scholarly journals DEFORMATION HISTORY AND CORRELATION OF PAIKON AND TZENA TERRANES (AXIOS ZONE, CENTRAL MACEDONIA, GREECE)

2017 ◽  
Vol 50 (1) ◽  
pp. 34 ◽  
Author(s):  
E. Katrivanos ◽  
A. Kilias ◽  
D. Mountrakis
Keyword(s):  
Upper Cretaceous ◽  
Crustal Thickening ◽  
Normal Faults ◽  
Polyphase Deformation ◽  
Basement Rocks ◽  
Deformation Phase ◽  
Basin Formation ◽  
Tectonic Window ◽  
Crustal Exhumation ◽  
Terrane Accretion

Paikon and Tzena terranes are situated in the centre part of Axios zone, between Almopia and Paionia ophiolitic belts. Tectonostratigraphic data reveal that both have been affected by the same polyphase deformation and metamorphism, as well that they have the same lithostratigraphic column. The first deformation phase took place during the Middle to Late Jurassic and is associated with ophiolite obduction, nappe- stacking, terrane accretion and crustal thickening (D1). Metamorphism does not exceed greenschist facies (M1). Relict HP-LT metamorphic assemblages predating M1 metamorphism are possibly developed during subduction processes and overloading of the obducted ophiolites on the continental margin, characterized the initial stages of deformation. Compressional tectonics and intense thrusting with the same kinematics continued in Lower Cretaceous time, affected all pre-Upper Cretaceous units and the obducted ophiolites (D2). This phase is associated with low-greenschist metamorphism (M2). The first main extensional event occurs in the Late Cretaceous, related to basin formation and sedimentation (D3). During Paleocene to Eocene, D4 intense imbrication of all tectonic units towards mainly SW takes place again. Nappes collapse and finally crustal exhumation taken place during Oligocene to Miocene, associated with low - angle normal faults, with a main top to the SW sense of movement (D5). In Miocene to recent times, high - angle normal and strike-slip faults are formed in an extensional to transtensional strain regime (D6), associated with Neogene to Quaternary basin formation and terrane dispersion. The basement rocks of both terranes are of Pelagonian origin, exhumed as a multiple tectonic window.

scholarly journals Neoproterozoic and post-Caledonian exhumation and shallow faulting in NW Finnmark from K–Ar dating and <i>p</i>∕<i>T</i> analysis of fault rocks

Solid Earth ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 923-951 ◽  
Author(s):  
Jean-Baptiste P. Koehl ◽  
Steffen G. Bergh ◽  
Klaus Wemmer
Keyword(s):  
Early Carboniferous ◽  
Late Carboniferous ◽  
Late Paleozoic ◽  
Normal Faults ◽  
Fault Rock ◽  
Fault Rocks ◽  
Basement Rocks ◽  
Iapetus Ocean ◽  
Tectonic Window ◽  
Brittle Faulting

Abstract. Well-preserved fault gouge along brittle faults in Paleoproterozoic, volcano-sedimentary rocks of the Raipas Supergroup exposed in the Alta–Kvænangen tectonic window in northern Norway yielded latest Mesoproterozoic (approximately 1050 ± 15 Ma) to mid-Neoproterozoic (approximately 825–810 ± 18 Ma) K–Ar ages. Pressure–temperature estimates from microtextural and mineralogy analyses of fault rocks indicate that brittle faulting may have initiated at a depth of 5–10 km during the opening of the Asgard Sea in the latest Mesoproterozoic–early Neoproterozoic (approximately 1050–945 Ma) and continued with a phase of shallow faulting to the opening of the Iapetus Ocean–Ægir Sea and the initial breakup of Rodinia in the mid-Neoproterozoic (approximately 825–810 Ma). The predominance and preservation of synkinematic smectite and subsidiary illite in cohesive and non-cohesive fault rocks indicate that Paleoproterozoic basement rocks of the Alta–Kvænangen tectonic window remained at shallow crustal levels (< 3.5 km) and were not reactivated since mid-Neoproterozoic times. Slow exhumation rate estimates for the early–mid-Neoproterozoic (approximately 10–75 m Myr−1) suggest a period of tectonic quiescence between the opening of the Asgard Sea and the breakup of Rodinia. In the Paleozoic, basement rocks in NW Finnmark were overthrusted by Caledonian nappes along low-angle thrust detachments during the closing of the Iapetus Ocean–Ægir Sea. K–Ar dating of non-cohesive fault rocks and microtexture mineralogy of cohesive fault rock truncating Caledonian nappe units show that brittle (reverse) faulting potentially initiated along low-angle Caledonian thrusts during the latest stages of the Caledonian Orogeny in the Silurian (approximately 425 Ma) and was accompanied by epidote–chlorite-rich, stilpnomelane-bearing cataclasite (type 1) indicative of a faulting depth of 10–16 km. Caledonian thrusts were inverted (e.g., Talvik fault) and later truncated by high-angle normal faults (e.g., Langfjorden–Vargsundet fault) during subsequent, late Paleozoic, collapse-related widespread extension in the Late Devonian–early Carboniferous (approximately 375–325 Ma). This faulting period was accompanied by quartz- (type 2), calcite- (type 3) and laumontite-rich cataclasites (type 4), whose cross-cutting relationships indicate a progressive exhumation of Caledonian rocks to zeolite-facies conditions (i.e., depth of 2–8 km). An ultimate period of minor faulting occurred in the late Carboniferous–mid-Permian (315–265 Ma) and exhumed Caledonian rocks to shallow depth at 1–3.5 km. Alternatively, late Carboniferous (?) to early–mid-Permian K–Ar ages may reflect late Paleozoic weathering of the margin. Exhumation rates estimates indicate rapid Silurian–early Carboniferous exhumation and slow exhumation in the late Carboniferous–mid-Permian, supporting decreasing faulting activity from the mid-Carboniferous. NW Finnmark remained tectonically quiet in the Mesozoic–Cenozoic.

scholarly journals THE NAPPE STRUCTURE OF THE TECTONIC WINDOW OF DOLIANA (CENTRAL PELOPONNESUS, GREECE)

2004 ◽  
Vol 36 (4) ◽  
pp. 1662 ◽  
Author(s):  
S. Lekkas ◽  
E. Skourtsos
Keyword(s):  
The Other ◽  
Metamorphic Rocks ◽  
Normal Faults ◽  
High Angle ◽  
Lower Miocene ◽  
The Core ◽  
Lower Oligocene ◽  
Deformation Phase ◽  
Tectonic Window ◽  
Geological Formations

In the tectonic window of Doliana (central Peloponnesus, Greece) a variety of geological formations occurs deriving from different sedimentation palaeoenvironments and characterized by different tectonometamorphic evolution. These rocks initially formed thrust nappes of great extension and thickness which stacked one over the other during the Lower Oligocene-Lower Miocene. The early compressing structures that were formed by the emplacement of the nappes were almost totally overprinted by the later-orogenic extension that affected the nappe-column in the Upper Miocene-Lower Pliocene. Its main tectonic characteristic was the formation of low-angle normal faults, which constitute the tectonic contacts of the nappes. These faults led to the exhumation of the formerly deeply buried metamorphic rocks that are forming the core of the tectonic window. Apart from these structures during the evolution of this deformation phase an intense thinning of the units of the upper plate took place, causing the upper units coming closer or next to the lower ones. After the Lower Pliocene a second extensional phase affected the already thinned nappe-column with the formation of high-angle normal faults.

Tectonique synsedimentaire d'age cretace superieur en Tunisie nord orientale; blocs bascules et reorganisation des aires de subsidence

2000 ◽  
Vol 171 (4) ◽  
pp. 431-440 ◽  
Author(s):  
Lahcen Boutib ◽  
Fetheddine Melki ◽  
Fouad Zargouni
Keyword(s):  
Structural Analysis ◽  
Upper Cretaceous ◽  
Tectonic Activity ◽  
Normal Faults ◽  
Half Graben ◽  
Combined Movements ◽  
Basin Floor ◽  
Tunisian Atlas ◽  
Facies Variation ◽  
Regional Tectonics

Abstract Structural analysis of late Cretaceous sequences from the northeastern Tunisian Atlas, led to conclude on an active basin floor instability. Regional tectonics resulted in tilted blocks with a subsidence reorganization, since the Campanian time. These structural movements are controlled both by N140 and N100-120 trending faults. The Turonian-Coniacian and Santonian sequences display lateral thickness and facies variation, due to tectonic activity at that time. During Campanian-Maastrichtian, a reorganization of the main subsidence areas occurred, the early Senonian basins, have been sealed and closed and new half graben basins developed on area which constituted previously palaeohigh structures. These syndepositional deformations are characterized by frequent slumps, synsedimentary tilting materials, sealed normal faults and progressive low angle unconformities. These tilted blocks combined to a subsidence axis migration were induced by a NE-SW trending extensional regime. This extension which affects the Tunisian margin during the Upper Cretaceous, is related to the Tethyan and Mesogean rifting phase which resulted from the combined movements of the African and European plates.

Fluid flow and faulting history of the Iano tectonic window (Southern Tuscany, Italy).

2021 ◽  
Author(s):  
Paolo Fulignati ◽  
Martina Zucchi ◽  
Andrea Brogi ◽  
Enrico Capezzuoli ◽  
Domenico Liotta ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Hydrothermal Fluids ◽  
Normal Faults ◽  
High Angle ◽  
Quartz Veins ◽  
History Of ◽  
Tectonic Window ◽  
Liquid Vapor

&lt;p&gt;In the Iano area (Southern Tuscany) a small tectonic window of Tuscan metamorphic units is observed. This belongs to the northernmost part of the so-called Mid-Tuscan ridge and, during Pliocene, formed a submarine high, now defining the easternmost shoulder of the Volterra Pliocene basin. The area gives the opportunity to investigate the complete cycle of negative inversion from crustal thickening to crustal thinning, which characterizes Southern Tuscany. Our new data focus on the western margin of the Iano ridge, and in particular on a system of high angle normal faults that represents the youngest structures of the investigated area. These structures, deformed low angle regional detachments locally juxtaposing the uppermost units of contractional nappe stack (the ophiolite-bearing Ligurian units), with the Tuscan metamorphic units, with an almost complete excision of at least 3.5 Km thick Mesozoic to Tertiary Tuscan nappe succession. The high angle normal faults show variable Plio-Quaternary vertical displacements from few meters to about 500 meters, and acted as pathways for the upwelling of hydrothermal fluids, as revealed by Pleistocene travertine deposits, hydrothermal alteration and occurrence of different generations of fluid inclusions in hydrothermal veins associated with these fault systems. Fluid inclusions were studied in quartz veins hosted in the Verrucano metasediments forming the top of the Tuscan metamorphic unit, as well as in some carbonate lithotypes (Cretaceous to Tertiary in age) of the overlying Tuscan Nappe. Two different kinds of fluid inclusions were documented. The Type 1 are multiphase (liquid + vapor + 1 daughter mineral) liquid-rich fluid inclusions whereas the Type 2 are two-phase (liquid + vapor) liquid-rich fluid inclusions. Type 1 fluid inclusions are primary in origin and were found only in quartz veins present in Verrucano metarudites, whereas Type 2 fluid inclusions occur in quartz veins present in both Verrucano phyllites and quartzites and in the carbonate units of the Tuscan Nappe. These are secondary and can be furthermore distinguished in two sub-populations (Type 2a and Type 2b) on the basis of petrographic observation and microthermometric data. Fluid inclusion investigation evidenced an evolution of the hydrothermal fluids from relatively high-T (~265&amp;#176;C) and hypersaline (35 wt.% NaCl&lt;sub&gt;equiv.&lt;/sub&gt;) fluids trapped at about 100 MPa, to lower temperature (~195&amp;#176;C) and salinity (~9.5 wt.% NaCl&lt;sub&gt;equiv.&lt;/sub&gt;) fluids, having circulated in the high-angle fault system. Based on the new data and a revision of the local tectonic setting a fluid-rock interaction history has been reconstructed with new hints and constraints for the Plio-Quaternary extensional history of the Volterra basin.&lt;/p&gt;

scholarly journals Influence of basement rocks on fluid evolution during multiphase deformation: the example of the Estamariu thrust in the Pyrenean Axial Zone

2020 ◽  
Author(s):  
Daniel Muñoz-López ◽  
Gemma Alías ◽  
David Cruset ◽  
Irene Cantarero ◽  
Cédric M. Jonh ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Crystalline Basement ◽  
Normal Faults ◽  
Published Data ◽  
Fluid Migration ◽  
Rock Interaction ◽  
Fluid Chemistry ◽  
Vein Formation ◽  
Basement Rocks ◽  
Calcite Veins

Abstract. Calcite veins precipitated in the Estamariu thrust during two tectonic events decipher the temporal and spatial relationships between deformation and fluid migration in a long-lived thrust and determine the influence of basement rocks on the fluid chemistry during deformation. Structural and petrological observations constrain the timing of fluid migration and vein formation, whilst geochemical analyses (δ13C, δ18O, 87Sr/86Sr, clumped isotope thermometry and elemental composition) of the related calcite cements and host rocks indicate the fluid origin, pathways and extent of fluid-rock interaction. The first tectonic event, recorded by calcite cements Cc1a and Cc2, is related to the Alpine reactivation of the Estamariu thrust, and is characterized by the migration of meteoric fluids, heated at depth (temperatures between 56 and 98 °C) and interacted with crystalline basement rocks before upflowing through the thrust zone. During the Neogene extension, the Estamariu thrust was reactivated and normal faults and shear fractures with calcite cements Cc3, Cc4 and Cc5 developed. Cc3 and Cc4 precipitated from hydrothermal fluids (temperatures between 127 and 208 °C and between 102 and 167 °C, respectively) derived from crystalline basement rocks and expelled through fault zones during deformation. Cc5 precipitated from low temperature meteoric waters percolating from the surface through small shear fractures. The comparison between our results and already published data in other structures from the Pyrenees suggests that regardless of the origin of the fluids and the tectonic context, basement rocks have a significant influence on the fluid chemistry, particularly on the 87Sr/86Sr ratio. Accordingly, the cements precipitated from fluids interacted with crystalline basement rocks have significantly higher 87Sr/86Sr ratios (> 0.710) with respect to those precipitated from fluids that have interacted with the sedimentary cover (

Bosphorus Volcano; Signs of an Ancient Volcano on an Ancient City

2020 ◽  
Author(s):  
Semih Can Ülgen ◽  
A.M. Celâl Şengör ◽  
Mehmet Keskin ◽  
Namık Aysal
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Contact Aureole ◽  
Magma Chambers ◽  
Basement Rocks ◽  
Ancient City ◽  
Nw Turkey ◽  
Dome Structure ◽  
Cretaceous Volcanism ◽  
Arc Volcano

&lt;p&gt;In many ancient and active volcanic provinces dyke systems represent radial and concentric patterns. In &amp;#304;stanbul, NW Turkey, late Cretaceous dykes, which are emplaced in pre-Cretaceous basement rocks consisting of sedimentary rocks of Palaeozoic and Triassic ages, have both patterns. In the region, late Cretaceous volcanism is represented by three elements, (1) The &amp;#199;avu&amp;#351;ba&amp;#351;&amp;#305; granitoid, (2) volcano-sedimentary units and (3) dykes.&lt;/p&gt;&lt;p&gt;Age of the &amp;#199;avu&amp;#351;ba&amp;#351;&amp;#305; granitoid is given as 67.91&amp;#177;0.63 to 67.59&amp;#177;0.5 Ma. It is emplaced in shallow depth and has an indistinct contact aureole. Volcano sedimentary units were deposited in an intra-arc basin. Three types of dykes are reported in the region: lamprophyre, diabase and intermediate to felsic dykes (72.49&amp;#177;0.79 to 65.44&amp;#177;0.93 Ma). Different petrology and the crystallization depths of the crystals in the dykes and the &amp;#199;avu&amp;#351;ba&amp;#351;&amp;#305; granitoid suggest two different magma chambers emplaced at two different depths, the &amp;#199;avu&amp;#351;ba&amp;#351;&amp;#305; granitoid representing the shallower one.&lt;/p&gt;&lt;p&gt;Upper Cretaceous dykes are concentrated around the &amp;#199;avu&amp;#351;ba&amp;#351;&amp;#305; granitoid and extend almost as far as 30 km away from the pluton. The intrusion of the plutonic body of the &amp;#199;avu&amp;#351;ba&amp;#351;&amp;#305; granitoid caused a dome structure in the basement rocks. The formation of this dome structure may have controlled the stress field and the orientation of the dyke system. Similar patterns are observed in the British Tertiary igneous province, Galapagos volcanoes, Boa Vista (Cape Verde), Summer Coon volcano, Spanish Peak Mountain and Dike Mountain (Colorado), Vesuvio, Etna and Stromboli (Italy).&lt;/p&gt;&lt;p&gt;We suggest that Upper Cretaceous volcanic edifice in the &amp;#304;stanbul region is related to an arc volcano similar to the andesitic volcanoes in the Sumatra Island; we name it the Bosphorus Volcano. &amp;#160;&lt;/p&gt;

The kinematic vorticity analysis of ductile shear zones of Ambaji Granulite, NW India and its tectonic implications

2020 ◽  
Author(s):  
Sudheer Kumar Tiwari ◽  
Anouk Beniest ◽  
Tapas Kumar Biswal
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Lateral Displacement ◽  
Pure Shear ◽  
Tectonic Setting ◽  
Shear Zones ◽  
Normal Faults ◽  
Temperature Phase ◽  
Brittle Ductile Transition ◽  
Deformation Phase

&lt;p&gt;The Neoproterozoic (834 &amp;#8211; 778 Ma) Ambaji granulite witnessed four deformation phases (D&lt;sub&gt;1&lt;/sub&gt;- D&lt;sub&gt;4&lt;/sub&gt;), of which the D&lt;sub&gt;2&lt;/sub&gt; deformation phase was most significant for the exhumation of granulites in the ductile regime. We performed a field study to investigate the tectonic evolution of the D&lt;sub&gt;2&lt;/sub&gt; deformation phase and investigated the deformation evolution of the ductile extrusion of the Ambaji granulite by estimating the vorticity of flow (Wm) with the Rigid Grain Net and strain ratio/orientation techniques.&lt;/p&gt;&lt;p&gt;During the D&lt;sub&gt;2&lt;/sub&gt; deformation phase, the S&lt;sub&gt;1&lt;/sub&gt; fabric was folded by F&lt;sub&gt;2&lt;/sub&gt; folds that are coaxial with the F&lt;sub&gt;1&lt;/sub&gt; folds. The F&lt;sub&gt;2&lt;/sub&gt; folds were produced in response to NW-SE compression. Because the large shear zones are oriented parallel to the axial plane of the F&lt;sub&gt;2&lt;/sub&gt; folds, they likely formed simultaneously during the D&lt;sub&gt;2&lt;/sub&gt; deformation phase. Compression during the D&lt;sub&gt;2&lt;/sub&gt; deformation phase accommodated most of the exhumation of the granulite along the shear zones. D&lt;sub&gt;2&lt;/sub&gt; shearing was constrained between 834&amp;#8239;&amp;#177;&amp;#8239;7 to 778&amp;#8239;&amp;#177;&amp;#8239;8&amp;#8239;Ma (Monazite ages).&lt;/p&gt;&lt;p&gt;The shear zones evolved from a high temperature (&gt;700&amp;#8239;&amp;#176;C) thrust-slip shearing event in the lower-middle crust to a low temperature (450&amp;#8239;&amp;#176;C) retrograde sinistral shearing event at the brittle-ductile-transition (BDT). The&amp;#160;Wm&amp;#160;estimates of 0.32&amp;#8211;0.40 and 0.60 coincide with the high temperature event and suggests pure shear dominated deformation. The low temperature phase coincides with&amp;#160;Wm&amp;#160;estimates of 0.64&amp;#8211;0.87 and ~1.0, implying two flow regimes. The shear zone was first affected by general non-coaxial deformation and gradually became dominated by simple shearing.&lt;/p&gt;&lt;p&gt;We interpreted that the high temperature event happened in a compressive tectonic regime, which led to horizontal shortening and vertical displacement of the granulite to the BDT. The low temperature event occurred in a transpressive tectonic setting that caused the lateral displacement of the granulite body at BDT depth. The Wm values indicate a non-steady strain during the exhumation of granulite. From the BDT to surface, the Ambaji granulite exhumed through the NW-SE directed extension for normal faults via brittle exhumation through crustal extension and thinning.&lt;/p&gt;

scholarly journals The Timing of Metamorphism, Magmatism, and Cooling in the Zanskar, Garhwal, and Nepal Himalaya

1995 ◽  
Vol 11 ◽  
Author(s):  
M. P. Searle
Keyword(s):  
Hanging Wall ◽  
Crustal Thickening ◽  
Indian Plate ◽  
Eastern Himalaya ◽  
Normal Faults ◽  
The Tibetan Plateau ◽  
Main Central Thrust ◽  
Southern Tibet ◽  
Peak Metamorphism ◽  
Exhumation Rates

Following India-Asia collision, which is estimated at ca. 54-50 Ma in the Ladakh-southern Tibet area, crustal thickening and timing of peak metamorphism may have been diachronous both along the Himalaya (pre-40 Ma north Pakistan; pre-31 Ma Zanskar; pre-20 Ma east Kashmir, west Garhwal; 11-4 Ma Nanga Parbat) and cross the strike of the High Himalaya, propagating S (in Zanskar SW) with time. Thrusting along the base of the High Himalayan slab (Main Central Thrust active 21-19 Ma) was synchronous with N-S (in Zanskar NE-SW) extension along the top of the slab (South Tibet Detachment Zone). Kyanite and sillimanite gneisses in the footwall formed at pressure of 8-10 kbars and depths of burial of 28-35 km, 30- 21 Ma ago, whereas anchimetamorphic sediments along the hanging wall have never been buried below ca. 5-6 km. Peak temperatures may have reached 750 on the prograde part of the P-T path. Thermobarometers can be used to constrain depths of burial assuming a continental geothermal gradient of 28-30 °C/km and a lithostatic gradient of around 3.5-3.7 km/kbar (or 0.285 kbars/km). Timing of peak metamorphism cannot yet be constrained accurately. However, we can infer cooling histories derived from thermochronometers using radiogenic isotopic systems, and thereby exhumation rates. This paper reviews all the reliable geochronological data and infers cooling histories for the Himalayan zone in Zanskar, Garhwal, and Nepal. Exhumation rates have been far greater in the High Himalayan Zone (1.4-2.1 mm/year) and southern Karakoram (1.2-1.6 mm/year) than along the zone of collision (Indus suture) or along the north Indian plate margin. The High Himalayan leucogranites span 26-14 Ma in the central Himalaya, and anatexis occurred at 21-19 Ma in Zanskar, approximately 30 Ma after the collision. The cooling histories show that significant crustal thickening, widespread metamorphism, erosion and exhumation (and therefore, possibly significant topographic elevation) occurred during the early Miocene along the central and eastern Himalaya, before the strengthening of the Indian monsoon at ca. 8 Ma, before the major change in climate and vegetation, and before the onset of E-W extension on the Tibetan plateau. Exhumation, therefore, was primarily controlled by active thrusts and normal faults, not by external factors such as climate change.

scholarly journals The Paleogene Tectonostratigraphy Of Northern Part Masalima Trench Basin

2016 ◽  
Vol 1 (1) ◽  
pp. 7
Author(s):  
Luhut Pardamean Siringoringo ◽  
Dardji Noeradi
Keyword(s):  
Depositional Environment ◽  
Middle Eocene ◽  
Normal Faults ◽  
Tectonic Structure ◽  
Shallow Marine ◽  
Early Oligocene ◽  
Basin Formation ◽  
Java Sea ◽  
Seismic Sections ◽  
Well Data

Northern part of Masalima Trench Basin is located in the southern part of the Strait of Makassar, which includes Masalima Trough and Massalima High. The area of research is an extension of the South Makassar Basin which extends from South Makassar Basin to the Northeast part of Java Sea. Subsurface data are used such as 2D seismic sections (21 lines) and data drilling wells (2 wells) to understand the tectonic structure in the basin formation and understand the stratigraphic order of basin. Based on well data can be known that Northern part Masalima Trench Basin is aborted rift because marked by post rift phase. Northern part Masalima Trench Basin was formed by normal faults which have trend northeast-southwest with  pre rift, early syn rift, late syn rift, and post rift sediment geometry. Early syn rift sediment was Middle Eocene, late syn rift sediment was Middle Eocene till Early Oligocene and post rift sediment was Early Oligocene till Early Miocene. The Depositional environment of early syn rift phase such as beach, shallow marine, and land. The Depositional environment of late syn rift phase such as beach till deep marine, and the depositional environment of post rift is deep marine.

scholarly journals Neoproterozoic and post-Caledonian exhumation and shallow faulting in NW Finnmark from K/Ar dating and p/T analysis of fault-rocks

2018 ◽  
Author(s):  
Jean-Baptiste P. Koehl ◽  
Steffen G. Bergh ◽  
Klaus Wemmer
Keyword(s):  
Sedimentary Rocks ◽  
Fault Gouge ◽  
Fault Rocks ◽  
Northern Norway ◽  
Basement Rocks ◽  
Iapetus Ocean ◽  
Tectonic Window ◽  
Brittle Faulting ◽  
Early Neoproterozoic

Abstract. Well-preserved fault gouge along brittle faults in Paleoproterozoic, volcano-sedimentary rocks of the Raipas Group exposed in the Alta-Kvænangen tectonic window in northern Norway yielded latest Mesoproterozoic (ca. 1050 ± 15 Ma) to mid Neoproterozoic (ca. 825–810 ± 18 Ma) K/Ar ages. Pressure-temperature estimates from microtextural and mineralogy analyses of fault-rocks indicate that brittle faulting may have initiated at depth of 5–10 km during the opening of the Asgard Sea in the latest Mesoproterozoic-early Neoproterozoic (ca. 1050–945 Ma), and continued with a phase of shallow faulting during to the opening of the Iapetus Ocean-Ægir Sea and the initial breakup of Rodinia in the mid Neoproterozoic (ca. 825–810 Ma). The predominance and preservation of synkinematic smectite and subsidiary illite in cohesive and non-cohesive fault-rocks indicate that Paleoproterozoic basement rocks of the Alta-Kvænangen tectonic window remained at shallow crustal levels (

Sign in / Sign up

Export Citation Format

Share Document