bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recognition and distinction of normal and forced regression in cyclothemic strata: a Plio-Pleistocene case study from eastern North Island, New Zealand
Authors: Haywick Douglas W. 
Published: April 2008

Abstract
The Tangoio block of eastern North Island, New Zealand contains an exceptionally well exposed, 550 m thick sequence of Plio-Pleistocene cyclothemic sedimentary rocks, the Petane Group, that were deposited along the western margin of a shallow (<200 m) pericontinental seaway. The cyclicity that characterizes the Petane Group in this area was generated through recurring 40 ka (sixth-order) sea-level changes of c. 75–150 m. Data from more than 100 sections indicates that the strata consist of five distinct cyclothems, each consisting of a lower formation of mudstone deposited in midshelf environments (highstand system tract, HST), and an upper formation dominated by coarse-grained facies deposited in shallow marine and occasionally non-marine environments. Western exposures of HST mudstones in the lower portion of the Petane Group shoal up into shallow marine siliciclastic sandstones, fluvial gravels and siltstones. The transition is gradational and is consistent with progradation of a siliciclastic shoreline during late sea-level highstand. The shoaling upward siliciclastic sandstone interval represents a regressive system tract (RST) whereas the fluvial beds represent a lowstand system tract (LST). LST gravel beds are sharply overlain by a transgressive surface of erosion and fining-upward siliciclastic sandstone facies of a transgressive systems tract (TST).
Carbonate sediments replaced siliciclastic sandstones as the dominant coarse-grained lithology in the upper Petane Group, probably due to bypass of siliciclastic sediment during sea-level fall. Transitions from HST mudstone into carbonate sand and bioclastic limestone (coquina) are generally sharp everywhere except the downdip eastern portions of the Tangoio block. The contacts represent regressive surfaces of erosion produced during falling stages of sea-level and/or ravinement surfaces formed during rising phases of sealevel (transgressive surfaces of erosion). Carbonate facies atop these erosional surfaces are generally interpreted as TST deposits, except for the uppermost limestones in the Petane Group that occur below a sequence boundary and therefore represent a forced regression systems tract (FRST). Stratal position is the only distinguishing characteristic of FRST limestones in the Petane Group, otherwise they are identical to TST deposits. In eastern portions of the Tangoio block, HST mudstones pass gradationally into RST calcareous sandstones and LST limestones. Systems tracts here are bounded by correlative conformities rather than erosive surfaces indicating continuous sedimentation during sea-level fall and lowstand. Differences in sedimentation and subsidence rates between carbonate and siliciclastic sedimentary systems, are responsible for the different stratal architecture of systems tracts in the Petane Group.
Late Permian Foraminiferal Biofacies Belts in Turkey: Palaeogeographic and Tectonic Implications
Authors: Altiner Demir , Özkan-Altiner Sevinç , Koçyiğit Ali 
Published: April 2008

Abstract

Upper Permian marine carbonates are distinguished in two contrasting biofacies belts in Turkey. The Southern Biofacies Belt, represented by low-energy inner platform deposits of the Tauride Belt and the Arabian Platform, is rich in algae and smaller foraminifera but poor in fusulines. The Kubergandian and Murgabian stages are missing, although the rest of the Upper Permian consists of monotonous, shallow-marine carbonate deposits. The extremely tectonised and fragmented Northern Biofacies Belt includes the Upper Permian of the Karakaya Orogen and outer platform or platform margin deposits of the Tauride Belt. These deposits are rich in parachomata-bearing fusulines comprising
Cancellina, Verbeekina, Afghanella, Sumatrina, Neoschwagerina
and
Yabeina
. The reconstructed biostratigraphic scheme indicates that all Upper Permian stages (Kubergandian-Dorashamian) are present.

The lateral continuity of the two biofacies belts is detected by the presence of tongues of he Northern Biofacies Belt pinching out in the Southern Biofacies Belt. Upper Permian blocks in the Karakaya Orogen display similar palaeontologic and biofacies characteristics, with the outer platform or platform margin deposits of the Taurides constituting the northernmost extension of the carbonate platform. This platform was probably facing a basin or a trough to the north. The lack of any transgressive Upper Permian deposits resting unconformably on the pre-Permian basement of the Sakarya Continent strongly suggests that such a basin was located between the Late Permian carbonate platform in the south and the basement rocks of the future Sakarya Continent in the north.
A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution
Authors: Göncüoğlu M. Cemal , Turhan Necati , Şentürk Kamil , Özcan Ahmet , Uysal Şükrü , Yaliniz M. Kenan 
Published: April 2008

Abstract
In the Central Sakarya area of Turkey there are two main Alpine continental units, separated by a south verging ophiolitic complex which represents the root zone of the İzmir-Ankara Suture Belt.
The Central Sakarya Terrane in the north includes two ‘Variscan’ tectonic units in its basement. The Söğüt Metamorphic rocks represent a Variscan ensimatic arc complex and the Tepeköy Metamorphic rocks are characteristically a forearc-trench complex. The unconformably overlying Triassic Soğukkuyu Metamorphic rocks correspond to a part of the Karakaya Formation and are interpreted as a Triassic rift basin assemblage. These units are unconformably overlain by a transgressive sequence of Liassic-Late Cretaceous age that represents the northeastward deepening carbonate platform of the Sakarya Composite Terrane.
The middle tectonic unit (the Central Sakarya Ophiolitic Complex) comprises blocks and slices of dismembered ophiolites, blueschists and basic volcanic rocks with uppermost Jurassic-Lower Cretaceous radiolarite-limestone interlayers. Geochemical data from basalt blocks suggest mid-ocean ridge basalt (MORB)- and suprasubduction-type tectonic settings within the Neotethyan İzmir-Ankara Ocean.
The southern tectonic unit includes basal polyphase metamorphosed clastic rocks (Sömdiken Metamorphics), intruded by felsic and basic dykes and overlain by thick-bedded marbles. This assemblage is unconformably overlain by continental clastic rocks gradually giving way to thick-bedded recrystallized limestones, cherty limestones and pelagic limestones intercalated with radiolarites, and finally by a thick high pressure-low temperature (HP-LT) metamorphic synorogenic flysch sequence. This succession is identical to the passive continental margin sequences of the Tauride Platform. It is suggested that this passive margin was subducted during the Late Cretaceous in an intraoceanic subduction zone and affected by HP-LT metamorphism. The emplacement of the allochthonous oceanic assemblages and the collision with the Central Sakarya Terrane was complete by the end of the Cretaceous.
Structural Correlation of the Southern Transcaucasus (Georgia)-Eastern Pontides (Turkey)
Authors: Yilmaz Alİ , Adamia Shota , Chabukiani Alexander , Chkhotua Tamara , ErdoĞan Kemal , Tuzcu SevİM , KarabiyikoĞlu Mustafa 
Published: April 2008

Abstract
The eastern Pontides (northeastern Turkey) and Transcaucasus (Georgia) belong to the same geological belt representing an active margin of the Eurasian continent. According to palaeotectonic-palaeogeographic reconstructions, based on regional geological, palaeomagnetic, palaeobiogeographical and petrological data, the eastern Pontides and the major part of the Transcaucasus, situated to the north of the North Anatolian-Lesser Caucasian ophiolitic suture, comprise island arc, forearc, back and interarc basins. The eastern Pontide segment of the belt consists of three structural units which, from north to south, are the northern, central and southern units. The northern unit, the southeastern Black Sea coast-Adjara-Trialeti Unit, represents a juvenile back arc basin formed during the Late Cretaceous (pre-Maastrichtian). This unit separates the southern and northern Transcaucasus zones. The central Artvin-Bolnisi Unit is also known as the northern part of the southern Transcaucasus and is characterized by Hercynian basement, unconformably overlying the Upper Carboniferous-Lower Permian molasse and Upper Jurassic-Cretaceous arc association. The southern unit is the imbricated Bayburt-Karabakh Unit and is known as the southern part of the southern Transcaucasus. This unit has a similar basement to the Artvin-Bolnisi Unit and also includes a chaotic assemblage; it unconformably overlies the Upper Jurassic-Cretaceous forearc association. The eastern Pontide system is interpreted as the product of interference between a spreading ridge and subduction zone during Late Jurassic-Cretaceous times. The North Anatolian-Lesser Caucasus Suture, comprising ophiolites, mélanges and an ensimatic arc association, separates the overlying system from the Anatolian-Iranian Platform in the south. Maastrichtian-Lower Eocene cover rocks in the region unconformably overlie all the other units. Middle Eocene rifting resulted in the formation of new basins, some of which closed during an Oligocene-Early Miocene regression. Others, such as the Black Sea and Caspian Basins, have survived to the present day as relict basins.
Neogene Paratethyan Succession in Turkey and Its Implications for the Palaeogeography of the Eastern Paratethys
Authors: Görür Naci , Çağatay Namik , Sakinç Mehmet , Akkök Remzi , Tchapalyga Andrey , Natalin Boris 
Published: April 2008

Abstract
The Neogene marginal succession of the Eastern Paratethys (EP) crops out along the southern Black Sea coast and in the Marmara region of Turkey, and provides important clues to the tectono-sedimentary and palaeoceanographic conditions.
In the Tarkhanian stage, the southern margin of the EP basin was largely a carbonate platform covered by warm, marine waters. From the end of the Tarkhanian to the Early Chokrakian there was an overall emergence throughout the basin, which is indicated by an influx of siliciclastic sediments. The fossil assemblage indicates that normal marine conditions persisted during most of this period, except for a salinity reduction towards the end due to an eustatic isolation of the basin, which in turn led to anoxic bottom water conditions. The Late Chokrakian isolation became even more severe during the Karaganian as indicated by the endemic fossil assemblage indicating brackish-marine conditions. Carbonate platform conditions prevailed in the northern Pontides during this time. In the Early Konkian, the basin was reconnected briefly with the world ocean by a transgression from the Indo-Pacific Ocean. In the Late Konkian there was a return to brackish-marine conditions.
Lower Sarmatian sediments are absent in the southern margin of the EP, but elsewhere in the basin this stage is characterized by a widespread marine transgression. In the Middle-Late Sarmatian, the EP basin was partially isolated with freshening and anoxic bottom-water conditions. During this time there was a brief marine transgression from the Mediterranean into the Marmara region, but it did not reach the Paratethyan basin. The Pontian is characterized by an extensive transgression from the EP that inundated the Marmara and northeastern Aegean regions. The connection with the Marmara Basin was cut off during the Kimmerian and re-established during the Late Akchagylian, when the EP basin was inundated by the Mediterranean waters via the Sea of Marmara as a result of increased North Anatolian Fault activity and a short-term global sea level rise.
Episodic Graben Formation and Extensional Neotectonic Regime in West Central Anatolia and the Isparta Angle: A Case Study in the Akşehir-Afyon Graben, Turkey
Authors: Koçyİğİt Alİ , ünay Engİn , Saraç Gerçek 
Published: April 2008

Abstract
Central and Western Anatolia form a continental back-arc region related to the Hellenic-Cyprus convergent plate boundary of the Anatolian and African Plates. The Akşehir-Afyon Graben (AAG), the easternmost extension of the west Anatolian horstgraben system, is located at the junction of Central Anatolia and eastern limb of the Isparta Angle. The AAG is 4–20 km wide and 90 km long. It trends west-northwest-east-southeast and is an actively growing rift containing two sedimentary infills of continental fluviolacustrine origin bounded on both sides by oblique-slip normal faults. The older infill is folded, thrust faulted and early Late Miocene in age. The younger infill, which is nearly horizontally bedded, is Plio-Quaternary in age and rests on the older infill with angular unconformity. The deformation of the older infill and the angular unconformity indicate a Late Miocene phase of compression, which separates two extensional periods. The second phase of extension has lasted since the Pliocene and is part of the current extensional neotectonic regime of both west Central Anatolia and the Isparta Angle, despite being previously reported as a compressional neotectonic regime.
The graben-bounding Akşehir Fault Zone (AFZ) and the Karagöztepe Fault Zone display well-preserved fault surfaces and slickenlines. Although stereographic plots of the fault slip data show that the graben-bounding structures are oblique-slip normal faults, the AFZ has also been described as a single reverse fault. Both the field and seismic data, particularly the 1921 Argıthanı-Akşehir and 1946 Ilgın-Argıthanı earthquakes, indicate that the AAG is an active neotectonic structure. However, it can also be interpreted to lie in a seismic gap when its rate of seismicity is compared with that of the Gediz-Simav Graben forming its west-northwestern extension.
Palaeomagnetic Study of the Erciyes Sector of the Ecemiş Fault Zone: Neotectonic Deformation in the Southeastern Part of the Anatolian Block
Authors: Tatar Orhan , Piper John D. A. , Gürsoy Halil 
Published: April 2008

Abstract

In the Turkish sector of the Afro-Eurasian collision zone, continuing northward motion of the Arabian promontory is extruding the Anatolian region to the west. Although the East Anatolian Fault Zone (EAFZ) is recognized as the southern boundary of this tectonic escape, distributed deformation is occurring across a broad zone extending for at least 300 km to the northwest, which includes a number of major dextral and sinistral fault lineaments. The longest of these lineaments is the Ecemiş Fault Zone, although the long-term significance of deformation, and specifically strike-slip, across this zone is disputed. This zone is also the locus of major volcanic activity in the Kayseri region. The present paper reports a palaeomagnetic study of young (1–2 Ma) lava flows which has aimed to identify recent block rotations resulting from regional deformation in this region. Rock magnetism shows the lavas to be dominated by low-Ti magnetite assemblages of primary cooling related origin. Although grain properties are predominantly multidomain, significant fractions of single domains are always present and responsible for a stable thermoremanence of normal and reversed polarity. Whilst group mean directions show that the blocks in this sector of Anatolia show the typical counterclockwise rotation resulting from tectonic escape, in this case by
c
. 10° during the last 1 Ma, larger differential rotations in both senses are identified across the Sultansazhği Depression. Comparable differential rotations recorded by the 2.8 ± 0.2 Ma Incesu Ignimbrite have resulted from the pull-apart in this sector of the Ecemiş Zone which has accommodated emplacement of the Erciyes volcanic centre since the termination of ignimbrite activity. Within the wedge-shaped terrane confined between the EAFZ in the south and the North Anatolian Fault Zone in the north, the degree of counterclockwise rotation during tectonic escape within the last 2–3 Ma has diminished from
c
. 25° in the east to
c
. 10° towards the southwest. This corresponds to a transition from highly strained to a less-strained lithosphere as the width of the semi-plastic Anatolian terranes confined between the Arabian-Eurasian pincer broadens out to the west.
S-I-A-type Intrusive Associations: Geodynamic Significance of Synchronism Between Metamorphism and Magmatism in Central Anatolia, Turkey
Authors: Boztuğ Durmuş 
Published: April 2008

Abstract

The Central Anatolian crystalline region, comprising metasediments, ophiolitic slabs and numerous intrusives, has been called the Kırşehir Massif, the Kırşehir Block or Central Anatolian Crystalline Complex. Intrusive associations in Central Anatolia are summarized as: (1) a syncollisional, S (or C
ST
)-type, peraluminous and two-mica leuco-granitic association; (2) a post-collisional, I (or H
LO
)-type, metaluminous, high-K calcalkaline, typically K-feldspar megacrystic monzonitic association; and (3) an A-type, post-collisional and within-plate alkaline association comprising a high-K and silica-oversaturated alkaline, K-feldspar megacrystic monzonitic and synoptic subgroup, and a silica-undersaturated alkaline feldspathoid-sodalite syenite porphyry subgroup.

Radiometric data suggest that metamorphism and magmatism in Central Anatolia were synchronous during the Late Cretaceous. This implies that metamorphism may have been generated by inverted metamorphism induced by the Anatolide-Pontide collision and was linked to a decreasing metamorphic grade from the north (i.e. from the main suture zone) towards the south (i.e. Taurides). Collision-related intrusive rocks within this crystalline body reflect differences in geological setting, mineralogical-chemical composition and associated ore deposition. Published data considering the distribution and timing of metamorphism and magmatism in the Central Anatolia suggest that both are related to the Anatolide-Pontide collision along the İzmir-Ankara-Erzincan Suture Zone in the Late Cretaceous. Various magmatic episodes affected along the passive margin of the Anatolides, including a syncollisional peraluminous episode, a post-collisional calc-alkaline hybrid and a post-collisional within-plate alkaline episode.
Sedimentation associated with estuarine frontal systems
Authors: McManus John 
Published: April 2008

Abstract

Estuarine fronts may develop in several locations, across the water body as transverse, halocline-related features, as overbank spills, or where tidal flats release waters into principal tidal channels. In many estuaries longitudinal fronts originate at headlands or are associated with major sandbanks (Bowman 1988). Commonly a front separates a nearshore water mass from that of the main flow of tidal waters. In the marginal waters flows are slower than in the main channels, and suspended sediments and pollutants released to these marginal zones do not mix freely with the principal tidal waters entering and leaving the estuary. These nearshore waters also often differ in temperature from the channel waters (Anderson
et al.
1992). It is suggested that the linear convergent frontal systems provide the ideal sites for the accumulation of sediment, and exert some control on the distribution of longitudinal estuarine sand banks. Some, but not all of these are associated with headlands. The geomorphological evolution of the sand bank systems within the upper and middle reaches of the Tay Estuary, Scotland, are discussed in relation to present and past locations of longitudinal fronts. The Middle Bank, off Dundee, is seen to occur between the lines of longitudinal fronts formed during the flood and ebb phases of the tide. The Naughton Bank, off Balmerino is related to an ebb phase headlnad-induced flow separation. In the seaward reaches longitudinal fronts locate the outer margins of the tidal flats and become axially convergent in the Tayport-Broughty Ferry narrows.
Processes controlling import of fine-grained sediment to tidal areas: a simulation model
Authors: Bartholdy Jesper 
Published: April 2008

Abstract
Salt marsh and mud flat sedimentation in the Wadden Sea and in similar depositional regions is usually dependent on the net import of fine-grained sediments from adjacent marine environments. This net import takes place as a result of several processes such as settling lag and scour lag. This paper utilizes a database comprising time series of tidal velocity and turbidity in the Grådyb tidal area of western Denmark as the basis of a simple conceptual model which describes the transport, deposition and resuspension of finegrained material in the area. The results demonstrate that: (a) grain sizes close to the sand/silt boundary are most sensitive to lag effects; (b) scour lag is much more important than settling lag; (c) raised temperatures enhance the net-lag effect for silt with increasing importance for finer grain sizes; (d) with increased suspended concentrations, the time it takes to resuspended the material deposited at slack water (the resuspension lag) is of increasing importance for the net-lag effect.
Shoreline change and fine-grained sediment input: Isle of Sheppey Coast, Thames Estuary, UK
Authors: Nicholls Robert J. , Dredge Andrew , Wilson Theresa 
Published: April 2008

Abstract

The northern coast of the Isle of Sheppey comprises actively-eroding cliffs up to 50 m high cut into the London Clay. From 1867 to 1998 the average cliff-top recession was about 1 m a
−1
, while the maximum recession was 1.9 ± 0.08 m a
−1
. From 1897 to 1998, this provided at least 4.5 × 10
5
t a
−1
of fine-grained sediment to the Thames Estuary system and southern North Sea. This sediment input due to erosion is comparable in magnitude with fluvial sediment input from the Thames. The sinks for this material are unclear, but it is likely that the Essex and Kent estuaries and marshes have historically been important in this regard. Given climate change and accelerated sea-level rise, estuaries will again act as sinks, and it is prudent to maintain these supplies of sediment so that these estuarine systems can adjust to this forcing. To maintain sediment supply, shoreline management and estuary management needs to recognize more explicitly the importance and scale of fine-grained sediment supply and transport, including any implications for statutory land use planning.
Physical modelling of the rheology of clean and sediment-rich polycrystalline ice using a geotechnical centrifuge: potential applications
Authors: Irving Duncan H. B. , Rea Brice R. , Harris Charles 
Published: April 2008

Abstract

A self-weight stress gradient is developed through the body of a glacier such that strain rates are highest in the lowest few metres as described by Glen’s flow law and other stress- and temperature-dependent relationships. Conventional laboratory technology limits the size and complexity of physical models of glacier ice, particularly in the complicated basal ice layers. A geotechnical centrifuge can be used to replicate such stress regimes in a controlled environment using a scaled model of the field ‘prototype’ that is subjected to an accelerational field that is a factor
N
greater than that of the Earth,
g
. The development of a technique employing a geotechnical centrifuge as a testbed for such physical models is described. Strain rates of 10
−6
–10
−7
s
−1
are calculated for models of low and moderate stress, high temperature ice. Relationships between the physical models and glacial systems suggest a scaling of the effects of transient creep by 1:
N
, diffusion creep by 1:
N
2
–1:
N
3
and power law creep by 1:1. Preliminary results demonstrate the potential applications of the technique in the fields of glaciology and glacial geomorphology, in particular where low stresses and high temperatures are key characteristics of a glacial system and in systems containing several stratigraphic units.