Cette étude vise à caractériser selon une approche multi-échelles et multi-techniques les propriétés structurales et pétrophysiques de deux analogues de surface de réservoirs de socle développés en contexte extensif. Cette démarche permet de proposer un modèle conceptuel de réservoir de socle à hydrocarbures pour chacun de ces systèmes étudiés. Ces modèles contribuent à améliorer la compréhension de ces systèmes pétroliers, depuis la zone de maturation jusqu’aux zones de stockage dans le socle. Cette étude représente une base pour les guides de prospection de ces réservoirs à hydrocarbures. Ce travail met en avant la distribution multi-échelles sur plus de dix ordres de grandeur de l’ensemble des éléments qui composent le réservoir, depuis l’échelle pluri- kilométrique des structures tectoniques majeures jusqu’à l’échelle infra-millimétrique de la microporosité secondaire des zones fracturées et altérées. L’étude de ces analogues met en évidence la nécessité pour ces réservoirs d’être affectés par plusieurs familles directionnelles de failles et fractures, fortement connectées. Les zones de failles majeures compartimentent le réservoir en délimitant un ensemble de blocs structuraux. Leurs intersections représentent des zones de drainage entre et au sein même de ces blocs structuraux. Les zones favorables de stockage correspondent aux zones endommagées des zones de failles, ainsi qu’aux niveaux altérés au toit du socle, développés par altération supergène lors de phases d’exhumation anté-rift. Les caractéristiques des réservoirs de socle résultent finalement de la longue évolution géodynamique de ce type de formations jusqu’à la phase de rifting et d’enfouissement du réservoir / This work aims to characterize with a multi-scale and multi-method approach the effects of both brittle deformation and weathering processes on the structural and petrophysical properties of two surface analogue case studies developed in extensive setting. This approach allows us to build a conceptual hydrocarbon basement reservoir model for both studied systems. These geological models enhance the understanding of those non-conventional petroleum systems from the maturation zone to storage in the basement. Moreover, this study can also provide information for exploration guides for those hydrocarbon reservoirs. This study points out the multi-scale distribution of all the features constituting the reservoir, over ten orders of magnitude from the pluri-kilometric scale of the major tectonics structures to the infra-millimetric scale of the secondary micro-porosity of fractured and weathered basements units. Major fault zones allow the “compartmentalization” of the reservoir by dividing it into several structural blocks. The analysis of these fault zones highlights the necessity for the basement reservoirs to be characterized by a highly connected fault and fracture system, where structure intersections represent the main fluid drainage areas between and within the reservoir’s structural blocks. The suitable fluid storage areas in these reservoirs correspond to the damage zone of the fault structures developed during the tectonic evolution of the basement and the weathered units of the basement roof developed during pre-rift exhumation phases. This study highlights therefore that basement reservoir properties are the result of the long geodynamic evolution of these rocks

The Hurricane Fault is a 250-km long, west dipping, Basin and Range-bounding normal fault in SW Utah and NW Arizona that initiated in the mid-Miocene to Pliocene. It has been primarily active in the Quaternary, with slip rates of 0.2 – 0.6 mm/yr. There are multiple hot springs along its 250-km length and multiple late Tertiary-Quaternary basaltic centers broadly parallel the fault. Possible sources of hot spring fluids include deeply-circulated meteoric water that experienced water-rock exchange at high temperatures (>100 °C) and deep-seated crustal fluids. Aside from the source of modern hot spring fluids and heat, questions about the spatio-temporal history of fluid flow along the Hurricane Fault remain unaddressed. Abundant damage zone veins, cements, and host rock alteration are present, indicative of past fluid flow. Carbonate veining and cementation is a key feature of the Hurricane Fault zone, and is the primary feature exploited to characterize the thermochemical history of fault-related paleofluids. A combination of macroscopic and microscopic carbonate observations, chemical composition, and precipitation temperature of calcite veins was used to determine past water-rock diagenetic interaction and vein evolution in the Hurricane Fault zone. Calcite iv in concretions and veins from the damage zone of the fault shows a wide range of carbon and oxygen stable isotope ratios, with δ13CPDB from -4.5 to 3.8 ‰ and δ18OPDB from -17.7 to -1.1‰. Fluid inclusion microthermometry homogenization temperatures range from 45 to 160 °C, with fluid salinities of 0 to 15 wt% NaCl calculated from melting temperatures. Combining the two datasets, two main fluids that interacted with the fault zone are inferred: (1) basin brines with a δ 18OSMOW of 9.2 ‰ and (2) altered meteoric fluids with a δ 18OSMOW of -11.9 to -8.3 ‰. Calculated dissolved CO2 δ 13CPDB (-8.5 to -1.3 ‰) indicates mixed marine carbonate and organic or magmatic sources. Fault zone diagenesis was caused by meteoric water infiltration and interaction with carbonate-rich rocks, mixed with upwelling basin brines. Fluid-rock interaction is concentrated in the damage zone, where fracture-related permeability was utilized for fluid flow. A distinct mineralization event punctuated this history, associated with basin brines that were chemically influenced by nearby basaltic magmatism. This implies a hydrologic connection between the fault and regional magmatism.

<p>Magnetic surveys are one of the principal geophysical methods employed to map the structure of basement rocks deeply buried below cover strata. In resource studies, aeromagnetic surveys are commonly acquired at regional scales (100-1000’s km2) while very few studies have attempted to resolve basement structures at site-scale (<10 >km2). In this study, high-resolution lake-based magnetic survey methods were evaluated for mapping of deeply-buried basement faults (Küçükçekmece Lagoon, Turkey; 6 km2) and a suspected meteorite impact crater (Charity Shoal, Lake Ontario; 9 km2). Total magnetic intensity (TMI) surveys were acquired using a single Overhauser magnetometer with 50-150 m line spacing. Interpretation of the magnetic data was aided by forward modelling of TMI data and depth to basement estimates using Euler and analytic signal methods. Total magnetic intensity (TMI) maps of Küçükçekmece Lagoon identify several north-northwest trending (340-350°) magnetic lineaments that are aligned with strike-slip faults mapped from offshore seismic data. The pattern of magnetic anomalies in the lagoon is consistent with extensional normal faulting of bedrock and lake sediments. Magnetic results from Charity Shoal reveal a large (>1400 nT) parabolic-shaped magnetic anomaly centered over the crater basin and an annular magnetic high (40-50 nT) corresponding with the basin rim. Modelling results exclude the origin of the CSS as a shallow glacial erosional or karst sinkhole feature and are most consistent with a pre-Paleozoic meteorite impact in the Precambrian basement.</p> / Master of Science (MSc)

Sweden's population is increasing every year, which means that cities must adapt their infrastructure to be able to follow the demographic trend. In the current situation, Stockholm plans a major expansion of its metro network where evaluating the bedrock quality is of paramount importance. For the new SL metro connection project Gula linjen that stretches between Odenplan and Arenastaden in Solna, the company WSP has previously done quality surveys of the bedrock in the area and dimensioning of the reinforcements in the planned tunnels. Previous survey of the lineaments and weakness zones in the area has been done by means of core drilling and observations in the field. This study examines if the lineaments in the area are associated to any structures below ground surface in the bedrock by examining rock samples from drill cores. A digital presentation tool called Astrock hyperdata report is evaluated in this study by comparing manual measurements of the orientation of the joints in drill cores and the software´s measurements. The studied bedrock in the drill cores varies in quality from very poor to very good. Further examinations of zones of particularly poor rock quality done in this study suggest that the two identified lineaments have different characteristics. The north-west/south-east lineament which runs parallel to the planned metro route is indicated to represent the surface trace of a water-bearing fracture zone in the bedrock. The lineament with the E/W direction is dominated by structures and fault rocks, such as fault gouge and crushed rock in the drill cores, which indicates a brittle deformation zone. For the Gula linjen project, this information becomes useful as the underground reinforcements such as bolting and grouting have to / Sveriges befolkning ökar varje år, vilket gör att städer måste anpassas och expandera för att kunna följa den demografiska utvecklingen. I Stockholm planeras i dagsläget en stor utbyggnad av dess tunnelbanenätverk där det sker mycket arbete kring utvärdering av berggrunden för att göra detta möjligt. För Stockholms lokaltrafiks (SL) tunnelbaneprojektet Gula linjen som ska gå mellan Odenplan och Solna har företaget WSP tidigare gjort kvalitetsundersökningar av berggrunden i området samt dimensioneringar av förstärkningar i de planerade tunnlarna. Studier av svaghetzoner och lineamenten i området har gjorts med hjälp av kärnborrning och fältobservationer. Denna studie undersöker om lineamenten som finns i området är kopplade till strukturer längre ner i berggrunden genom att undersöka bergprov i form av borrkärnor. Som komplement har det digitala redovisningsverktyget Astrock hyperdata report använts för att kunna jämföra strukturer i berget med de egna mätningarna i studien. Programmet kommer även att utvärderas i studien. De erhållna värdena från undersökningen på borrkärnorna varierar i kvalitet från väldigt dålig till väldigt bra. Närmare studier på zoner av särskilt dålig kvalitet tyder på att de båda lineamenten karaktäriseras av olika typer av strukturer. Det nordväst-/sydöstliga lineamentet, som går parallellt med den planerade tunnelbanesträckan, domineras av strukturer som tyder på att lineamentet representerar en vattenförande sprickzon under markytan. I lineamentet med öst-västlig riktning dominerar strukturer som tyder på förekomsten av en förkastningszon. För projektet Gula linjen blir denna information användbar då den vattenförande sprickzonen kan innebära att tunnelförstärkning med injektering måste göras för ytterligare skydd mot vatteninträngning.

Cette thèse vise à étudier les propriétés thermo-poro-mécaniques de roches de faille, à partir de l'analyse structurale et microstructurale d'une faille aujourd'hui à l'affleurement et à partir d'expériences menées en laboratoire, en vue de déterminer les processus qui contrôlent l'efficacité de deux mécanismes responsables de d'affaiblissement cosismiques : la pressurisation thermique et le mécanisme d'affaiblissement par drainage. L'étude de terrain a été conduite sur deux affleurements appartenant à une faille décrochante potentiellement active appartenant au système de failles du Chugoku occidental (Japon) : la faille d'Usukidani. Le travail expérimental a quant à lui été mené dans le laboratoire de déformation des roches de l'Université de Kyoto. Les résultats majeurs de ce travail sont exposés ci-dessous. <br /> Les propriétés hydrologiques et poro-élastiques de la gouge et de la brèche de la faille d'Usukidani ont été determinées à partir d'échantillons prélevés sur le terrain. Ces données hydrauliques ont ensuite été utilisées dans un modèle numérique afin d'évaluer l'importance du phénomène de pressurisation thermique dans le cas d'un glissement cosismique le long de la zone de glissement principale et le long de zones de glissement secondaires. Les résultats de cette modélisation suggèrent que le mécanisme de pressurisation thermique n'est efficace que si la rupture reste localisée le long des zones de glissement contenant de la gouge, avec comme facteur de contrôle l'épaisseur de cette zone de glissement. <br /> Afin d'identifier les processus dynamiques particulaires responsables de l'affaiblissement cosismique dans la zone de glissement, plusieurs essais de friction ont été menés sur une machine à cisaillement annulaire. Ces expériences ont été conduites à des vitesses cosismiques (équivalentes à 0,09, 0,9 et 1,3 m/s) en conditions humides ou conditions sèches. Les données obtenues montrent que quelles que soient les conditions d'humidité initiales, les failles simulées montrent toutes un affaiblissement lors du déplacement. Un examen détaillé des microstructures des gouges cisaillées obtenues une fois l'équilibre frictionnel atteint permet de définir deux types de microstructures impliquant deux régimes de déformation : un régime de déformation par roulement avec la formation d'agrégats argileux, et un régime de déformation par glissement avec la formation d'une zone de cisaillement complexe localisée à l'interface gouge-éponte. L'affaiblissement observé lors des expériences semble être lié à une diminution de la proportion de grains roulants par rapport à celle de grains glissants, et semble être favorisé par le développement des agrégats argileux, lesquels sont contrôlés par la teneur en eau.<br /> A partir d'un modèle numérique (P2 FEM) et des données de contrainte cisaillante obtenues lors des essais de friction, il a été possible de calculer l'évolution de la température de la gouge en fonction du déplacement. Les résultats suggèrent que la distance dc pourrait représenter la distance nécessaire à une faille pour produire et diffuser assez de chaleur afin de casser les ponts d'eau capillaire (forces d'adhésion) et ainsi permettre à l'eau contenue dans la gouge d'être libérée. Ce mécanisme est appelé mécanisme d'affaiblissement par drainage.

Die stärksten Erdbeben treten an Subduktionszonen auf, so z.B. das stärkste instrumentell jemals gemessene Erdbeben vom 22. Mai 1960 mit einer Magnitude von 9,5 Mw in Süd Chile. In dieser Arbeit werden lokal gewonnene seismologische Daten aus dem zentralen Bereich des 1960er-Bebens vorgestellt. Das seismologische Netzwerk umfasste den chilenischen Forearc zwischen Tiefseegraben und den vulkanischen Bogen zwischen 41,5°-43,5°S und überdeckte sowohl die Insel Chiloé als auch die Nord-Süd-streichende Liquiñe-Ofqui Störungszone (LOFZ). Zwischen November 2004 und Oktober 2005 konnten 364 lokale Ereignisse registriert werden. Die gewonnen Aufzeichnungen erlauben Aussagen sowohl über das aktuelle Spannungsfeld im Forearc als auch über das lokale Geschwindigkeitsmodell und die Geometrie der subduzierten Benioff-Zone. Mit einer Auswahl von P- und S-Laufzeiten von gut lokalisierbaren Erdbeben wurden ein Minimum 1-D Geschwindigkeitsmodell, Stationsresiduen und die Hypozentralparameter invertiert. Dieses Geschwindigkeitsmodell diente als Startmodell für die 2-D Tomographie. Das 2-D vp-Modell zeigt eine Zone erhöhter Geschwindigkeiten unterhalb des Längstals und des östlichen Bereiches der Insel Chiloé, die als Mantelaufwölbung interpretiert werden kann. Die Benioff-Zone wird als eine mit ca. 30° ostwärts einfallende Struktur abgebildet. Die seismische Hauptaktivität findet parallel zur Küste der Insel Chiloé in Tiefen zwischen 12 und 30 km statt; es handelt sich um Beben, die wahrscheinlich auf der Plattengrenzfläche stattfinden. In Tiefen über 70 km lässt die Seismizität bereits stark nach, die tiefsten Beben wurden in 120 km Tiefe registriert. Die Abwesenheit tieferer Seismizität wird auf das junge Alter (und eine damit verbundene hohe Temperatur) der ozeanischen Platte zurückgeführt. Neben der Seismizität in der Benioff-Zone treten flache, krustale Beben in verschiedenen Häufungen entlang des magmatischen Bogens auf. Diese Bereiche erhöhter Seismizität sind räumlich mit der LOFZ und den Vulkanen Chaitén, Michinmahuida und Corcovado verknüpft. Beben bis zu einer Magnitude von 3,8 Mw zeigen die gegenwärtige Aktivität der LOFZ. Herdflächen entlang der LOFZ wurden aus Momententensor-Inversion anhand von Amplitudenspektren von Raumwellen gewonnen. Ergebnisse einer Spannungsfeldinversion zeigen ein Blattverschiebungsregime für den magmatischen Bogen und ein Überschiebungsregime für Beben in der Benioff-Zone auf. Die hier gemachten seismologischen Beobachtungen, zusammen mit teleseismischen Erdbeben und geologischen Befunden, unterstützen die Modellvorstellung eines sich nordwärts bewegenden kontinentalen Forearc-Blocks für Süd Chile. / While the northern and central part of the South American subduction zone has been intensively studied, the southern part has attracted less attention, which may be due to its difficult accessibility and lower seismic activity. However, the southern part exhibits strong seismic and tsunamogenic potential with the prominent example of the Mw=9.5 May 22, 1960 Valdivia earthquake. In this study data from an amphibious seismic array (Project TIPTEQ) is presented. The network reached from the trench to the active magmatic arc incorporating the Island of Chiloé and the north-south trending Liquiñe-Ofqui fault zone (LOFZ). 364 local events were observed in an 11-month period from November 2004 until October 2005. The observed seismicity allows to constrain for the first time the current state of stress of the subducting plate and magmatic arc, as well as the local seismic velocity structure. The downgoing Benioff zone is readily identifiable as an eastward dipping plane with an inclination of ~30°. Main seismic activity occurred predominantly in a belt parallel to the coast of Chiloé Island in a depth range of 12-30 km, which is presumably related to the plate interface. The down-dip termination of abundant intermediate depth seismicity at approximately 70 km depth seems to be related to the young age (and high temperature) of the oceanic plate. A high-quality subset of events was inverted for a 2-D velocity model. The vp model resolves the sedimentary basins and the downgoing slab. Increased velocities below the longitudinal valley and the eastern part of Chiloé Island suggest the existence of a mantle bulge. Apart from the events in the Benioff Zone, shallow crustal events were observed mainly in different clusters along the magmatic arc. These crustal clusters of seismicity are related to the LOFZ, as well as to the volcanoes Chaitén, Michinmahuida and Corcovado. Seismic activity up to a magnitude of 3.8 Mw reveals the recent activity of the fault zone. Focal mechanisms for the events along the LOFZ were calculated using a moment tensor inversion of amplitude spectra for body waves which mostly yield strike-slip mechanisms indicating a SW-NE striking of sigma_1 for the LOFZ. Focal mechanism stress inversion indicates a strike-slip regime along the arc and a thrust regime in the Benioff zone. The observed deformation - which is also revealed by teleseismic observations - suggests a confirmation for the proposed northward movement of a forearc sliver acting as a detached continental micro-plate.

Ever since the first plate-tectonic model for the Appalachians was proposed, the Laurentian margin has been interpreted as having experienced a collision-related dynamo-thermal event during the Middle Ordovician Taconic orogeny. In the western Newfoundland Appalachians, evidence for this collision is well-preserved in the Dashwoods subzone. Nevertheless, rocks of the neighbouring Corner Brook Lake block (CBLB), which is located in the heart of the Laurentian realm, did not show evidence for such an event. Instead, it was affected by Early Silurian Salinic deformation and associated peak metamorphism. Even though this difference in Early Palaeozoic tectonic history between the Dashwoods and the CBLB is widely known, it has not been satisfactorily explained. To better understand the Early Palaeozoic history of the region, in particular to test and better explain the lack of a Taconic dynamo-thermal event in the CBLB, field mapping, microscopic work, and U-Pb and 40Ar/39Ar geochronological studies were undertaken in the western and northern part of the Dashwoods subzone, and in the southern part of the CBLB. In addition, the kinematic history of the Baie Verte-Brompton Line - Cabot Fault Zone (BCZ), the tectonic zone that separates the two unique tectonic fragments, was studied. The western and northern parts of the Dashwoods subzone contain variably foliated igneous units of Middle Ordovician age (ca. 460 Ma) that are associated with the regionally voluminous Notre Dame continental arc. A ca. 455 Ma conjugate set of late syn-tectonic pegmatite dykes in the BCZ demonstrates a dextral sense of shear along the BCZ (DBCZ-1) during the Late Ordovician to earliest Silurian, and constrains the minimum age of the main phase of ductile deformation in the Dashwoods subzone. The fault-bounded CBLB has been affected by a single west-vergent deformational event, constrained between ca. 434 and ca. 427 Ma. More importantly, no evidence – neither petrographic nor geochronological – is present that would indicate that the CBLB was affected by a significant Taconic dynamo-thermal event. Hence, the CBLB and Dashwoods could not have been juxtaposed until after the late Early Silurian. Furthermore, the basement to the CBLB is devoid of any Grenville (sensu lato; ca. 1.0-1.3 Ga) U-Pb ages, which is in sharp contrast with crystalline basement elsewhere in the region, such as the Long Range Inlier. Therefore, it is highly unlikely that the CBLB represents the para-autochthonous leading edge of the Laurentian craton in the Newfoundland Appalachians, as commonly accepted. The CBLB is interpreted as a suspect terrane that has moved over 500 km parallel to the strike of the orogen. Docking to the external Humber Zone is likely to have occurred during the Early Silurian. Final juxtaposition with the Dashwoods took place after the late Early Silurian (post-Salinic) as a result of protracted dextral movement along the BCZ (DBCZ-2 and DBCZ-5). Current tectonic models for the Newfoundland Appalachians mainly focus on well-documented Early Palaeozoic orthogonal convergence of various terranes with the Laurentian margin, but large-scale orogen-parallel movements have rarely been considered. The possibility of large-scale strike-slip tectonics documented here, in addition to the convergent motions, may have significant implications for the tectonic interpretation of the Early Palaeozoic evolution of the Newfoundland Appalachians.

Enhancement methods applied on various satellite images (ASTER, ETM and RADAR SAT-1) facilitated the identification and mapping of tectonic fractures in the Zagros fold-and-thrust belt in southwest Iran. The results of the fracture analysis on these enhanced images reveal four principal fracture sets within each fold structure: (i) an axial set defined by normal faults oriented parallel to the fold axial trace, (ii) a cross-axial, extensional fracture set oriented perpendicular to the fold axial trace, (iii) and two sets of intersecting shear fractures, oriented at an acute angle to the cross-axial set. Study of the enhanced images also revealed five fracture sets along the Kazerun fault zone: (i) Riedel R- and R'-shear fracture sets, (ii) extensional T fracture set oriented at a high angle to the trace of the main Kazerun fault, (iii) oblique, synthetic P-shear fracture set, at a low angle to the trace of the main Kazerun fault, and (iv) synthetic Y-shear displacement fracture set, oriented sub-parallel to the main trace of the fault. The estimated mean azimuths of the shortening that developed the fold- and fault-related fracture systems are remarkably close, and are oriented perpendicular to the general NW-SE trend of the Zagros fold-and-thrust belt. The sampling and analysis of the fold- and fault-related fracture systems were done in a GIS environment. This study shows that an analysis of enhanced satellite images can reveal significant information on the deformation style, timing, and kinematics of the Zagros fold-and-thrust belt. This study suggests that the Zagros orogenic belt, which has mainly been forming since Miocene, due to the convergence of the Iranian and Arabian subplates, has evolved both by thin- and thick-skinned tectonics. Reconfiguration of the Precambrian basement blocks, and the ensuing slip and rotation along the Precambrian faults during the Zagros orogeny, have deformed the folds, and redistributed the fold-related fractures through rigid-body rotation.

Ever since the first plate-tectonic model for the Appalachians was proposed, the Laurentian margin has been interpreted as having experienced a collision-related dynamo-thermal event during the Middle Ordovician Taconic orogeny. In the western Newfoundland Appalachians, evidence for this collision is well-preserved in the Dashwoods subzone. Nevertheless, rocks of the neighbouring Corner Brook Lake block (CBLB), which is located in the heart of the Laurentian realm, did not show evidence for such an event. Instead, it was affected by Early Silurian Salinic deformation and associated peak metamorphism. Even though this difference in Early Palaeozoic tectonic history between the Dashwoods and the CBLB is widely known, it has not been satisfactorily explained. To better understand the Early Palaeozoic history of the region, in particular to test and better explain the lack of a Taconic dynamo-thermal event in the CBLB, field mapping, microscopic work, and U-Pb and 40Ar/39Ar geochronological studies were undertaken in the western and northern part of the Dashwoods subzone, and in the southern part of the CBLB. In addition, the kinematic history of the Baie Verte-Brompton Line - Cabot Fault Zone (BCZ), the tectonic zone that separates the two unique tectonic fragments, was studied. The western and northern parts of the Dashwoods subzone contain variably foliated igneous units of Middle Ordovician age (ca. 460 Ma) that are associated with the regionally voluminous Notre Dame continental arc. A ca. 455 Ma conjugate set of late syn-tectonic pegmatite dykes in the BCZ demonstrates a dextral sense of shear along the BCZ (DBCZ-1) during the Late Ordovician to earliest Silurian, and constrains the minimum age of the main phase of ductile deformation in the Dashwoods subzone. The fault-bounded CBLB has been affected by a single west-vergent deformational event, constrained between ca. 434 and ca. 427 Ma. More importantly, no evidence – neither petrographic nor geochronological – is present that would indicate that the CBLB was affected by a significant Taconic dynamo-thermal event. Hence, the CBLB and Dashwoods could not have been juxtaposed until after the late Early Silurian. Furthermore, the basement to the CBLB is devoid of any Grenville (sensu lato; ca. 1.0-1.3 Ga) U-Pb ages, which is in sharp contrast with crystalline basement elsewhere in the region, such as the Long Range Inlier. Therefore, it is highly unlikely that the CBLB represents the para-autochthonous leading edge of the Laurentian craton in the Newfoundland Appalachians, as commonly accepted. The CBLB is interpreted as a suspect terrane that has moved over 500 km parallel to the strike of the orogen. Docking to the external Humber Zone is likely to have occurred during the Early Silurian. Final juxtaposition with the Dashwoods took place after the late Early Silurian (post-Salinic) as a result of protracted dextral movement along the BCZ (DBCZ-2 and DBCZ-5). Current tectonic models for the Newfoundland Appalachians mainly focus on well-documented Early Palaeozoic orthogonal convergence of various terranes with the Laurentian margin, but large-scale orogen-parallel movements have rarely been considered. The possibility of large-scale strike-slip tectonics documented here, in addition to the convergent motions, may have significant implications for the tectonic interpretation of the Early Palaeozoic evolution of the Newfoundland Appalachians.

Turkey is one of the most earthquake prone countries in the world. The study area, Erbaa, is located in a seismically active fault zone known as North Anatolian Fault Zone (NAFZ). Erbaa is one of the towns of Tokat located in the Middle Black Sea Region. According to the Earthquake zoning map of Turkey, the study area is in the First Degree Earthquake Zone. The city center of Erbaa (Tokat) was previously settled on the left embankment of Kelkit River. After the disastrous 1942 Niksar-Erbaa earthquake (Mw = 7.2), the settlement was moved southwards. From the period of 1900s, several earthquakes occurred in this region and around Erbaa. The 1942 earthquake is the most destructive earthquake in the center of Erbaa settlement. In this study, the geological and geotechnical properties of the study area were investigated by detailed site investigations. The Erbaa settlement is located on alluvial and Pliocene deposits. The Pliocene clay, silt, sand, and gravel layers exist in the southern part of Erbaa. Alluvium in Erbaa region consists of gravelly, sandy, silty, and clayey layers. The alluvial deposits are composed of stratified materials of heterogeneous grain sizes, derived from various geological units in the vicinity. The main objective of this study is to prepare a seismic microzonation map of the study area for urban planning purposes since it is getting more essential to plan new settlements considering safe development strategies after the disastrous earthquakes. In this respect, seismic hazard analyses were performed to deterministically assess the seismic hazard of the study area. Afterwards, the essential ground motions were predicted regarding near fault effects as the study area is settled on an active fault zone. 1-D equivalent linear site response analyses were carried out to evaluate the site effects in the study area. Amplification values obtained from site response analyses reveal that the soil layers in the study area is quite rigid. Furthermore, liquefaction potential and post liquefaction effects including lateral spreading and vertical settlement were also delineated for the study area. The above-mentioned parameters were taken into account in order to prepare a final seismic microzonation map of the study area. The layers were evaluated on the basis of overlay methodologies including Multi-Criteria Decision Analysis (MCDA). Two different MCDA techniques, Simple Additive Weighting (SAW) and Analytical Hierarchical Process (AHP), were carried out in GIS environment. The seismic microzonation maps prepared by SAW and AHP methods are compared to obtain a final seismic microzonation map. Finally, the map derived from the AHP method is proposed to be the final seismic microzonation map of Erbaa. As an overall conclusion, the northwestern part of the study area where the loose alluvial units exist is found to be vulnerable to earthquake-induced deformations. On the other hand, the Pliocene units in the southern and alluvial units in the northeastern part are quite resistant to earthquake effects. In addition, the proposed final seismic microzonation map should be considered by urban planners and policy makers during urban planning projects in Erbaa.