Lattice preferred orientation in omphacite: Examples from the Tauern Window, Austria and the Western Gneiss Region, Norway

It is lively debated how eclogites find their way from deep to mid-crustal levels during exhumation. Different exhumation models for high-pressure and ultrahigh-pressure rocks were suggested in previous studies, based mainly on field observations and less on microstructural studies on the exhumed rocks. The development and improvement of electron microscopy techniques allows it, to focus interest on direct investigations of microstructures and crystallographic properties in eclogites. In this case, it is of importance to study the applicability of crystallographic measurements on eclogites for exhumation processes and to unravel which processes affect eclogite textures. Previous studies suggested a strong relationship between deformation and lattice preferred orientation (LPO) in omphacite but it is still unclear if the deformation is related to the exhumation of eclogites. This study is focused on the questions which processes affect omphacite LPO and if textural investigations of omphacite are applicable for studying eclogite exhumation. Therefore, eclogites from two examples in the Alps and in the Caledonides were collected systematically and investigated with respect to omphacite LPO by using the electron backscattered diffraction (EBSD) technique. Omphacite textures of the Tauern Window (Austria) and the Western Gneiss Region (Norway) were studied to compare lattice preferred orientation with field observations and suggested exhumation models from previous studies. The interpretation of omphacite textures, regarding the deformation regime is mainly based on numerical simulations in previous studies. Omphacite LPO patterns of the Eclogite Zone are clearly independent from any kind of exhumation process. The textures were generated during omphacite growth on the prograde path of eclogite development until metamorphic peak conditions. Field observations in the Eclogite Zone show that kinematics in garnet mica schist, surrounding the eclogites, strongly indicate an extrusion wedge geometry. Stretching lineations show top-N thrusting at the base and a top-S normal faulting with a sinistral shear component at the top of the Eclogite Zone. The different shear sense on both sides of the unit does not affect the omphacite textures in any way. The omphacite lattice preferred orientation patterns of the Western Gneiss Region can not be connected with any exhumation model. The textures were probably generated during the metamorphic peak and reflect the change from subduction to exhumation. Eclogite Zone and Western Gneiss Region differ significantly in size and especially in metamorphic conditions. While the Eclogite Zone is characterized by constant P-T conditions (600-650°C, 20-25 kbar), the Western Gneiss Region contains a wide P-T range from high- to ultrahigh pressure conditions (400-800°C, 20-35 kbar). In contrast to this, the omphacite textures of both units are very similar. This means that omphacite LPO is independent from P-T conditions and therefore from burial depth. Further, in both units, omphacite LPO is independent from grain and subgrain size as well as from any shape preferred orientation (SPO) on grain and subgrain scale. Overall, omphacite lattice preferred orientation are generated on the prograde part of omphacite development. Therefore, textural investigations on omphacite LPO are not applicable to study eclogite exhumation.

Post-colonial (American?) English Presence on the North-Western Pacific Island of Kosrae: A cross-linguistic analysis of the overlaps and divergences of Kosraean English compared to standard American English

Kosrae is the most remote island of the Federated States of Micronesia (FSM), with a population of less than 7,000 inhabitants, located in the Pacific Ocean between Hawaii and Guam. FSM is an independent sovereign nation consisting of four states in total: Pohnpei, Chuuk, Yap, and Kosrae. Having passed through the hands of Spain, Germany and Japan, the United States gained administrative control of FSM after WWII, as commissioned by the UN. The FSM became an independent nation in 1986 while still retaining affiliation with the US under a ‘Compact of Free Association’. Now both Kosraean and English are considered to be the two official languages and the variety of Kosraean English which has arisen proves for an interesting comparative study. In order to obtain the relevant data, I spent three months on the island of Kosrae, interviewing 90 local speakers, ranging in age (16-70), occupation, sex and time spent off island. The 45 minute long interviews were informal but supported by participant information to capture relevant data and conversations were guided in a way that aimed to reveal language and cultural attitudes. With reference to these samples, I examine the effects of American English on the language use in Kosrae. This paper aims to present a broad analysis of phonological, morphosyntactic and pragmatic features, such as pro-dropping, discourse markers and other practices in order to demonstrate the similarities and differences between the two varieties, which are coming to shape the variety developing on Kosrae. Having transcribed conversations using the tool Elan, I will put particular focus on [h] deletion and insertion, a rare occurrence found in a variety of post-colonial American English which I believe is of particular interest. I assess the presence of English in Kosrae with reference to sociological influences, past and present. First, I discuss the extralinguistic factors which have shaped the English that is currently used on Kosrae, including migration between US and FSM, and English as a language of administration, social media usage and visual media presence. Secondly, I assess the use of English in this community in light of Schneider’s (2007) ‘Dynamic Model’, with reference to America’s contribution as an ‘exploitation colony’ as defined by Mufwene (2001). Finally, an overview of the salient linguistic characteristics of Kosraean English, based on the data collected will be presented and compared to features associated with standard American English in view of examining overlap and divergence. The overall objective is to present a cross-linguistic description of a hitherto unexamined English emerging in a postcolonial environment with a juxtaposed contact variety. Mufwene, Salikoko S. 2001. The ecology of language evolution. Cambridge: Cambridge University Press. Schneider, E. (2007). Postcolonial Englishes. Cambridge: Cambridge University Press. Segal, H.G. (1989) Kosrae, The Sleeping Lady Awakens. Kosrae: Kosrae Tourist Division, Dept. Of Conservation and Development. Keywords: American English, Global English, Pacific English, Morphosyntactic, Phonological, Variation, Discourse

Geochemical composition of a representative collection of manganese nodules and slabs collected in the Western Pacific

Chemical analyses were performed on seveteen manganese nodules collected from the Pacific Ocean floor. The results were discussed compared with the previous data on the manganese nodules. Minerals were found to be todorokite, delta-MnO2 and other silicates, montmorillonite, illite, phillipsite and alpha-SiO2. Average composition shows that copper is concentrated on the deep sea nodules more than the shallow ones, and that the todorokite rich nodules contain more copper and nickel than the delta-MnO2 rich ones.

(Table 1) Age of Cretaceous seamounts in the Western Pacific

Dynamics of the Pacific Plate is recorded in the systematic variation of location and the 40Ar-39Ar age of seamounts in the Western Pacific from 120 to 65 Ma ago. The seamounts are grouped into three linear zones as long as 5000 km. The seamounts become younger in the southeastern direction along the strike of these zones. Correlation between age and location of seamounts allows to divide the history of their formation into three stages. Rate of seamount growth was relatively low (2-4 cm/yr) during the first and the third stages within intervals of 120-90 and 85-65 Ma, whereas during the second stage (90-85 Ma), the seamounts were growing very fast (80-100 cm/yr). In the midst of this stage, at ~87 Ma ago, magmatic activity increased abruptly. Dynamics of seamount building is in good agreement with (1) pulses in development of the Ontong Java, Manihiki, and Caribbean-Colombian oceanic plateaus; (2) age of spreading acceleration in the mid-Cretaceous; and (3) a short period when the Izanagi Plate ceased to exist and the Kula Plate was formed. Variation in seamounts' age and location are in consistence with the hypothesis of diffuse extension of the Pacific Plate in course of its motion with formation of impaired zones of decompression melting. Direction of extension (325°-340° NW) calculated from the strike of seamount zones is consistent with the path of the Pacific Plate (330° NW) in the Late Cretaceous. Immense perioceanic volcanic belts were formed at that time along the margin of the Asian continent. The Okhotsk-Chukchi Peninsula Belt extends at a right angle to the compression vector. Three stages of this belt's evolution are synchronous with the stages of seamount formation in the Pacific Plate. Delay in origination of the East Sikhote-Alin Volcanic Belt and its different orientation were caused by counterclockwise rotation of the vector of convergence of oceanic and continental plates in the mid-Cretaceous. At the same time, i.e. 95-85 Ma ago, volcanic activity embraced the entire continental margin and tin granites were emplaced everywhere in the Eastern Asia. This short episode (90+/-5 Ma) corresponds to the mid-Cretaceous maximum of compression of the continental margin, and its age fits well a culmination in extension of the Pacific Plate.

Paleomagnetic properties of igneous rocks from several DSDP and ODP sites, western Pacific

Oceanic basalts and other related igneous rocks are considered excellent recorders of the Earth's paleomagnetic field. Consequently, basalt core paleomagnetic data are valuable for the constraints they provide on plate tectonic motions, especially for oceanic plates such as the Pacific. Unfortunately, few Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) boreholes have been cored very deeply into the ocean crust. The result is that there are only a few sites at which a large enough number of basalt flows have been cored to properly average secular variation (e.g., Kono, 1980, doi:10.2973/dsdp.proc.55.135.1980; Cox and Gordon, 1984, doi:10.1029/RG022i001p00047). Furthermore, there are a number of sites where basaltic core samples were retrieved but the cores were not measured. Often this occurs because leg scientists had more important sections to work on, or the section was ignored because it was too short to record enough time to average secular variation and obtain a reliable paleolatitude. Even though it may not be possible to determine a precise paleolatitude from such short sections, measurements from a small number of flows are important because they can be combined with other coeval paleomagnetic data from the same plate to calculate a paleomagnetic pole (Gordon and Cox, 1980, doi:10.1111/j.1365-246X.1980.tb02642.x; Cox and Gordon, 1984, doi:10.1029/RG022i001p00047). For this reason, I obtained samples for paleomagnetic measurements from eight Pacific sites (169, 170, 171, 581, 597, 800, 803, and 865), most of which have not been previously measured for paleomagnetism.

Geochemistry of volcanic glass from ODP holes 129-801C and 185-801C in the western Pacific

Major element chemistry of basalt from the southern East Pacific Rise (EPR) is different from that of the EPR at the time of the formation of the Pacific Plate at 170 Ma.Glass recovered from Jurassic age (170 Ma) Pacific ocean crust (Bartolini and Larson, 2001, doi:10.1130/0091-7613(2001)029<0735:PMATPS>2.0.CO;2) at Ocean Drilling Program Hole 801C records higher Fe8 (10.77 wt%) and marginally lower Na8 (2.21 wt%) compared to the modern EPR, suggesting deeper melting and a temperature of initial melting that was 60°C hotter than today.Trace element ratios such as La/Sm and Zr/Y, on the other hand, show remarkable similarities to the modern southern EPR, indicating that Site 801 was not generated on a hotspot-influenced ridge and that mantle composition has changed little in the Pacific over the past 170 Ma. Our results are consistent with the observation that mid-ocean ridge basalts (MORBs) older than 80 Ma were derived by higher temperature melting than are modern MORBs (Humler et al., 1999, doi:10.1016/S0012-821X(99)00218-6), which may have been a consequence of the Cretaceous superplume event in the Pacific.Site 801 predates the formation of Pacific oceanic plateaus and 801C basalt chemistry indicates that higher temperatures of mantle melting beneath Pacific ridges preceded the initiation of the superplume.

Neogene and Quaternary radiolarians from the Izu-Bonin Forearc in the western Pacific Ocean

Radiolarians were recovered from three of the five holes investigated during Leg 125. Relative abundances are estimated at Holes 782A and 784A, where preservation is poor to good. Rare, poorly preserved radiolarians are present in Hole 786A. Seven radiolarian zones are recognized in the latest early- middle Miocene to early Pleistocene of Holes 782A and 784A. These zones are approximately correlated to the zones of Sanfilippo and others published in 1985.

(Table 1) Oxygen and carbon isotope compositions of altered carbonates from DSDP Hole 6-53 from the western Pacific Ocean

In the lower part of DSDP core 53.0, partly recrystallized carbonate sediments and well recrystallized limestone breccias of Oligo-Miocene age are associated with altered volcanic flows, lithified tuffs, and tuff breccias, suggesting that carbonate alteration was the result of thermal metamorphism. However, the oxygen isotope compositions of these carbonates (-3.4 to +0.6 per mil rel. PDB) are not compatible with recrystallization and isotope exchange with sea water at high temperatures. Evaluating the effects of the composition of the water which exchanged with the carbonates and of carbonate-water isotope exchange in closed systems yields the following approximate maximum temperature of recrystallization: limestone breccias, 100°C; calcite veins rimming breccia clasts, 30°C; and unconsolidated sediments overlying the breccias, 20°C. Therefore, the volcanics at site 53.0 must have been emplaced into the primary carbonate sediments at relatively low temperatures. Subsequent carbonate alteration was probably a consequence of chemical changes in ambient pore waters resulting from the submarine weathering of volcanic material.

Mineralogy and geochemistry of aerosols from the Western Pacific

Aerosols collected by net method over the Western Pacific were investigated. Distribution of eolian material, its mineral and chemical compositions are controlled by the climatic and circumcontinental zonalities. It was stated that Fe and Mn were bound with mineral components of aerosols, while trace elements are bound with organogenic matter. Fluxes of aerosols and their components on the ocean surface were determined.

Geochemistry of volcaniclastites of the western Pacific Ocean

Samples collected from the coarse basal portions of mid-Cretaceous volcaniclastic turbidites from the Mariana and Pigafetta basins are remarkably similar in terms of the petrographic and chemical features of their igneous clasts and bulk rock composition. Clasts of magmatic origin are dominated by glassy vesicular shards, variably phyric, holocrystalline basalts, and crystal fragments (olivine, clinopyroxene, plagioclase, amphibole, and biotite). The composition of the pyroxenes and amphiboles are typical of those found in differentiated hydrous alkali basalts. The bulk chemical composition of the volcaniclastites (based on stable incompatible elements and their ratios in highly vitric samples) is characteristic of alkali basalts found in within-plate oceanic eruptive environments. Miocene volcaniclastites from Site 802 are broadly similar to the Cretaceous samples in terms of clast type and bulk composition, and have also been derived from an oceanic alkali basalt source. The chemistry of the Miocene volcaniclastites differ, however, in having distinctive Zr/Y and Zr/Nb ratios and a more restricted chemical composition. The magmatic products of nearly emergent seamounts within the western Pacific basins appears to have been dominated by alkali basalt volcanism during the mid-Cretaceous and also the Miocene. The highly vitric nature of the Cretaceous and Miocene volcaniclastites, together with the morphology and vesicularity of their shards, suggests that they are the reworked (via mass flow) products of hyaloclastite accumulations produced in a shallow-water eruptive environment, such as that adjacent to nearly emergent seamounts or ocean islands. The association of ooids, reefal debris, and, in rare cases, woody material with the volcaniclastites supports their shallow-water derivation.