009
11 pages; International audience; Based on new, bed-rock controlled material from Oman and Utah, USA, the Early Triassic genus Guodunites, which was recently erected on the basis of scarce specimens from northwestern Guangxi, South China, is now shown to be a representative of Proptychitidae. This solves the question of the previously unknown phylogenetic affinity of this genus. The genus is restricted to the late middle Smithian, and to date, its biogeographical distribution comprises Oman, South China and Utah, thus indicating an essentially low palaeolatitudinal distribution during the Early Triassic. Its palaeobiogeographical distribution further strengthens the existence of significant…
Early Triassic conodont clusters from South China: revision of the architecture of the 15 element apparatuses of the superfamily Gondolelloidea
2012
Several fused clusters of conodont elements of the genera Neospathodus and Novispathodus were recovered from limestone beds at the Dienerian-Smithian and Smithi- an-Spathian boundaries, respectively, from several localities in Guangxi province, South China. Conodont clusters are otherwise extremely rare in the Triassic, and these are first described for the Early Triassic. The exceptional specimens partially preserve the relative three-dimensional position and orientation of ramiform elements and are therefore extremely important for testing hypotheses on the architecture of appa- ratuses. These specimens partly confirm the previous recon- struction of the Novispathodus apparatus by Orchard…
Conodont biostratigraphy of the Yujiang Formation (Emsian, Lower Devonian) at Shizhou, Guangxi, South China
2018
Abstract We study conodonts from the upper part of the Shizhou Member of the Yujiang Formation in Liujing area for the first time. Relatively abundant conodonts were collected from six sampling levels located between the uppermost part of the Shizhou Member to the lowermost part of the Daliancun Member at the Shizhou section, Liujing, Guangxi. The material includes Polygnathus excavatus excavatus Carls and Gandl, P. excavatus ssp. 114 Carls and Valenzuela-Rios, P. nothoperbonus Mawson, P. perbonus (Philip) as well as “ Ozarkodina ” midundenta (Wang and Ziegler) and “ O. ” prolata Mawson. The lowest record of P. nothoperbonus is documented 0.35 m below the boundary between the Shizhou and Da…
Globacrochordiceras gen. nov. (Acrochordiceratidae, late Early Triassic) and its significance for stress-induced evolutionary jumps in ammonoid linea…
2013
<i>Globacrochordiceras transpacificum</i> gen. et sp. nov. is an ammonoid (Ammonoidea, Cephalopoda) with a shell characterized by plicate ribbing (rounded and undulating ribs strengthening on the venter without interruption), increasing involution through ontogeny, overhanging and deep umbilical wall, absence of tuberculation, subtriangular whorl section, globose adult shape with a closed umbilicus followed by an abrupt egressive coiling, and a subammonitic adult suture line. This new taxon occurs in Nevada (USA) and in Guangxi (South China). It has its typical occurrence within the <i>Neopopanoceras haugi</i> Zone of late Spathian age (Early Triassic). The plicate r…
Biostratigraphy of Triassic Ammonoids
2015
The Triassic is a turning point in the evolutionary history of ammonoids, characterized by the flourishing Ceratitida and the appearance of the first heteromorphs. Following the end-Permian mass extinction, ammonoids were among the first groups to rediversify by producing many new taxa. Already in the late nineteenth century, the still currently recognized Triassic stages and substages were introduced. The historical development of Triassic ammonoid biostratigraphy is a good example of worldwide cooperation between many geographically-diverse research groups, which initially began in Germany and the European Alps. This cooperation was then extended to North America, Transcaucasia, North Ind…
Ordovician echinoderms from the Tabas and Damghan regions, Iran: palaeobiogeographical implications
2005
Abstract Two echinoderm assemblages are described in the Middle Ordovician of Iran (Darriwilian). The Simeh Kuh section (Damghan area, eastern Alborz range) has yielded a rich and diverse blastozoan fauna consisting of fistuliporite (Echinosphaerites, Heliocrinites) and dichoporite rhombiferans (cheirocrinids indet., hemicosmitids indet.), as well as aristocystitid (Sinocystis) and sphaeronitid diploporites (Glyptosphaerites, Tholocystis). Heliocrinites, cheirocrinids, hemicosmitids, Glyptosphaerites, and Tholocystis are reported for the first time in the Ordovician of Iran. A less diverse assemblage was collected in the Shirgesht section (Tabas area, Derenjal Mountains), and represents the…
Polygnathids (Conodonta) around the Pragian/Emsian boundary from the Dacun-1 section (central Guangxi, South China)
2019
AbstractThe base of the Emsian, which is defined by the first appearance of the conodont Polygnathus kitabicus, has never been successfully demonstrated in the South China Block (including Guangxi and eastern Yunnan). As a result, we studied conodonts from the lowermost part of the Shizhou Member of the Yukiang Formation at the Dacun-1 section in the Liujing area, Guangxi. This new investigation has revealed a conodont fauna only consisting of Polygnathus pireneae, P. sokolovi, P. kitabicus, P. sp. and Pandorinellina exigua philipi, which can be assigned to the uppermost part of the pireneae Zone and the lowermost part of the kitabicus Zone in ascending order. The Pragian/Emsian boundary at…