published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

This thesis deals with the stratigraphy and brachiopod systematic palaeontology of the latest Devonian (Famennian) to Early Permian (Kungurian) sedimentary sequences of the Tarim Basin, NW China. Brachiopod faunas of latest Devonian and Carboniferous age have been published or currently in press in the course of the Ph.D candidature and are herein appendixed, while the Early Permian brachiopod faunas are systematically described in this thesis. The described Early Permian brachiopod faunas include 127 species, of which 29 are new and 12 indeterminate, and six new genera (subgenera) are proposed; Tarimella, Bmntonella, Marginifera (Arenaria), Marginifera (Nesiotia), Baliqliqia and Ustritskia. A new integrated brachiopod biostratigraphical zonation scheme is proposed, for the first time, for the latest Devonian-Early Permian sequences of the entire Tarim Basin on the basis of this study as well as previously published information (including the Candidate's own published papers). The scheme consists of twenty three brachiopod acm biozones, most of which replace previously proposed assemblage or assemblage zones. The age and distribution of these brachiopod zones within the Tarim Basin and their relationships with other important fossil groups are discussed. In terms of regional correlations and biostratigraphical affinities, the Late Devonian to Early Carboniferous brachiopod faunas of the Tarim Basin are closest to those from South China, while the Late Carboniferous faunas demonstrate strong similarities to coeval faunas from the Urals, central Asia, North China and South China. During the Asselian-Sakmarian, strong faunal links between the Tarim Basin and those of the Urals persisted, while at the same time links with central Asia, North China and South China weakened. On the other hand, during the Artinskian-Kungurian times, affinities of the Tarim faunas with the Urals/Russian Platform rapidly reduced, when those with peri-Gondwana (South Thailand, northern Tibet) and South China increased. Thirty lithofacies (or microfacies) types of four facies associations are recognised for the Late Devonian to early Permian sediments. Based on detailed lithostratigraphy, biostratigraphy and facies analysis, 23 third-order sequences belonging to four supcrsequences are identified for the Late Devonian to Early Permian successions, from which sea-level fluctuation curves are reconstructed. The sequence stratigraphical analysis reveals that four major regional regressions, each marking a distinct supersequence boundary, can be recognised; they correspond to the end-Serpukhovian, end-Moscovian, late Artinskian and end-Kungurian times, respectively. The development of these sequences is considered to have been formed and regulated by the interplay of both eustasy and tectonism. Using the system tract of a sequence as the mapping time unit, a succession of 47 palaeogeographical maps have been reconstructed through the Late Devonian to Early Permian. These maps reveal that the Tarim Basin was first immersed by southwest-directed (Recent geographical orientation) transgression in the late Famennian after the Caledonian Orogeny. Since then, the basin had maintained its geometry as a large, southwest-mouthed embayment until the late Moscovian when most areas were the uplifted above sea-level. The basin was flooded again in late Asselian-Artinskian times when a new transgression came from a large epicontinental sea lying to its northwest. Thereafter, marine deposition was restricted to local areas (southwestern and northwestern margins until the late Kungurian, while deposition of continental deposits prevailed and continued through the Middle and late Permian into the Triassic.

This study focuses on the burial practices in the Bronze Age Xiaohe-Gumugou cemeteries, north-west China, in order to understand how people constructed their social identities and delivered the social cognitions through generations. The Xiaohe-Gumugou cemeteries, as the main sites of the Xiaohe cultural horizon, have central roles for the understanding of the formation of the Bronze Age cultural groups and the cultural interactions between the west and the east in the Tarim Basin. However, current research is lacking in-depth examinations of the material culture of the cemeteries, and the contexts of the surrounding archaeological cultures in a timespan from Bronze Age to Iron Age. Through detailed comparisons of the construction of coffins and monuments, the dress of the dead, and the burial goods assemblages, this study provides an overview of the social structural development, from the Gumugou group’s heterogenous condition to the Xiaohe group’s homogeneous and mature state. Also, through relating to the results of biological and osteological analyses, and applying geographical analyses to the material, this study suggests that the early settlers in the Tarim Basin, the Xiaohe-Gumugou people have created their own social identities. Although the Xiaohe-Gumugou people might have migrated from southern Siberia or Central Asia, the archaeological material shows indications of their own typical features. When newcomers joined the society, the local burial customs were accepted and applied in a new cultural setting. / Denna studie fokuserar på gravskick på gravfälten Xiaohe och Gumugou i nordvästra Kina, för att förstå hur människor konstruerade social identitet och överförde kulturella föreställningar mellan generationer. Xiaohe-Gumugou-gravfälten, som de viktigaste platserna i Xiaohe-kulturhorisonten, är centrala för förståelsen av bildandet av bronsålderns kulturgrupper och de kulturella växelverkningarna mellan väst och öst i Tarimbäckenet. Tidigare forskning saknar fördjupade undersökningar av gravfältens materiella kultur samt den historiska kontexten med de omgivande arkeologiska kulturerna under tidsperioden från bronsålder till järnålder. Genom detaljerade jämförelser av konstruktionen av kistor och monument samt de dödas klädsel och gravgåvor, ger denna studie en översikt över utvecklingen av sociala strukturer, från Gumugou-gruppens heterogena situation till Xiaohe-gruppens homogena och mogna tillstånd. Genom att relatera till resultaten från biologiska och osteologiska analyser och tillämpa geografiska analyser på materialet, tyder den här studien på att de tidiga bosättarna i Tarimbäckenet, Xiaohe-Gumugou-folket, har utvecklat egna sociala identiteter. Trots att Xiaohe-Gumugou-folket kan ha migrerat från södra Sibirien eller Centralasien visar det arkeologiska materialet indikationer på egna typiska egenskaper. När nykomlingar anslöt till samhället accepterades de lokala begravningssederna och tillämpades i ett nytt kulturellt sammanhang.

Deux questions scientifiques critiques sont adressées dans cette thèse présentées comme suit. ( 1 ) L’évolution mésozoïque du bassin d’avant-pays dans les piémonts nord et sud du Tian Shan. ( 2 ) L’évolution au Cénozoïque précoce du soulèvement du Tian Shan. Dans le chapitre 1, l'évolution du nord Tian Shan est étudiée par datation U/Pb (LA- ICP-MS) de zircons détritiques sur 14 échantillons de grès d'une série continue d’âge fin Paléozoïque à Quaternaire dans la marge sud du bassin de Junggar (région de Manasi). Dans le chapitre 2, l'évolution encore mal contrainte entre le Mésozoïque et le début du Cénozoïque de la marge sud-ouest du Tian Shan est étudiée en utilisant les datations U/Pb ( LA- ICP-MS ) sur zircons détritiques et les traces de fission sur apatites détritiques. Dans le chapitre 3, nous présentons une étude magnétostratigraphique détaillée de la zone Ulugqat au sud-ouest du Tian Shan, dans le but d'améliorer la compréhension de son soulèvement et de l'histoire de la déformation de la région au cours du Cénozoïque. Ce travail à permis de montrer que l'érosion du paléo-Tian Shan commencée au Trias moyen s’est traduite par le pénéplanation générale au Mésozoïque du Tian Shan qui était dominé par un système de drainage large pendant une longue période de quiescence tectonique. Le piémont nord du Tian Shan était caractérisé par un bassin en subsidence thermique post- extensive avec peu d'activité tectonique, et le piémont sud a également connu un aplanissement général de la topographie. Au cours du début du Jurassique, du Crétacé inférieur et du Crétacé supérieur, trois inversions tectoniques mineures sont identifiées avec des ajustements du bassin d’avant-pays du Tian Shan. Ces inversions peuvent correspondre respectivement à l’accrétion des terrains Cimmérien, de Lhassa, et du Kohistan-Dras à la limite sud de la plaque eurasienne. Les données U-Pb sur zircons détritiques et les données traces de fission sur apatite indiquent une première réorganisation du bassin à la fin du Crétacé – début du tertiaire, contemporaine d’une réactivation de l’érosion le long du piémont sud du Tian Shan. Nous avons interprété cette réactivation fin Crétacé – début Paléogène du Tian Shan sud à la réponse initiale des effets lointains de la collision Inde-Eurasie. Pendant le reste du Cénozoïque, la principale réactivation du Tian Shan est initiée fin Oligocène – début Miocène. Cela est attesté dans le piémont nord du Tian Shan par nos données U-Pb sur zircons détritiques et dans le piémont sud du Tian Shan par les données traces de fission sur apatite suggérant des chevauchements entre 18 et 16 Ma, par les résultats magnétostratigraphiques révélant une importante lacune de sédimentation oligocène ainsi que l’augmentation des taux d’accumulation à ~ 18.5 Ma. / Two critical scientific issues are adressed in the présent thesis as follows. (1) Mesozoic basin-range relationship in the northern and southern piedmonts of the Tian Shan. (2) Spatio-temporal differences in the Early Cenozoic uplift of the Tian Shan. In chapter 1, the évolution of the northern Tian Shan is investigated through U/Pb (LA-ICP-MS) dating of detrital zircons from 14 sandstone samples from a continuous series ranging in age from latest Palaeozoic to Quaternary in the southern margin of the Junggar Basin (Manasi area). In chapter 2, the still poorly constrained Mezosoic to early Cenozoic evolution of the southwestern Tian Shan piedmont is investigated using U/Pb (LA-ICP-MS) dating of detrital zircons and fission track analysis on detrital apatites. In chapter 3, we present a detailed magnetostratigraphic study from the Ulugqat area in piedmont of the Southwest Tian Shan, in order to improve understanding of the uplift and deformation history of the Southwest Tian Shan during the Cenozoic. This work enabled to show that erosion of the Paleo-Tian Shan initiated in the Middle Triassic results in the general peneplanation of the Mesozoic Tian Shan dominated by a wide drainage system and long-lasting tectonic quiescence. The northern piedmont of the Tian Shan was characterized by a post-extensional thermally subsiding basin without much tectonic activity, and the southern piedmont also experienced a general flattening of topography. During the Early Jurassic, Early Cretaceous and Late Cretaceous, three identified minor tectonic inversions and adjustments of basin-range pattern in the Tian Shan, may potentially correspond respectively to the accretions of Cimmerian, Lhasa, and Kohistan-Dras in the southern margin of the Eurasian plate. Detrital zircon U-Pb and apatite fission-track data indicate an initial late Cretaceous – Early Tertiary basin reorganization and coeval renewed erosion along the southern Tian Shan piedmont. We interpreted this late Cretacesou to Paleogene activity in STS as the initial response of the distant effects of India-Eurasia collision as previously argued. During the Late Cenozoic, the major reactivation of the Tian Shan initiated around the Late Oligocene-Early Miocene times. This is evidenced mainly from the detrital zircon U-Pb geochronology in the northern piedmont of the Tian Shan, the apatite fission-track data suggesting a possible activation of the Talas Fergana Fault between 18 and 16 Ma, the major Oligocene depositional hiatus and conspicuous increase in accumulation rates at ~ 18.5 Ma revealed by the magnetostratigraphic results in the southern piedmont of the Tian Shan.