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Most major Phanerozoic mass extinctions induced permanent or transient changes in ecological and anatomical characteristics of surviving benthic communities. Many infaunal marine organisms produced distinct suites of biogenic structures in a variety of depositional settings, thereby leaving an ichnological record preceding and following each extinction. This study documents a decrease in burrow size in Thalassinoides-dominated ichnoassemblages across the Cretaceous-Paleogene (K-Pg) boundary in shallow-marine sections along the Atlantic Coastal Plain (Walnridge Farm, Rancocas Creek, and Inversand Quarry, New Jersey) and the Gulf Coastal Plain (Braggs, Alabama and Brazos River and Cottonmouth Creek, Texas). At New Jersey sites, within a regionally extensive ichnoassemblage, Thalassinoides ichnospecies (isp.) burrow diameters (DTh) decrease abruptly by 26-29% (mean K=15.2 mm, mean Pg=11.2 mm; n=1767) at the base of the Main Fossiliferous Layer (MFL) or laterally equivalent horizons. The MFL has been previously interpreted as the K-Pg boundary based on last occurrence of Cretaceous marine reptiles, birds, and ammonites, as well as iridium anomalies and associated shocked quartz. Across the same event boundary at Braggs, Alabama, DTh of simple maze Thalassinoides structures from recurring depositional facies decrease sharply by 22% (mean K=13.1 mm, mean Pg=10.2 mm; n=26). Similarly, at the Cottonmouth Creek site, Texas, Thalassinoides isp. occurring above the previously reported negative £_13C shift and the first occurrence of Danian planktonic foraminifera are 17% smaller in diameter (mean K=21.5 mm, mean Pg=17.9 mm; n=53) than those excavated and filled prior to deposition of a cross-bedded, ejecta-bearing sandstone complex commonly interpreted as the Chicxulub ¡¥event deposit¡¦. At both of these impact-proximal regions, the Cretaceous and Paleogene burrows were preserved in similar lithologies, suggesting that a reduction in size cannot be attributed to sedimentological factors. At all localities, up-section trends in DTh are statistically significant (fÑfnf¬0.05; non-parametric Kruskal-Wallis test). Using the burrow diameter as a proxy for tracemaker body size, a reduction in DTh above the K-Pg boundary likely reflects dwarfing within the post-extinction community of decapod crustaceans. Dwarfing during the early recovery stages of the end-Cretaceous mass extinction, as recorded by ichnofossils, occurred within glauconite-producing (New Jersey), carbonate (Alabama), and siliciclastic (Texas) depositional environments and appears to be widespread. Because this ichnological signal appears to be a general phenomenon across the crisis interval, trace-fossil analysis provides a potential in-situ field method for constraining and correlating the stratigraphic position of the K-Pg and other extinction events, particularly in the absence of other macroscopic, microscopic, and geochemical indicators. Whereas overprinting of the original marine ichnofabric by morphologically similar continental traces is not a concern in lithified sections of Alabama and Texas, such an occurrence must be considered within unconsolidated sections. Within the Hornerstown Formation of New Jersey, a pervasive Thalassinoides framework contains traces of burrowing bees and wasps. Due to their penetration of up to 1 m, excavations just beyond the weathering front are insufficient for exposing the original marine ichnofabric. Insect burrow diameters (7-25 mm) are within the range of Thalassinoides traces (4-31 mm), exhibit occasional branching, and lack of ornamentation (bioglyphs) on the burrow walls. Therefore neither size nor gross morphology are adequate for distinguishing these widely diachronous and unrelated ichnites, especially when the insect burrows have been filled. However, the presence of backfill menisci and a beige clay halo help distinguish the ancient marine burrows, whereas highly oxidized fill and the occurrence of a terminal brooding chamber are diagnostic of modern insect burrows. / Geology

Our understanding of fine-grained sediment regarding the processes in which they are transported and deposited is rapidly evolving. However, developing a depositional model and characterizing the vertical variability within mud-dominated deposits has seldom been done. A 103m Upper Mancos Shale core retrieved from the San Juan Basin, New Mexico was analysed with detailed thin-bedded facies analysis to observe vertical variability in lithology, sedimentary structures, bioturbation intensity, and depositional processes. Lithological variation suggests there are 3 full sequences, 9 system tracts, and 92 parasequences. Facies observed revealed multiple facies successions indicating depositional processes including ignitive turbidite, storms (tempestite), wave enhanced sediment gravity flows (WESGFs), tidal, biogenic reworking, fluid mud, suspension settling, and general bedload transport. Relationships between lithology, bioturbation intensity, sedimentary structures and depositional processes were observed to be interrelated in that energetic processes (i.e., storms, ignitive turbidite) were associated with coarser deposits and low bioturbation intensity; whereas lower energy processes (i.e., biogenic reworking, suspension settling, WESGFs) were associated with finer deposits and relatively higher bioturbation intensities. Furthermore, lithological variability integrated with depositional models indicated temporal changes in environment of deposition across shelf. / Thesis / Master of Science (MSc)

The Upper Cretaceous Tropic Shale of southern Utah captures critical oceanographic changes that occurred during Oceanic Anoxic Event 2 (OAE 2) and the transgression of the Greenhorn Sea. We investigated the response of planktic and benthic foraminifera in a shallow (<100 >m) marine environment stressed by the onset of OAE 2 during the Cenomanian-Turonian boundary (CTB; 93.9 Ma) to determine the oceanographic mechanisms controlling the observed turnovers in the foraminiferal record. This study is based on high-resolution quantitative foraminifera counts and isotope paleoecology (d18O and d13C) from a 40-m outcrop. The OAE 2 interval is identified by a distinctive d13Corg signature and by correlation of bentonites and limestones across the seaway. Results of assemblage analyses indicate discrete intervals of environmental perturbations across the CTB interval. At the onset of OAE 2, surface waters were dominated by planktic Guembelitra cenomana with minor species of Heterohelix. Benthic abundances increase and were initially dominated by oxygen tolerant infaunal Neobulimina albertensis. Epifaunal Gavelinella dakotaensis briefly proliferated during the core of the OAE 2 and coinciding with the planktic “Heterohelix shift” and increasing accumulation of organic matter. The peak of OAE 2 at ~17 m is marked by a rapid shift to infaunal Neobulimina dominance. We suspect incursion of oxygen-poor Tethyan intermediate waters with peak transgression during the early Turonian, coupled with high productivity in surface waters resulted in the rapid depletion of benthic oxygen. The foraminiferal record reveals strong cyclicity in planktic/benthic ratio resembling parasequences that correlate to the GSSP in central Colorado.

The Mount Somers Volcanic Group (MSVG) and Mandamus Igneous Complex (MIC) are the magmatic manifestations of the transition from convergence to extension at the Gondwana margin, which culminated in the separation of New Zealand from Australia and Antarctica. The MIC has been correlated both geochemically and temporally with the Central Marlborough Igneous Province (CMIP). The MSVG and CMIP are located in the Eastern Province of New Zealand. The MSVG is restricted to the Rakaia terrane, whereas the CMIP is restricted to the Pahau terrane. The Rakaia and Pahau terranes are thick accretionary complexes, which were strongly deformed as a result of prolonged subduction at the Gondwana margin. The Pahau terrane is the younger of the two and continued to be deposited and deformed until the abrupt cessation of subduction, which in the Marlborough sedimentary record occurred in the Motuan (100 - 105 Ma). Following the cessation of subduction, after an interval of 2-7 Ma of relative quiescence and subsidence of the Pahau terrane, the MSVG and MIC were erupted/emplaced. The production of MSVG and MIC magmas occurred simultaneously and the activity was of short-lived duration. SHRIMP geochronology yielded crystallisation ages of 97.0 ± 1.5 Ma to 98.0 ± 1.2 Ma from zircons separated from MSVG rhyolites. The SHRIMP ages are within error of the previously published Rb-Sr age for the MIC. The SHRIMP geochronology also confirmed the presence of inherited zircons which yielded ages consistent with their derivation from the Rakaia terrane. Ar-Ar geochronology confirmed the coeval nature of the MSVG and MIC magmatism, but yielded consistently younger ages (94.5 ± 3 Ma for the MSVG and 94.2 ± 1.7 Ma for the MIC). The systematic differences in ages obtained by SHRIMP and Ar-Ar are believed to be method-dependent. The MSVG comprises a calc-alkaline volcanic assemblage, which ranges in composition from basaltic-andesite lavas (SiO₂ = 54.5%) to high-silica rhyolites and ignimbrites (SiO₂ ≤ 78.1%). The MSVG had an original extent of at least 18 000 km². The magmas from the MSVG had high LILE/HFSE, high LILE/REE and moderately high LREE/HFSE which are characteristic of subduction derived magmas. Geochemical modelling suggests that the MSVG magmas were formed from partial melting of a subduction-modified mantle wedge, with high degrees of crustal assimilation. The assimilant had an isotopic composition similar to that of the Rakaia terrane, which is consistent with the geological setting of the MSVG. The MSVG has ⁸⁷Sr/⁸⁶Sri from 0.7055 to 0.7100 and ¹⁴³Nd/¹⁴⁴Ndi from 0.51254 to 0.51230 (ɛNd +0.5 to -4.2), which reflects varying degrees of contamination by Rakaia terrane. Radiogenic isotope modelling suggests that the MSVG end-members were derived from the same parent magma, which evolved through AFC processes from basaltic-andesite to rhyolite. The modelling strongly suggests that assimilation played a lesser role in the petrogenesis of the Malvern Hills magmas than in the petrogenesis of the other units. AFC modelling requires the degree of assimilation to increase as the magmas evolved. Oxygen isotope data are consistent with high degrees of crustal assimilation, and may indicate that the assimilant had higher ¹⁸O characteristics than the Rakaia terrane samples analysed. The MIC is an alkaline suite which ranges in composition from basalt and gabbro to syenite, trachyte and phono-tephrite. The MIC is interpreted to have formed from enriched asthenospheric mantle, with a composition similar to HIMU (²⁰⁶Pb/²⁰⁴Pbi ranges from 19.2 to 20.3). The samples range in isotopic composition from ⁸⁷Sr/⁸⁶Sri = 0.7030 to 0.7036, ¹⁴³Nd/¹⁴⁴Ndi = 0.51275 to 0.51268 (ɛNd +4.6 to +3.3). The range in isotopic composition is due to varying degrees of contamination by Pahau terrane, which reaches a maximum of 25% but in most samples is < 10%. The MIC is contaminated to a much lesser extent than the MSVG which is interpreted to be related to the thinner nature of the Pahau crust in the mid-Cretaceous. The latest phases of activity in the MIC were subjected to lower degrees of contamination which is interpreted to reflect the passage of magmas through pre-existing pathways. The onset of MSVG and CMIP magmatism coincided with the initiation of major rift-related depositional basins, and the eruption of the MSVG is demonstrably associated with normal faulting. The tectonic trigger responsible for the sudden onset of magmatism and rifting in the Eastern Province terranes was the detachment of the previously subducting slab following the cessation of subduction due to the arrival of the Hikurangi Plateau at the margin and the subsequent stalling of the Pacific spreading centre. The capture of the Gondwana margin led to the propogation of extension into the margin by the divergent Pacific plate. The ensuing extension aided the detachment of the subducting slab beneath the Eastern Province terranes. The slab-detachment promoted decompression melting of the sub-lithospheric mantle wedge to produce the MSVG magmas and triggered the ascent of asthenospheric mantle through the slab window, which melted through decompression to produce the CMIP magmatism. The asthenospheric mantle tapped by the slab detachment episode was highly enriched relative to N-MORB and is akin to the similar age HIMU-OIB affinity melts documented from Antarctica and Australia. The short-lived duration of activity is typical of slab-detachment related magmatism which occurs as a passive response to plate reconfiguration. The similarity in geochemistry of the MIC with OIB-affinity igneous centres in Australia and Antarctica implies an enriched mantle domain of large geographical extent. The distribution of relatively small volumes of OIB magmatism is suggestive of a fossil plume component, which was tapped in response to lithospheric extension producing relatively short-lived HIMU magmatism. The same fossil plume component has previously been implicated in the formation of the Cenozoic West Antarctic Rift System and may be responsible for the late Cretaceous magmatism in the Chatham Islands and Tertiary volcanics of the South Island of New Zealand.

Bien qu'ayant fait l'objet d'études depuis près de deux siècles, les sélaciens (requins et raies) du Crétacé supérieur du Bassin Anglo-Parisien ne sont que partiellement connus. L'étude de 22 faunes provenant de gisements d'âges Cénomanien à Campanien en Grande Bretagne et nord de la France a permis d'améliorer significativement les connaissances sur ces communautés de sélaciens. Les horizons échantillonnés, principalement représentés par des craies phosphatées, ont livré environ 38000 restes dentaires. Ces derniers ont permis l'identification et la description de 150 taxa comprenant 130 espèces de requins et 20 espèces de batoïdes. En plus d'un nombre important de nouvelles occurrences stratigraphiques et géographiques, cette étude décrit 25 nouvelles espèces et 7 nouveaux genres en dehors de taxa, probablement nouveaux, laissés en nomenclature ouverte. Le nombre important de taxa considérés, combiné à des données publiées sur les sélaciens du nord-ouest de l'Europe et du Western Interior Seaway, ont permis d'étudier différents événements dans la diversité de ce groupe, à travers l'utilisation de méthodes de raréfaction et de ré-échantillonnage. Plusieurs bioévénements ont pu être identifiés et corrélés à différents changements environnementaux. De nombreux aspects paléoécologiques de ces faunes sont aussi discutés. Diverses méthodes d'ordination (clusters, analyses de correspondance) ont été appliquées à la fois sur les données morpho-fonctionelles (types dentaires préalablement testés sur des faunes actuelles) et taxonomiques des 22 faunes considérées. Plusieurs facteurs environnementaux sont proposés pour expliquer la distribution observée et les affinités paléoenvironnementales de certains taxa sont discutées. Différentes mesures de diversité ont permis d'identifier l'hétérogénéité de l'habitat comme principal facteur contrôlant la diversité et dominance d'espèces dans les faunes santoniennes et campaniennes. La diversité beta des nombreuses faunes du Campanien inférieur a été étudiée et indique une absence de provincialité dans le bassin. Enfin, les comparaisons faites avec des faunes publiées du nord-ouest de l'Euro pe ont permis d'identifier les distributions paléoécologiques générales pour ce groupe. / Although studied for nearly two centuries, Late Cretaceous selachians (sharks, rays and skates) from the Anglo-Paris Basin are still imperfectly known. The study of 22 selachians (sharks, rays and skates) faunas from Cenomanian to Campanian horizons in Great Britain and northern France allowed a significant advance in our knowledge on these assemblages and their communities. The (mainly phosphatic) chalks sampled yielded about 38 000 selachian fossil remains, mostly teeth. 150 taxa, comprising 130 shark and 20 batoid species, were identified and described. In addition to the large number of new stratigraphic and geographic ranges recognised here, 25 new species and 7 new genera are described beside a number of new taxa that are left in open nomenclature. The large number of taxa included in this work, along with other published data from NW Europe and Western Interior Seaway, allowed diversity patterns of Late Cretaceous selachians to be studie d through the use of various rarefaction and re-sampling methods. The various bioevents identified could all be correlated to global environmental changes such as temperature and sea level variations as well as changes in water mass distribution. Several palaeoecological aspects of these assemblages are also discussed. The use of morpho-functional dental types provided a promising approach area in assessing changes in the morpho-functional structure of some modern selachian assemblages depending on environmental conditions. Ordination methods (clusters, CA) used on both the taxonomic and morpho-functional structure of the faunas considered here, allowed the identification of groupings among the different assemblages. Accordingly, various environmental factors are proposed to explain the observed distribution and the palaeoenvironmental affinities of some taxa are discussed. Diversity measurements proved to be rich in information and allowed the identification of habitat hete rogeneity as the main controlling factor on the diversity and evenness of the Santonian-Campanian faunas. The beta diversity of the numerous Early Campanian faunas is also discussed and indicates low provinciality in the basin. Finally, comparisons with other assemblages from other NW basins allowed general palaeoecological distributions to be identified.

As a result of ground water pumping in the Střeleč quarry there has been developed a depression in ground water surface during recent 30 years impacting an area of approx. 10 km2 . Due to the existence of steep hydraulic gradient in the quarry surroundings subsurface erosion occurs resulting in a development of underground channels. The biggest one developed in the years 2000 - 2002. Its length was 300 m reaching in some place the height of 17 m. During field works in the quarry in the years 2009 - 2010 the only accessible channel was mapped. In the channel two main types of cracks were discovered. On the crossing of these cracks slumping of the sandstone occurs which causes difficulties for the mining company. A hydraulic gradient higher than 5% was determined to be critical for sand transport in the channels and widening the initial conduits into channels. The channel development and releasing of static ground water reserves also influenced chemical composition of ground water emerging in the quarry. In the period of the most intensive channel development in 2001 the ratio of ground water from static reserves on the total amount pumped was 56%. Also in this period the concentration of sulphates in the ground water of the streams in the quarry decreased significantly. In the year 2010 there were...