strong biological controls on sr ca ratios in aragonitic marine bivalve shells 1 it is well known that skeletal remains of carbonate secreting organisms can provide a wealth of information about past environments sr ca ratios have been successfully used as a temperature proxy in corals and sclerosponges previous work on aragonitic bivalve shells has not been conclusive but suggests a major control of growth rate on sr ca ratios as many studies have used bivalve growth rates to determine temperature we tested if sr ca ratios could predict temperature through its relationship with growth rate shells from the two species of clams from the same family veneroidea studied here saxidomus giganteus and mercenaria mercenaria show vastly different seasonal sr ca profiles a strong relationship between average annual sr ca ratios and annual growth rate was found in s giganteus shells from both washington r2 0 87 and alaska r2 0 64 usa but not in m mercenaria shells from north carolina usa furthermore the sr ca growth rate relationship was also evident upon a more detailed inspection of subannual growth rates in s giganteus r2 0 73 although there were significant positive correlations between sr ca ratios and temperature in s giganteus shells the correlations were weak 0 09 r2 0 27 and thus sr ca ratios cannot be used as a reliable temperature proxy in these species of aragonitic bivalves it is clear from this study that sr ca ratios are not under thermodynamic control in either clam species since thermodynamics predict a negative correlation between sr ca ratios and temperature in aragonite this points toward dominance of biological processes in the regulation of sr2 this is also reflected by the largely differing sr ca partition coefficients dsr in these shells dsr 0 25 when compared to inorganic coral and sclerosponge studies dsr 1 all of which show a negative dependence of sr ca on temperature we suggest that caution be taken when using sr ca in any biogenic aragonite as a temperature proxy when the dsr greatly deviates from one as this indicates the dominance of biological controls on sr ca ratios

chondrules in h3 chondrites textures compositions and origins major and minor element bulk compositions of 90 individual chondrules and 16 compound chondrule sets in unequilibrated type 3 h group chondrites were determined in polished thin sections by broad beam electron probe analysis and the chondrules were classified petrographically into six textural types barred olivine porphyritic olivine porphyritic pyroxene barred pyroxene radiating pyroxene fine grained although analyses of individual chondrules scatter widely the mean composition of each textural type except barred pyroxene is rather distinct as verified by discriminant function analysis al2o3 tio2 and na3o are correlated in chondrules but al2o3 and cao do not correlate compound chondrule sets were found to consist almost entirely of chondrules or partial chondrules of similar texture and composition the data suggest that composition played a conspicuous role in producing the observed textures of chondrules though other factors such as cooling rates and degrees of supercooling prior to nucleation were also important if compound chondrules formed and joined when they were still molten or plastic then the data suggest that chondrules of each textural type could have formed together in space or time the correlation of al2o3 and tio2 with na2o and not with cao appears to rule out formation of chondrules by direct equilibrium condensation from the nebula we conclude that the most reasonable model for formation of the majority of chondrules is that they originated from mixtures of differing fractions of high intermediate and low temperature nebular condensates that underwent melting in space a small percentage of chondrules might have formed by impacts in meteorite parent body regoliths

thermochronology and the three dimensional cooling pattern of a granitic pluton an example from the toki granite central japan the three dimensional spatial variations in the cooling pattern of the toki granitic body a zoned pluton in central japan have been evaluated quantitatively by thermochronology using cooling age determination based on the different closure temperatures for target mineral species the toki granite has hornblende k ar ages of about 74 3 3 7 ma n 2 closure temperature of 510 25 c biotite k ar ages of 78 5 3 9 to 59 7 1 5 ma n 33 300 50 c and zircon fission track ages of 75 6 3 3 to 52 8 2 6 ma n 44 240 50 c the spatial variation in the biotite k ar age is similar to that in the zircon fission track age in samples collected from 11 boreholes and seven outcrop sites in the toki granite indicating that cooling was effectively from the roof and also from the northwest margin this cooling pattern shows a strong correlation with the alumina saturation index asi distribution of the body larger asi values correspond to earlier and more rapid cooling after emplacement and smaller value to slower cooling toki granite was effectively cooled from the peraluminous regions where assimilation of country sedimentary rock was most extensive

long term stability of flow path structure in crystalline rocks distributed in an orogenic belt japan most evaluations of the contaminant retardation processes likely to be important in geological disposal e g for high level radioactive waste hlw consider only the present characteristics of fractures and associated mineral infills relatively little attention has been given to possible long term changes in these features and their influence on groundwater flow the work reported here seeks to provide analogous evidence that such changes are not likely to be important and hence to improve confidence in the presently adopted evaluation methodology and its long term applicability in the orogenic belt that is formed by the japanese islands there are wide areas of crystalline rock the rocks in each area have a distinctive age sequence which is partly reflected in the characteristics of the fracture systems and associated mineral fillings that occur these characteristics generally imply that groundwater and solutes can be conducted through fracture networks except in the cases of fault zones or crushed zones the structural and mineralogical features of these networks readily illustrate how certain contaminants might react and be retarded by the fracture fillings and open pore geometry due to chemical sorption and or physical retardation here we describe the fracture systems developed in crystalline rocks with different ages that are intruded into the japanese orogenic belt the aim is to build a model for the long term fracturing process and hence to evaluate fracture dstabilityt i n particular the comparisons are made between the fracture geometries and the frequencies observed in the 1 9 0 8 ma takidani granodiorite the youngest exposed pluton in the world the ca 67 ma toki granite and the ca 117 ma kurihashi granodiorite located in central to northwest japan the observations show that all these crystalline rocks have similar fracture frequencies with 1 to 2 fractures per meter in the massive part of rock bodies mineralogical studies and dating analyses of fracture fillings also suggest that fractures are relatively physically stable major new fractures tend not to be created in the massive part of rock bodies even when a pluton has been subjected to the regional stresses of plate movements with a duration of about 100 ma the results show the unique characteristics of the fracture forming process and the relatively stable geometries of fracture network systems in crystalline rocks distributed within the orogenic belt this analogue also enables us to provide a model to build confidence in a technical approach applicable for modeling of hydrogeology and geology over long time scales under the

plagioclase rich chondrules in the reduced cv chondrites evidence for complex formation history and genetic links between calcium aluminum rich inclusions and ferromagnesian chondrules plagioclase rich chondrules prcs in the reduced cv chondrites efremovka leoville vigarano and grosvenor mountains gro 94329 consist of magnesian low ca pyroxene al ti cr rich pigeonite and augite forsterite anorthitic plagioclase feni metal sulfide nodules and crystalline mesostasis composed of silica anorthitic plagioclase and al ti cr rich augite the silica grains in the mesostases of the cv prcs are typically replaced by hedenbergitic pyroxenes whereas anorthitic plagioclase is replaced by feldspathoids nepheline and minor sodalite some of the prcs contain regions that are texturally and mineralogically similar to type i chondrules and consist of forsterite low ca pyroxene and abundant feni metal nodules several prcs are surrounded by igneous rims or form independent compound objects twelve prcs contain relic calcium aluminum rich inclusions cais composed of anorthite spinel high ca pyroxene forsterite and al rich low ca pyroxene anorthite of these cais is generally more heavily replaced by feldspathoids than anorthitic plagioclase of the host chondrules this suggests that either the alteration predated formation of the prcs or that anorthite of the relic cais was more susceptible to the alteration than anorthitic plagioclase of the host chondrules these observations and the presence of igneous rims around prcs and independent compound prcs suggest that the cv prcs may have had a complex multistage formation history compared to a more simple formation history of the cr prcs relatively high abundances of moderately volatile elements such as cr mn and si in the prcs suggests that these chondrules could not have been produced by volatilization of ferromagnesian chondrule precursors or by melting of refractory materials only we infer instead that prcs in carbonaceous chondrites formed by melting of the reduced chondrule precursors magnesian olivine and pyroxene feni metal mixed with refractory materials relic cais composed of anorthite spinel high ca pyroxene and forsterite the mineralogical chemical and textural similarities of the prcs in several carbonaceous chondrite groups cv co ch cr and common presence of relic cais in these chondrules suggest that prcs may have formed in the region s intermediate between the regions where cais and ferromagnesian chondrules originated

uplift and denudation history of the akaishi range a thrust block formed by arc arc collision in central japan insights from low temperature thermochronometry and thermokinematic modeling fission track ft u th he he and u pb data were used to identify the denudation history of the akaishi range central japan the northern akaishi range is bounded on the east by the itoigawa shizuoka tectonic line fault zone istl fz the thermochronometric ages progressively decreases with the decreasing distance to the istl fz thermo kinematic calculations suggest that the age pattern observed can be explained by a 5 7 5 mm yr reverse slip on the istl fz that dips 34 45 west and soles onto detachment at a20 22 5 km depth by assuming the same geometry and slip rate of the fault thebedrock uplift rates and denudation rates are estimated at 4 mm yr thus the uplift and denudation style of the northern akaishi range is well explained asa simple tilted thrust block that has been exhumed along the listric istl fz on the other hand considering both the difference in apatite ft age and the active fault distribution the southern akaishi range might be different in uplift origin and timing although the difference in apatite ft ages between them may be attributable to the chlorine content variation in apatite the inferred total denudation is larger than several kilometers and likely exceeds 10 km since the beginning of the northern akaishi range uplift suggesting that the low relief surfaces on the ridges and the relatively constant elevations of the summits reflect post uplift denudation rather than pre existing low relief landforms

origin of the cenozoic mesozoic magnetite series and ilmenite series granitoids in east asia abstract among the phanerozoic granitoids of east asia the most prevailing cenozoic mesozoic rocks are reviewed with respect to gabbro granite ratio bulk composition of granitoids redox state and o and sr isotopic ratios quaternary volcanic rocks ranging from basalt to rhyolite but typically felsic andesite in terms of bulk composition in island arcs are oxidized type possibly due to oxidants from subducting oceanic crust into the source regions miocene plutonic rocks in the back arc of japan could be a root zone for such volcanism but are more felsic in composition cenozoic mesozoic plutonic zones are classified by 1 the redox state magnetite ilmenite series and 2 average bulk composition granodiorite granite the granodioritic magnetite series occur with fairly abundant gabbro and diorite in the back arc of island arcs greentuff belt and intercontinental rapture zones yangtze block these rocks are mostly juvenile in terms of the 87sr 86sri and 18o values the granitic magnetite series with some gabbroids occur in rapture zones along the continental coast gyeongsang basin fujian coast and the back arc of island arc sanin belt they were generated mostly in felsic continental crust with the help of heat and magmas from upper mantle the generated granitic magmas had little interaction with c and s bearing reducing materials due probably to extensional tectonic settings the 18o value gives narrow ranges but the 87sr 86sri ratio varies greatly depending upon the age and composition of the continental crust granitic ilmenite series are characterized by high 18o values implying much contribution of sediments the 87sr 86sri ratios are low in island arcs but very high in continental interior settings amount of mafic magmas from the upper mantle seems a key to control the composition of granitoid series in island arc settings while original composition of the protolith may be the key to control granitoid composition in continental interiors

quantitative evaluation of quaternary crustal deformation around the takayama basin central japan a paleomagnetic and numerical modeling approach abstract neotectonic crustal deformation in central japan is described quantitatively on the basis of paleomagnetic measurements and numerical modeling the welded part of the earliest quaternary nyukawa pyroclastic flow deposit npfd preserves stable remanent magnetization detailed paleo rock magnetic experiments reveal that remanence of the npfd near the takayama basin resides in unimodal titanomagnetite and comprises a component of thermoremanent magnetization trm and three components of thermoviscous remanent magnetization tvrm scatter in the untilted declinations of the syn depositional trm component represents differential rotation about vertical axes related to quaternary activity of three faults enako makigahora and harayama associated with the takayama basin the normal and reversed tvrm components probably acquired by warm water circulation near the active faults during the jaramillo subchron record a complicated rotational sequence since ca 1 ma dislocation modeling successfully simulates the spatial distribution of rotation and the uplift subsidence pattern around the takayama basin assuming strike slip motion on the enako and makigahora faults along the basin margin and vertical displacements on the harayama fault within the basin temporal changes in rotational motions recorded in the tvrms of near fault sites can be modeled by considering transition of active segments of the three faults which is geologically constrained

the potential of arctica islandica growth records to reconstruct coastal climate in north west scotland uk this paper describes potential methods for reconstructing past marine environmental and climatic variability in scottish coastal waters through the investigation of annual growth increments measured from shells of the long lived marine bivalve arctica islandica l this is accomplished by using a combination of sclerochronological and dendrochronological techniques which were employed to determine the age of specimens and to create growth chronologies using negative exponential detrending methods a preliminary a islandica master chronology for the lynn of lorn scotland has been produced this chronology indicates highly suppressed growth between the mid 1940s and late 1980s the growth response of this species to the sea surface temperatures in scottish coastal waters appears to be complex most notably during recent decades when land use changes and marine aquaculture may influence shell growth at this site

an extremely large magnitude eruption close to the plio pleistocene boundary reconstruction of eruptive style and history of the ebisutoge fukuda tephra central japan abstract an extremely large magnitude eruption of the ebisutoge fukuda tephra close to the plio pleistocene boundary central japan spread volcanic materials widely more than 290 000 km2 reaching more than 300 km from the probable source characteristics of the distal air fall ash 150 km away from the vent and proximal pyroclastic deposits are clarified to constrain the eruptive style history and magnitude of the ebisutoge fukuda eruption eruptive history had five phases phase 1 is phreatoplinian eruption producing 105 km3 of volcanic materials phases 2 and 3 are plinian eruption and transition to pyroclastic flow plinian activity also occurred in phase 4 which ejected conspicuous obsidian fragments to the distal locations in phase 5 collapse of eruption column triggered by phase 4 generated large pyroclastic flow in all directions and resulted in more than 250 350 km3 of deposits thus the total volume of this tephra amounts over 380 490 km3 this indicates that the volcanic explosivity index vei of the ebisutoge fukuda tephra is greater than 7 the huge thickness of reworked volcaniclastic deposits overlying the fall units also attests to the tremendous volume of eruptive materials of this tephra numerous ancient tephra layers with large volume have been reported worldwide but sources and eruptive history are often unknown and difficult to determine comparison of distal air fall ashes with proximal pyroclastic deposits revealed eruption style history and magnitude of the ebisutoge fukuda tephra hence recognition of the ebisutoge fukuda tephra is useful for understanding the volcanic activity during the pliocene to pleistocene is important as a boundary marker bed and can be used to interpret the global environmental and climatic impact of large magnitude eruptions in the past

impacts of explosive volcanism on distal alluvial sedimentation examples from the pliocene holocene volcaniclastic successions of japan abstract volcanic activities can create cataclysmic hazards to surrounding environments and human life not only during the eruption but also by hydrologic remobilisation lahar processes after the cessation of eruptive activity although there are many studies dealing with the assessment and mitigation of volcanic hazards these are mostly concentrated on primary eruptive processes in areas proximal to active volcanoes however the influence of volcaniclastic resedimentation may surpass the impacts of primary eruptive activity in terms of both extent and persistence and can ultimately result in severe hazards in downstream areas examination of the volcaniclastic successions of non marine pliocene holocene sedimentary basins in japan has revealed hydrological volcaniclastic sedimentation in fluvial and lacustrine environments hundreds of kilometres from the inferred source volcano impacts on these distal and often spatially separated basins included drastic changes in depositional systems caused by sudden massive influxes of remobilised pyroclastic material typical volcaniclastic beds comprise centimetre to decimetre thick primary pyroclastic fall deposits overlain by metre to 10s of metres thick resedimented volcaniclastic deposits intercalated in sedimentary successions of non volcanic provenance the relatively low component of primary pyroclastic fall deposits in the volcaniclastic beds suggests that 1 potential volcanic hazards would be underestimated on the basis of primary pyroclastic fall events alone and 2 the majority of resedimented material was likely derived from erosion of non welded pyroclastic flow deposits in catchment areas rather than remobilisation of local fallout deposits from surrounding hillslopes the nature distribution and sequence of facies developed by distal volcaniclastic sediments reflect the influence of 1 proximity to ignimbrite but not directly with the distance to the eruptive centre 2 ignimbrite nature non welded or welded and volume 3 temporal changes in sediment flux from the source area 4 the physiography and drainage patterns of the source area and the receiving basin and any intervening areas and 5 the formation of ephemeral dam lakes and intra caldera lakes whose potential catastrophic failure can impact distal areas models of the styles and timing of distal volcaniclastic resedimentation are thus more complicated than those developed for proximal settings of stratovolcanoes and their volcaniclastic aprons and hence present different challenges for hazard assessment and mitigation

north pacific climate recorded in growth rings of geoduck clams a new tool for paleoenvironmental reconstruction 1 to better understand north pacific climate variability at interannual to interdecadal scales we have developed a new tool for paleoenvironmental reconstruction we show that growth rings in long lived geoduck clams panopea abrupta can provide high quality annually resolved records of sea surface temperature sst we used shell samples from the strait of juan de fuca in washington state to extend the coastal sst record back to 1877 the spatial correlation pattern between the growth index and gridded ssts bears a strong resemblance to the leading pattern of interdecadal global sst variations and underscores the remarkable long distance coherence evident among coastal sst records in the northeast pacific our results also indicate that the 1990s was the warmest decade in this region since at least the 1850s

reconstructing mid to high latitude marine climate and ocean variability using bivalves coralline algae and marine sediment cores from the northern hemisphere quantifying the role and contribution of the world s oceans in past present and future global change is an essential goal in climate paleoclimate and environmental studies although the global oceans interact and influence climate greatly the marine environment is substantially under represented in key climate assessment reports especially during the last millennium ipcc 2007 see palaeoclimate chapter 6 6 the last 2000 years the under representation of marine records in key climate documents likely results from the often imprecise chronologies associated with many marine based archives which greatly hinders singular climate comparisons lag lead phasing relationships with well dated and or annually resolved archives however several marine archive records have excellent chronological constraint in particular many marine bivalve taxa and coralline algae have annual increments that form within their carbonate framework that can be used to establish an absolutely dated chronology via cross dating techniques from the marine environment additionally in some cases where sedimentation rates are high and alternative chronological dating methods exist e g tephrochronology other than radiocarbon measurements often greater than 40 years uncertainty sediment archives can provide continuous sub decadal records of environmental change for centuries to millennia this brief introductory article and accompanying special issue will focus on the utilization of bivalves coralline algae and high resolution marine sediment cores in paleoclimate and environmental studies within the most recent millennium with a focus on the northern hemisphere

relationship among o mg isotopes and the petrography of two spinel bearing compound chondrules the petrological properties and o and al mg isotopic compositions of two spinel bearing chondrules from the allende cv chondrite were investigated using scanning electron microscopy and secondary ion mass spectrometry a coarse spinel grain in a barred olivine bo chondrule is less enriched in 16o 17o 5 17o 17o 0 52 18o whereas smaller spinel grains in a plagioclase rich chondrule member of a compound chondrule are extremely 16o rich 17o 17 and the spinels have a strongly serrated character the petrological features and 16o enrichments of the spinels in the plagioclase rich chondrule indicate that spinels originating in coarse grained ca al rich inclusions cais were incorporated into chondrule precursors and survived the chondrule forming event the degree of 16o excesses among minerals within each chondrule is correlated to the crystallization sequences this evidence suggests that the o isotopic variation among minerals may have resulted from incomplete exchange of o isotopes between 16o rich chondrule melt and 16o poor nebular gas aqueous alteration also has changed the o isotope compositions in the mesostasis the feldspathic mesostasis in the bo chondrule shows a disturbed mg al isochron indicating that the bo chondrule experienced secondary alteration while plagioclase in the plagioclase rich chondrule member of the compound chondrule shows slight 26mg excesses corresponding to 26al 27al 0 4 6 4 0 2 10 6 nepheline formed by secondary alteration shows no detectable excess the al mg isotopic system of these chondrules was disturbed by aqueous alteration and thermal metamorphism on the allende parent body

depositional processes of primary to reworked volcaniclastics on an alluvial plain an example from the lower pliocene ohta tephra bed of the tokai group central japan abstract a change from primary to reworked volcaniclastic deposits in the lower pliocene ohta tephra bed has been identified using facies analysis the ohta tephra bed is a widespread marker tephra distributed over a distance of more than 130 km the source volcano of this tephra is inferred to lie 50 to 100 km north of the most proximal ohta tephra bed the ohta tephra bed shows a change in volcaniclastic facies in distal areas eight sedimentary facies are recognized these are interpreted as pyroclastic fall pyroclastic flow and reworked mudflow flood flow channel fill swamp or backswamp lacustrine and ephemeral pond deposits in underlying and overlying non volcaniclastic beds four sedimentary facies are recognized indicating a fluvio lacustrine depositional system on an alluvial plain from the successions of volcaniclastic sedimentary facies deposition of the ohta tephra bed can be divided into stages i to vi each depositional stage is intimately related to volcanic activity stage i is the first eruption during which only the northern part of the study area was covered with fallout ash the second eruption stage of stage ii involved fallout ash distributed over all the study area these two fallout ash beds are derived from precursor eruptions stage iii reflects a period of volcanic quiescence and development of widespread lacustrine conditions the fallout ash may have destroyed vegetation and prompted greater discharge to form the large lacustrine deposits of stage iii a pyroclastic flow stage in stage iv is associated with an explosive eruption and resulted in pyroclastic flow deposits reaching the northern part of the study area stage v is characterized by mudflow deposits widespread mudflow deposits also originated from high water and clastics discharge on the unvegetated surface mudflows extend more than 180 km from the source volcano abundant supply of volcaniclastic material and high water and clastic discharge enhanced a rapid progradation of alluvial plains final reworking occurred during stage vi when volcaniclastic sediments were deposited from a fluvio lacustrine system the reworking system comprises initial mudflows followed by a normal fluvial system normal stream flow the mudflow deposits of stage v are traceable with roughly constant thickness but the volcaniclastic content of the deposits decreases in distal areas the fluvial system deposits of stage vi are thicker and have less abundant volcaniclastics in distal areas fluvial systems were braided streams promoted by volcanic eruption while they were meandering streams during the pre eruption period some eruption induced braided streams remained for a while following the cessation of volcanic activity

a key to the past element ratios as environmental proxies in two arctic bivalves 2016 elsevier b v understanding rapid climate change in the arctic and its ecosystem implications requires more information on the environment at temporal resolutions and time periods not available from instrumental records such information can be acquired through geochemical proxy records but sub annual records are rare we analyzed shell material of bivalve mollusks serripes groenlandicus and ciliatocardium ciliatum placed on oceanographic moorings for one year in two arctic fjords to assess the potential use of shell elemental ratios as environmental proxies li ca mg ca li mg li sr mn ca sr ca mo ca and ba ca were determined using laser ablation inductively coupled plasma mass spectrometry combining data from moorings with previously derived sub annual shell growth models allowed us to relate the elemental ratio patterns to oceanographic parameters temperature salinity and fluorescence shell ba ca profiles were characterized by abrupt peaks occurring 11 to 81 days after the phytoplankton bloom as indicated by an index of seawater fluorescence li ca and mg ca values exhibited significant logarithmic relationships with shell growth rate indicated by marginal r2 values of 0 43 and 0 30 respectively these ratios were also linearly related to temperature with marginal r2 values of 0 15 and 0 17 respectively mn ca and sr ca ratios exhibited variability among individuals and their temporal pattern was likely controlled by several unidentified factors mo ca patterns within the shells did not demonstrate correlations with any of the oceanographic parameters our results reflect complex relationships between elemental ratios and bivalve metabolism methodological limitations as well as contemporaneous environmental processes suggesting that none of the studied elemental ratios can be used as unequivocal proxies of seawater temperature salinity paleoproductivity or shell growth rate despite this ba ca and li ca can be used as sub annual temporal anchors in further studies because the variability of these elements was synchronized in each fjord

parallelepiped cooling joint and anisotropy of p wave velocity in the takidani granitoid japan alps correlations between anisotropy of joint systems and physical rock properties particularly p wave velocities were investigated characterization of fracture networks in the takidani granitoid japan alps was obtained by field observation and laboratory measurement of p wave velocities three preferred joint sets with no shear displacement were identified and their directions change and spacing progressively increases from the margin to the center of the pluton the azimuthal variation of p wave velocity vp is minimal perpendicular to one of the preferred joint orientations the orientation of microcracks observed at grain scale and joints at outcrop scale show a good correlation vp and the preferred orientation of microcracks are in harmony with anisotropy of the joint system allowing reconstruction of the joint structure in the takidani granitoid thus we were able to evaluate joint anisotropy in terms of vp anisotropy

climate records from a bivalved methuselah arctica islandica mollusca iceland we measured annual shell growth rates of a 374 year old radiometrically confirmed bivalve mollusk specimen of arctica islandica linnaeus this bivalve represents the oldest ever reported individual animal in addition we analyzed 1051 individual powder samples from ontogenetic years two to 40 80 of the entire shell height for isotope analyses oxygen and carbon isotopes exhibit clear intra annual cycles the highest measured carbon isotope values on average 2 73x occurred during summer i e during maximum primary productivity the d 18 oaragonite derived temperature time series cover the period of ad 1496 1533 temperatures calculated from oxygen isotopes ranged from 4 5 to 9 3 8c and exhibit a mean value of 6 2 8c the latter coincides well with the 1854 2003 mean value of 6 81 8c for sea surface temperature between february and september growing season of a islandica neither oxygen nor carbon isotopes exhibit age related unidirectional trends however d 13 caragonite and d 18 oaragonite values fluctuated at decadal periods of four six and eight to nine years nao type periods as well as 12 14 years which may represent teleconnections to cycles in the tropical atlantic annual shell growth is positively correlated to intra annual d 18 oaragonite minima i e warm summer temperatures r 2 0 34 and to intra annual d 13 caragonite minima higher food supply r 2 0 42 using a linear multiregression model 65 of the variation in annual shell growth can be explained by summer temperature and food supply the formation of extremely narrow annual increments coincides with major volcanic eruptions e g tambora 1815 a period of extremely variable growth occurred during the culmination of the little ice age in iceland between ca ad 1550 and 1620 shell growth during ad 1765 1780 however was characterized by very little year to year variability probably as the result of extremely mild climate near the end of the little ice age this study demonstrates that shells of a islandica provide

anorthite rich chondrules in cr and ch carbonaceous chondrites genetic link between ca al rich inclusions and ferromagnesian chondrules anorthite rich chondrules in cr and ch carbonaceous chondrites consist of magnesian low ca pyroxene and forsterite phenocrysts feni metal nodules interstitial anorthite al ti cr rich low ca and high ca pyroxenes and crystalline mesostasis composed of silica anorthite and high ca pyroxene three anorthite rich chondrules contain relic ca al rich inclusions composed of anorthite spinel al diopside and forsterite a few chondrules contain regions which are texturally and mineralogically similar to magnesian type i chondrules and consist of forsterite low ca pyroxene and abundant feni metal nodules anorthite rich chondrules in cr and ch chondrites are mineralogically similar to those in cv and co carbonaceous chondrites but contain no secondary nepheline sodalite or ferrosilite relatively high abundances of moderately volatile elements such as cr mn and si in the anorthite rich chondrules suggest that these chondrules could not have been produced by volatilization of the ferromagnesian chondrule precursors or by melting of the refractory materials only we infer instead that anorthite rich chondrules in carbonaceous chondrites formed by melting of the reduced chondrule precursors olivine pyroxenes feni metal mixed with the refractory materials including relic cais composed of anorthite spinel high ca pyroxene and forsterite the observed mineralogical and textural similarities of the anorthite rich chondrules in several carbonaceous chondrite groups cv co ch cr may indicate that these chondrules formed in the region s intermediate between the regions where cais and ferromagnesian chondrules originated this may explain the relative enrichment of anorthite rich chondrules in 16o compared to typical ferromagnesian chondrules russell et al 2000

petrography and uplift history of the quaternary takidani granodiorite could it have hosted a supercritical hdr geothermal reservoir abstract the quaternary takidani granodiorite japan alps is analogous to the type of deep seated 3 5 km deep intrusive hosted fracture network system that might support supercritical hot dry wet rock hdr hwr energy extraction the i type takidani granodiorite comprises porphyritic granodiorite porphyritic granite biotite hornblende granodiorite hornblende biotite granodiorite biotite hornblende granite and biotite granite facies the intrusion has a reverse chemical zonation characterized by 70 wt sio2 at its inferred margin and 600 c hypersaline 35 wt nacleq fluids of magmatic origin with inferred minimum pressures of formation being 600 750 bar which corresponds to fluid entrapment at 2 4 3 0 km depth al in hornblende geobarometry indicates that hornblende crystallization occurred at about 1 45 ma 7 7 9 4 km depth in the marginal eastern takidani granodiorite but later at 1 25 ma and shallower 6 5 7 0 km near the core of the intrusion the average rate of uplift across the takidani granodiorite from the time of hornblende crystallization has been 5 1 5 9 mm yr although uplift was about 7 5 mm yr prior to 1 2 ma which is faster than average uplift rates in the japan alps 3 mm yr during the last 2 million years a temperature depth time window when the takidani granodiorite had potential to host an hdr system would have been when the internal temperature of the intrusive was cooling from 500 c to 400 c taking into account the initial 7 5 mm yr rate of uplift and effects of erosion an optimal temperature time depth window is proposed for 500 c at 1 54 1 57 ma and 5 2 0 9 km drilling depth and 400 c at 1 36 1 38 ma and 3 3 0 8 km drilling depth which is within the capabilities of modern drilling technologies and similar to measured temperature depth profiles in other active hydrothermal systems e g at kakkonda japan

three monthly coral sr ca records from the chagos archipelago covering the period of 1950 1995 a d reproducibility and implications for quantitative reconstructions of sea surface temperature variations in order to assess the fidelity of coral sr ca for quantitative reconstructions of sea surface temperature variations we have generated three monthly sr ca time series from porites corals from the lagoon of peros banhos 71 e 5 s chagos archipelago we find that all three coral sr ca time series are well correlated with instrumental records of sea surface temperature sst and air temperature however the intrinsic variance of the single core sr ca time series differs from core to core limiting their use for quantitative estimates of past temperature variations averaging the single core data improves the correlation with instrumental temperature r 0 7 and allows accurate estimates of interannual temperature variations 0 35 c or better all sr ca time series indicate a shift towards warmer temperatures in the mid 1970s which coincides with the most recent regime shift in the pacific ocean however the magnitude of the warming inferred from coral sr ca differs from core to core and ranges from 0 26 to 0 75 c the composite sr ca record from peros banhos clearly captures the major climatic signals in the indo pacific ocean i e the el nino southern oscillation and the pacific decadal oscillation moreover composite sr ca is highly correlated with tropical mean temperatures r 0 7 suggesting that coral sr ca time series from the tropical indian ocean will contribute to multi proxy reconstructions of tropical mean temperatures

the palu metamorphic complex nw sulawesi indonesia origin and evolution of a young metamorphic terrane with links to gondwana and sundaland abstract the palu metamorphic complex pmc is exposed in a late cenozoic orogenic belt in nw sulawesi indonesia it is a composite terrane comprising a gneiss unit of gondwana origin a schist unit composed of meta sediments deposited along the se sundaland margin in the late cretaceous and early tertiary and one or more slivers of amphibolite with oceanic crust characteristics the gneiss unit forms part of the west sulawesi block underlying the northern and central sections of the western sulawesi province the presence of late triassic granitoids and recycled proterozoic zircons in this unit combined with its isotopic signature suggests that the west sulawesi block has its origin in the new guinea margin from which it rifted in the late mesozoic it docked with sundaland sometime during the late cretaceous u th pb dating results for monazite suggest that another continental fragment may have collided with the sundaland margin in the earliest miocene high pressure hp and ultrahigh pressure uhp rocks granulite peridotite eclogite are found as tectonic slices within the pmc mostly along the palu koro fault zone a major strike slip fault that cuts the complex mineralogical and textural features suggest that some of these rocks resided at depths of 60 120 km during a part of their histories thermochronological data u th pb zircon and 40ar 39ar from the metamorphic rocks indicate a latest miocene to mid pliocene metamorphic event which was accompanied by widespread granitoid magmatism and took place in an extensional tectonic setting it caused recrystallization of and new overgrowths on pre existing zircon crystals and produced andalusite cordierite sillimanite staurolite assemblages in pelitic protoliths indicating ht lp buchan type metamorphism the pmc was exhumed as a core complex at moderate rates c 0 7 1 0 mm yr accompanied by rapid cooling in the plio pleistocene some of the uhp rocks were transported to the surface at significantly higher rates 16 mm yr the results of our study do not support recent plate tectonic reconstructions that propose a nw australia margin origin for the west sulawesi block e g hall et al 2009

coralline algal growth increment widths archive north atlantic climate variability over the past decade coralline algae have increasingly been used as archives of paleoclimate information encrusting coralline algae which deposit annual growth increments in a high mg calcite skeleton are amongst the longest lived shallow marine organisms in fact a live collected plant has recently been shown to have lived for at least 850 years based on radiometric dating while a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures less attention has been paid to employ growth increment widths as a temperature proxy here we explore the relationship between growth and environmental parameters in clathromorphum compactum collected in the subarctic northwestern atlantic results indicate that growth increment widths of individual plants are poorly correlated with instrumental sea surface temperatures sst however an averaged record of multiple growth increment width time series from a regional network of c compactum specimens up to 800 km apart reveals strong correlations with annual instrumental sst since 1950 hence similar to methods applied in dendrochronology averaging of multiple sclerochronological records of coralline algae provides accurate climate information a 115 year growth increment width master chronology created from modern collected and museum specimens is highly correlated to multidecadal variability seen in north atlantic sea surface temperatures positive changes in algal growth anomalies record the well documented regime shift and warming in the northwestern atlantic during the 1990s large positive changes in algal growth anomalies were also present in the 1920s and 1930s indicating that the impact of a concurrent large scale regime shift throughout the north atlantic was more strongly felt in the subarctic northwestern atlantic than previously thought and may have even exceeded the 1990s event with respect to the magnitude of the warming

new research in the methods and applications of sclerochronology abstract because the instrumental record is short and does not extend to periods before the initiation of significant human impacts full understanding of the processes and dynamics involved in the modern phase of very rapid global change depends on the interpretation of high resolution and precisely dated proxy archives the identification of very long lived species of bivalve mollusc in the extratropical marine environment has been a crucial recent advance these molluscs form patterns of periodic usually annual banding in their shells that are synchronous within populations so that long centennial and millennial stacked chronologies can be built by crossdating from live collected to fossil shells the variable growth rates and precisely dated geochemical data from the shell material provide long term real world data that can in principle be used to constrain climate models and to define long baselines for environmental monitoring however the signals in these data usually result from the complex interaction of multiple influences and the deconvolution and understanding of these influences is a major target of the scientific field of sclerochronology this special issue presents some of the latest research into the sclerochronology of mollusc shells it includes contributions to our understanding of shell growth including the identification of endogenous non environmental growth rhythms that persist throughout ontogeny and analysis in two papers of variability through ontogeny in the season of growth and the implications of such variability for temperature reconstruction one paper presents a new network of bivalve chronologies for uk waters with a 200 year seawater temperature reconstruction three papers cover trace element geochemistry including a novel approach to sampling for la icp ms that enables giant clam shells to be sampled at daily resolution an attempt to identify an independent temperature proxy for coastal waters using limpet shells and a detailed study of the drivers of variability in sr ca and ba ca ratios one study looks at shell microstructure as a temperature proxy finding a coherent temperature response in the shape of the prisms

ion microprobe u pb dating of quaternary zircon implication for magma cooling and residence time abstract an ion microprobe u pb dating method of quaternary zircon is developed using the sensitive high resolution ion microprobe shrimp and applied to igneous rocks from japan total pb u isochron age of 1 36 0 23 ma 95 confidence limit cl mswd 1 03 was obtained for zircons extracted from takidani granodiorite in central japan this may provide a constraint on magma cooling when coupled with fission track ages of the zircon as well as rb sr and k ar ages on co existing minerals the closure temperature determined by each method has lead to exponentially declining cooling history the history is consistent with a simple conductive cooling model of a small magma body 10 2 10 3 km 3 a pb u isochron age of 271 58 ka 95 cl mswd 0 85 has been determined for volcanic zircons from torihama dacite sw japan the age is significantly older than the 238 u 230 th ionium age of 145 33 ka and fission track age of 163 8 ka found in the literature suggesting either the magma residence time of 100 kyr or a rapid cooling rate of about 6 c kyr in contrast a tephrochronological estimate of 240 10 ka agrees well with the observed pb u age implying that the ionium and fission track ages are incorrect the pb u isochron age of 90 29 ka 95 cl mswd 1 04 is obtained for zircons in pyroclastic rocks from the unzen eruption in 1991 sw japan the age is again older than the eruptive age which suggests a magma residence time of 90 kyr in a shallow reservoir

the late cenozoic uplift climate change paradox the geologic evidence for worldwide uplift of mountain ranges in the neogene is ambiguous estimates of paleoelevation vary according to whether they are based on the characteristics of fossil floras on the masses and grain sizes of eroded sediments or on calculations of increased thickness of the lithosphere as a result of faulting detrital erosion rates can be increased both by increased relief in the drainage basin and by a change to more seasonal rainfall patterns the geologic record provides no clear answer to the question whether uplift caused the climatic deterioration of the neogene or whether the changing climate affected the erosion system in such a way as to create an illusion of uplift we suggest that the spread of c4 plants in the late miocene may have altered both the erosion and climate systems these changes are responsible for the apparent contradictions between data supporting uplift and those supporting high elevations in the past

an intractable climate archive sclerochronological and shell oxygen isotope analyses of the pacific geoduck panopea abrupta bivalve mollusk from protection island washington state usa abstract annual growth increment patterns of cardinal teeth ct of panopea abrupta conrad can reportedly provide information about past climate variations however little is known about the intra annual timing and rate of shell growth necessary to interpret such records in addition it remains unclear whether actual temperatures can be reliably inferred from 18o values of geoduck goo e duk shells this study compared high resolution environmental records hourly to monthly resolved temperature bi weekly to monthly 18owater and salinity data with temperatures reconstructed from oxygen isotope values of the outer shell layer t 18oosl and cardinal tooth portions t 18oct of different contemporaneous specimens alive at the same locality results indicate that shell growth mainly occurred between march april and november december with a maximum during may august this finding must be considered when comparing the annual growth increment width chronologies to environmental parameters in addition intra annual 18oshell values require the calculation of weighted averages instead of arithmetic means during ontogeny the duration of the growing season remained nearly unchanged an important finding for paleoclimate studies based on inter annual growth patterns seasonal shell growth was strongly correlated with temperature r 0 93 r2 0 86 p

volcaniclastic resedimentation in distal fluvial basins induced by large volume explosive volcanism the ebisutoge fukuda tephra plio pleistocene boundary central japan the ebisutoge fukuda tephra plio pleistocene boundary central japan has a well recorded eruptive style history magnitude and resedimentation styles despite the absence of a correlative volcanic edifice this tephra was ejected by an extremely large magnitude and complex volcanic eruption producing more than 400 km 3 total volume of volcanic materials volcanic explosivity index 7 which extended more than 300 km away from the probable eruption centre remobilization of these ejecta occurred progressively after the completion of a series of eruptions resulting in thick resedimented volcaniclastic deposits in spatially separated fluvial basins more than 100 km from the source facies analysis of resedimented volcaniclastic deposits was carried out in distal fluvial basins the distal tephra 100 300 km from the source comprises two different lithofacies primary pyroclastic fall deposits and reworked volcaniclastic deposits the resedimented volcaniclastic succession shows five distinct sedimentary facies interpreted as debris flow deposits facies a hyperconcentrated flow deposits facies b channel fill deposits facies c floodplain deposits with abundant flood flow deposits facies d and floodplain deposits with rare flood deposits facies e resedimented volcaniclastic materials at distal locations originated from unconsolidated deposits of a climactic large ignimbrite forming eruption factors controlling inter and intrabasinal facies changes are 1 temporal change of introduced volcaniclastic materials into the basin 2 proximaldistal relationship and 3 distribution pattern of pyroclastic flow deposits relative to drainage basins thus studies of the ebisutoge fukuda tephra have led to a depositional model of volcaniclastic resedimentation in distal areas after extremely large magnitude eruptions an aspect of volcaniclastic deposits that has often been ignored or poorly understood

youngest exposed granitoid pluton on earth cooling and rapid uplift of the pliocene quaternary takidani granodiorite in the japan alps central japan the takidani granodiorite is a pluton 13 x 4 km situated along a major axis of the japan alps that was intruded into late pliocene age 2 4 ma volcanic rocks rb sr k ar and fission track dates on coexisting minerals from the pluton are 1 9 0 8 ma geology and mineral dates for the takidani granodiorite indicate that emplacement and cooling of the pluton occurred from late pliocene to quaternary time making the takidani granodiorite the youngest granitoid pluton exposed on earth9s surface mineral ages give a nearly straight path on a temperature time t t diagram according to the closure temperature of the minerals the linearity of the t t path indicates high thermal input from deeper levels in the early stage and cooling through rapid uplift in the late stage the rapid exposure of the takidani granodiorite resulted from more than 2000 m of quaternary uplift along the major axis of the japan alps

pacific decadal oscillation documented in a coral record of north pacific winter temperature since 1873 1 the pacific decadal oscillation pdo the leading mode of sea surface temperature sst anomalies in the extratropical north pacific ocean has widespread impacts on precipitation in the americas and marine fisheries in the north pacific however marine proxy records with a temporal resolution that resolves interannual to interdecadal sst variability in the extratropical north pacific are extremely rare here we demonstrate that the winter sr ca and u ca records of an annually banded reef coral from the ogasawara islands in the western subtropical north pacific are significantly correlated with the instrumental winter pdo index over the last century the reconstruction of the pdo is further improved by combining the coral data with an existing eastern mid latitude north pacific growth ring record of geoduck clams the spatial correlations of this combined index with global climate fields suggest that sst proxy records from these locations provide potential for pdo reconstructions further back in time

features of fractures forming flow paths in granitic rock at an lpg storage site in the orogenic field of japan the biggest underground storage facility for liquefied petroleum gas lpg in the world has been constructed in sub seabed cretaceous granitic rock located in the seto inner sea area of western japan this lpg facility is being operated using a water curtain system in order to control the flow of groundwater and pore pressure and thereby ensure long term safe lpg storage to design this water curtain system it was essential to understand the hydrological and structural features of flow path fp fractures in the granitic host rock therefore detailed fp mapping structural characterization and grouting after hydrological examination were carried out as a result two types of fp were distinguished in the host granitic rock one is a planar type fracture which constitutes a major fp at the site hydrologically the fractures of this type are well connected and readily controlled by grouting the other type is a micro sheeting type fracture which is characterized by an assemblage of micro fractures fractures of this second type were formed under an unloading stress field while the granitic body underwent uplift however these fractures have quite low groutability owing to the poor connectivity of their micro pores the physical characteristics of the fracture fillings e g calcite within both kinds of fps reflect the processes of fp formation and evolution of the host rock the structural and mineralogical features of the fps can be explained by the development of fractures and fluid circulation due to the relatively rapid uplift of the granite during orogenesis the two kinds of fp can be considered typical of groundwater conductive features in an orogenic stress field inevitably such features will be encountered in other plutons formed at continental margins

a fistful of shells amplifying sclerochronological and palaeoclimate signals from molluscan death assemblages agrowingbodyofliteratureisusingsclerochronologicalinformationtoinferpastclimates sclerochronologies are based on series of skeletal growth records of molluscs that have been correctly aligned in time incremental series are obtained from a number of shells to assess the temporal control and improve the climate signal in the final chronology much of the sclerochronological theory has been adopted from tree ring science due to the longer tradition and more firmly established concepts of chronology construction in dendrochronology compared to tree ring studies however sclerochronological datasets are often characterized by relatively small sample size here we evaluate how effectively palaeoclimatic signal can be extracted from such a suite of samples in so doing the influences of the very basic methods that are applied in nearly every sclerochronological study to remove the non climatic growth variability prior to palaeoclimatic interpretations are ranked by their capability to amplify the desired signal the study is performed in the context of six shells that constitute a bicentennial growth record from annual shell increments of freshwater pearl mussel it was shown that when the individual series were detrended using the models set by the mean or the median summary curves for ageing that is applying regional curve standardization rcs instead of fitting the ageing mode statistically to each series the resulting sclerochronology displayed more low frequency variability consistently the added low frequency variability evoked higher proxy climate correlations these results show the particular benefit of using the rcs method to develop sclerochronologies and preserve their low frequency variations moreover calculating the ageing curve and the final chronology by median instead of mean resulted in an amplified low frequency climate signal the results help to answer a growing need to better understand the behaviour of the sclerochronological data in addition we discuss the pitfalls that may potentially disrupt palaeoclimate signal detection in similar sclerochronological studies pitfalls may arise from shell taphonomy water chemistry time variant characters of biological growth trends and small sample size

enso like interdecadal variability 1900 93 a number of recent studies have reported an enso like eof mode in the global sea surface temperature sst field whose time variability is marked by an abrupt change toward a warmer tropical eastern pacific and a colder extratropical central north pacific in 1976 77 the present study compares this pattern with the structure of the interannual variability associated with the enso cycle and documents its time history back to 1900 the analysis is primarily based on the leading eofs of the sst anomaly and anomaly deviation fields in various domains and the associated expansion coefficient or principal component time series which are used to construct global regression maps of sst sea level pressure slp and a number of related variables the use of anomaly deviations i e departures of local sst anomalies from the concurrent global mean sst anomaly reduces the influence of global mean sst trends upon the structure of the eofs and their expansion coefficient time series an important auxiliary time series used in this study is a southern oscillation index based on marine surface observations by means of several different analysis techniques the time variability of the leading eof of the global sst field is separated into two components one identified with the enso cycle related variability on the interannual timescale and the other a linearly independent residual comprising all the interdecadal variability in the record the two components exhibit rather similar spatial signatures in the global sst slp and wind stress fields the sst signature in the residual variability is less equatorially confined in the eastern pacific and it is relatively more prominent over the extratropical north pacific the corresponding slp signature is also stronger over the extratropical north pacific and its counterpart in the cold season 500 mb height field more closely resembles the pna pattern the amplitude time series of the enso like pattern in the residual variability reflects the above mentioned shift in 1976 77 as well as a number of other prominent features including a shift of opposite polarity during the 1940s

modification of the regional stress field by magma intrusion and formation of tabular granitic plutons granitic intrusions typically have large aspect ratios with an horizontal major axis about 4 8 times the vertical one combined structural and geophysical gravity data allows distinction between two main types of plutons flat floored plutons the most represented are rather thin 3 4 km and extend in every horizontal direction with a gently dipping floor toward several root zones these contrast with the thick 10 km wedge shaped plutons more elongated in one direction with a few root zones we interpret the shape of flat floored plutons as the result of a switch in the stress pattern caused by the emplacement of magma magma is preferentially emplaced into the plane 1 2 perpendicular to the least principal stress component 3 this plane is initially vertical except for compressional conditions this dilation causes a local re organization of the stress field by increasing the minor and intermediate principal stress components when they overcome the lithostatic load a drastic change in the orientation of the opening plane results switching from vertical to horizontal this constitutes a change from vertically oriented dike shaped intrusions to sub horizontal laccoliths crustal anisotropies vertical faults or horizontal zones of different rheology also contribute to modify the shape of the intrusions the continual exchange of the intermediate stress components also explains the rounded shape of intrusions in strongly extended regions our analysis suggests that the concept of magmas rising to a level of neutral buoyancy is not applicable to many settings rather we suggest that the feedback between displacements resulting from magma intrusion and the local stress pattern controls the geometry of magma emplacement

preserving low frequency climate signals in growth records of geoduck clams panopea abrupta abstract the capacity of geoduck clams panopea abrupta to preserve detailed records of climatic change in their shells is limited primarily by longevity unlike the multi centennial growth records commonly available from trees shells rarely yield more than 160 years of data consequently low frequency signals may be lost when band width series are processed here we investigate use of regional curve standardization rcs to preserve decadal to centennial scale growth trends in the relatively short segment lengths available from individual clams advantages of this method over the more common exponential treatment are first explored through simulation experiments using sine waves embedded in geoduck growth curves both standardization methods are then used to remove biological trends from growth records of geoduck shells sampled near protection island in the strait of juan de fuca the resulting chronologies are compared in terms of their spectral properties their correlations with historical air temperature records and their agreement with historical observations of the marine environment simulation experiments illustrated the potential benefits of using the rcs growth model to standardize shell growth series but empirical results were inconclusive the rcs chronology exhibited enhanced spectral power at periods exceeding the length of growth segments and provided stronger correlation with coastal air temperature records especially during the earliest portion of the chronology over the full period of comparison however the correlation coefficients were essentially identical observational data from the mid to late 1800s appears to support the rcs results northward range expansions of several marine fish species coincide with a period of conspicuously high values in the rcs chronology and suggest that the coastal ocean was unusually warm along western north america from the 1850s through the 1870s

late quaternary activity of faults and recurrence interval of earthquakes in the eastern hokuriku region northern central japan on the basis of precise cryptotephra analysis of fluvial terrace sequences abstract about 2000 active faults are known to exist within the land area of japan most of these active faults have deformed the topographic surfaces which were formed in the late quaternary including fluvial terraces and the formative ages of these terraces are estimated mainly by tephrochronology fluvial terraces in the eastern hokuriku region comprising the toyama tonami and kanazawa plains northern central japan are widely distributed and have been deformed by reverse active faults the formative age of terraces in this area has not been reported as volcanic ash deposits are rarely visible within terrace deposits and the overlying loamy soil and outcrops of fluvial terraces are quite scarce in this area in the present study we carried out a drilling survey on these terraces to obtain samples of the overlying loamy soil and upper part of terrace deposits from these samples we extracted some well known widespread volcanic ash from which we were able to estimate the approximate age of the terraces and the vertical slip rate of the active faults late quaternary fluvial terraces in eastern hokuriku are divided into 12 levels terraces 1 to 12 in descending order widespread tephras such as the kikai tozurahara tephra k tz 95 ka are contained in the lowest part of the loamy soil in terrace 4 and the daisen kurayoshi pumice dkp 55 ka is present in the lowest part of the loamy soil in terrace 6 from the ages and the vertical displacements of the fluvial terraces the late quaternary average vertical slip rates of active faults in eastern hokuriku are estimated to be 0 2 0 9 mm year uozu fault 0 1 0 4 mm year kurehayama fault 0 1 0 3 mm year takashozu fault 0 1 0 4 mm year hohrinji fault and 0 5 0 8 mm year morimoto togashi fault we also estimated the recurrence interval of earthquakes related to active faults from displacement per event and ages of terraces and no significant difference in vertical displacement per single earthquake for different active faults and recurrence intervals tend to be inversely proportional to vertical displacement rates this study demonstrates that a combination of drilling of loamy soil and precise cryptotephra analysis of fluvial terraces can be used to estimate the formative age of the terraces and the average slip rate of active faults in areas where volcanic ash deposits are rare

distribution of shortening landward and oceanward of the eastern nankai trough due to the izu ogasawara ridge collision abstract the convergence of the philippine sea and eurasia plates is accommodated primarily by plate subduction along the nankai trough west of about 137 3 e but additionally by widely distributed onshore and offshore deformation to the east this zone with a total dimension of 200 km parallel to the nankai trough by 350 km has developed as one highly coupled region since the collision of the izu peninsula with mainland japan about 1 2 m y ago the onshore faulting in central japan is consistent with a wnw ese direction of maximum horizontal stress while the oceanward deformation is driven by diffuse nw se shortening of the izu ogasawara volcanic ridge which produces a kinematic discontinuity with respect to the philippine sea oceanic crust to its west the strain release associated with the 1891 nobi earthquake and the onshore deformation as a whole suggests that the philippine sea eurasia convergence is partially accommodated by onshore shortening between the tsuruga bay ise bay tectonic line and the izu peninsula

syncollisional rapid granitic magma formation in an arc arc collision zone evidence from the tanzawa plutonic complex japan the tanzawa plutonic complex tpc central japan is a suite of tonalitic gabbroic plutons exposed in a globally unique arc arc collision zone where an active intraoceanic izu bonin mariana ibm arc is colliding against the honshu arc the tpc has been widely accepted as an exposed middle crust section of the ibm arc chiefly because of geochemical similarities between the tpc and ibm rocks and previously reported precollisional miocene k ar ages however new zircon u pb ages show that the main pulse of tpc magmatism was syncollisional and that plutons were emplaced rapidly and cooled soon after pliocene collision trace element compositions of tpc zircon show distinctively elevated th nb ratios compared to zircon from other noncollisional ibm silicic plutonic rocks indicating the involvement of continental sediments from the honshu arc in their magma genesis

multi proxy reconstructions of northeastern pacific sea surface temperature data from trees and pacific geoduck abstract we demonstrate the potential for developing sea surface temperature sst reconstructions in the northeast pacific from combinations of tree ring and growth increment chronologies of the long lived marine bivalve the pacific geoduck six pacific geoduck chronologies developed from site along the washington british columbia coast are compared and combined with tree ring chronologies from california to alaska all chronologies are annually resolved and strongly relate to local to regional scale sst though differences in the response season as well as the spectral properties of the two proxies are observed both proxy types closely track sst and when used in combination yield a more robust sst reconstruction than tree ring or geoduck chronologies could provide alone in total variance explained in sst is 63 9 at the regional scale and 68 2 at a local scale providing sst estimates for more than 60 years prior to the start of continuous instrumental records in this region this study represents one of the few climate reconstructions where both proxies are annually resolved and is the first to integrate regional networks of geoduck chronologies and tree ring chronologies

composition of stable isotopes in geoduck panopea abrupta shells a preliminary assessment of annual and seasonal paleoceanographic changes in the northeast pacific abstract we tested the suitability of using panopea abrupta geoduck shells to evaluate changes in both annual and seasonal sea surface temperature geoducks are long lived and deposit annual growth increments within their shell each winter making them potentially excellent paleoceanographic archives shells were sampled by thin section from the hinge plate region where the first 20 30 years of growth provide relatively wide annual increments suitable for sampling for isotopic analysis the geoducks used in this study were collected in ad 2000 from west of protection island located at the eastern end of the strait of juan de fuca the isotopic record is compared to the historic instrumental record as well as the thickness of geoduck growth increment measurements which were also correlated with water temperature strom a francis r c mantua n j miles e l peterson d l 2004 north pacific climate recorded in growth rings of geoduck clams a new tool for paleoenvironmental reconstruction geophysical research letters 31 p lo6206 doi 10 1029 2004gl019440 the annual average oxygen isotopic values from two geoduck clams whose first years of growth correspond to the early historic instrumental record ad 1920 appear to be recording trends in sea surface temperature intra annual sampling of annual growth increments indicates that the shells also appear to be recording seasonal changes in sea surface temperature preliminary analysis of carbon isotopic data on both the annual and seasonal timescales indicate the potential for assessing productivity changes in ambient seawater

sodium metasomatism in chondrules in co3 chondrites relationship to parent body thermal metamorphism we have studied the mineralogy and petrology of mesostases of 783 type i chondrules in seven co3 chondrites that range in petrologic subtype from 3 0 to 3 7 chondrule mesostases in the co chondrite of subtype 3 0 consist mainly of primary glass and plagioclase while chondrule mesostases in the co chondrites of higher subtypes 3 2 3 7 contain various amounts of nepheline in addition to glass and plagioclase nepheline has replaced glass and plagioclase forming finegrained aggregates and thin parallel lamellar intergrowths with plagioclase the nephelinization has proceeded preferentially from the outer margins of chondrules toward the inside although the degree of nephelinization differs widely among chondrules in each of the metamorphosed chondrites our modal analyses and bulk chemical analyses of individual mesostases indicate that the amounts of nepheline in chondrules systematically increase with the increasing petrologic subtype of the host chondrites nepheline also has a tendency to increase in grain size with increasing petrologic subtype we conclude that nepheline in chondrules in the co3 chondrites has formed largely as a result of effects related to heating on the meteorite parent body we suggest that nepheline initially formed as hydrous nepheline under the presence of aqueous fluids and subsequently was dehydrated after exhaustion of aqueous fluids the degree of hydrothermal activity must have increased with increasing degree of heating and thus chondrules in more thermally metamorphosed chondrites produced larger amounts of nepheline the results imply that co3 chondrites have gone through lowgrade aqueous alteration and subsequent dehydration at the early stage of heating on the meteorite parent body

formation processes of compound chondrules in cv3 carbonaceous chondrites constraints from oxygen isotope ratios and major element concentrations abstract we found thirty compound chondrules in two cv3 carbonaceous chondrites the abundance in each meteorite relative to single chondrules is 29 1846 1 6 in allende and 1 230 0 4 in axtell we examined petrologic features major element concentrations and oxygen isotopic compositions textural compositional and isotopic evidence suggests that multiple different mechanisms are responsible for the formation of compound chondrules seven compound chondrules are composed of two conjoined porphyritic chondrules with a blurred boundary at the boundary region of this type of compounds a poikilitic texture is commonly observed this suggests that the two chondrules were melted when they came to be in contact on the other hand seventeen compound chondrules consist of two conjoined chondrules with a discrete boundary the preservation of spherical boundary planes of an earlier formed chondrule of this type implies that it already solidified before fusing with a later formed chondrule that was still melted six samples out of 17 compound chondrules of this type are composed of two bo chondrules the bo bo compound chondrules have a unique textural feature in common the directions of the barred olivines are mostly parallel between two chondrules this cannot be explained by a simple collision process and forces another mechanism to be taken into consideration the remaining six compound chondrules differ from the others they consist of an earlier formed chondrule enclosed by a later formed chondrule a large feo enrichment was observed in the later formed chondrules and the enrichment was much greater than that in the later formed chondrules of other types of compounds this is consistent with the relict chondrule model which envisages that the later formed chondrule was made by a flash melting of a porous feo rich dust clump on an earlier formed chondrule the textural evidence of this type of compound shows that the earlier formed chondrule has melted again to varying degrees at the second heating event this implies that feo concentrations in bulk chondrules increases during the second heating event if an earlier formed chondrule was totally melted together with the feo rich dust aggregates silicate minerals such as olivine and low ca pyroxene in compound chondrules have oxygen isotope compositions similar to those in single chondrules from cv3 chondrites the oxygen isotope composition of each part of the compound chondrule is basically similar to their chondrule pair but silicates in some chondrules show varying degrees of 16 o enrichment down to 15 in 18 o while those in their partners have 16 o poor invariable compositions near 0 in 18 o this implies that the two chondrules in individual compounds formed in the same environments before they became conjoined and the heterogeneous oxygen isotope compositions in some chondrules resulted from incomplete exchange of oxygen atoms between 16 o rich chondrule melts and 16 o poor nebular gas

stratigraphy of the kazusa group boso peninsula an expanded and highly resolved marine sedimentary record from the lower and middle pleistocene of central japan major climatic reorganizations including changes in the nature of glacial interglacial cycles through the pleistocene are a key issue for improving the understanding of earth s climate system highly resolved marine sedimentary records are essential to reconstruct the details of these past climatic changes and investigate the mechanisms responsible for them the kazusa group located in the central part of the japanese island chain is well exposed and contains a remarkably continuous and thick deep and shallow water marine sedimentary succession this group also contains well preserved marine microfossils pollen paleomagnetic reversal events geochemical signatures and a large number of tephra beds these features allow us to establish a robust chronological and stratigraphic framework for the kazusa group and provide a rare opportunity to study oceanic and terrestrial climatic and environmental changes at high resolution especially through the lower and lower middle pleistocene in the boso peninsula chiba prefecture the kazusa group is deeply incised yielding spectacular river cut exposures the matuyama brunhes paleomagnetic reversal is observed immediately above the widespread byakubi e byk e tephra in the chiba composite section within the kokumoto formation kazusa group because the matuyama brunhes boundary customarily serves as the primary guide for the lower middle pleistocene subseries boundary the chiba composite section is considered an excellent candidate for its global boundary stratotype section and point gssp this study reviews the published data for the kazusa group hitherto almost exclusively in japanese in order to place the chiba composite section within its broader depositional and chronostratigraphic context

geological characterisation of the active atera fault in central japan implications for defining fault exclusion criteria in crystalline rocks around radioactive waste repositories abstract in the orogenic field of the japanese archipelago faults are inevitably distributed in all types of potential host rocks for high level radioactive waste hlw repositories these faults could have an adverse impact on a repository if they were to provide a short circuit to the biosphere so allowing any radionuclides released from the repository a more rapid transport pathway to the surface than would be the case otherwise associated with many faults is a damage zone with fault gouge and crushed rock developed in and alongside the main fault plane the specific characteristics of a damage zone are considered to be a reflection of the process of faulting and may be used to understand the influence of fault movement on the surrounding host rocks in order to clarify the geological characteristics by which potentially transmissive features of faults can be avoided when siting a radioactive waste repository for hlw in a crystalline host rock the active atera fault which is located in central japan has been studied relationships between the morphological features of the fault its associated damage zone and the fracture frequency have been investigated detailed mapping of the damage zone shows that the fractures formed by later faulting activity can be distinguished from the early fractures developed in the rock by using the microscopic textures and the differences between fracture filling minerals in particular a network of shortly transected fractures filled by carbonate and iron oxyhydroxide minerals was preferentially formed in the damage zone along the atera fault probably by recent fault movement the density of fractures also suggests that the mechanical damage zone formed by faulting extends for up to ca 200 m on each side of the main fault plane however the geochemically influenced zone has been spatially restricted by geochemical buffering reactions involving crushed fracture filling materials along the fault the results provide a basis for defining exclusion zones around faults that might be identified in a future crystalline repository host rock the methodology is applicable to site characterization and the appropriate allocation of repository panels and deposition holes for waste canisters

inter annual climate variability in europe during the oligocene icehouse abstract new sclerochronological data suggest that a variability comparable to the north atlantic oscillation nao was already present during the middle oligocene about 20 myr earlier than formerly assumed annual increment width data of long lived marine bivalves of oligocene 30 25 ma strata from central europe revealed a distinct quasi decadal climate variability modulated on 2 12 mainly 3 7 year cycles as in many other modern bivalves these periodic changes in shell growth were most likely related to changes in primary productivity which in turn were coupled to atmospheric circulation patterns stable carbon isotope values of the shells 13 c shell further corroborated the link between shell growth and food availability sub decal oscillations in the 3 7 year band in other annually resolved fossil archives were often interpreted as el nino southern oscillation enso cycles this possibility is discussed in the present study however combined shell derived proxy and numerical climate model data lend support to the interpretation of a nao like variability according to numerical climate models winter sea level pressure wslp and precipitation rate wpr across central europe during the oligocene exhibited a pattern similar to the modern nao the simulated nao index for the oligocene shows periodicities coherent with those revealed by the proxy data 2 5 6 years yet on shorter wavelengths than the modern nao biennial and 6 10 year cycles likely the different paleogeography and elevated atmospheric co 2 concentrations not only influenced the sea level pressure pattern but also the temporal variability of the nao precursor the present study represents the first attempt to characterize the inter annual climate variability in central europe during the oligocene and sets the basis for future studies on the early phase of the cenozoic icehouse climate state

active strike slip faulting and macroscopically nonrigid deformation of volcanic rocks in central japan inferred from a paleomagnetic study abstract detailed paleomagnetic investigation of a pyroclastic flow deposit has clarified the deformation mode around an active fault in central japan the early quaternary nyukawa pyroclastic flow deposit is cut by the active dextral enako fault activity level of the fault is evaluated on the basis of geological and geomorphological surveys then paleomagnetic samples are collected from 22 sites at exposures located on a lineament that is adjoining and parallel to the enako fault stable thermoremanent magnetization trm of the pyroclastic deposit is isolated through progressive thermal and or alternating field demagnetization tests untilted site mean directions of the trms simultaneously acquired during initial cooling indicate significant clockwise vertical axis rotation the lineament was then activated with right lateral motions through the early quaternary together with the late quaternary activities along the adjoining enako fault evaluated by our study the present result exemplifies a migration of active segments within a fault system during the quaternary paleomagnetic directions on the strike slip fault are not concordant with uniform deformation predicted by the model of rotation of rigid blocks aligned on a master fault but suggestive of a periodic deformation as a result of intense fracturing and differential rotation of blocks bounded by nested parallel faults

bomb produced radiocarbon validation of growth increment crossdating allows marine paleoclimate reconstruction abstract the bivalve pacific geoduck panopea generosa has been used in the eastern north pacific ocean to create proxies for environmental factors such as temperature and oceanographic conditions this type of research depends upon accurate age determination of pacific geoducks which historically was based on shell growth increment counts a recent study comparing age estimates generated by the dendrochronology tree ring science procedure of crossdating to those estimated from growth increment counts found a significant difference between the methods for geoduck older than 30 years compared to the traditional age determination method of counting growth increments the crossdating method estimates a greater longevity in this species with some individuals living in excess of 150 years in the present study the accuracy of each method was independently assessed using bomb produced radiocarbon 14c techniques specimens whose birth years were estimated to be within the era of the bomb produced marine 14c increase and where the differences between ages estimated by the two methods were greatest were selected for 14c analysis the difference between age estimates from traditional growth increment counts and those from crossdating was evaluated using their respective 14c chronologies in comparisons to a reference chronology as a standard the comparisons relied on bayesian nonlinear models using markov chain monte carlo simulation this method of analysis showed that with a 50 probability geoducks were aged correctly when using the crossdating method compared to the growth increment counts which had a 50 probability of underestimating the age by 4 years therefore the crossdated age estimates were found to be more accurate than increment counts furthermore these results provide new confidence in using pacific geoduck biochronologies for paleoclimate and paleoenvironmental reconstruction