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Suture Zone (suture + zone)

Distribution by Scientific Domains

Earth and Environmental Science	65%
Life Sciences	35%

Selected Abstracts

DO SUTURE ZONES EXIST?

EVOLUTION, Issue 11 2004
Nathan G. Swenson
Abstract Remington (1968) argued that 13 suture zones exist in North America. Remington defined a suture zone as, "a band of geographic overlap between major biotic assemblages, including some pairs of species or semispecies which hybridize in the zone" (p. 322). Although initially controversial, the idea that suture zones exist has picked up momentum over the past decade, due largely to the phylogeographic work of Hewitt, Avise, and their colleagues. Nevertheless, the reality of suture zones has not yet been subjected to rigorous analysis using statistical and geographic information system (GIS) approaches. To test for the existence of Remington's suture zones, we first identified 117 terrestrial hybrid zones in Canada and the United States through a literature search for the key words "cline,""contact zone,""hybrid zone," and "hybridization" in articles published between 1970 and 2002. The 117 hybrid zones were mapped using a GIS approach and compared with a digitized version of Remington's original suture zone map. Overall, there does appear to be an association between hybrid zones and suture zones, but this association is largely attributable to clustering of hybrid zones in only two of the 13 suture zones recognized by Remington. The results suggest that evolutionary biologists should retain some skepticism toward Remington's suture zones. [source]

The syn-collisional Danac,obas, biotite leucogranite derived from the crustal thickening in central Anatolia (K,r,kkale), Turkey

GEOLOGICAL JOURNAL, Issue 5 2005
bel Tatar
Abstract The Behrekda, composite batholith, which crops out as a huge N,S-trending plutonic body in central Anatolia, Turkey, consists of five mappable granitoid units of Late Cretaceous age. They are (1) the S-type, peraluminous Danac,obas, biotite leucogranite, (2) the I-type, hybrid, metaluminous Konur K-feldspar megacrystic quartz monzonite, (3) the mafic A-type, alkaline Kizdede monzogabbro, (4) the felsic A-type, alkaline Hasandede quartz syenite/monzonite, and (5) the M-type, low-K tholeiitic Yeniköy tonalite. The S-type Danac,obas, biotite leucogranite constitutes the oldest intrusive unit in the mapped area. It has coarse- to medium-crystalline texture and consists of quartz, orthoclase and plagioclase, with variable amounts of biotite and accessory minerals, including apatite, zircon and opaque phases. K-Ar age dating of biotite separates, yields cooling ages of 69.1,±,1.42 and 71.5,±,1.45,Ma for the Danac,obas, biotite leucogranite. Major-element, trace-element, and rare-earth element geochemical data suggest an exclusively peraluminous, S-type, high-K calc-alkaline, upper crustal genesis for the Danac,obas, biotite leucogranite. This petrogenetic interpretation is also supported by oxygen-isotope data from quartz separates, with a mean value of 10.58,±,0.11 , of ,18OVSMOW value. The magma source of the Danac,obas, biotite leucogranite is proposed to have been a syn-collisional leucogranitic melt derived by anatexis of high-grade metasediments of the Central Anatolian Crystalline Complex during peak conditions of regional metamorphism. This metamorphic event was induced by crustal thickening which was a result of Late Cretaceous collision between the Eurasia and Tauride,Anatolide Platform along the ,zmir,Ankara,Erzincan Suture Zone in central Anatolia. Copyright © 2005 John Wiley & Sons, Ltd. [source]

DO SUTURE ZONES EXIST?

Lithosphere structure of Europe and Northern Atlantic from regional three-dimensional gravity modelling

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002
T. P. Yegorova
Summary Large-scale 3D gravity modelling using data averaged on a 1° grid has been performed for the whole European continent and part of the Northern Atlantic. The model consists of two regional layers of variable thickness,the sediments and the crystalline crust, bounded by reliable seismic horizons,the ,seismic' basement and the Moho surface. Inner heterogeneity of the model layers was taken into account in the form of lateral variation of average density depending on the type of geotectonic unit. Density parametrization of the layers was made using correlation functions between velocity and density. For sediments, sediment consolidation with depth was taken into account. Offshore a sea water layer was included in the model. As a result of the modelling, gravity effects of the whole model and its layers were calculated. Along with the gravity modelling an estimation of isostatic equilibrium state has been carried out for the whole model as well as for its separate units. Residual gravity anomalies, obtained by subtracting the gravity effect of the crust from the observed field, reach some hundred mGal (10,5 m s,2) in amplitude; they are mainly caused by density heterogeneities in the upper mantle. A mantle origin of the residual anomalies is substantiated by their correlation with the upper-mantle heterogeneities revealed by both seismological and geothermal studies. Regarding the character of the mantle gravity anomalies, type of isostatic compensation, crustal structure, age and supposed type of endogenic regime, a classification of main geotectonic units of the continent was made. As a result of the modelling a clear division of the continent into two large blocks,Precambrian East-European platform (EEP) and Variscan Western Europe,has been confirmed by their specific mantle gravity anomalies (0 ÷ 50 × 10,5 m s,2 and ,100 ÷,150 × 10,5 m s,2 correspondingly). This division coincides with the Tornquist,Teisseyre Zone (TTZ), marked by a gradient zone of mantle anomalies. In the central part of the EEP (over the Russian plate) an extensive positive mantle anomaly, probably indicating a core of ancient consolidation of the EEP, has been distinguished. To the west and to the east of this anomaly positive mantle anomalies occur, which coincide with a deep suture zone (TTZ) and an orogenic belt (the Urals). Positive mantle anomalies of the Alps, the Adriatic plate and the Calabrian Arc, correlating well with both high-velocity domains in the upper mantle and reduced temperatures at the subcrustal layer, are caused by thickened lithosphere below these structures. Negative mantle anomalies, revealed in the Western Mediterranean Basin and in the Pannonian Basin, are the result of thermal expansion of the asthenosphere shallowing to near-Moho depths below these basins. [source]

The 1994 Sefidabeh earthquakes in eastern Iran: blind thrusting and bedding-plane slip on a growing anticline, and active tectonics of the Sistan suture zone

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2000
M. Berberian
Summary In 1994 a sequence of five earthquakes with Mw 5.5,6.2 occurred in the Sistan belt of eastern Iran, all of them involving motion on blind thrusts with centroid depths of 5,10 km. Coseismic ruptures at the surface involved bedding-plane slip on a growing hanging-wall anticline displaying geomorphological evidence of uplift and lateral propagation. The 1994 earthquakes were associated with a NW-trending thrust system that splays off the northern termination of a major N,S right-lateral strike-slip fault. Elevation changes along the anticline ridge suggest that displacement on the underlying thrust dies out to the NW, away from its intersection with the strike-slip fault. This is a common fault configuration in eastern Iran and accommodates oblique NE,SW shortening across the N,S deforming zone, probably by anticlockwise rotations about a vertical axis. This style of fault kinematics may be transitional to a more evolved state that involves partitioning of the strike-slip and convergent motion onto separate subparallel faults. [source]

Discovery of Jurassic ammonoids from the Shyok suture zone to the northeast of Chang La Pass, Ladakh, northwest India and its tectonic significance

ISLAND ARC, Issue 1 2007
Masayuki Ehiro
Abstract Callovian (late Middle Jurassic) ammonoids Macrocephalites and Jeanneticeras were recovered from the Shyok suture zone, northeast of Chang La Pass, Ladakh, northwest India. They are the first reliable Jurassic fossils and the oldest chronologic data from the Shyok suture zone. The ammonoid-bearing Jurassic strata, newly defined as the Tsoltak Formation, consist largely of terrigenous mudstone with thin sandstone beds and were probably a part of the continental basement to the Cretaceous Ladakh Arc. [source]

P,T evolution of glaucophane,omphacite bearing HP,LT rocks in the western Tianshan Orogen, NW China:new evidence for ,Alpine-type' tectonics

JOURNAL OF METAMORPHIC GEOLOGY, Issue 2 2002
R. Klemd
Abstract The late Palaeozoic western Tianshan high-pressure /low-temperature belt extends for about 200 km along the south-central Tianshan suture zone and is composed mainly of blueschist, eclogite and epidote amphibolite/greenschist facies rocks. P,T conditions of mafic garnet omphacite and garnet,omphacite blueschist, which are interlayered with eclogite, were investigated in order to establish an exhumation path for these high-pressure rocks. Maximum pressure conditions are represented by the assemblage garnet,omphacite,paragonite,phengite,glaucophane,quartz,rutile. Estimated maximum pressures range between 18 and 21 kbar at temperatures between 490 and 570 °C. Decompression caused the destabilization of omphacite, garnet and glaucophane to albite, Ca-amphibole and chlorite. The post-eclogite facies metamorphic conditions between 9 and 14 kbar at 480,570 °C suggest an almost isothermal decompression from eclogite to epidote,amphibolite facies conditions. Prograde growth zoning and mineral inclusions in garnet as well as post-eclogite facies conditions are evidence for a clockwise P,T path. Analysis of phase diagrams constrains the P,T path to more or less isothermal cooling which is well corroborated by the results of geothermobarometry and mineral textures. This implies that the high-pressure rocks from the western Tianshan Orogen formed in a tectonic regime similar to ,Alpine-type' tectonics. This contradicts previous models which favour ,Franciscan-type' tectonics for the southern Tianshan high-pressure rocks. [source]

Trilobite faunas of the Duncannon Group: Caradoc stratigraphy, environments and palaeobiogeography of the Leinster Terrane, IReland

PALAEONTOLOGY, Issue 2 2000
Alan W. Owen
The Burrellian trilobite faunas of the Leinster terrane comprise at least 31 species from a spectrum of faunal associations. Strong faunal links with the Anglo-Welsh area confirm the likely close proximity of these parts of Avalonia during the mid Caradoc but together with existing magmatic and palaeomagnetic data, the Leinster faunas also indicate that the existing simple structural models of the relationship between these areas need to be reappraised. Of the 22 identifiable trilobite genera, eight are not known from equivalent or older horizons in the Anglo-Welsh area and indicate a significant link with Scoto-Appalachian faunas on the margins of Laurentia. This colonization by trilobites of Scoto-Appalachian origin may have been achieved by ,volcanic island hopping' across the shrinking Iapetus Ocean. The Leinster trilobites are therefore critical in documenting the breakdown of faunal provincialism and in fingerprinting the faunas and likely palaeogeographical setting of terranes now caught up in the Iapetus suture zone to the north. Eighteen species are described or discussed in detail including a new species of AmpyxinaA. hibernica sp. nov., a probable new species of Calyptaulax and revision of the M'Coy species Trinodus agnostiformis, Autoloxolichas laxatus, Flexicalymene forcipata Remopleurides platyceps. [source]

Ophiolites from the Mianlüe Suture in the Southern Qinling and Their Relationship with the Eastern Paleotethys Evolution

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2004
LAI Shaocong
Abstract The Mianlüe suture extends from Derni-Nanping-Pipasi-Kangxian to the Lüeyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melangé associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island-arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo-ocean basin. The Mianlüe paleo-ocean basin experienced its main expansion and formation process during the Carboniferous-Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system. [source]

A Study of the Kunlun-Qilian-Qinling Suture System

ACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 4 2001
BIAN Qiantao
It is basically divided into the western, central and eastern sectors. The western sector consists of the Küda-Subashi suture zone, the Mazar-Kangxiwar suture and the central West Kunlun microblock. The central sector covers the following five suture zones: the Altun, North Qilian, Qaidam northern marginal, Qimantag-Wutuo and East Kunlun southern marginal sutures, in addition to some microblocks such as the mid-south Qilian, Qaidam, Ayakkum and Maqen microblocks. The eastern sector is composed of the Shangdan suture zone, Mianlüe suture zone and central Qinling-Dabie microblock. The KQQ suture system experienced (1) extending-rifting of the Rodinia super-continent in the early-middle Sinian (,780,600 Ma); (2) the formation and evolution of the KQQ archipelagic ocean during the Late Sinian-Ordovician (,600,440 Ma), and (3) closing of the KQQ ocean and forming of the KQQ suture system during the Late Ordovician,early Silurian (,440,400 Ma). As a system comprising many suture zones and microblocks, the KQQ suture system constitutes the foundation of the Central Orogenic Belt of China. [source]

DO SUTURE ZONES EXIST?

EVIDENCE FOR HISTORICAL INTROGRESSION ALONG A CONTACT ZONE BETWEEN TWO SPECIES OF CHAR (PISCES: SALMONIDAE) IN NORTHWESTERN NORTH AMERICA

EVOLUTION, Issue 5 2002
Z. Redenbach
Abstract Phylogeographic analyses can yield valuable insights into the geographic and historical contexts of contact and hybridization between taxa. Two species of char (Salmonidae), Dolly Varden (Salvelinus malma) and bull trout (S. confluentus) have largely parapatric distributions in watersheds of northwestern North America. They are, however, sympatric in several localities and hybridization and some introgression occurs across a broad area of contact. We conducted a comparative phylogenetic analysis of Dolly Varden and bull trout to gain a historical perspective of hybridization between these species and to test for footprints of historical introgression. We resolved two major Dolly Varden mitochondrial DNA (mtDNA) clades (with 1.4,2.2% sequence divergence between haplotypes) that had different geographical distributions. Clade N is distributed across most of the range of Dolly Varden, from southern British Columbia through to the Kuril Islands in Asia. Clade S had a much more limited distribution, from Washington state, at the southern limit of the Dolly Varden range, to the middle of Vancouver Island. The distribution and inferred ages of the mtDNA clades suggested that Dolly Varden survived the Wisconsinan glaciation in a previously unsuspected refuge south of the ice sheet, and that Dolly Varden and bull trout were probably in continuous contact over most of the last 100,000 years. When bull trout were included in the phylogenetic analysis, however, the mtDNA of neither species was monophyletic: Clade S Dolly Varden clustered within the bull trout mtDNA clade. This pattern was discordant with two nuclear phylogenies produced (growth hormone 2 and rRNA internal transcribed sequence 1), in which Dolly Varden and bull trout were reciprocally monophyletic. This discordance between mtDNA- and nDNA-based phylogenies indicates that historical introgression of bull trout mtDNA into Dolly Varden occurred. Percent sequence divergence within these introgressed Dolly Varden (clade S) was 0.2,0.6%, implying that the introgression occurred prior to the most recent glaciation. Our analysis and other evidence of contact between divergent lineages in northwestern North America strongly suggests that the area may be the site of previously unsuspected suture zones of aquatic biotas. [source]

Ophiolite-bearing mélanges in southern Italy

GEOLOGICAL JOURNAL, Issue 2 2009
Luigi Tortorici
Abstract In southern Italy two ophiolite-bearing belts, respectively involved in the Adria-verging southern Apennines and in the Europe-verging thrust belt of the northern Calabrian Arc, represent the southward extension of the northern Apennines and of ,Alpine Corsica' ophiolitic units, respectively. They form two distinct suture zones, which are characterized by different age of emplacement and opposite sense of tectonic transport. The ophiolite-bearing units of the southern Apennines are represented by broken formation and tectonic mélange associated with remnants of a well-developed accretionary wedge emplaced on top of the Adria continental margin, with an overall NE direction of tectonic transport. These units consist of a Cretaceous-Oligocene matrix, which includes blocks of continental-type rocks and ophiolites with remnants of their original Upper Jurassic to Lower Cretaceous pelagic cover. The innermost portion of the accretionary wedge is represented by a polymetamorphosed and polydeformed tectonic units that underwent a Late Oligocene high pressure/low temperature (HP/LT) metamorphism. The northern Calabria ophiolitic-belt is indeed composed of west-verging tectonic slices of oceanic rocks which, embedded between platform carbonate units of a western continental margin at the bottom and the basement crystalline nappes of the Calabrian Arc at the top, are affected by a Late Eocene-Early Oligocene HP/LT metamorphism. The main tectonic features of these two suture zones suggest that they can be interpreted as the result of the closure of two branches of the western Neotethys separated by a continental block that includes the crystalline basement rocks of the Calabrian Arc. We thus suggest that the north-east verging southern Apennine suture constituted by a well-developed accretionary wedge is the result of the closure of a large Late Jurassic-Early Cretaceous oceanic domain (the Ligurian Ocean) located between the African (the Adria Block) and European continental margins. The northern Calabria suture derives indeed from the deformation of a very narrow oceanic-floored basin developed during the Mesozoic rifting stages within the European margin separating a small continental ribbon (Calabrian Block) from the main continent. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Phylogeography of a northeast Asian spruce, Picea jezoensis, inferred from genetic variation observed in organelle DNA markers

MOLECULAR ECOLOGY, Issue 16 2007
M. AIZAWA
Abstract Range-wide genetic variation of the widespread cold-temperate spruce Picea jezoensis was studied throughout northeast Asia using maternally inherited mitochondrial DNA and paternally inherited chloroplast DNA markers. This study assessed 33 natural populations including three varieties of the species in Japan, Russia, China, and South Korea. We depicted sharp suture zones in straits around Japan in the geographical distribution pattern of mitochondrial haplotypes (GST = 0.901; NST = 0.934). In contrast, we detected possible extensive pollen flow without seed flow across the straits around Japan during the past population history in the distribution pattern of chloroplast haplotypes (GST = 0.233; NST = 0.333). The analysis of isolation by distance of the species implied that by acting as a barrier for the movement of seeds and pollen, the sharp suture zones contributed considerably to the level of genetic differentiation between populations. Constructed networks of mitochondrial haplotypes allowed inference of the phylogeographical history of the species. We deduced that the disjunction with Kamchatka populations reflects range expansion and contraction to the north of the current distribution. Within Japan, we detected phylogeographically different types of P. jezoensis between Hokkaido and Honshu islands; P. jezoensis in Honshu Island may have colonized this region from the Asian continent via the Korean peninsula and the species in Hokkaido Island is likely to have spread from the Asian continent via Sakhalin through land bridges. Japanese endemism of mitochondrial haplotypes in Hokkaido and Honshu islands might have been promoted by separation of these islands from each other and from the Asian continent by the straits during the late Quaternary. [source]

Evolutionary history of the bank vole Myodes glareolus: a morphometric perspective

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2010
RONAN LEDEVIN
The bank vole experienced a complex history during the Quaternary. Repeated isolation in glacial refugia led to the differentiation of several lineages in less than 300 000 years. We investigated if such a recent differentiation led to a significant divergence of phenotypic characters between European lineages, which might provide insight into processes of intraspecific differentiation. The size and shape of the first and third upper molars, and first lower molar, of bank voles genetically attributed to different lineages were quantified using an outline analysis of their occlusal surface. The three teeth present similar trends of decreasing size towards high latitudes. This trend, the inverse of Bergmann's rule, is interpreted as the result of a balance between metabolic efficiency and food availability, favouring small body size in cold regions. Molar shape appeared to differ between lineages despite genetic evidence of suture zones. A mosaic pattern of evolution between the different teeth was evidenced. The analysis of such phenotypic features appears as a valuable complement to genetic analyses, providing a complementary insight into evolutionary processes, such as selective pressures, that have driven the differentiation of the lineages. It may further allow the integration of the paleontological dimension of the bank vole phylogeographic history. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 681,694. [source]