Neotethyan Suture Zone Research Articles

Geochemical and geochronological constraints on the origin of the Sabzevar ophiolites (NE Iran): forced far-field subduction initiation in the upper-plate of the Neo-Tethys subduction zone

The Sabzevar ophiolites, located at the northern margin of the Central-East Iranian microcontinent (CEIM), are part of the Mesozoic-Paleogene Neotethyan suture zone developed along the Alpine-Himalayan convergence zone. These ophiolites consist mostly of oceanic lithospheric remnants, covered by early Campanian-late Maastrichtian volcano-sedimentary successions. A distinctive characteristic of the Sabzevar ophiolites is the occurrence of mafic dike swarms (gabbros, gabbronorites and diorites) with forearc-arc-tholeiitic geochemical signature, intruding the mantle section. Occurrence of orthopyroxene, development of pegmatitic texture, crystallization of clinopyroxene prior to plagioclase, and the presence of anorthite-rich plagioclase imply relatively high H2O content in the magmatic plumbing system. Rare plagiogranites (tonalite and trondhjemite compositions) show geochemical features compatible with a supra-subduction setting, whereas late (hornblende-bearing) gabbro dikes show a within-plate signature. The bimodal geochemical affinity (subduction vs. intraplate) is also attested by clinopyroxene compositions. The gabbroic, plagiogranitic and gabbronoritic samples yield Early Cretaceous SHRIMP zircon U-Pb ages of 96.7 ± 1, 98 ± 1 and 94 ± 1 Ma, respectively. A progression from tholeiitic MORB-like to more depleted high-Mg andesite and eventually alkaline affinities is here proposed, framing the magma evolution as generated in an evolving forearc setting that post-dated (of at least 9 Myr) the formation of the metamorphic sole during the infant stages of subduction of the Sabzevar Ocean.A scenario of far-field forced subduction initiation of the Sabzevar Ocean is proposed as consequence of propagation of the residual stresses transmitted from the Arabia-Eurasia convergence zone across the CEIM during Cretaceous times (Albian-Campanian).

Neogene restoration of geometry of the Neotethyan suture zone in Central Anatolia (Turkey)

ABSTRACT We have restored the geometries of suture zones that involved various continental blocks in central Anatolia during the Neogene, using palaeomagnetic data. Previously, the Kırşehir Block was proposed to be an NNE-SSW striking tectonic block broken into three fragments that they underwent clockwise rotations in the north and counter-clockwise rotations in the south during the Palaeogene, due to collision and N-S shortening of the Kırşehir Block between Tauride-Menderes Block in the south and the Pontides in the north. Our new results point out five distinct Neogene tectonic domains with distinct rotation patterns that indicate the rotational deformation of Central Anatolia is far more complex than generally presumed. Among these, 1) Kırıkkale-Bala Domain is rotated ~18° clockwise, 2) the Tuz Gölü Domain underwent ~14° counter-clockwise rotation, 3) the Alcı-Orhaniye Domain rotated ~35° counter-clockwise sense, 4) the Northern Haymana Domain underwent ~12° counter-clockwise rotation while 5) the Southern Haymana Domain underwent very small (~5° clockwise) net rotation since the early Miocene. The results also indicated that pre-Neogene configuration of the Izmir-Ankara Suture Zone was striking almost E-W while Inner-Tauride and Ankara-Erzincan suture zones were almost N-S in the study area. In addition, the fault zones that define the these domains extend from the Kırşehir Block into the over-riding blocks (Pontides) continuously without any deflection indicating that they were active during the Neogene and fragmented and dislocated the suture zones in the region.

Geological and mineralization characteristics of the Kestanelik epithermal Au-Ag deposit in the Tethyan Metallogenic Belt, NW Turkey

Kestanelik epithermal gold deposit is situated in the Biga Peninsula, which hosts numerous metallic deposits belonging to the Tethyan Metallogenic Belt. In the Biga peninsula the Tethyan Metallogenic Belt is represented by a Neo-Tethyan suture zone. Discovered deposits along the belt are commonly associated with Cenozoic magmatism ranging between 52 and 18 Ma in age, formed due syn- to post-collisional tectonics. In this study, we focus on the deposit-scale geological and mineralization characteristics of Kestanelik in order to determine the formation and evolution of the deposit within the tectono-magmatic history of the Biga Peninsula. We (1) mapped the geology of the deposit area (2) conducted paleostress analyses, (3) observed and examined the macroscopic and petrographical textural, mineralogical and alteration characteristics of the mineralization and (4) interpreted geophysical resistivity survey and geochemical assay data. The stratigraphic age of the Kestanelik deposit, bracketed by cross cutting relations and supported by the geophysical data, is middle Lutetian-early Priabonian which also implies that the deposit has a genetic link with the Cenozoic post-collisional calc-alkaline magmatism. A NE-SW oriented compressional regime determined from the paleostress analyses is consistent with the kinematics of the vein system and is attributed to the collision and further convergence after the closure of the northern branch of the Neo-Tethys Ocean. The fracture system provided structural pathways for the transport of the hydrothermal fluids. The common presence of pseudo-bladed quartz and hydrothermal breccias, and the low total sulphide and base metal contents in the mineralized veins indicate that the Kestanelik is a low sulphidation epithermal-type gold deposit. Boiling, mixing (hypogene oxidation) and supergene enrichment are the likely gold deposition and enrichment processes respectively.

Age and compositional evolution of Sahand volcano in the context of post-collisional magmatism in northwestern Iran: Evidence for time-transgressive magmatism away from the collisional suture

Sahand volcano along with the two neighbouring volcanic systems of Saray and Sabalan are three Late Miocene-Quaternary volcanoes that formed in the wake of the collision between the Arabian and Eurasian continental plates along the Neo-Tethyan suture zone in northwestern Iran. Sahand volcano is an isolated, extensive (3707 m elevation; >3000 km2 area) stratovolcanic complex, which is located ~165 km north of the Neo-Tethyan suture zone and was constructed over ~45 km thick continental crust. Andesitic to dacitic pyroclastic deposits, ignimbrites, and lava flows form the now strongly eroded Paleo- and Meso-Sahand edifice. Paleo-Sahand rocks are mostly restricted to the central part the edifice, where they underlie Meso-Sahand deposits. By contrast, Neo-Sahand volcanic rocks intruded older volcanic successions within and outside a largely eroded caldera margin, which likely formed during the Meso-Sahand stage. Neo-Sahand units comprise several basaltic andesitic to rhyolitic domes in the center of the complex as well as small parasitic cones along with subvolcanic dikes. High spatial resolution and sensitivity U-Pb geochronology using secondary ionization mass spectrometry (SIMS) define the formation of Paleo-, Meso-, and Neo-Sahand to ca. 8 to 3 Ma, ca. 1 Ma, and ca. 600 to <173 ka, respectively, with dating mostly focusing on Neo-Sahand. Antecrystic zircon crystals in Sahand volcanic deposits also indicate that post-collisional magmatism initiated locally at about the same time or slightly earlier than at Saray volcano to the west of Sahand. The initiation of volcanic activity subsequently migrated to the northeast over a distance of ~300 km away from the Neo-Tethyan suture, where activity started at Sabalan volcano at ca. 4.5 to 2.9 Ma. This time corresponds to a magmatic lull of Sahand before the Meso-Sahand eruptive activity resumed at ca. 1 Ma. Subsequently, Neo-Sahand and Neo-Sabalan erupted synchronously throughout the middle and possibly into the late Pleistocene. Paleo- and Neo-Sahand volcanic rocks are characterized by enrichments of large-ion lithophile (LILE) and light rare earth elements (LREE) relative to high-field strength and heavy rare earth elements (HREE), respectively, and prominent negative Ti, Nb, and Ta anomalies relative to primitive mantle compositions. The least evolved magmas at Sahand have formed by 1–5% partial melting of garnet- and spinel-peridotite and were subsequently overprinted through assimilation – fractional crystallization (AFC) processes acting in the continental crust. Although Sahand and Sabalan volcanic rocks share many geochemical characteristics indicative of a continental subduction setting, Sahand is less potassic and less enriched in incompatible trace elements compared to Sabalan. Another difference is that Sahand primitive magmas were formed by smaller degrees of partial melting in the mantle than is the case for Sabalan. Both effects likely result from variable distances from the suture zone and crustal thickening away from the suture towards the northeast. Overall, the apparent age progression and geochemical variation of the post-collisional volcanism, lack of asthenospheric mantle components, and the subduction-affinity of Sahand and Sabalan volcanic rocks supports a scenario where mantle melting was triggered by slab roll back and break-off shortly after continental collision, followed by migration of the slab edge towards the northeast at plate-like velocities.

Petrogenesis and tectonomagmatic significance of Eocene mafic intrusions from the Neotethyan suture zone in the Muslim Bagh–Khanozai region, Pakistan

New geochemical data for mafic intrusions within the Eocene Nisai Formation along the suture zone between the Indian and Eurasian plates are used to constrain their petrogenesis and assess the local tectonics and mantle dynamics. Petrological and geochemical data indicate that these alkalic intrusions have moderately enriched incompatible trace element compositions similar to ocean island basalt magmatism. Modelling suggests that these intrusions are the result of 1–5% melting of a deep, enriched, predominantly garnet lherzolite, with a small amount of subduction-derived fluids. These melts then underwent fractional crystallization at lithospheric depths of c . 30 km. Supplementary materials: Detailed information on each analysed sample including field notes and latitude and longitude, replicate analysis of standards, and fractional crystallization modelling are available at http://www.geolsoc.org.uk/SUP18893 .

Late Eocene–Neogene sedimentary geology of the Girne (Kyrenia) Range, northern Cyprus: A case history of sedimentation related to progressive and diachronous continental collision

Sedimentary geology can shed light on the processes of continental collision. The easternmost Mediterranean provides an exceptional opportunity to study sediments deposited during progressive and diachronous continental collision, with implications for comparable settings elsewhere. Here, we focus on sediment sources, pathways and deposition of mostly deep-sea clastic sediments exposed in northern Cyprus. The sedimentary basin forms part of the northern continental margin of the Southern Neotethys ocean and is represented by a ca. 200km-long, E–W-trending, arcuate lineament, encompassing northern Cyprus and its submarine link with Turkey. The Upper Eocene–Upper Miocene basin was divided into northerly and southerly sub-basins during Mid- to Late Miocene time by an E–W-trending, inferred syn-depositional fault lineament. The sequence begins with non-marine to shallow-marine basal conglomerates (Late Eocene) that abruptly fine upwards into siliciclastic turbidites (Oligocene), followed by biogenic calciturbidites and marls (Aquitanian–Langhian). During Mid–Late Miocene the northerly sub-basin was characterised by thin- to medium-bedded calciturbidites and marls (Serravallian), overlain by thick-bedded, medium-grained lithic sandstones (Tortonian). In contrast, the southern sub-basin is dominated by siliciclastic turbidites with abundant sole structures (Burdigalian–Tortonian). Palaeocurrent evidence indicates dominantly westward sediment transport, especially during the Late Miocene. The Serravallian–Tortonian sandstones of the northern sub-basin are relatively rich in carbonates, while the southern sub-basin contains more siliciclastic and ophiolite-derived detritus indicating differences in sediment supply. In general, the Upper Eocene basal conglomerates were mainly derived from the north, from within the Girne (Kyrenia) Range and its inferred northward extension. In response to rapid subsidence (reflecting possible southward subduction zone retreat) clastic sediment sources to the north then submerged while clastic sediment was instead mainly supplied from the South Neotethyan suture zone to the east and northeast in southern Turkey. Reflecting diachronous collision, deep-water deposition persisted in the easternmost Mediterranean basin further west until this was terminated in northern Cyprus by thrusting/folding during latest Miocene–earliest Pliocene. Quaternary collision-related uplift ensued. Similar sedimentary development is to be expected in collisional settings elsewhere (e.g. Tethyan closure in the Himalayas; Iapetus closure in the Appalachians).

Southward migration of arc magmatism during latest Cretaceous associated with slab steepening, East Pontides, N Turkey: New paleomagnetic data from the Amasya region

A new paleomagnetic study was carried out on the Fındıklı formation in the Amasya region, which is to the north of the Ankara-Erzincan Neotethyan suture zone, in order to better understand the paleogeographic evolution of the Pontides tectonic belt during the Maastrichtian. Samples were collected from volcanoclastic sandstones and lavas at 51 sites. Rock magnetic experiments identified pseudo-single domain (PSD) titanomagnetite as the main magnetic carriers at the majority of sites. Progressive thermal and alternating demagnetization revealed that the characteristic remanent component is removed between 400 and 580 °C or 20–100 mT, respectively. A high temperature component, which indicates the presence of titano-hematite, is found only in some lavas. Declinations show a systematic dispersion across the study area related to tectonic rotations about vertical axes. Inclinations are consistent, however, and yield a mean paleolatitude of 20.0°N ± 2.5° for the Maastrichtian. Comparison of the results from this study with the reference direction of the East Pontides from the Turonian–Campanian is best explained with a model involving slab roll-back and marginal basin formation between 90 and 65 Ma period.

Tectono-stratigraphy of the Çankırı Basin: Late Cretaceous to early Miocene evolution of the Neotethyan Suture Zone in Turkey

Abstract The Çankırı Basin straddles the İzmir–Ankara–Erzincan Suture Zone which demarcates the former position of the northern branch of the Neotethys. It includes more than 3 km of pre-Middle Miocene in-fill related to late Cretaceous to pre-Middle Miocene evolution of the region. The basin has developed on the upper Cretaceous subduction complex and arc related basins of the Neotethys Ocean. The basin fill includes an upper Cretaceous forearc sequence overlain by Paleocene with a local unconformity. The upper Cretaceous configuration of the Çankırı basin is interpreted as a part of a forearc basin. The Paleocene and younger history is interpreted as a foreland sequence dominated by progressively southwards migrated depocenters in front of southward migrating thrust faults upon which a series of piggy-back basins were developed. Termination of the forearc setting and beginning of foreland basin conditions indicates complete subduction of the Neotethyan oceanic crust and onset of collision between the Pontides (Laurasia) and the Taurides (Gondwana) in the Paleocene. Thrusting and related sedimentation continued until the Aquitanian (Early Miocene).

Geochemical characteristics of mafic lavas from the Neotethyan ophiolites in western Turkey: implications for heterogeneous source contribution during variable stages of ocean crust generation

AbstractThe Late Triassic to Late Cretaceous age mafic lavas from the Neotethyan suture zone ophiolites in western Turkey exhibit a wide diversity of geochemical signatures, indicating derivation from extremely heterogeneous mantle sources. The rocks as a whole can be divided into three broad subdivisions based on their bulk-rock geochemical characteristics: (1) mid-ocean ridge basalts (MORB) that range in composition from light rare earth element (LREE)-depleted varieties (N-MORB; (La/Sm)N&lt;1) through transitional MORB to LREE enriched types (E-MORB; (La/Sm)N&gt;1); (2) the ocean island basalt (OIB)-type alkaline volcanic rocks with significant enrichment in LILE, HFSE and L-MREE, and a slight depletion in HREE, relative to normal mid-ocean ridge basalts (N-MORB); and (3) the supra-subduction zone (SSZ)-type tholeiites originated from arc mantle sources that are characterized by selective enrichments in fluid-soluble large ion lithophile elements (LILE) and LREE relative to the high field strength elements (HFSE). The formation of MORB tholeiites with variable enrichments and depletions in incompatible trace elements is probably related to the processes of crust generation along an oceanic spreading system, and the observed MORB–OIB associations can be modelled by heterogeneous source contribution and mixing of melts from chemically discrete sources from sub-lithospheric reservoirs. Evaluation of trace element systematics shows that the inferred heterogeneities within the mantle source regions are likely to have originated from continuous processes of formation and destruction of enriched mantle domains by long-term plate recycling, convective mixing and melt extraction. The origin of SSZ-type tholeiites with back-arc basin affinities, on the other hand, can be attributed to the later intra-oceanic subduction and plate convergence which led to the generation of supra-subduction-type oceanic crust as a consequence of imparting a certain extent of subduction component into the mantle melting region. Mixing of melts from a multiply depleted mantle source, which subsequently received variable re-enrichment with a subduction component, is suggested to explain the generation of supra-subduction-type oceanic crust. The geodynamic setting in which much of the SSZ-type ophiolitic extrusive rocks from western Turkey were generated can be described as an arc-basin system that is characterized by an oceanic lithosphere generation most probably associated with melting of mantle material along a supra-subduction-type spreading centre.

Transient, synobduction exhumation of Zagros blueschists inferred from P‐T, deformation, time, and kinematic constraints: Implications for Neotethyan wedge dynamics

We present the first P‐T, deformation time, and kinematic constraints on the only known blueschist facies rocks (BS) present in the Zagros (Hajiabad area). The BS were underplated below the Sanandaj‐Sirjan zone and crop out as kilometer‐scale bodies within extensive colored melange units marking discontinuously the Neotethyan suture zone. P‐T estimates point to high‐pressure/low‐temperature (HP‐LT) conditions around 11 kbar and 520–530°C for the majority of BS, along a ∼15°C km−1 gradient. Some exotic blocks in matrix serpentinite reached 17–18 kbar at ∼500°C. In situ laser probe 40Ar‐39Ar radiometric age constraints on phengite cluster between 85 and 95 Ma and suggest that (1) synconvergence exhumation of Zagros BS from 35–50 km to depths &lt;15–20 km was accomplished before 80 Ma, (2) BS exhumation corresponded to a transient process with respect to the long‐lived subduction beneath Iran (∼150–35 Ma), and (3) age constraints for Zagros BS are 5–10 Myr older than for the nearby Oman HP‐LT rocks and broadly coincide with obduction processes in the region (circa 95–70 Ma). We propose that the mechanical coupling across the Neotethyan subduction zone (NSZ) beneath Iran was modified by the large‐scale plate rearrangement accompanying obduction, allowing for a short‐lived exhumation of Zagros BS. Exhumation ceased at the end of obduction, when subduction of the Arabian continental margin stopped. Kinematic calculations suggest that convergence velocities across the NSZ likely doubled (to ∼5–6 cm yr−1) during the period 118–85 Ma, so that BS exhumation may have been promoted by a combination of obduction movements and increased convergence velocities.

Uppermost Cretaceous–Lower Tertiary Ulukışla Basin, south-central Turkey: sedimentary evolution of part of a unified basin complex within an evolving Neotethyan suture zone

The Ulukışla Basin, the southerly and best exposed of the Lower Tertiary Central Anatolian Basins, sheds light on one of the outstanding problems of the tectonic assembly of suture zones: how large deep-water basins can form within a zone of regional plate convergence. The oldest Ulukışla Basin sediments, of Maastrichtian age, transgressively overlie mélange and ophiolitic rocks that were emplaced southwards onto the Tauride microcontinent during the latest Cretaceous time. The Niğde-Kirşehir Massif forming the northern basin margin probably represents another rifted continental fragment that was surrounded by oceanic crust during Mesozoic time. The stratigraphic succession of the Ulukışla Basin begins with the deposition of shallow-marine carbonates of Maastrichtian–Early Palaeocene age, then passes upwards into slope-facies carbonates, with localised sedimentary breccias and channelised units, followed by deep-water clastic turbidites of Middle Palaeocene–Early Eocene age. This was followed by the extrusion of c. 2000 m of basic volcanic rocks during Early to Mid Eocene time. After volcanism ended, coral-bearing neritic carbonates and nummulitic shelf sediments accumulated along the northern and southern margins of the basin, respectively. Deposition of the Ulukışla Basin ended with gypsum deposits including turbidites, debris flows, and sabkhas, followed by a regional Oligocene unconformity. The Ulukışla Basin is interpreted as the result of extension (or transtension) coupled with subsidence and basic volcanism. After post-volcanic subsidence, the basin was terminated by regional convergence, culminating in thrusting and folding in Late Eocene time. Comparisons of the Ulukışla Basin with the adjacent central Anatolian basins (e.g. Tuzgölü, Sivas and Şarkişla) support the view that these basins formed parts of a regional transtensional (to extensional) basin system. In our preferred hypothesis, the Ulukışla Basin developed during an intermediate stage of continental collision, after steady-state subduction of oceanic crust had more or less ended (“soft collision”), but before the opposing Tauride and Eurasian continental units forcefully collided (“hard collision”). Late Eocene forceful collision terminated the basinal evolution and initiated uplift of the Taurus Mountains.

U–Pb zircon ages from the Spontang Ophiolite, Ladakh Himalaya

The Spontang Ophiolite in the Ladakh Himalaya consist of a thrust sheet of upper mantle and oceanic crustal rocks obducted onto the northern passive continental margin of India during the late Cretaceous. Precise isotopic ages of Himalayan ophiolites are presently unavailable. U–Pb dating of zircons from a dioritic segregation in the high-level gabbros of the Spontang ophiolite shows that the complex formed at 177±1 Ma (mid-Jurassic) and we suggest that it represents a fragment of Neo-Tethyan oceanic crust. This Jurassic age contrasts with late Cretaceous ages (91–95 Ma) previously reported for the formation of the Troodos and Oman ophiolite complexes further west along the Neo-Tethyan suture zone and also predates the early to mid-Cretaceous Masirah ophiolite (c. 150 Ma) and its alkaline volcanic seamounts (115–125 Ma). An andesitic rock from an arc sequence overlying the Spontang ophiolite was also dated using as 88±5 Ma. This Late Cretaceous age constrains the minimum age of initiation of subduction beneath the Spontang Ophiolite. The complex was emplaced during the Turonian–Maastrictian, some 80 Ma after its formation when the Indian continental margin collided with a Cretaceous arc about 25 Ma before the India–Asia collision. The lack of a sub-ophiolite metamorphic sheet beneath the Spontang mantle sequence may be explained by the fact that the ophiolite was old and cold at the time of obduction.

Rockfall avalanche deposits associated with normal faulting in the NW of Canklrl basin: implications for the postcollisional tectonic evolution of the Neo-Tethyan suture zone

The NNE-trending Neo-Tethyan suture zone between Ankara and Çanklrl, thrusts eastward onto different stratigraphic levels of the Neogene succession; however, its western side shows a normal fault relationship. This E-vergent tectonic sliver was inactive during the accumulation of the Miocene–Lower Pliocene sedimentary succession and was created by the movement of the North Anatolian Fault Zone and its splay after the late Pliocene, indicating internal deformation of the Anatolian plate. These results are inconsistent with the previous suggestion that intracontinental convergence related to Neo-Tethyan orogeny continued until the Pliocene (Ankara Orogenic Phase).

Geological Units and Structures in Suture Zone Around Balıkesir NW Anatolia

The region norheast of Balıkesir comprises different group of rocks reflecting different tectonic settings. Sakarya zone and Tavşanlı Zone are separated by a Mesozoic Tethyan suture zone called İzmir-Ankara suture. Sakarya zone, represented by Karakaya Complex in the study area, is located to the north of a major fault, which marks the northern boundary of Neo-Tethyan suture zone. The Karakaya complex reflects active continental margin units that were formed by southward subduction of Paleo-Tethyan oceanic crust during Permo- Triassic. At this perod, Karakaya complex units were internally imbricated. The closure of the Neo-Tethys ocean, leading HP/LT metamorphizm of northward subducting platform sediments (Orhaneli unit), resulted in the formation of two distinct tectonic units during late Mesozoic to Paleocene; an ophiolotic melange (Ovacık melange) and fault controlled wild-flysch (Bornova flysch). Ovacık melange, which was originally tectonically underlein by Orhaneli unit, detached during uplift of blueschist. Bornova flysch has back-thrushed over Sakarya zone during late Paleocene-?Eocene. A large garnitic pluton, Çatldağ granodiorite, which is a pruduct of extensive calc-alkaline magmatism in NW Anatolia, emplaced into the older units during Early Miocene, and caused titing of older structures around pluton.

A magmatic belt within the Neo-Tethyan suture zone and its role in the tectonic evolution of northern Turkey

The Sakarya and Kırşehir continental fragments of Northern Turkey were separated by the Ankara-Erzincan ophiolitic suture zone, which is the remnant of the northern branch of the Neo-Tethys, namely the Ankara-Erzincan Ocean. This ocean branch opened during the Lias between these two continental fragments and started to close at the beginning of the Late Cretaceous, by the consumption of its floor, along two north-dipping subduction zones. The northern one was along the southern margin of the Sakarya Continent. As a result of this subduction zone, an ensialic magmatic arc, some fore-arc basins and a mélange belt developed from north to south on the Sakarya Continent. The second subduction zone, located to the south, gave rise to a mélange belt and an island arc developed with and on it. Hot-spot magmatics (seamounts), which were scraped from the subducting oceanic crust, also accreted into this ophiolitic-volcanic belt. At the end of the late Cretaceous, the central part of the Ankara-Erzincan Ocean closed due to the collision of the Kırşehir and the Sakarya continents. As a result of this collision, mélange belts and ensimatic arc volcanics formed the Ankara-Yozgat suture between these continental fragments.