The vast distribution and long duration of the Late Mesozoic magmatism in the eastern part of South China presents a unique case in the world. This offers a natural laboratory to study the process of magma genesis, the magma emplacement mode, the relationship between magmatism and tectonics, the geodynamic role on the magma emplacement and lithospheric evolution. Since 50's, particularly 90's of the last century, geoscientists have made important efforts in geological cartography and carried out numerous studies with remarkable scientific achievements, building a solid background to understand the tectonic evolution of the South China Block (SCB). However, certain fundamental questions mentioned above remain unsolved and/or are in hot debate. In order to make progress in these scientific issues, we have carried out in a multi-disciplinary study in the Late Mesozoic Qingyang-Jiuhua massif, Hengshan massif and Fujian coastal zone according to their distance with respect to the paleo subduction zone of the Paleo-Pacific plate, the ages of granitic massifs and related tectonics, including field observation on the structure geology, micro-observation on thin section, U-Pb dating on monazite, AMS, paleomagnetism, gravity modeling and P condition concern the granite emplacement. In the view of deformation in these granitic massifs and their country rocks, mode and influence of regional tectonics on the emplacement, though each studied zone reveals its distinguished characteristics, they show some intrinsic and common relationships between them. With our new results and integrating previous data, in this thesis, we discuss the tectonic context of emplacement of these Late Mesozoic magmatic massifs and the geodynamic evolution of the SCB., We propose a 3-step geodynamic model: (1) during 145-130 Ma period, the Paleo-Pacific plate subducted northwestwardly, the West Philippines micro-continent, approaching to SCB, important subduction-related arc volcanism was produced in the coastal areas of Southeast China coast (Zhejiang-Fujian-Guangdong), forming a back-arc extension tectonic system in SCB; (2) during 130-110 Ma period, due to the collision between the West Philippines microcontinent and SCB, the compressional tectonic structures were developed in the Changle-Na'ao coastal zone, producing ductile deformation zones. However, the inland of the eastern part of SCB was under a NW-SE extensional tectonic regime; (3) during 105-90 Ma period, a new subduction zone was developed in the SE flank of the West Philippines micro-continent, the subducting slab reached the Changle-Nan'ao tectonic belt, with the possible break-off of slab, the asthenospheric ascent was responsible for the important emplacement of plutonic massifs and dykes. The tectonics of the eastern part of SCB was characterized by a general extensional system in this period. This tectonic pattern has been significantly disturbed by the Oligocene-Eocene opening of the South China sea,and the Miocene shortening of the SCB margin in Taiwan. Of course, this model should be improved by more geological, geophysical and geochemical investigations.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O relevo da Serra da Bocaina revela o forte controle das estruturas dúcteis e rúpteis relacionadas à Faixa Ribeira gerada na Orogênese Brasiliana (ca. 790-480 Ma) e às reativações mesozóica-cenozóicas. As rochas são agrupadas em 4 terrenos tectônicos colados nas etapas colisionais brasilianas, que formaram as estruturas mais penetrativas: foliação com mergulho para NW, zonas de cisalhamento dúcteis NESW e dobras. Zonas de cisalhamento rúptil-dúcteis NW marcam o colapso orogênico. A abertura do Atlântico Sul (ca. 135-120 Ma) é registrada pelos enxames de diques toleíticos NNE e ENE, em parte condicionados pelas estruturas brasilianas. No Planalto da Bocaina uma idade de traço de fissão em apatita (TFA) de ca. 145 Ma data o resfriamento ainda da fase pré-rifte do Gondwana. O soerguimento da margem continental na fase rifte pode ter alçado este nível para fora da zona de apagamento parcial do TFA. A reativação neocretácea é datada pelo TFA (ca. 85 Ma) na costa e na escarpa atlântica, indicando novo pulso de denudação e soerguimento da margem continental. Isto também concorda com o extenso aporte de sedimentação siliciclástica na Bacia de Santos. No Paleógeno, a formação dos Riftes Continentais do Sudeste Brasileiro (RCSB) gerou a reativação das estruturas dúcteis NE da Faixa Ribeira, falhas e fraturas NW, E-W, além de fraturas NE na Baía da Ilha Grande. O contato tectônico entre os Terrenos Paraíba do Sul e Embu é a principal zona reativada na Serra da Bocaina. Idades TFA (ca. 55 Ma) registram o estágio inicial do RCSB, que provocou o rebaixamento do nível de base e a formação de uma escarpa no interior. A Serra da Bocaina parece constituir uma região elevada desde a formação da Cordilheira Ribeira, incrementada pelos soerguimentos das fases rifte e pós-rifte do Atlântico e do RCSB. Estes eventos tectônicos que elevaram a Serra da Bocaina, também geraram as estruturas que conduzem sua denudação. Neste contexto, destaca-se o par de estruturas NE (foliação e zonas de cisalhamento reativadas ou não) e NW (fraturas e falhas), as mais freqüentes, que orienta a rede de drenagem, os níveis de base locais (knickpoints) e as formas côncavas das encostas (cabeceiras de canais). Diques toleíticos também conduzem a dissecação dos vales fluviais. Por outro lado, granitos e ortognaisses que sustentam as elevações e segmentos de escarpas mostram o papel da erosão diferencial em rochas mais resistentes. A denudação do Planalto da Bocaina e o recuo de suas escarpas (atlântica e interior) são regulados por diferentes níveis de base (p.ex. nível do mar, rio Paraíba do Sul no RCSB, diversos knickpoints), sensíveis aos eventos de reativações tectônicas (soerguimento), variações eustáticas e à erosão diferencial. Os pulsos erosivos vêm dissecando de modo diferencial os vales suspensos do planalto, através da incisão fluvial e reativação das cabeceiras de canais, que avançam sobre as encostas promovendo a quebra dos divisores e capturas de drenagens. Este processo rebaixamento de relevo parece levar à formação das superfícies colinosas que ocorrem em diferentes níveis topográficos. As idades TFA antigas indicam baixas taxas de denudação na porção mais elevada do Planalto da Bocaina, o que contrasta com as altas taxas da região costeira. Este caráter diferencial da denudação condicionada pelo substrato geológico e pelos eventos de soerguimento, vem preservando antigas paisagens no Planalto da Bocaina. No outro extremo, a denudação propagada pelo recuo das duas escarpas vem degradando as bordas e introduzindo a dissecação no interior do planalto. As duas escarpas geradas por eventos riftes distintos vêm se ajustando ao controle das rochas e estruturas da Faixa Ribeira. / The Bocaina Ridge landscape is strongly controlled by both ductile and brittle structures related to the Ribeira Belt (Brasiliano Orogeny ca. 790-480Ma) and also to the mesozoic-cenozoic reactivations. The rocks were subdivided in four tectonic terrains accreted in the brasiliano collisional stages. The most prominent structures related to these collisions are: NW dipping foliation, NE-SW ductile shear zones, and folds. NW ductile-brittle shear zones represent the orogenic collapse stage. The South Atlantic opening (ca.135-120 Ma) is registered in NNE and ENE tholeitic dike swarms, partly conditioned by brasiliano structures. In the Bocaina Plateau one apatite fission track age (AFT) of ca.145Ma represents pre-rift Gondwana cooling. The continental margin uplift associated to the rift phase might have raised this level out of the AFT partial annealing zone. Neocretaceous reactivation (ca. 85Ma) was AFT dated both in the coast and the atlantic scarp, pointing out to a newer continental margin denudation and uplift pulse. This reactivation is in accordance with the Santos basin significant siliciclastic sedimentation. In paleogene times, the Southeastern Brazil Continental Rift System (SBCR) development was responsible for: the reactivation of the Ribeira Belt NE ductile structures, NW and E-W faulting and fracturing, and NE fracturing in Ilha Grande Bay. The tectonic boundary between Paraíba do Sul and Embu Terrains is the main reactivation zone in the Bocaina Ridge. AFT ages of ca. 55 Ma register the initial stage of the SBCR, which produced base level lowering and the formation of an inland scarp. The Bocaina Ridge seems to constitute an elevated region since the development of the Ribeira Cordillera, increased by the South Atlantic rift and post-rift uplifts and also by the SBCR.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O relevo da Serra da Bocaina revela o forte controle das estruturas dúcteis e rúpteis relacionadas à Faixa Ribeira gerada na Orogênese Brasiliana (ca. 790-480 Ma) e às reativações mesozóica-cenozóicas. As rochas são agrupadas em 4 terrenos tectônicos colados nas etapas colisionais brasilianas, que formaram as estruturas mais penetrativas: foliação com mergulho para NW, zonas de cisalhamento dúcteis NESW e dobras. Zonas de cisalhamento rúptil-dúcteis NW marcam o colapso orogênico. A abertura do Atlântico Sul (ca. 135-120 Ma) é registrada pelos enxames de diques toleíticos NNE e ENE, em parte condicionados pelas estruturas brasilianas. No Planalto da Bocaina uma idade de traço de fissão em apatita (TFA) de ca. 145 Ma data o resfriamento ainda da fase pré-rifte do Gondwana. O soerguimento da margem continental na fase rifte pode ter alçado este nível para fora da zona de apagamento parcial do TFA. A reativação neocretácea é datada pelo TFA (ca. 85 Ma) na costa e na escarpa atlântica, indicando novo pulso de denudação e soerguimento da margem continental. Isto também concorda com o extenso aporte de sedimentação siliciclástica na Bacia de Santos. No Paleógeno, a formação dos Riftes Continentais do Sudeste Brasileiro (RCSB) gerou a reativação das estruturas dúcteis NE da Faixa Ribeira, falhas e fraturas NW, E-W, além de fraturas NE na Baía da Ilha Grande. O contato tectônico entre os Terrenos Paraíba do Sul e Embu é a principal zona reativada na Serra da Bocaina. Idades TFA (ca. 55 Ma) registram o estágio inicial do RCSB, que provocou o rebaixamento do nível de base e a formação de uma escarpa no interior. A Serra da Bocaina parece constituir uma região elevada desde a formação da Cordilheira Ribeira, incrementada pelos soerguimentos das fases rifte e pós-rifte do Atlântico e do RCSB. Estes eventos tectônicos que elevaram a Serra da Bocaina, também geraram as estruturas que conduzem sua denudação. Neste contexto, destaca-se o par de estruturas NE (foliação e zonas de cisalhamento reativadas ou não) e NW (fraturas e falhas), as mais freqüentes, que orienta a rede de drenagem, os níveis de base locais (knickpoints) e as formas côncavas das encostas (cabeceiras de canais). Diques toleíticos também conduzem a dissecação dos vales fluviais. Por outro lado, granitos e ortognaisses que sustentam as elevações e segmentos de escarpas mostram o papel da erosão diferencial em rochas mais resistentes. A denudação do Planalto da Bocaina e o recuo de suas escarpas (atlântica e interior) são regulados por diferentes níveis de base (p.ex. nível do mar, rio Paraíba do Sul no RCSB, diversos knickpoints), sensíveis aos eventos de reativações tectônicas (soerguimento), variações eustáticas e à erosão diferencial. Os pulsos erosivos vêm dissecando de modo diferencial os vales suspensos do planalto, através da incisão fluvial e reativação das cabeceiras de canais, que avançam sobre as encostas promovendo a quebra dos divisores e capturas de drenagens. Este processo rebaixamento de relevo parece levar à formação das superfícies colinosas que ocorrem em diferentes níveis topográficos. As idades TFA antigas indicam baixas taxas de denudação na porção mais elevada do Planalto da Bocaina, o que contrasta com as altas taxas da região costeira. Este caráter diferencial da denudação condicionada pelo substrato geológico e pelos eventos de soerguimento, vem preservando antigas paisagens no Planalto da Bocaina. No outro extremo, a denudação propagada pelo recuo das duas escarpas vem degradando as bordas e introduzindo a dissecação no interior do planalto. As duas escarpas geradas por eventos riftes distintos vêm se ajustando ao controle das rochas e estruturas da Faixa Ribeira. / The Bocaina Ridge landscape is strongly controlled by both ductile and brittle structures related to the Ribeira Belt (Brasiliano Orogeny ca. 790-480Ma) and also to the mesozoic-cenozoic reactivations. The rocks were subdivided in four tectonic terrains accreted in the brasiliano collisional stages. The most prominent structures related to these collisions are: NW dipping foliation, NE-SW ductile shear zones, and folds. NW ductile-brittle shear zones represent the orogenic collapse stage. The South Atlantic opening (ca.135-120 Ma) is registered in NNE and ENE tholeitic dike swarms, partly conditioned by brasiliano structures. In the Bocaina Plateau one apatite fission track age (AFT) of ca.145Ma represents pre-rift Gondwana cooling. The continental margin uplift associated to the rift phase might have raised this level out of the AFT partial annealing zone. Neocretaceous reactivation (ca. 85Ma) was AFT dated both in the coast and the atlantic scarp, pointing out to a newer continental margin denudation and uplift pulse. This reactivation is in accordance with the Santos basin significant siliciclastic sedimentation. In paleogene times, the Southeastern Brazil Continental Rift System (SBCR) development was responsible for: the reactivation of the Ribeira Belt NE ductile structures, NW and E-W faulting and fracturing, and NE fracturing in Ilha Grande Bay. The tectonic boundary between Paraíba do Sul and Embu Terrains is the main reactivation zone in the Bocaina Ridge. AFT ages of ca. 55 Ma register the initial stage of the SBCR, which produced base level lowering and the formation of an inland scarp. The Bocaina Ridge seems to constitute an elevated region since the development of the Ribeira Cordillera, increased by the South Atlantic rift and post-rift uplifts and also by the SBCR.

This thesis deals with systematic revision, evolutionary trends, palaeoecology and migration patterns of crustaceans (Cirripedia and Decapoda) from the Upper Cretaceous of the Bohemian Cretaceous Basin. Thesis is presented as a compilation of 9 papers that were published in scientific peer-reviewed journals and includes not only old museum material, but also numerous crustacean specimens which have been recovered in the last decade. Besides, short remarks on fossil crustaceans currently under study or in the process of being published (Paraclythia, Oncopareia, Acrothoracica) are also included in this thesis. In view of the fact that the fossil crustaceans from the BCB were most recently recorded in the turn of the 19th and the 20th centuries (and partially revised in the first half of the 20th century) and since the systematics and taxonomy have changed significantly, all papers presented here focus primarily on systematic revision and modern description. The essential part of the thesis thus deals with taphonomy and its bearing on the identification of fossil material. Thanks to a modern description, new species of Ctenocheles fritschi (axiidean shrimp), Archaeochionelasmus nekvasilovae (acorn barnacle), Myolepas reussi and Capitulum sklenari (pedunculate barnacles) were erected. C. fritschi is...

No description available.

Italian Trap Allochthon is a rare upper-plate exposure of Paleozoic metasedimentary and Precambrian to Tertiary crystalline tectonites in the Santa Catalina-Rincon metamorphic core complex. Elsewhere in the complex, metasedimentary tectonite is usually restricted to an autochthononous position. The internal structures of the allochthon consist of numerous low-angle faults, tear faults, and overturned asymmetric and upright folds. Close association of the low-angle faults and asymmetric folds, and vergence of the folds, indicates that these folds were formed during westward transport along the low-angle faults. The structures of the allochthon are truncated and rotated to the northeast by a listric (?) normal fault. The probable shape of the fault surface, together with the northeastward rotation of the internal structures, suggests translation of the allochthon from the northeast to the southwest. The fact that metasedimentary tectonites are found in upper- plate position indicates that the listric (?) normal faulting post-dates the metamorphism of the Paleozoic and Mesozoic strata. Metamorphism in turn was part of the development of the Santa Catalina-Rincon metamorphic core complex. It is inferred that the Italian Trap Allochthon was emplaced in the final stages of profound regional extension which prevailed during the mid-Tertiary in southern Arizona.

No description available.

Rocks of the Morenci-Metcalf district consist of Precambrian metaquartzite-schist, granodiorite, and granite overlain by Paleozoic and Mesozoic sediments. Intrusion of igneous rocks, emplacement of breccia masses, and associated hydrothermal activity occurred in Laramide time. Breccias of the district are associated with the youngest sialic intrusive complex. This sequence includes intrusion of the Older Granite Porphyry stock, main stage district hydrothermal alteration, quartz veining, breccia formation, main stage district hydrothermal mineralization, and intrusion of the Younger Granite Porphyry plug. Breccia formation in the Morenci-Metcalf district is similar to breccia descriptions reported in the literature for other porphyry copper deposits. Three breccia types, of separate and distinct origins, are herein described as the Morenci, Metcalf and King, and Candelaria Breccias. The Morenci Breccia is an intrusion breccia that has formed along a pre-existing structural feature during the ascent and emplacement of the Older Granite Porphyry stock. It exhibits an oblate lenticular shape with angular to subrounded fragments in a matrix of quartz, K-feldspar, biotite, and minor rock flour. The Metcalf-King Breccias and numerous smaller breccia masses are the remnants of an original Older Granite Porphyry mantle above the ascending Younger Granite Porphyry complex. The breccia masses occur as large 'xenoliths' floating within the Younger Granite Porphyry plug and were formed by surging and collapse during emplacement of this intrusive. Fragments in the Metcalf and King Breccias grade from angular in the central core to rounded at the contacts and occur in a matrix of sericite, K- feldspar, quartz, and rock flour. The Candelaria Breccia is an explosion pipe and is the largest continuous breccia mass in the district. It is oval with an inverted cone appearance consisting of angular to subangular equidimensional fragments in a matrix of sericite, quartz, specularite, and rock flour. All the breccia masses occur within and subsequent to the district phyllic (quartz-sericite-pyrite) alteration zone. Main stage district copper mineralization postdates emplacement of the Older Granite Porphyry stock and breccia formation, and is prior to the intrusion of the Younger Granite Porphyry plug. Late stage quartz-sericite-pyrite-chalcopyrite veinlets occur in the Metcalf-King Breccia group. Field mapping and laboratory studies indicate that the Older Granite Porphyry stock appears to have been the main district mineralizer.

<p dir="ltr">The Intermontane terranes represent one of the largest composite accreted terranes that built the northern Cordillera. To better understand the interactions between the continental margin of Laurentia and the Intermontane terranes, this study analyzes twelve detrital zircon samples (n=3232) from a Neoproterozoic (?) to Cretaceous metasedimentary stratigraphic section exposed in central Alaska. Distinct detrital zircon populations have been identified and are interpreted to represent four stages in the geologic development of this part of western North America. Stage 1 extends from the Neoproterozoic (?) to the Early Paleozoic, and is characterized by Proterozoic and Archean detrital zircon populations that correlate with Laurentian sources of sediment. We interpret Stage 1 to represent deposition along the northwestern continental margin of Laurentia. Stage 2 extends from the Silurian (?) to the Devonian and is characterized by a dominant Devonian and Silurian detrital zircon population. We interpret Stage 2 to have been deposited in a backarc basin coeval with active volcanism as the Yukon-Tanana terrane was rifted away from the Laurentian continental margin as the Slide Mountain Ocean opened. Stage 3 extends from the Mississippian to the Jurassic and records a shift back to sediment sources with abundant Proterozoic and Archean zircon. We interpret this stage to represent deposition of Laurentian detritus along the eastern margin of the Slide Mountain Ocean basin. Stage 4 is represented by the Lower Cretaceous strata of the Manley basin that contain one major Late Triassic to Early Jurassic detrital zircon population. We interpret this population to be sourced from the syn-collisional and post-collisional Late Triassic to Early Jurassic plutons and related sedimentary basins of the Intermontane terranes that were exhumed and eroded during the closure of the Slide Mountain Ocean and the subsequent collision with the Laurentian continental margin. We interpret the Manley basin as a syn- to post-collisional extensional basin associated with regional detachment faults that formed because of crustal thickening in the collisional zone. From a regional perspective, an extensive clastic wedge prograded northward away from the zone of crustal thickening and can be identified in a series of Mesozoic sedimentary basins that are discontinuously exposed over 1500 km in southern Alaska. Results of our study better delineate the tectonic processes that set the framework for the construction of the Late Mesozoic and Cenozoic Cordilleran orogen.</p>

The Dakota Group surrounding Las Vegas, New Mexico, consists of three units: 1) a basal, predominately trough cross-stratified, conglomeratic sandstone, 2) middle intercalated, thin-bedded sandstone and carbonaceous shale, and 3) upper, predominately tabular-planar cross-stratified, sandstone containing trace fossils. These units represent, respectively, 1) a fluvial piedmont plain, 2) fluvial coastal plain, and 3) a beach, littoral, and shallow marine complex. The cross-stratification in the lower sandstone unit indicates an easterly paleoslope. The cross-stratification in the upper sandstone unit has a bimodal distribution almost at right angles to the paleoslope, suggesting deposition by longshore currents. The standard deviation of the cross-stratification in the lower sandstone unit of 78° is typical of fluvial deposits. The standard deviation in the upper sandstone unit of 97° indicates a marine origin.