Les érymides sont des crustacés décapodes marins ayant une morphologie comparable à celle des homards actuels. Ils sont regroupés au sein d’une unique famille, les Erymidae Van Straelen, 1925, caractérisée par la présence d’une plaque intercalaire dorsale. Ces crustacés sont présents dès la fin du Permien. Ils se sont diversifiés et répandus dans le monde entier au Jurassique et ont perduré jusqu’au Paléocène. Ils sont particulièrement abondants au Jurassique, fossilisés dans des dépôts issus d’environnements variés : de faible profondeur – comme les calcaires lithographiques de Solnhofen (Allemagne) –, très profonds – comme La Voulte (France) –, ou encore dans différents milieux de plate-forme – comme le Terrain à Chailles (France). Depuis les premières descriptions d’érymides, au début du XIXe siècle, de nombreux auteurs se sont attachés à décrire de nouvelles formes et à tenter d’élucider les affinités phylogénétiques de ces crustacés éteints. Ces nombreux travaux ont abouti à l’installation et à la propagation de confusions rendant douteuse la systématique des érymides tant au niveau des genres que des espèces. Ces problèmes taxinomiques particulièrement marqués chez les érymides — on parle d’ailleurs de « problème érymidien » — sont accompagnés d’un débat sur leur classification au sein des Pleocyemata. Jusqu’au début du XXIe siècle, la majorité des auteurs les classaient dans l’infraordre des Astacidea mais de récentes analyses phylogénétiques suggèrent l’intégration des érymides au sein des Glypheidea. Une autre étude a même abouti à la remise en cause du statut éteint des érymides. En effet, Schram & Dixon (2004) ont observé la plaque intercalaire sur l’actuel Enoplometopus A. Milne Edwards, 1862. Leur analyse a ensuite conduit au regroupement de cette forme actuelle avec les érymides au sein d’un même clade nommé Erymida. Les objectifs de cette thèse sont donc de remédier aux problèmes taxinomiques des érymides, d’élucider leurs affinités phylogénétiques et d’apporter des éléments permettant de mieux comprendre leur mode de vie et leur succès évolutif. Pour ce faire, une révision systématique aussi exhaustive que possible, appuyée sur l’étude de plus d’un millier de spécimens, a été réalisée. Elle a permis d’homogénéiser la description des 6 genres et des 75 espèces reconnues et d’identifier les caractères nécessaires à l’étude phylogénétique. L’arbre obtenu montre clairement que les érymides constituent un groupe particulier d’Astacidea auquel Enoplometopus n’appartient pas. De plus, la topologie de l’arbre de strict consensus soutient une refondation complète de la systématique du groupe. D’une unique famille, les érymides se retrouvent désormais répartis dans deux familles, distinguées par la présence/absence de la zone post-orbitaire : les Enoploclytidae n. fam. et les Erymidae. Cette dernière est d’ailleurs elle-même divisée en sous-familles, Eryminae Van Straelen, 1925 et Tethysastacinae n. s.–fam., en raison de l’architecture très simple des sillons de la carapace de Tethysastacus Devillez et al., 2016 comparée à celle des autres genres. Cette étude a aussi été l’occasion de formuler des hypothèses paléobiogéographiques qui demeurent, hélas, en grande partie spéculatives et incomplètes du fait des importantes discontinuités géographiques et stratigraphiques du registre fossile. Les observations de stades larvaires, des yeux, de la morphologie des pinces, de pores cuticulaires et de la variabilité intraspécifique chez certains spécimens ont également permis, en s’appuyant sur les formes actuelles, d’émettre des hypothèses sur le mode de vie de ces crustacés disparus. Enfin, la grande tolérance environnementale déduite des différentes formations géologiques ayant livré des érymides fossiles est probablement une des clés de leur succès au Mésozoïque et soulève la question des raisons de leur extinction. / Erymids are marine decapod crustaceans with a morphology close to that of extant lobsters. They are grouped within an unique family, Erymidae Van Straelen, 1925, based on the presence of a characteristic intercalated plate. These crustaceans were already present in the Permian, have become diversified and widespread during the Jurassic and have lasted until the Paleocene. The erymids are abundant during the Jurassic. They fossilized in deposits from various paleoenvironments: shallow water environments – like lithographic limestones from Solnhofen (Germany) –, from deep environments – like in La Voulte (France) –, and also from different platform environments – like the Terrain à Chailles (France). Since the first descriptions of erymids in the first part of the XIXth century, numerous authors have described new species and have attempted to establish the phylogenetic affinities of these extinct crustaceans. This high number of studies resulted with the apparition and propagation of confusions. So, the systematics of the erymids has become doubtful at both generic and specific levels. These taxonomic problems strongly affecting the erymids — the so called « erymidian problem » — are increased by their uncertain phylogenetic relationships among the Pleocyemata. Until the XXIst century, most of the authors classified the erymids within the infraorder Astacidea but recent phylogenetic analyses suggest an integration within Glypheidea. Moreover, a study has led to question the extinct status of the erymids. Indeed, Schram & Dixon (2004) have observed an intercalated plate in the extant Enoplometopus A. Milne Edwards, 1862. Their analysis has resulted with the clustering of this extant lobster together with the erymids within a same clade named Erymida. So, the purposes of this thesis are to rectify the taxonomic problems of the erymids, to elucidate their phylogenetic affinities and to provide observations which enable a better comprehension of their lifestyles and their evolutionary success. To reach these goals, a systematic review, supported by the examination of more than a thousand specimens, has been done. It has resulted in a homogenisation of the descriptions of the 6 genera and 75 species herein recognized and in the identification of useful characters for the phylogenetic study. The phylogenetic tree obtained clearly shows that erymids form a particular group of Astacidea and that Enoplometopus does not belong to this group. Moreover, the topology of the strict consensus tree supports a new systematic building of the group. From a unique family, the erymids are now spread into two families supported by the absence/presence of a post-orbital area: Enoploclytidae n. fam. and Erymidae. The last is also divided in subfamilies, Eryminae Van Straelen, 1925 and Tethysastacinae n. s.-fam., based on the very simple carapace groove pattern of Tethysastacus Devillez et al., 2016. This new study on the erymids was also an occasion to provide some paleobiogeographic hypotheses. But, unfortunately, they remain speculative and incomplete due to geographic and stratigraphic discontinuities of the fossil record. Observations of larval stages, of eyes, of P1 chela morphologies, of cuticular pores, and of intraspecific variability on some specimens have also enabled comparisons with extant forms. These observations led to provide hypotheses on the lifestyle of these extinct lobsters. Finally, the strong environmental tolerance was probably one of the keys of the success of the erymids during the Mesozoic but raised interrogations about the reasons of their extinction.

La ceinture orogénique de Longmenshan (LMTB) constitue la frontière orientale du plateau tibétain, qui est reconnue par sa topographie escarpée, son activité tectonique intensive ainsi ses la complexité de ses structures. Comme une orogène typique, le LMTB a subi une forte déformation intracontinentale au cours du Mésozoïque. Ainsi, la connaissance sur l’évolution tectonique du Mésozoïque de la LMTB est cruciale pour comprendre l’orogenèse intracontinentale et la surrection du plateau tibétain. Une ceinture de clivage verticaux divise la LMTB en une zone occidentale et une orientale. La Zone orientale présente un top-to-SE cisaillement tandis que la zone occidentale présente un top-to-NW cisaillement. La zone orientale peut être subdivisée en quatre sous-unités avec de foliations orientées du SE au NW. Le granite syntectonique et les données géochronologiques contraignent cette déformation principale au Mésozoïque inférieur (environ 219 Ma). L’analyse structurale, l’AMS, l’étude microstructurale et la modélisation gravimétrique sur le complexe de Pengguan, l’un des complexes de l’orogène néoprotérozoïques au milieu de segment de la LMTB), révèlent une structure des slices du socle imbriquées de la LMTB et la zone adjacente. Les âges connus, l’exhumation rapide localisée et la subsidence du bassin flextual suggèrent que les slices du socle sont imbriquées au cours du Mésozoïque supérieur (166-120 Ma). La LMTB se trouve loin de la limite de la plaque contemporaine, et est absence de matériel ophiolitique, donc elle peut être considéré comme une orogène intracontinentale. Pendant le début du Mésozoïque, le Yangtze plate subductait vers l’ouest en fermant l’océan paléo-Téthys. Cette tectonique a exhumé des matériaux de différentes profondeurs en surface par des chevauchements vers le SE et chevauchements arrières vers le NW. Au cours de la fin du Mésozoïque, le socle a été soulevé davantage en raison de la collision entre les blocs de Lhasa et de l’Eurasie, qui a conduit à une imbrication des slices du socle et épaissi la croûte. / The Longmenshan Thrust Belt (LMTB), constituting the eastern boundary of the Tibetan Plateau, is well known by its steep topography, intensive tectonic activities and the complicated structures. As a typical composite orogen, the LMTB experienced extensive intracontinental deformation during the Mesozoic. The knowledge on the Mesozoic tectonic evolution of the LMTB therefore is crucial to understand the intracontinental orogeny and uplifting of the Plateau. The vertical cleavage belt divides the LMTB into a Western Zone and an Eastern Zone. The Eastern Zone displays a top-to-the-SE shearing while the western zone a top-to-the-NW shearing. The Eastern Zone can be further divided into four subunits with foliations deepening from SE to NW. The syntectonic granite and published geochronologic data constrain this main deformation to the Early Mesozoic around 219 Ma. Structural analysis, AMS and microstructural study and gravity modeling on the Pengguan complex, one of the orogen-parallel Neoproterozoic complexes located in the middle segment of the LMTB, reveal a basement-slice imbricated structure of the LMTB and adjacent areas. Published ages, localized fast exhumation rate and flexural subsidence of the foreland basin suggest that the basement-slices imbricated southeastwards during Late Mesozoic (166-120 Ma). The LMTB is far away from the contemporaneous plate boundary and devoid of ophiolite-related material, therefore, it is supposed to be an intracontinental orogen. During the Early Mesozoic, the Yangtze basement underthrusted westwards due to the far-field effect of the Paleo-Tethys’ obliteration, and the materials in different structural levels have been exhumated to the surface by southeastward thrusting and contemporaneous backward thrusting. During the Late Mesozoic, the basement is further underthrusted due to the collision between the Lhasa and Eurasia blocks, which led to SE-ward imbrication of the basementslices that may thicken the crust.

Graduation date: 1994

No description available.

In north-central Arizona, the Moenkopi Formation of Triassic age consists of generally unfossiliferous red mudstones, siltstones, gypsum, and sandstones that contain abundant sedimentary structures, such as ripple marks, cross-stratification, ripple laminae, salt crystal casts, mud cracks, sole marks, parting lineation, and core-and-shell structures. Three informal members were established for this study: the lower member, the lower massive sandstone, and the upper member. Flaser, wavy, and lenticular bedding, bimodal distribution of ripple laminae dips, parallel ripple marks dominant over cuspate ripple marks, gypsum beds and veins, salt crystal casts, and lack of channel deposits are the suite of sedimentary features that are interpreted to indicate a tidal-flat environment during deposition of the lower member. The very fine grained lower massive sandstone can be divided into four subunits, which were formed by a transgression-regression of the sea. Wavy and ripple laminated beds in subunit one were probably deposited in very shallow water. Medium-scale wedge-planar and trough sets of cross strata with mean dip directions to the southeast make up subunit 2 and indicate megaripples formed by longshore drift. Subunit 3 consists of lenticular, wavy, pod-shaped beds that were created in water shallower than that for subunit 2. Continuous, large-scale, low-angle cross strata of uniform thickness and medium-scale wedge-planar and trough sets of cross strata characterize subunit 4 and are typical of beach deposits. The significant sedimentary features in the upper member are unimodal distribution of ripple laminae dips, cuspate ripple marks dominant over parallel ripple marks, channel deposits with shallow trough cross strata, an increase in the number and thickness of sandstone and siltstone beds compared with the lower member, plus vertebrate bones, tracks, and plant impressions. This suite of features indicates a flood-plain environment. Early in Moenkopi time, north-central Arizona was a tidal flat and sabkha. The sea to the west fluctuated east and west and finally transgressed over the entire area. As the sea regressed, a beach formed, and rivers flowing from the east deposited sediment on a westward-prograding flood plain. In the northern, southern, and central portions of the region, sabkhas existed for a time during regression. At the end of Moenkopi time, the entire area was a flood plain. Considering the association of red beds and evaporites, the absence of fossils in the lower member and the lower massive sandstone, the paleowind directions, and the theory of continental drift, the climate during early and middle Moenkopi time was probably hot and arid. The influx of sandstones, the presence of Calamites (?) impressions, and trackways and bones of amphibians in the upper member suggest that the climate became more humid at the end of Moenkopi time.

The stratigraphy and sedimentology of Mesozoic carbonate platform-margins cropping out in southern Italy are investigated. New strati graphic data are presented from northern and eastern slopes of the Apennine carbonate platform, based on locallycorrelated field sections. Thin-section petrography is used to demonstrate the spatial and temporal distribution of derived lithoclasts. Results indicate that southern Apennine platforms underwent repeated erosion during Cretaceous time and possible reasons for this are discussed. Petrographic studies also provided outline sediment parageneses for slopes and platforms, with special reference to the detailed geochemistry of secondary dolomite formation on the eastern margin of the Apulian platform, whose growth is indicated by proton microprobe microanalysis to have been influenced by redox changes. The sedimentary facies and sediment geometries of Upper Cretaceous to Lower Tertiary slope sediments mapped in the Frosolone area are discussed in a case-study. Cross-sections showing geometries of key beds are presented, and depositional controls are discussed. Outcrop data suggest an Early to Middle Jurassic age of basin formation of this sector of the Lagonegro-Molise basin. A further case study from the Mesozoic slope in the Gran Sasso shows sediment geometries at reflection seismic scale, and relates them to possible depositional control by relative sea-level fluctuations. Finally, data from southern Apennine platforms and basins are combined in a tentative sequence stratigraphic framework for the Middle Cretaceous. The results of onedimensional subsidence modelling are presented in order to separate and describe the signals of local tectonics and relative sea-level fluctuations affecting the southern passive-margin of Mesozoic Tethys.

Made available in DSpace on 2014-06-11T19:26:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-27Bitstream added on 2014-06-13T19:33:38Z : No. of bitstreams: 1 franco_aob_me_rcla.pdf: 2573807 bytes, checksum: 574f9f24f539eb53bda347597a2b1d4d (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A evolução do Arco de Ponta Grossa, na região sudeste brasileira, durante o Meso-Cenozóico, apresenta uma estreita relação com os eventos tectono-magmáticos responsáveis pela abertura do Oceano Atlântico- Sul. A utilização do Método de Datação por Traços de Fissão em apatitas, nessa região, permitiu a identificação de cinco eventos térmicos, responsáveis pela estruturação dessa feição, a partir do Cretáceo. São eles: Evento A - Aquecimento em 130 Ma, relacionado ao evento de ruptura do Gondwana Sul-Ocidental e geração do Oceano Atlântico-Sul; Evento B - Resfriamento em 110 Ma, associado à reativação de antigas zonas de cisalhamento e/ou falhas geradas na ocasião do evento de ruptura do Gondwana Sul-Ocidental; Evento C - Aquecimento em 90 Ma, associado à um soerguimento regional, interpretado como alçamento de isógradas, provavelmente como reflexo do soerguimento do Arco de Ponta Grossa e conseqüente sedimentação correlativa (Grupo Bauru ls, no interior continental, e seqüência inferior da Formação Santos, na Bacia homônima), bem como de intrusões alcalinas; Evento D - Resfriamento em 60 Ma, correlacionado à um evento erosivo, que propiciou a formação de uma extensa superfície de erosão, neste caso a Superfície Sulamericana, amplamente registrada tanto na parte continental como na porção submersa adjacente ao Arco de Ponta Grossa (sob a forma de discordância regional na Bacia de Santos); Evento E - Resfriamento em 30/20 Ma, associado à atuação de ciclos erosivos, instalação de bacias tafrogênicas e, localmente, intrusões alcalinas. / The evolution of Ponta Grossa Arch, in southeastern Brazil, during Mesozoic-Cenozoic, seems to be related to the tectono-thermal events related to South Atlantic opening. The use of Apatite fission Track Method, in this region, allowed the recognition of five thermal events, responsible for the formation of this feature, since Cretaceous, which are: Event A - Heating event in 130 Ma, related to the Southeastern Gondwana break-up and the origin of South Atlantic Ocean; Event B - Cooling event in 110 Ma, associated to the shear zones reactivation and/or faults generated during Gondwana break-up; Event C - Heating event in 90 Ma, associated with a regional uplift, interpreted as uplift isotherms, probably as a reflection of Ponta Grossa Arch uplift and correlated sedimentation (Bauru Group ls, in continent and the inferior sequence of Santos Formation, in Santos Basin), and alkaline intrusions; Event D - Cooling event in 60 Ma, correspondent to an erosional event, that formed an extended erosional surface, in this case, Sulamericana Surface, registered both in continental region and in offshore portion (registered as a regional discordance in Santos Basin); Event E - Cooling in 30/20 Ma, related to erosional cycles, tafrogenic basins origin and, locally, alkaline intrusions.

Resumo: A evolução do Arco de Ponta Grossa, na região sudeste brasileira, durante o Meso-Cenozóico, apresenta uma estreita relação com os eventos tectono-magmáticos responsáveis pela abertura do Oceano Atlântico- Sul. A utilização do Método de Datação por Traços de Fissão em apatitas, nessa região, permitiu a identificação de cinco eventos térmicos, responsáveis pela estruturação dessa feição, a partir do Cretáceo. São eles: Evento A - Aquecimento em 130 Ma, relacionado ao evento de ruptura do Gondwana Sul-Ocidental e geração do Oceano Atlântico-Sul; Evento B - Resfriamento em 110 Ma, associado à reativação de antigas zonas de cisalhamento e/ou falhas geradas na ocasião do evento de ruptura do Gondwana Sul-Ocidental; Evento C - Aquecimento em 90 Ma, associado à um soerguimento regional, interpretado como alçamento de isógradas, provavelmente como reflexo do soerguimento do Arco de Ponta Grossa e conseqüente sedimentação correlativa (Grupo Bauru ls, no interior continental, e seqüência inferior da Formação Santos, na Bacia homônima), bem como de intrusões alcalinas; Evento D - Resfriamento em 60 Ma, correlacionado à um evento erosivo, que propiciou a formação de uma extensa superfície de erosão, neste caso a Superfície Sulamericana, amplamente registrada tanto na parte continental como na porção submersa adjacente ao Arco de Ponta Grossa (sob a forma de discordância regional na Bacia de Santos); Evento E - Resfriamento em 30/20 Ma, associado à atuação de ciclos erosivos, instalação de bacias tafrogênicas e, localmente, intrusões alcalinas. / Abstract: The evolution of Ponta Grossa Arch, in southeastern Brazil, during Mesozoic-Cenozoic, seems to be related to the tectono-thermal events related to South Atlantic opening. The use of Apatite fission Track Method, in this region, allowed the recognition of five thermal events, responsible for the formation of this feature, since Cretaceous, which are: Event A - Heating event in 130 Ma, related to the Southeastern Gondwana break-up and the origin of South Atlantic Ocean; Event B - Cooling event in 110 Ma, associated to the shear zones reactivation and/or faults generated during Gondwana break-up; Event C - Heating event in 90 Ma, associated with a regional uplift, interpreted as uplift isotherms, probably as a reflection of Ponta Grossa Arch uplift and correlated sedimentation (Bauru Group ls, in continent and the inferior sequence of Santos Formation, in Santos Basin), and alkaline intrusions; Event D - Cooling event in 60 Ma, correspondent to an erosional event, that formed an extended erosional surface, in this case, Sulamericana Surface, registered both in continental region and in offshore portion (registered as a regional discordance in Santos Basin); Event E - Cooling in 30/20 Ma, related to erosional cycles, tafrogenic basins origin and, locally, alkaline intrusions. / Orientador: Peter Christian Hackspacher / Coorientador: Antonio Roberto Saad / Banca: Julio Cesar Hadler Neto / Banca: Delzio de Lima Machado Junior / Mestre

The stratigraphy and structure of Upper Palaeozoic and Mesozoic sedimentary and volcanic rocks, and of amphibolitic rocks of unknown age, were studied in an area of about 140 square miles in the Cascade Mountains of southwestern British Columbia. The amphibolitic rocks are probably of diverse origins; their stratigraphic relationship to the other rocks is not known, although they may, in part, be equivalent to pre-Devonian rocks in northwestern Washington. Upper Palaeozoic rocks comprise the Chilliwack Group. The base is not exposed. Oldest rocks are volcanic arenites and argillites which are overlain by an argillaceous limestone, about 100 feet thick, in which Early Pennsylvanian (Morrowan) fusulinids occur. Apparently conformably overlying the limestone is a succession of argillites, coarse volcanic arenites, minor conglomerate and local tuff, which contains both marine and terrestrial fossils and ranges in thickness from 450 to 800 feet. A cherty limestone, generally about 300 feet thick, in which there is an Early Permian (Leonardian) fusulinid fauna, is conformable upon the clastic sequence. Altered lavas and tuffs are in part laterally equivalent to this Permian limestone, and, in part, overlie it; these volcanic rocks range in thickness from 700 to 2,000 feet. Disconformably above the Permian volcanic rocks are argillites and volcanic arenites of the Cultus Formation. This formation is apparently about 4,000 feet thick, contains Late Triassic, Early and Late Jurassic fossils and no stratigraphic breaks have been recognized within it. All of these rocks underwent two phases of deformation between Late Jurassic and Miocene time. The first phase, correlated with mid-Cretaceous deformation in northwestern Washington, was the most severe., and thrusts and major, northeast-trending recumbent folds were formed. These structures subsequently were folded and faulted along a northwest trend, possibly in response to differential uplift of the Cascade Mountains. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Near Terrace, British Columbia, the eastern margin of the Central Gneiss Complex (CGC) is a 3-4 km thick, gently northeast dipping, ductile-brittle shear zone with northeast movement of the upper plate. Along Shames River, deformed amphibolite-facies rocks to the west are juxtaposed against lower greenschist to amphibolite facies units to the east along the steep, east side down, brittle Shames River fault (SRF). Gentle to moderate northwest and northeast dips west of SRF contrast with steep southeast dips to the east. Lineations plunge gently northeast and southwest. West of SRF, the Shames River mylonite zone (SRMZ) separates granitoid rocks below from less deformed granitoid rocks, orthogneiss and metasedimentary rocks above. West of Exstew River, the moderately northeast dipping, ductile Exstew River fault, juxtaposes the SRMZ against metamorphic rocks and granitoids of the CGC. The SRMZ is cut by anastomosing brittle-ductile shear zones. Most kinematic indicators show northeast directed shear. Heterogeneous strain in SRMZ accommodates a minimum upper plate movement of 25 km to the east-northeast. Hornblende geobarometry indicates a structural omission of 13.4 km across SRMZ. East of SRF, amphibolite and greenschist facies supracrustal and plutonic rocks of Lower Permian and older Stikine Assemblage are thrust above greenschist facies volcanic strata correlated with Telkwa Formation of the Lower to Middle Jurassic Hazelton Group. Foliation in late synkinematic, 69 Ma granodiorite which intrudes this thrust package dips steeply southeast. Stikine Assemblage is comprised of lower greenstone, granitoid rocks, volcanic breccia and flows overlain by fusulinid-rich marble. A deformed intrusive rock in Stikine Assemblage has a minimum Pb-Pb date of 317 ± 3 Ma. Hazelton Group contains lower andesitic and upper dacitic to rhyolitic packages comprised of agglomerate, volcanic breccia, tuff, and plagioclase porphyry flows. The earliest recognised metamorphism and deformation in the SRMZ, at upper amphibolite grade, affects 188 ± 8 Ma orthogneiss, and occurred before intrusion of a garnet-biotite granite dated by Woodsworth et al. (1983) at 83.5 Ma. Early fabrics are overprinted by Campanian to Paleocene ductile deformation and a second metamorphism. The second deformation waned during intrusion of three granitic intrusions with concordant U-Pb zircon crystallization dates of 68.7 - 69 Ma. A late to post-kinematic granite dyke in the SRMZ has a U-Pb zircon crystallization date of 60 ± 6 Ma. The second phase of metamorphism began before, and outlasted ductile deformation. The SRF and other high angle normal faults cut 69 Ma granodiorite, but do not significantly offset Eocene (46.2-52.3 Ma) K-Ar biotite cooling isothermal surfaces. The 60 Ma granite is deformed by low angle semi-brittle faulting with upper plate movement to the northeast. A 48 ± 3 Ma synkinematic granite dyke in the footwall of SRMZ was intruded during this deformation, which ended before 46.2 - 46.5 ± 1.6 Ma, the K-Ar biotite cooling dates from SRMZ. The entire region is deformed by post-ductile open, upright, east-northeast plunging folds. K-Ar biotite dates for granitoid rocks range from 51.1 Ma in the upper plate to 46.2 Ma in SRMZ, indicating downward progression of cooling. North-northwest trending brittle faults and lamprophyre dykes cut the SRMZ, and are therefore younger than mid-Eocene. Thermobarometry of pelitic and granitoid rocks indicates increasing metamorphic grade with increasing structural depth. Al-j; in hornblende geobarometry indicates slightly lower pressure of crystallization for the interior than the margin of a granodiorite body east of SRF.In the upper plate of SRMZ, west of SRF, sillimanite-staurolite-garnet schist records ductile deformation and metamorphism at 3.8 ± 1.6 kbar and 570 ± 50°C. The schist is intruded by orthogneiss cut by 68.7 Ma granodiorite. The granodiorite crystallized at 3.4 ± 1 kbar, and was deformed at 2.2 ± 1 kbar at 68.7 Ma. In SRMZ, hornblende in pre-kinematic, 188 ± 8 Ma granodiorite crystallized at 5.5 ± 1 kbar. Deformation and synkinematic metamorphism occurred at 4.9 ± 1 kbar, between 83.5 and before 60 ± 6 Ma. East of SRF, greenschist conditions prevailed, except near the southern margin of the 69 Ma granodiorite body, where amphibolite facies was stable during ductile deformation. A metapelitic sample gives near-peak metamorphic conditions of 4.9 ± 1.6 kbar and 700 ± 50°C, and contact metamorphic conditions of 2.9 ± 1.6 kbar and 610 ± 50°C during intrusion of late synkinematic, 69 Ma granodiorite. P-T-time paths for the upper plate of SRMZ west of Shames River indicate initial rapid, near-isothermal decompression beginning before 69 Ma, continuing to 69 Ma, followed by rapid cooling to 0.9-1.1 kbar, at 51.1 Ma. Paleogene to middle Eocene deformation was probably extensional in nature. It occurred in a vigorous magmatic arc, in response to, and possibly coeval with, crustal thickening. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate