Low-temperature thermochronology of fault zones

2020 ◽  
Author(s):  
Takahiro Tagami
Keyword(s):  
Low Temperature ◽  
Fault Zone ◽  
Fission Track ◽  
Thermal Sensitivity ◽  
Fault Zones ◽  
Fault System ◽  
Vein Formation ◽  
Fission Track Thermochronology ◽  
Mineral Vein ◽  
Host Rocks

<p>Thermal signatures as well as timing of fault motions can be constrained by thermochronological analyses of fault-zone rocks (e.g., Tagami, 2012, 2019).  Fault-zone materials suitable for such analyses are produced by tectocic and geochemical processes, such as (1) mechanical fragmentation of host rocks, grain-size reduction of fragments and recrystallization of grains to form mica and clay minerals, (2) secondary heating/melting of host rocks by frictional fault motions, and (3) mineral vein formation as a consequence of fluid advection associated with fault motions.  The geothermal structure of fault zones are primarily controlled by the following three factors: (a) regional geothermal structure around the fault zone that reflect background thermo-tectonic history of studied province, (b) frictional heating of wall rocks by fault motions and resultant heat transfer into surrounding rocks, and (c) thermal influences by hot fluid advection in and around the fault zone.  Geochronological/thermochronological methods widely applied in fault zones are K-Ar (<sup>40</sup>Ar/<sup>39</sup>Ar), fission-track (FT), and U-Th methods.  In addition, (U-Th)/He, OSL, TL and ESR methods are applied in some fault zones, in order to extract temporal information related to low temperature and/or recent fault activities.  Here I briefly review the thermal sensitivity of individual thermochronological systems, which basically controls the response of each method against faulting processes.  Then, the thermal sensitivity of FTs is highlighted, with a particular focus on the thermal processes characteristic to fault zones, i.e., flash and hydrothermal heating.  On these basis, representative examples as well as key issues, including sampling strategy, are presented to make thermochronological analysis of fault-zone materials, such as fault gouges, pseudotachylytes and mylonites, along with geological, geomorphological and seismological implications.  Finally, the thermochronological analyses of the Nojima fault are overviewed, as an example of multidisciplinary investigations of an active seismogenic fault system.</p><p> </p><p>References:</p><ol><li>Tagami, 2012. Thermochronological investigation of fault zones. Tectonophys., 538-540, 67-85, doi:10.1016/j.tecto.2012.01.032.</li> <li>Tagami, 2019. Application of fission track thermochronology to analyze fault zone activity. Eds. M. G. Malusa, P. G. Fitzgerald, Fission track thermochronology and its application to geology, 393pp, 221-233, doi: 10.1007/978-3-319-89421-8_12.</li> </ol>

Recent and active deformation in the North Evia domain, a diffuse plate boundary between Eurasia and Aegean plates in the Western termination of the North Anatolian Fault. 

2021 ◽  
Author(s):  
Fabien Caroir ◽  
Frank Chanier ◽  
Virginie Gaullier ◽  
Julien Bailleul ◽  
Agnès Maillard-Lenoir ◽  
...  
Keyword(s):  
Fault Zone ◽  
Plate Boundary ◽  
Fault Zones ◽  
North Anatolian Fault ◽  
Fault System ◽  
Eurasian Plate ◽  
Slip Rates ◽  
The North ◽  
South West ◽  
North Aegean

<p>The Anatolia-Aegean microplate is currently extruding toward the South and the South-West. This extrusion is classically attributed to the southward retreat of the Aegean subduction zone together with the northward displacement of the Arabian plate. The displacement of Aegean-Anatolian block relative to Eurasia is accommodated by dextral motion along the North Anatolian Fault (NAF), with current slip rates of about 20 mm/yr. The NAF is propagating westward within the North Aegean domain where it gets separated into two main branches, one of them bordering the North Aegean Trough (NAT). This particular context is responsible for dextral and normal stress regimes between the Aegean plate and the Eurasian plate. South-West of the NAT, there is no identified major faults in the continuity of the NAF major branch and the plate boundary deformation is apparently distributed within a wide domain. This area is characterised by slip rates of 20 to 25 mm/yr relative to Eurasian plate but also by clockwise rotation of about 10° since ca 4 Myr. It constitutes a major extensional area involving three large rift basins: the Corinth Gulf, the Almiros Basin and the Sperchios-North Evia Gulf. The latter develops in the axis of the western termination of the NAT, and is therefore a key area to understand the present-day dynamics and the evolution of deformation within this diffuse plate boundary area.</p><p>Our study is mainly based on new structural data from field analysis and from very high resolution seismic reflexion profiles (Sparker 50-300 Joules) acquired during the WATER survey in July-August 2017 onboard the R/V “Téthys II”, but also on existing data on recent to active tectonics (i.e. earthquakes distribution, focal mechanisms, GPS data, etc.). The results from our new marine data emphasize the structural organisation and the evolution of the deformation within the North Evia region, SW of the NAT.</p><p>The combination of our structural analysis (offshore and onshore data) with available data on active/recent deformation led us to define several structural domains within the North Evia region, at the western termination of the North Anatolian Fault. The North Evia Gulf shows four main fault zones, among them the Central Basin Fault Zone (CBFZ) which is obliquely cross-cutting the rift basin and represents the continuity of the onshore Kamena Vourla - Arkitsa Fault System (KVAFS). Other major fault zones, such as the Aedipsos Politika Fault System (APFS) and the Melouna Fault Zone (MFZ) played an important role in the rift initiation but evolved recently with a left-lateral strike-slip motion. Moreover, our seismic dataset allowed to identify several faults in the Skopelos Basin including a large NW-dipping fault which affects the bathymetry and shows an important total vertical offset (>300m). Finally, we propose an update of the deformation pattern in the North Evia region including two lineaments with dextral motion that extend southwestward the North Anatolian Fault system into the Oreoi Channel and the Skopelos Basin. Moreover, the North Evia Gulf domain is dominated by active N-S extension and sinistral reactivation of former large normal faults.</p>

The Miocene plutonic event of the Patagonian Batholith at 44° 30′ S: thermochronological and geobarometric evidence for melting of a rapidly exhumed lower crust

2000 ◽  
Vol 91 (1-2) ◽  
pp. 169-179 ◽  
Author(s):  
M. A. Parada ◽  
A. Lahsen ◽  
C. Palacios
Keyword(s):  
Late Miocene ◽  
Lower Crust ◽  
Fission Track ◽  
Strike Slip ◽  
Fault System ◽  
Apatite Fission Track ◽  
Axial Zone ◽  
Exhumation Rates ◽  
Fission Track Ages ◽  
Host Rocks

The Patagonian Batholith was formed by numerous plutonic events that took place between the Jurassic and the Miocene. North of 47° S, the youngest plutons occupy the axial zone adjacent to the Liquiñe-Ofqui Fault Zone, which is a major intra-arc strike-slip fault system active since the Miocene. The Queulat Complex, located at 44° 30′ S, includes two Miocene plutonic units: the Early Miocene Queulat diorite (QD) and the Late Miocene Puerto Cisnes granite (PCG). The QD includes hornblende + clinopyroxene diorites and tonalites, whereas the PCG includes slightly peraluminous garnet ± sillimanite granites and granodiorites.Eleven mineral Ar–Ar ages and three apatite fission track ages were obtained from the Queulat Complex and surrounding host rocks. Hornblende and biotite Ar–Ar ages of c. 16-18 Ma and 9-10 Ma, respectively, were obtained for the QD. The youngest ages of the QD are similar to the age of emplacement of the PCG as previously determined. Ar–Ar ages for muscovites and biotites of 6·6 ± 0·3 Ma and 5·6 ± 0·1 Ma, respectively, were obtained for the PCG. Biotites and muscovites from mylonites and pelitic hornfelses adjacent to the PCG yielded Ar—Ar ages between 5·1 Ma and 5·5 Ma. The apatite fission track ages of the QD and PCG overlap within the error margin (2•2 ± 1·1-3·3 ± 1·4 Ma).The Al-in-hornblende geobarometer yielded pressures for the QD emplacement equivalent to depths in the 19-24 km range, which is substantially higher than the 10 km depth estimated previously for the PCG emplacement. Exhumation rates (v) up to 2·0mm/yr were calculated for the time elapsed between the QD and PCG emplacements. A v value of 1·0mm/yr was calculated for the PCG subsequent to its emplacement. Using the silica—Ca-tschermak-anorthite geobarometer, we estimate the QD magma generation to be at c. 33 km, which is similar to the current crustal thickness. Melting of mafic and metapelitic lower crust was possible at > 30km depth during a period when v was between 1·0mm/yr and 2·0mm/yr.

Faults and magma reservoirs along the Southern Andes Volcanic zone (SAVZ): linking oservations and numerical models of stress change controlling magmatic and hydrothermal fluid flow

2020 ◽  
Author(s):  
Javiera Ruz ◽  
Muriel Gerbault ◽  
José Cembrano ◽  
Pablo Iturrieta ◽  
Camila Novoa Lizama ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Stress Field ◽  
Fault Zone ◽  
Numerical Models ◽  
Fluid Pressure ◽  
Seismic Inversion ◽  
Fault Zones ◽  
Fault System ◽  
Far Field ◽  
Trigger Failure

<p> The Chilean margin is amongst the most active seismic and volcanic areas on Earth. It hosts active and fossil geothermal and mineralized systems of economic interest documenting significant geofluid migration through the crust. By comparing numerical models with field and geophysical data, we aim at pinning when and where fluid migration occurs through porous domains, fault zone conduits, or remains stored at depth awaiting a more appropriate stress field. <span>Dyking and volcanic activity occur within fault zones</span> <span>along the S</span><span>A</span><span>VZ, linked with stress field variations</span> <span>in spatial and temporal association with</span> –<span>short therm-</span> <span>seismicity</span> <span>and -long term- oblique </span><span>plate </span><span>convergence.</span> <span>Volcanoes and geothermal domains are mostly located along or at the intersection of margin-oblique fault zones (Andean Transverse Faults), and along margin-parallel strike slip zones, some which may cut the entire lithosphere (Liquiñe-Ofqui fault system). Wh</span><span>ereas</span><span> the big picture displays</span> <span>fluid flow straight to the surface, at close look significant offsets between crustal structures occur. 3D numerical models using conventional elasto-plastic rheology provide insights on the interaction of (i) an inflating magmatic cavity, (ii) a slipping fault zone, and (iii) regional tectonic stresses. Applying either (i) a magmatic overpressure or (ii) a given fault slip can trigger failure of the intervening rock, and generate either i) fault motion or ii) magmatic reservoir failure, respectively, but only for distances less than the structures' breadth even at low rock</span> <span>strength. However, at greater inter-distances the bedrock domain in between the fault zone and the magmatic cavity undergoes dilatational strain of the order of 1-5x10-5. This dilation opens the bedrock’s pore space and forms «pocket domains» that may store up-flowing over-pressurized fluids, which may then further chemically</span> interact<span> with the bedrock, for the length of time</span> <span>that</span> <span>these pockets remain open. These porous pockets</span> <span>can reach kilometric size, questioning their parental link with outcropping plutons along the margin. Moreover, bedrock permeability may also increase as fluid flow diminishes effective bedrock friction and cohesion. Comparison with rock experiments indicates that such stress and fluid pressure changes may eventually trigger failure at the intermediate timescale (repeated slip or repeated inflation). Finally, incorporating far field compression (iii)</span> <span>loads the bedrock to</span> <span>a state of stress at the verge of failure. Then, failure around the magmatic </span><span>reservoir</span><span> or </span><span>at</span> <span>the fault zone occurs for lower load</span><span>ing</span><span>.</span> <span>Permanent tectonic loading on the one hand, far field episodic seismic inversion of the stress field on the other, and localized failure all together promote a transient stress field, thus explaining the occurrence of transient fluid pathways on seemingly independent timescales. These synthetic models are then discussed with regards to specific cases along the SVZ, particularly the Tatara-San Pedro area (~36°S), where magnetotelluric profiles </span><span>document</span><span> conductive volumes at different depths underneath active faults, volcanic edifices and geothermal vents. We discuss the mechanical link between these deep sources and surface structures</span>.</p>

scholarly journals The role of oroclinal bending in the structural evolution of the Central Anatolian Plateau: evidence of a regional changeover from shortening to extension

2011 ◽  
Vol 62 (4) ◽  
pp. 345-359 ◽  
Author(s):  
Erman Özsayin ◽  
Kadir Dirik
Keyword(s):  
Fault Zone ◽  
Structural Evolution ◽  
Shear Zones ◽  
Fault Zones ◽  
Fault System ◽  
Western Boundary ◽  
Southeastern Part ◽  
Anatolian Plateau ◽  
Isparta Angle

The role of oroclinal bending in the structural evolution of the Central Anatolian Plateau: evidence of a regional changeover from shortening to extensionThe NW-SE striking extensional Inönü-Eskişehir Fault System is one of the most important active shear zones in Central Anatolia. This shear zone is comprised of semi-independent fault segments that constitute an integral array of crustal-scale faults that transverse the interior of the Anatolian plateau region. The WNW striking Eskişehir Fault Zone constitutes the western to central part of the system. Toward the southeast, this system splays into three fault zones. The NW striking Ilıca Fault Zone defines the northern branch of this splay. The middle and southern branches are the Yeniceoba and Cihanbeyli Fault Zones, which also constitute the western boundary of the tectonically active extensional Tuzgölü Basin. The Sultanhanı Fault Zone is the southeastern part of the system and also controls the southewestern margin of the Tuzgölü Basin. Structural observations and kinematic analysis of mesoscale faults in the Yeniceoba and Cihanbeyli Fault Zones clearly indicate a two-stage deformation history and kinematic changeover from contraction to extension. N-S compression was responsible for the development of the dextral Yeniceoba Fault Zone. Activity along this structure was superseded by normal faulting driven by NNE-SSW oriented tension that was accompanied by the reactivation of the Yeniceoba Fault Zone and the formation of the Cihanbeyli Fault Zone. The branching of the Inönü-Eskişehir Fault System into three fault zones (aligned with the apex of the Isparta Angle) and the formation of graben and halfgraben in the southeastern part of this system suggest ongoing asymmetric extension in the Anatolian Plateau. This extension is compatible with a clockwise rotation of the area, which may be associated with the eastern sector of the Isparta Angle, an oroclinal structure in the western central part of the plateau. As the initiation of extension in the central to southeastern part of the Inönü-Eskişehir Fault System has similarities with structures associated with the Isparta Angle, there may be a possible relationship between the active deformation and bending of the orocline and adjacent areas.

scholarly journals CENOZOIC TECTONIC EVOLUTION OF THE EASTERN ALPS – A RECONSTRUCTION BASED ON 40AR/39AR WHITE MICA, ZIRCON AND APATITE FISSION TRACK, AND APATITE (U/Th)-He THERMOCHRONOLOGY

2017 ◽  
Vol 43 (1) ◽  
pp. 299
Author(s):  
W. Kurz ◽  
A. Wölfler ◽  
R. Handler
Keyword(s):  
Tectonic Evolution ◽  
Fission Track ◽  
Eastern Alps ◽  
White Mica ◽  
Fault Zones ◽  
Apatite Fission Track ◽  
Major Fault ◽  
Fission Track Ages ◽  
Fault Gouges ◽  
Host Rocks

The Cenozoic tectonic evolution of the Eastern Alps is defined by nappe assembly within the Penninic and Subpenninic units and their subsequent exhumation. The units above, however, are affected by extension and related faulting. By applying distinct thermochronological methods with closure temperatures ranging from ~450° to ~40°C we reveal the thermochronological evolution of the eastern part of the Eastern Alps. 40Ar/39Ar dating on white mica, zircon and apatite fission track, and apatite U/Th-He thermochronology were carried out within distinct tectonic units (Penninic vs. Austroalpine) and on host rocks and fault- related rocks (cataclasites and fault gouges) along major fault zones. We use particularly the ability of fission tracks to record the thermal history as a measure of heat transfer in fault zones, causing measurable changes of fission track ages and track lengths. Additionally, these studies will provide a general cooling and exhumation history of fault zones and adjacentcrustal blocks.

Thermo-tectonic imaging of the Afro-Arabian Rift System

2020 ◽  
Author(s):  
Samuel Boone ◽  
Fabian Kohlmann ◽  
Maria-Laura Balestrieri ◽  
Malcolm McMillan ◽  
Barry Kohn ◽  
...  
Keyword(s):  
Low Temperature ◽  
Red Sea ◽  
Fission Track ◽  
Normal Fault ◽  
Eastern Africa ◽  
Fault System ◽  
Rift System ◽  
Gulf Of Aden ◽  
Apatite Fission Track ◽  
Continental Scale

<p>Low-temperature thermochronology has long been utilised in the Afro-Arabian Rift System (AARS) to examine exhumation cooling histories of normal fault footwalls and elucidate rifting chronologies where datable syn-rift strata and/or markers are absent. In particular, apatite fission track (AFT) and (U-Th)/He (AHe) analyses have constrained the timing and rate of rift-related, upper crustal thermal perturbations between ~30 and 120 °C (up to ~5 km depth). In turn, these provide insights into the spatio-temporal evolution of individual rift basins, morphotectonic rift shoulder development, normal fault system growth and, in some cases, the thermal influence of igneous intrusions and circulation of hot fluids. However, the relatively limited number of samples and confined areas generally involved in individual case studies have precluded insights into longer wavelength tectonic and geodynamic phenomena, such as regional denudation trends and the growth of topography due to plume impingement.</p><p>Here, we present a synthesis of >2000 apatite fission track (AFT) and ~1000 (U-Th)/He (AHe) analyses from the Eocene-Recent AARS collated using LithoSurfer, a new cloud-based geoscience data platform. This continental-scale low-temperature thermochronology synthesis, the first of its kind in Africa, provides novel insights into the upper crustal evolution of the AARS that were previously difficult to decipher from an otherwise cumbersome and intractably large dataset. The data record a series of pronounced episodes of upper crustal cooling related to the development of the Red Sea, Gulf of Aden and East African Rift System (EARS). They also provide insights into the inherited tectono-thermal histories of these regions which controlled the spatial and temporal distribution of subsequent extensional strain.</p><p>Thermochronology data trends along the AARS reflect a combination of rift maturity, structural geometry and geothermal regime, intrinsically linked to lithospheric architecture and magmatic activity. These relationships are best illustrated by contrasting the upper crustal thermal evolution of different AARS segments of varying age and complexity: for example, between the nascent Okavango, mature Ethiopian and evolved Red Sea rifts, wide (e.g. Turkana Depression) versus narrow (e.g. Main Ethiopian Rift) zones of deformation, between areas of transtensional (Dead Sea Transform), oblique (e.g. Gulf of Aden) and sub-orthogonal rifting (e.g. Malawi Rift), and the magmatic eastern versus amagmatic western branches of the EARS.</p><p>A regional interpolation of standardised thermal history models generated from the mined AFT, AHe and, in some cases, vitrinite reflectance data yield Mesozoic-recent heat maps, extrapolated to produce paleo-denudation and burial histories for eastern Africa and Arabia. Integrating these thermotectonic images with other regional datasets allows for the interrelationship between tectonic and dynamic topography development, the denudation history of the land surface, and sediment transport and deposition to be explored in new ways.</p><p> </p>

scholarly journals Fluid Inclusions Record Hydrocarbon Charge History in the Shunbei Area, Tarim Basin, NW China

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Ziye Lu ◽  
Yingtao Li ◽  
Ning Ye ◽  
Shaonan Zhang ◽  
Chaojin Lu ◽  
...  
Keyword(s):  
Fault Zone ◽  
Fluid Inclusions ◽  
Tarim Basin ◽  
Homogenization Temperature ◽  
Fault Zones ◽  
Carbonate Reservoirs ◽  
Fault System ◽  
Middle Ordovician ◽  
History Of ◽  
Hydrocarbon Charge

The exploration of deeply buried hydrocarbon is still a challenge for the petroleum geology. The Shunbei area is a newly discovered oil fields, located in the center of the Tarim Basin. The oil is mainly yielded from the Middle–Lower Ordovician carbonate reservoirs with depth > 7000  m in the Shunbei No. 1 and No. 5 fault zones. Calcite cements filled in vugs (v-calcite) and fractures (f-calcite) are identified in limestones and dolostones of the carbonate reservoirs. F-calcites in the Shunbei No. 1 fault zone trap secondary inclusions in trails, which comprise liquid-dominated biphase aqueous inclusions, liquid-dominated biphase oil inclusions, and/or oil-bearing triphase inclusions. F-calcite and v-calcite in the No. 5 fault zone trap secondary inclusions in trails, which consist of liquid-only monophase aqueous inclusions, liquid-dominated biphase aqueous inclusions, liquid-dominated biphase oil inclusions, liquid-only monophase oil inclusions, and/or oil-bearing triphase inclusions. The ranges of the homogenization temperature ( T h ) and ice-melting temperature ( T m − ice ) in the Shunbei No. 1 fault zone are, respectively, 130–150°C and -2.1–-1.5°C. The coexistence of liquid-only and liquid-dominated aqueous inclusions in the Shunbei No. 5 fault zone indicates that the aqueous inclusions are trapped at low temperatures. The aqueous inclusions in the Shunbei No. 5 fault zone show a range from -0.4 to -0.2°C in T m − ice which is very close to the meteoric fluid. In the context of the burial-thermal history and the Cambrian source rock evolution, the charging process of hydrocarbon in the Shunbei No. 1 and No. 5 fault zones corresponds to the Silurian and Middle Ordovician, respectively. Results of fluid inclusions indicate a tightly coupling relationship between the hydrocarbon charging process and fault system evolution in the Shunbei area. This study reveals the application of fluid inclusion under the systemically petrographic constraints to decipher the charging history of hydrocarbon, especially for the deeply buried reservoirs.

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