bluuebunny/crossref_metadata_2025_split huggingface dataset:
Docking and post-docking escape tectonics in the southern Philippines
Authors: Pubellier M. , Quebral R. , Aurelio M. , Rangin C. 
Published: April 2008

Abstract
The structure of the Philippine archipelago results from the juxtaposition, between the Late Miocene and the present, of a volcanic belt against fragments of the Eurasian margin and associated marginal basins. The southern Philippines offers the opportunity of studying the mechanics of the deformation from active contraction to a more complex post-docking setting. The docking period is characterized by a compression which began during the early Late Miocene in the central Philippines and has been recently studied in the island of Mindanao. There, deformation initiated in the Late Miocene-Early Pliocene on a NW-trending wrench zone, and continued until the Late Pliocene with thrusting on west-verging flats and ramps within the arc and east-verging thrusts within the Sangihe forearc. This deformation is still active to the south in the Molucca Sea. The post-docking period began in the Early Pleistocene in northern Mindanao and is represented by a new geodynamic framework with a paired subduction zone and strike-slip fault. However, convergence is still active in the Manila and the Negros trenches, although the Philippine fault is not offset. Large wrench faults, which reactivate the ramp faults of the collision stage, transfer strain from the Philippine fault to the Manila and Negros trenches. These observations imply active intra-arc extension and fragmentation within the Philippine mobile belt.
Basement structural controls on Carboniferous-hosted base metal mineral deposits in Ireland
Authors: Johnston J. D. , Coller D. , Millar G. , Critchley M. F. 
Published: April 2008

Abstract
Explorationists have long recognized the importance of structural control of Irish base metal deposits, but the kinematics and timing of the structures relative to the mineralization are subject to wildly differing interpretations. This paper presents a combination of structural, magnetic and gravity data that show that the fundamental structural controls are easterly to northeasterly-trending basement (Caledonian) structures which have been reactivated in dextral transtension by northeasterly to north-northeasterly extension during the Dinantian. In general, in the north of the country the ore-controlling faults dip south, while in the south of the country they dip north. The structures have evolved through a temporal kinematic history of early normal faulting, later oblique slip, and some show evidence of later reverse movements. Part of this evolution may reflect burial history, although it also reflects the transition from Dinantian transtension to Variscan (Hercynian) compression. The bulk of the mineralization appears to post-date the normal faulting, and pre-date Variscan compression. Mineralization is thought to be post-compactional and could have occurred during the dextral transtension, although some of the sulphides could post-date most of the transtensional movement.
Cyclic emersion surfaces and channels within Dinantian limestones hosting the giant Navan Zn-Pb deposit, Ireland
Authors: Rizzi Giancarlo , Braithwaite Colin J. R. , Rizzi Giancarlo 
Published: April 2008

Abstract
The Carboniferous succession in the Navan Mine area, which lies near the northern margin of the Dublin Basin, rests unconformably on folded Lower Palaeozoic rocks. The informal stratigraphic nomenclature of the mine is used throughout. Sedimentation began in the late Devonian-early Courceyan with Red Beds reflecting deposition in braided streams and alluvial fans. The overlying Laminated Beds consist of shallow-marine barrier sandstones, tidal-flat/lagoonal mudstones, and sabkha evaporites. The Muddy Limestone is a mud-dominated carbonate sequence reflecting deposition in an open clastic-influenced lagoon. The Pale Beds that follow, and on which attention is focused here, contain at least 44 peritidal and shallow-shelf depositional cycles. The overlying Shaley Pale and Argillaceous Bioclastic Limestones reflect deeper water open-sea conditions. This sequence is truncated by a conspicuous erosion surface overlain by Chadian submarine debris-flows and limestone turbidites.
The succession reflects a progressive deepening of the waters as subsidence outpaced sediment accumulation, but emersion surfaces capping cycles indicate that neither deposition nor relative sea-level rise were continuous. Cyclicity and emergence are believed to reflect the interaction of regional subsidence, glacio-eustatic sea-level oscillation, and sediment supply.

Emersion surfaces occur in the Laminated Beds and throughout the Pale Beds, and include palaeosols,
in situ
breccias, pinnacled and hummocky surfaces, and karst-modified topography. Deeply incised channels at four intervals point to larger-scale incision. The lithoclast-bearing conglomerates which they contain indicate extensive emergence nearby. The distribution of these features may be related to the margins of outcrops of Old Red Sandstone and Lower Palaeozoic rocks.

The Dinantian limestones in this region host several Zn-Pb ore deposits including Europe’s largest at Navan. The results of this study suggest a relationship to the margins of former emergent carbonate terrains.
Microfacies associations in Asbian carbonates: an example from the Urswick Limestone Formation of the southern Lake District, northern England
Authors: Horbury A. D. , Adams A. E. 
Published: April 2008

Abstract

Semi-quantitative analysis of allochems from the Urswick Limestone Formation (Asbian) of the southern Lake District area of northern England has revealed a distinctive cyclicity of the microfacies. Cycle-top grainstone microfacies contain an algal flora comprising
Koninckopora, Anatolipora
and
Polymorphocodium
, with
Girvanella
filmaents and
Ortonella
lumps. Other allochems include intraclasts, large peloids and thick-shelled bivalves and gastropods. The middles of cycles are mostly packstones and micro-grainstones and contain allochems dominated by small peloids and the algae
Kamaeena, Kamaenella
and
Epistacheoides
, with the microproblematicum
Ungdarella
and relatively high abundances of micritic-walled formainifera such as endothyrids. Cycle bases contain a diverse algal assemblage including
Coelosporella
and
Stacheoides
, with other allochems represented by trilobites, ostracodes,
Saccamminopsis
, foraminifera such as Archaediscidae, the base late Asbian guide
Howchinia
, the base early Asbian guides
Gigasbia gigas
and
Vissariotaxis
, bivalves, small gastropods, bryozoans, sponge spicules and bored grains. Other allochems are found throughout most cycles, decreasing only in the very shallowest (intertidal) facies, or have an irregular distribution, and include brachiopod debris, crinoid ossicles and coral fragments.

There are significant variations in allochem distribution according to palaeogeography. Close to the shelf margin there are higher abundances in the cycle top grainstones of the algae
Koninckopora
and
Anatolipora
, and also of the calcified filaments
Girvanella
and
Ortonella
, with thick-shelled gastropods, intraclasts and coarse peloids. At cycle bases, echinoderm arm plates and bryozoans are particularly abundant in packstone-wackestone textures. Platform interior facies are differentiated into a diverse open-marine type, with a high total abundance of bioclasts in the cycle base pack-wackestones including trilobites,
Coelosporella, Stacheoides, Kamaena
and bored grains, grainstones are dominated by small peloids,
Kamaenella
and
Ungdarella
), and a more restricted cycle type, in which total bioclast abundances are low.
Mid-Dinantian brachiopod biofacies from western Ireland
Authors: Harper David A. T. , Jeffrey Anna L. 
Published: April 2008

Abstract

New silicified brachiopod faunas from lower and middle Viséan horizons have been retrieved from the vicinity of Loughs Carra, Corrib and Mask in west Connaught. In addition, carbonate shell beds dominated by
Linoprotonia
are recorded from mid County Galway. At present over 40 species of brachiopod are known, from current sampling programmes and the literature, variably associated with bryozoan, coral, echinoderm, mollusc and trilobite faunas; microvertebrates such as sharks teeth are locally common. Four main assemblages are recognized; in ascending order, Arundian strata at Ardnasillagh, Lough Carra, Kibeg Wood and Ballintober in a northern belt are variably dominated by
Rhipidomella, Schizophoria, Leptagonia, Rugosochonetes, Krotovia, Echinoconchus, Tylothyris, Punctospirifer
and
Spiriferellina
. In addition to genera recorded from Arundian strata elsewhere,
Streptorhynchus, Plicochonetes, Dictyoclostus, Pleuropugnoides
and ‘
Spirifer
’ also occur in the diverse Kiltiernan fauna assembled last century. In a southern belt, possible Holkerian horizons at Dunsandle are less diverse, with faunas dominated by
Composita
, whereas limestones of Holkerian-early Asbian age at Kiltullagh Bridge have quite different faunas with
Schizophoria, Brochocarina, Minythyra
and
Cleiothyridina
; these faunas are more similar to the diverse Asbian assemblages described from County Fermanagh in the north of Ireland. In a central belt, in the Bunoghanaun area, Holkerian to early Asbian horizons are dominated by relatively thick shell beds in pure limestones with mainly opportunist large linoproductids; this fauna is not silicified.
Volcano instability development: a planetary perspective
Authors: Head James W. 
Published: April 2008

Abstract
Analysis of the types and causes of volcano instability using the record seen on other planets, where volcanoes form in a wide variety of environments and are often better preserved, provides a perspective on the processes involved and deposits produced in edifices on Earth. The records on these bodies illustrate the potential significance of neutral buoyancy zones and rheological boundaries in relation to initial magma ascent and storage, related eruption styles, and subsequent edifice development and behaviour. On the Moon no Hawaii-like shield volcanoes are observed; the thick low-density anorthositic crust provided a density barrier to mantle plumes and the low frequency of dyke-emplacement events precluded development of shallow reservoirs and large shields. On Venus, the very high atmospheric pressure reduces volatile exsolution and fragmentation, inhibiting the formation of neutral buoyancy zones (NBZ) and shallow magma reservoirs near or below mean planetary radius; eruptions are predicted to be characterized by relatively high total volumes and effusion rates, and poorly developed edifices. Decrease in atmospheric pressure with elevation favours the development of NBZs and reservoirs at higher elevations. These and other factors result in low and broad volcanic edifices, with reservoirs predominantly in the substrate. Smaller loads, thicker lithospheres, and dry substrates combine to minimize large-scale vertical edifice growth and instability development. Exceptions include a wide array of collapse runout features associated with steep-sided domes. On Mars, low gravity and low surface atmospheric pressure cause density profile differences and flow length differences and massive volcanoes have been emplaced over long periods on a stable lithospheric plate and a volatile-containing upper crust. They exhibit a wide range of rift zone development, internal deformation related to lithospheric loading and flexure, flank and slope failure, and summit failure and caldera development. These planetary examples permit one to begin to isolate various factors in the development of volcano instabilities, including edifice geometry (height/width) and size, relation to lithospheric thickness as a function of time, potential role of neutral buoyancy zones and magma reservoir size and development, and the presence of fluids in the substrate. The extensive and well-preserved flank-failure deposits on Mars provide a significant areal perspective and analogue for the interpretation of less-well preserved deposits on Earth.
Slope stability and eruption prediction on the eastern flank of Mount Etna
Authors: Murray J. B. , Voight B. 
Published: April 2008

Abstract
Recent work applying knowledge of the failure of materials to volcanic eruptions in Kamchatka, Alaska and mainland USA, has shown that inverse rate analysis of seismic data can accurately predict eruption times up to 2 or 3 weeks in advance. We find evidence that application of the same principles to ground deformation data on Mt Etna’s eastern flank prior to the eruptions of 1985 and 1989 provides good eruption time predictions more than 3 months in advance. The same data also point to an eruption triggering mechanism involving an interplay between slope creep and magma pressure that has not been described before.
A simple model for the genesis of large gravitational landslide hazards in the Canary Islands
Authors: Carracedo J. C. 
Published: April 2008

Abstract
Natural hazards in the Canarian Archipelago are mainly in relation to volcanism (at least five islands with Holocene eruptive activity, 17 eruptions in the last 500 years) and massive gravitational landslides related to edifice overgrowth and dyke intrusion. In the volcanically active islands, the emission vents tend to group in clearly aligned clusters, evolving to form steep ridges that behave as true polygenetic active volcanoes with clear rift affinities, and constitute by far the most probable location of any future volcanic eruption in the archipelago. Tunnels excavated for water mining show a narrow band of tightly packed parallel dykes running through the centre of the rifts. The rift zones play a key role in the growth and shape of the island edifices and in the generation of massive landslides. Cumulative gravitational stresses related to the growth of the volcanic edifices and more ephemeral mechanisms associated with intense eruptive phases, such as dyke wedging, increase of slope angles and strong local seismicity associated with magma movement can finally exceed the trigger-threshold of gravitational slides. This mechanism may be the explanation for the numerous horseshoe-type valleys and calderas developed in the Canary Islands. The geometry of these rift zones is frequently three-branched at 120°C (Mercedes-Benz star configuration), suggesting a least-effort fracturing by magma-induced upwelling. The rift zones play a major role in the distribution of geological hazards: eruptive vents and the failure planes of gravitational landslides are located preferentially along these volcanic lineaments.
Volcanological and structural evolution of Roccamonfina volcano (Italy): origin of the summit caldera
Authors: De Rita D. , Giordano G. 
Published: April 2008

Abstract

Roccamonfina volcano (Roman Magmatic Province) sits at the margin of the NE-trending Garigliano graben. The most important episodes in the volcano’s history (630–50 ka
bp
) have been controlled by tectonic activity associated with the graben’s master-faults. Roccamonfina volcano comprises two main parts: a stratovolcano developed inside the graben, and a complex of centres developed on the south-eastern horst. The summit of the stratovolcano is truncated by a horse-shoe shaped caldera (dimensions 6.5 km by 5.5 km) with the longest axis trending NW. The caldera opens towards the SE along NE-trending faults, which belong to the same system as the graben faults. Stratigraphical evidence indicates that caldera collapse was not caused by explosive eruptive events emplacing ignimbrites, or by sector collapse preceding ignimbrite eruptions. Geomorphological and structural observations, together with geophysical evidence, suggest that collapse of the volcano summit occurred as a mechanical re-adjustment to the high rate of the Garigliano graben extension during a climax of the regional tectonism at around 400 ka
bp
. The present elliptical shape of the collapsed area is due to the superposition of a linear NE-trending graben structure in the east, and a sector collapse in the west.
Structural evolution of the Bracciano volcano-tectonic depression, Sabatini Volcanic District, Italy
Authors: De Rita D. , Di Filippo M. , Rosa C. 
Published: April 2008

Abstract

The Latian volcanoes of Central Italy form several K-rich volcanic districts, some of which are characterized by large volcano-tectonic depressions filled with lakes. The development of these large depressions (>8 km in diameter) occurred from 0.4–0.3 Ma
bp
, during a climax of regional extension. Analysis of geophysical and deep drilling data and detailed field analysis, allows reconstruction of the evolution of the Bracciano volcanotectonic depression in the Sabatini Volcanic District, northwest of Rome. This depression developed during the Upper Pleistocene inside a NE-trending half-graben structure. The evolution of the half-graben has been driven by NE-trending regional faults which were reactivated during volcanism. Magma rose along these faults and came to rest at 4–7 km depth, probably as a laccolithic body, and was then erupted with emplacement of large volume ignimbrites. A lava plateau recognized by drilling data in the southern and western sectors of the depression is interpreted as being associated with NE-striking swarms of feeder dykes. The final downsagging was caused by NE and NW-trending regional faults after 0.17 Ma. The eastern depression morphology was modified by late Pleistocene N-trending strike-slip faults which were accompanied by intense hydromagmatic activity. Hydromagmatic craters are distinguished in the eastern margin of the area and in the southeastern part of Lake Bracciano in high-frequency seismic sections.
Modified volcanic domes and associated debris aprons on Venus
Authors: Bulmer M. H. , Guest J. E. 
Published: April 2008

Abstract
The Magellan SAR images show that volcanic domes occur on the surface of Venus. Edifices with scalloped margins are similar to volcanic domes and fall within a spectrum ranging from unmodified to remnant forms. Over 320 domes have been located of which more than 80% have modified morphologies. Broadly, the modified domes can be described by five sub-categories which are related to three unmodified dome sub-categories. Many modified domes have deposits associated with them that possess characteristics indicative of their having been formed from mass movements. Evidence for slope failure is not seen on volcanic shields on Venus due to them having shallow flanks. Several steep-sided cones show some evidence of slope failure but on a much smaller scale than failures associated with domes. Slope failures on venusian domes appear to have been triggered by non-explosive and explosive events. Collapse on the edges of domes, either as a result of explosive events of oversteepening, is common on Earth but the collapses on Venus are on a scale that is more in common with major sector collapses of volcanoes on Earth. Four morphological sub-groups of debris deposit have been recognized. The deposits in groups one and two are analogous to terrestrial volcanic debris avalanche deposits and the deposits in group three are analogous to pyroclastic flows on Earth. The characteristics of the fourth group of deposits are similar to those resulting from deep-seated slides on Earth.
High-grade metamorphism of 2.45–2.4 Ga age in mafic intrusions of the Belomorian Belt in the northeastern Baltic Shield
Authors: Bogdanova S. V. 
Published: April 2008

Abstract
In the Late Archaean Belomorian Belt of the Baltic Shield, shearing and high-grade metamorphism occurred in association with bimodal gabbroic-granitic igneous activity between 2.45 and 2.40 Ga. That period is generally regarded as one of anorogenic rifting and extension. In the studied case of the Tolstik intrusion, the time of metamorphism is constrained by the 2434 ± 7 Ma age of a metamorphosed mafic intrusion and the 2405 ± 20 Ma age of a subsequently intruded potassic granite. Several generations of mafic dykes allow a detailed study of the metamorphic evolution during that time span.

The conditions of post-intrusion peak metamorphism in the mafic intrusion were 700–800°C and 11–12 kb which was followed first by near-isothermal decompression and, after the loss of
c.
5 km crustal thickness, by near-isobaric cooling to
c.
600° C at 8–9 kb.

These results suggest metamorphism possibly triggered by igneous intrusions into previously thickened crust, but the P/T-ratios of metamorphism were moderately high. Later followed crustal extension concomitantly with continuous igneous input and the P/T- ratios decreased. Finally, a post-extensional period of cooling ensued as igneous activity ceased.
The Palaeoproterozoic Southeastern Churchill Province of Labrador-Quebec, Canada: orogenic development as a consequence of oblique collision and indentation
Authors: Wardle R. J. , Van Kranendonk M. J. 
Published: April 2008

Abstract

Palaeoproterozoic orogenic development in the northeastern Canadian Shield was controlled by the successive, oblique collision of the Archaean Nain (North Atlantic) and Superior cratons with a southwards projecting promontory of the Archaean Rae Province (part of the northern Churchill Province hinterland). By this process the Rae Province became sutured to the Nain craton by the Torngat Orogen and to the Superior craton by the New Quebec Orogen, resulting in the formation of a 400 km wide orogenic belt known as the Southeastern Churchill Province (SECP). Initial rifting at 2.45–2.1 Ga, and early (arc?) magmatism and deformation at 2.3–1.9 Ga, were restricted to the Rae Province. They were followed by arc magmatism in the Torngat Orogen at
c.
1.91–1.88 Ga and Rae/Nain collision 1.87–1.86 Ga, which resulted in the formation of an orogen with east- and west-verging structures. Arc magmatism in the New Quebec Orogen commenced at
c.
1.845 Ga and was succeeded by Rae/Superior collision and widespread deformation across the SECP at
c.
1.83 Ga. Deformation at this time was dominated by west-vergent thrusting in the New Quebec Orogen and Rae Province, and by renewed east-vergent thrusting in Torngat Orogen. Deformation was then progressively transferred to major sinistral (1.845–1.82 Ga in the eastern SECP) and dextral (1.83–1.80 Ga? in the western SECP) shear systems that accommodated continued northwards motion of the Nain and Superior cratons relative to the Rae Province. Juvenile crust expelled by thrusting effectively doubled crustal thickness in parts of the Rae Province and the northwestern edge of the Nain craton. Late stage development (1.8–1.71 Ga), was restricted to the margins of the SECP, where deformation was associated with renewed outward-directed overthrusting and transcurrent shear in conjunction with uplift of the orogenic core.