a penultimate glacial monsoon record from hulu cave and two phase glacial terminations oxygen isotope records of three stalagmites from hulu cave china extend the previous high resolution absolute dated hulu asian monsoon record from the last to the penultimate glacial and deglacial periods the penultimate glacial monsoon broadly follows orbitally induced insolation variations and is punctuated by at least 16 millennial scale events we confirm a weak monsoon interval between 135 5 1 0 and 129 0 1 0 ka prior to the abrupt increase in monsoon intensity at asian monsoon termination ii based on correlations with both marine ice rafted debris and atmospheric ch 4 records we demonstrate that most of marine termination ii the full rise in antarctic temperature and atmospheric co 2 and much of the rise in ch 4 occurred within the weak monsoon interval when the high northern latitudes were probably cold from these relationships and similar relationships observed for termination i we identify a two phase glacial termination process that was probably driven by orbital forcing in both hemispheres affecting the atmospheric hydrological cycle and combined with ice sheet dynamics

new views of lunar geoscience an introduction and overview beyond the earth the moon is the only planetary body for which we have samples from known locations the analysis of these samples gives us ground truth for numerous remote sensing studies of the physical and chemical properties of the moon and they are invaluable for our fundamental understanding of lunar origin and evolution prior to the return of the apollo 11 samples the moon was thought by many to be a primitive undifferentiated body e g urey 1966 a concept shattered by the data returned from the apollo and luna missions ever since new data have helped to address some of our questions but of course they also produced new questions in this chapter we provide a summary of knowledge about lunar geologic processes and we describe major scientific advancements of the last decade that are mainly related to the most recent lunar missions such as galileo clementine and lunar prospector 1 1 the moon in the planetary context compared to terrestrial planets the moon is unique in terms of its bulk density its size and its origin fig 1 1a c all of which have profound effects on its thermal evolution and the formation of a secondary crust fig 1 1d numerous planetary scientists considered the moon as an endmember among the planetary bodies in our solar system because its lithosphere has been relatively cool rigid and intact throughout most of geological time a one plate planet and its surface has not been affected by plate recycling an atmosphere water or life therefore the moon recorded and preserved evidence for geologic processes that were active over the last 4 4 5 b y and offers us the unique opportunity to look back into geologic times for which evidence on earth has long been erased fig 1 1c d impact cratering an exterior process is considered the most important surface process on the moon internal

volcanism on mercury evidence from the first messenger flyby for extrusive and explosive activity and the volcanic origin of plains the first messenger flyby of mercury obtained images of 21 of the surface not seen by mariner 10 including the center and western half of the caloris basin and regions near the terminator that show details of the nature of smooth and intercrater plains these new data have helped to address and resolve a series of longstanding questions on the existence and nature of volcanism on mercury and the distribution of volcanic materials data from the mercury dual imaging system mdis on the messenger spacecraft have shown the following 1 numerous volcanic vents in the form of irregularly shaped rimless depressions are concentrated around the interior edge of the caloris basin 2 these vents appear to be sources for effusive volcanism that in one case built a shield in excess of 100 km in diameter and in some cases formed bright haloes around the vents that are interpreted to represent pyroclastic eruptions 3 lobate margins of plains units seen previously in mariner 10 data are documented in messenger images with more clarity and are often distinctive in morphology and color properties supporting the interpretation that these features are the edges of lava flow units 4 the interior of the caloris basin is filled with plains units spectrally distinctive from the rim deposits and comparison with the lunar imbrium basin and superposed impact crater stratigraphy provide evidence that these units are volcanic in origin detailed differences in the mineralogy of lava flow units so prominent in imbrium are not seen in the caloris interior 5 some of the smooth plains surrounding the exterior of the caloris basin show distinct differences in color and morphological properties supporting a volcanic origin 6 some smooth and intercrater plains units distant from the caloris basin show evidence of flooding and embayment relations unrelated to caloris ejecta emplacement local and regional geological and color relationships support a volcanic origin for these plains 7 large impact craters show a sequence of embayment of interior floor and exterior ejecta deposits that supports a volcanic origin for the embayment and filling processes 8 crater embayment and flooding relationships in selected areas suggest volcanic plains thicknesses of many hundreds of meters and local thicknesses inside impact craters of up to several kilometers 9 impact crater size frequency distributions for caloris exterior deposits including the facies of the caloris group and relatively high and low albedo smooth plains show that they are younger than plains interior to caloris and thus must be dominantly the product of post caloris volcanism these new data provide evidence that supports and confirms earlier hypotheses from mariner 10 data that volcanism was important in shaping the surface of mercury the emerging picture of the volcanic style of mercury is similar to that of the moon the other small one plate planetary body there are no major shield volcanoes e g comparable to tharsis montes on mars shallow magma reservoirs are rare and there is little evidence for surface deformation or long lived volcanic sources related to sites of upwelling mantle the close association of volcanic plains and surface deformation features suggests that future observations and analyses can help document the relation between the volcanic flux and the evolving state and magnitude of stress in the lithosphere of mercury

persistent solar influence on north atlantic climate during the holocene surface winds and surface ocean hydrography in the subpolar north atlantic appear to have been influenced by variations in solar output through the entire holocene the evidence comes from a close correlation between inferred changes in production rates of the cosmogenic nuclides carbon 14 and beryllium 10 and centennial to millennial time scale changes in proxies of drift ice measured in deep sea sediment cores a solar forcing mechanism therefore may underlie at least the holocene segment of the north atlantic9s 1500 year cycle the surface hydrographic changes may have affected production of north atlantic deep water potentially providing an additional mechanism for amplifying the solar signals and transmitting them globally

marine isotope stage 11 palaeoclimates palaeoenvironments and its role as an analogue for the current interglacial abstract interglacials of the quaternary period are currently the focus of a great deal of attention within the scientific community this is primarily because they play a vital role in distinguishing between natural and human climate change in the current interglacial and in understanding how the holocene would evolve in the absence of anthropogenic greenhouse warming in this respect marine isotope stage 11 mis 11 ca 410 000 yr bp is one of the key interglacial stages of the past 450 000 yr the pattern of insolation variability that occurs during mis 11 matches that which occurs in the holocene more closely than in any other warm stage of the past half a million years in addition there is now an extensive range of evidence for mis 11 palaeoclimates and palaeoenvironments from marine ice core lacustrine and terrestrial sequences the aim of this paper is to provide a comprehensive review of the current state of our understanding of mis 11 this is the first paper to provide a detailed review of mis 11 that incorporates the wide range of marine ice core long lacustrine and terrestrial records that have been generated over the last ten years since the last major overview crucially it is the first review of mis 11 that incorporates a detailed synthesis of the high resolution terrestrial sequences of western and central europe this paper therefore provides a holistic integration of a diverse range of proxies and archives to provide a detailed understanding of the expression of mis 11 in the earth system in particular the review focuses on 1 the climatic background of mis 11 2 the robustness of the identification of mis 11 in a diverse range of sequences 3 the climatic structure of mis 11 4 the magnitude of warmth that occurred in this warm stage 5 mis 11 sea level magnitude and variability 6 the duration of mis 11 7 evidence for abrupt climatic events within the interglacial of mis 11 and 8 precipitation patterns and trends during this interglacial the paper concludes by considering how useful mis 11 is as an analogue for holocene climates and compares it with other proposed analogues such as mis 19 with particular reference to the early anthropogenic hypothesis

methods for determining deformation history for chocolate tablet boudinage with fibrous crystals abstract chocolate tablet boudinage with fibrous crystal growths between the boudinaged plates from two localities were studied in one from leytron valais switzerland the deformation history was found to be a succession of plane strain increments with the shortening direction perpendicular to the boudinaged sheet and the extension direction showing a progressive change in orientation within the sheet the incremental and finite strains were evaluated the other specimen from parys mountain anglesey great britain was found to have a more complex history with diachronous break up of the competent layer and flattening strain increments it was found that under these circumstances the direct graphical methods of determining finite and incremental strains gave inconsistent results a numerical model was developed which allowed the simulation of chocolate tablet structure with a complex deformation history the model was applied to the anglesey specimen and three possible strain histories for this structure were tried

epica dome c record of glacial and interglacial intensities abstract climate models show strong links between antarctic and global temperature both in future and in glacial climate simulations past antarctic temperatures can be estimated from measurements of water stable isotopes along the epica dome c ice core over the past 800 000 years here we focus on the reliability of the relative intensities of glacial and interglacial periods derived from the stable isotope profile the consistency between stable isotope derived temperature and other environmental and climatic proxies measured along the edc ice core is analysed at the orbital scale and compared with estimates of global ice volume mis 2 12 and 16 appear as the strongest glacial maxima while mis 5 5 and 11 appear as the warmest interglacial maxima the links between edc temperature global temperature local and global radiative forcings are analysed we show i a strong but changing link between edc temperature and greenhouse gas global radiative forcing in the first and second part of the record ii a large residual signature of obliquity in edc temperature with a 5 ky lag iii the exceptional character of temperature variations within interglacial periods focusing on mis 5 5 the warmest interglacial of edc record we show that orbitally forced coupled climate models only simulate a precession induced shift of the antarctic seasonal cycle of temperature while they do capture annually persistent greenland warmth models fail to capture the warming indicated by antarctic ice core d we suggest that the model data mismatch may result from the lack of feedbacks between ice sheets and climate including both local antarctic effects due to changes in ice sheet topography and global effects due to meltwater thermohaline circulation interplays an mis 5 5 sensitivity study conducted with interactive greenland melt indeed induces a slight antarctic warming we suggest that interglacial edc optima are caused by transient heat transport redistribution comparable with glacial north south seesaw abrupt climatic changes

eight glacial cycles from an antarctic ice core the antarctic vostok ice core provided compelling evidence of the nature of climate and of climate feedbacks over the past 420 000 years marine records suggest that the amplitude of climate variability was smaller before that time but such records are often poorly resolved moreover it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records here we report the recovery of a deep ice core from dome c antarctica that provides a climate record for the past 740 000 years for the four most recent glacial cycles the data agree well with the record from vostok the earlier period between 740 000 and 430 000 years ago was characterized by less pronounced warmth in interglacial periods in antarctica but a higher proportion of each cycle was spent in the warm mode the transition from glacial to interglacial conditions about 430 000 years ago termination v resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases but there are significant differences in the patterns of change the interglacial stage following termination v was exceptionally long 28 000 years compared to for example the 12 000 years recorded so far in the present interglacial period given the similarities between this earlier warm period and today our results may imply that without human intervention a climate similar to the present one would extend well into the future

the use of syntectonic fibres to determine strain estimates and deformation paths an appraisal abstract fibrous pressure shadows developed adjacent to rigid brittle inclusions are familiar features in many tectonites belief that these structures reflect the deformation path as once adjacent grains move apart has led to the derivation of a variety of techniques to determine both incremental and finite strain estimates these methods which can be divided into rigid fibre models e g durney and ramsay and deformable fibre models e g ellis display potentially serious problems when applied to field examples recent studies of microstructures within veins and pressure shadows support the concept that syntectonic fibre complexes can reflect deformation paths and are therefore useful markers of incremental and finite strain the problems mentioned therefore stem directly from the application of the techniques worked examples using these techniques give a variety of strain values dependent upon the extent to which a particular technique allows for volume change or fibre deformation this is useful locally however if the results are to be meaningful on a regional scale then it is imperative that the same technique be applied in the analysis of all fibres regardless of the local deformation path in such studies the merits of a particular technique in determining a correct strain value come second to allowing the spatial distribution of strain to be determined semi quantitatively and thus allowing comparison of similarly derived results with one another

interglacial hydroclimate in the tropical west pacific through the late pleistocene records of atmospheric carbon dioxide concentration pco 2 and antarctic temperature have revealed an intriguing change in the magnitude of interglacial warmth and pco 2 at around 430 000 years ago 430 ka but the global climate repercussions of this change remain elusive here we present a stalagmite based reconstruction of tropical west pacific hydroclimate from 570 to 210 ka the results suggest similar regional precipitation amounts across the four interglacials contained in the record implying that tropical hydroclimate was insensitive to interglacial differences in pco 2 and high latitude temperature in contrast during glacial terminations drying in the tropical west pacific accompanied cooling events in northern high latitudes therefore the tropical convective heat engine can either stabilize or amplify global climate change depending on the nature of the climate forcing

book reviewthe techniques of modern structural geology vol 1 strain analysis j g ramsay and m i huber academic press london 1983 xiii 307 pp us 55 00 28 00 hardcover

magma source transition of lunar mare volcanism at 2 3 ga mare basalts provide insights into the composition and thermal history of the lunar mantle the ages of mare basalts suggest a first peak of magma activity at 3 2 3 8 ga and a second peak at 2 ga in this study we reassess the correlation between the titanium contents and the eruption ages of mare basalt units using the compositional and chronological data updated by selene kaguya using morphological and geological criteria we calculated the titanium content of 261 mare units across a representative area of each mare unit in the procellarum kreep terrane where the latest eruptions are located an increase in the mean titanium content is observed during the eratosthenian period as reported by previous studies we found that the increase in the mean titanium content occurred within a relatively short period near approximately 2 3 ga suggesting that the magma source of the mare basalts changed at this particular age moreover the high titanium basaltic eruptions are correlated with a second peak in volcanic activity near 2 ga the high titanium basaltic eruptions occurring during the last volcanic activity period can be explained by the three possible scenarios 1 the ilmenite bearing cumulate rich layer in the core mantle boundary formed after the mantle overturn 2 the basaltic material layers beneath the lunar crust formed through upwelling magmas and 3 ilmenite bearing cumulate blocks remained in the upper mantle after the mantle overturn

stratigraphic sequence and ages of volcanic units in the gruithuisen region of the moon 1 several domes indicative of non mare volcanism morphologically as well as spectrally distinct from surrounding mare and highland units are located in the gruithuisen region in northern oceanus procellarum the determination of the nature and age of non mare volcanism helps to put constraints on lunar crustal evolution the ages of the domes were previously thought to be mid imbrian or possibly even eratosthenian in order to assess more closely the stratigraphic relationships in this region we carried out geologic mapping and crater size frequency measurements 1 on the gruithuisen volcanic domes 2 on the adjacent mare units and 3 in the highland areas 4 the nearby iridum impact event was also dated by means of crater counts a recently updated and improved version of the lunar production function polynomial was used to fit measured crater size frequency distributions of geologic units and a cratering chronology model was applied in order to assign these units to the periods and epochs of the lunar chronology system oceanus procellarum mare materials in the study area were found to range in age from late imbrian to eratosthenian and show peak cratering model ages at 3 55 gyr 1 gyr 1 billion years 3 2 3 3 gyr and about 2 4 gyr some mare units show evidence for at least two events in their crater size frequency distributions these are most likely due to the superposition of later thin lava flows mare volcanism hence has lasted over a period of several hundred million years in the gruithuisen region the gruithuisen domes show a much more restricted age range they were found to range in age from 3 85 to 3 72 gyr and thus were formed in the early part of the late imbrian an older age than previously thought iridum crater stratigraphically older than the gruithuisen domes was formed about 3 7 3 8 gyr ago the iridum impact event and the formation of the two gruithuisen domes cannot be well separated by means of crater counts a few stratigraphically older highland units and some mare areas show ages of less than 2 0 gyr but these are less reliable due to 1 the crater distributions being close to saturation 2 less effective crater retention on slopes and 3 erosional removal of craters

climate an exceptionally long interglacial ahead today9s comparatively warm climate has been the exception more than the rule during the last 500 000 years or more if recent warm periods or interglacials are a guide then we may soon slip into another glacial period but berger and loutre argue in their perspective that with or without human perturbations the current warm climate may last another 50 000 years the reason is a minimum in the eccentricity of earth9s orbit around the sun

interglacials of the last 800 000 years interglacials including the present holocene period are warm low land ice extent high sea level end members of glacial cycles based on a sea level definition we identify eleven interglacials in the last 800 000 years a result that is robust to alternative definitions data compilations suggest that despite spatial heterogeneity marine isotope stages mis 5e last interglacial and 11c 400 ka ago were globally strong warm while mis 13a 500 ka ago was cool at many locations a step change in strength of interglacials at 450 ka is apparent only in atmospheric co2 and in antarctic and deep ocean temperature the onset of an interglacial glacial termination seems to require a reducing precession parameter increasing northern hemisphere summer insolation but this condition alone is insufficient terminations involve rapid nonlinear reactions of ice volume co2 and temperature to external astronomical forcing the precise timing of events may be modulated by millennial scale climate change that can lead to a contrasting timing of maximum interglacial intensity in each hemisphere a variety of temporal trends is observed such that maxima in the main records are observed either early or late in different interglacials the end of an interglacial glacial inception is a slower process involving a global sequence of changes interglacials have been typically 10 30 ka long the combination of minimal reduction in northern summer insolation over the next few orbital cycles owing to low eccentricity and high atmospheric greenhouse gas concentrations implies that the next glacial inception is many tens of millennia in the future

centennial scale vegetation dynamics and climate variability in se europe during marine isotope stage 11 based on a pollen record from lake ohrid abstract to better understand climate variability during marine isotope stage mis 11 we here present a new centennial scale resolution pollen record from lake ohrid balkan peninsula derived from sediment cores retrieved during an international continental scientific drilling program icdp campaign our palynological data augmented by quantitative pollen based climate reconstructions provide insight into the vegetation dynamics and thus also climate variability in se europe during one of the best orbital analogues for the holocene comparison of our palynological results with other proxy data from lake ohrid as well as with regional and global climate records shows that the vegetation in se europe responded sensitively both to long and short term climate change during mis 11 the chronology of our palynological record is based on orbital tuning and is further supported by the detection of a new tephra from the vico volcano central italy dated to 410 2 ka our study indicates that mis 11c 424 398 ka was the warmest interval of mis 11 the younger part of the interglacial i e mis 11b 11a 398 367 ka exhibits a gradual cooling trend passing over into mis 10 it is characterized by considerable millennial scale variability as inferred by six abrupt forest contraction events interestingly the first forest contraction occurred during full interglacial conditions of mis 11c this event lasted for 1 7 kyrs 406 2 404 5 ka and was characterized by substantial reductions in winter temperature and annual precipitation most notably it occurred 7 ka before the end of mis 11c and 15 ka before the first strong ice rafted debris event in the north atlantic our findings suggest that millennial scale climate variability during mis 11 was established in southern europe already during mis 11c which is earlier than in the north atlantic where it is registered only from mis 11b onwards

orbital and millennial antarctic climate variability over the past 800 000 years a high resolution deuterium profile is now available along the entire european project for ice coring in antarctica dome c ice core extending this climate record back to marine isotope stage 20 2 800 000 years ago experiments performed with an atmospheric general circulation model including water isotopes support its temperature interpretation we assessed the general correspondence between dansgaard oeschger events and their smoothed antarctic counterparts for this dome c record which reveals the presence of such features with similar amplitudes during previous glacial periods we suggest that the interplay between obliquity and precession accounts for the variable intensity of interglacial periods in ice core records

sea level rise due to polar ice sheet mass loss during past warm periods background although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level gmsl rise over the last century mass loss from the greenland and antarctic ice sheets is expected to exceed other contributions to gmsl rise under future warming to better constrain polarice sheetresponse to warmer temperatures we draw on evidence from in terglacial periods in the geologic record that ex perienced warmer polar temperatures and higher gmsls than present coastal records of sea level from these previous warm periods dem onstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales inferring gmsl and ice volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models advances interdisciplinary studies of geo logic archives have ushered in a new era of deciphering magnitudes rates and sources of sea level rise advances in our understanding of polar ice sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea level reconstructions better ice sheet constraints and the recognition that several geophysical processes cause spatially complex patterns in sea level in particular accounting for glacial isostatic processes helps to decipher spatial variability in coastal sea level records and has reconciled a number of site specific sea level reconstructions for warm periods that have oc curred within the past several hundred thou sand years this enables us to infer that during recent interglacial periods small increases in

ice age terminations 230th dated oxygen isotope records of stalagmites from sanbao cave china characterize asian monsoon am precipitation through the ends of the third and fourthmost recent ice ages as a result am records for the past four glacial terminations can now be precisely correlated with those from ice cores and marine sediments establishing the timing and sequence of major events in all four cases observations are consistent with a classic northern hemisphere summer insolation intensity trigger for an initial retreat of northern ice sheets meltwater and icebergs entering the north atlantic alter oceanic and atmospheric circulation and associated fluxes of heat and carbon causing increases in atmospheric co2 and antarctic temperatures that drive the termination in the southern hemisphere increasing co2 and summer insolation drive recession of northern ice sheets with probable positive feedbacks between sea level and co2

anomalously weak labrador sea convection and atlantic overturning during the past 150 years the atlantic meridional overturning circulation amoc is a system of ocean currents that has an essential role in earth s climate redistributing heat and influencing the carbon cycle1 2 the amoc has been shown to be weakening in recent years 1 this decline may reflect decadal scale variability in convection in the labrador sea but short observational datasets preclude a longer term perspective on the modern state and variability of labrador sea convection and the amoc1 3 5 here we provide several lines of palaeo oceanographic evidence that labrador sea deep convection and the amoc have been anomalously weak over the past 150 years or so since the end of the little ice age lia approximately ad 1850 compared with the preceding 1 500 years our palaeoclimate reconstructions indicate that the transition occurred either as a predominantly abrupt shift towards the end of the lia or as a more gradual continued decline over the past 150 years this ambiguity probably arises from non amoc influences on the various proxies or from the different sensitivities of these proxies to individual components of the amoc we suggest that enhanced freshwater fluxes from the arctic and nordic seas towards the end of the lia sourced from melting glaciers and thickened sea ice that developed earlier in the lia weakened labrador sea convection and the amoc the lack of a subsequent recovery may have resulted from hysteresis or from twentieth century melting of the greenland ice sheet 6 our results suggest that recent decadal variability in labrador sea convection and the amoc has occurred during an atypical weak background state future work should aim to constrain the roles of internal climate variability and early anthropogenic forcing in the amoc weakening described here

silicic lunar volcanism testing the crustal melting model lunar silicic rocks were first identified by granitic fragments found in samples brought to earth by the apollo missions followed by the discovery of silicic domes on the lunar surface through remote sensing although these silicic lithologies are thought to make up a small portion of the lunar crust their presence indicates that lunar crustal evolution is more complex than originally thought models currently used to describe the formation of silicic lithologies on the moon include in situ differentiation of a magma magma differentiation with silicate liquid immiscibility and partial melting of the crust this study focuses on testing a crustal melting model through partial melting experiments on compositions representing lithologies spatially associated with the silicic domes the experiments were guided by the results of modeling melting temperatures and residual melt compositions of possible protoliths for lunar silicic rocks using the thermodynamic modeling software rhyolite melts rhyolite melts simulations predict liquidus temperatures of 950 1040 c for lunar granites under anhydrous conditions which guided the temperature range for the experiments monzogabbro alkali gabbronorite and kreep basalt were identified as potential protoliths due to their ages locations on the moon i e located near observed silicic domes chemically evolved compositions and the results from rhyolite melts modeling partial melting experiments using mixtures of reagent grade oxide powders representing bulk rock compositions of these rock types were carried out at atmospheric pressure over the temperature range of 900 1100 c because all lunar granite samples and remotely sensed domes have an elevated abundance of th some of the mixtures were doped with th to observe its partitioning behavior run products show that at temperatures of 1050 and 1100 c melts of the three protoliths are not silicic in nature i e they have 63 wt sio2 by 1000 c melts of both monzogabbro and alkali gabbronorite approach the composition of granite but are also characterized by immiscible si rich and fe rich liquids furthermore th strongly partitions into the fe rich and not the si rich glass in all experimental runs our work provides important constraints on the mechanism of silicic melt formation on the moon the observed high th content of lunar granite is difficult to explain by silicate liquid immiscibility because through this process th is not fractionated into the si rich phase results of our experiments and modeling suggests that silicic lunar rocks could be produced from monzogabbro and alkali gabbronorite protoliths by partial melting at t 1000 c additionally we speculate that at higher pressures p 0 005 gpa the observed immiscibility in the partial melting experiments would be suppressed

variability of surface water characteristics and heinrich like events in the pleistocene midlatitude north atlantic ocean biomarker and xrd records from iodp site u1313 mis 16 9 1 a reconstruction of milankovitch to millennial scale variability of sea surface temperature sst and sea surface productivity in the pleistocene midlatitude north atlantic ocean marine isotope stage mis 16 9 and its relationship to ice sheet instability was carried out on sediments from integrated ocean drilling program iodp site u1313 this reconstruction is based on alkenone and n alkane concentrations u37k index total organic carbon toc and carbonate contents x ray diffraction data magnetic susceptibility and accumulation rates increased input of ice rafted debris occurred during mis 16 12 and 10 characterized by high concentrations of dolomite quartz and feldspars and elevated accumulation rates of terrigenous matter minimum input values of terrigenous matter on the other hand were determined for mis 13 and 11 peak values of dolomite coinciding with quartz plagioclase and kalifeldspar peaks and maxima in long chain n alkanes indicative for land plants are interpreted as heinrich like events related to sudden instability of the laurentide ice sheet during early and late deglacial phases of the glacials the coincidence of increased toc values with elevated absolute concentrations of alkenones suggests increased glacial productivity probably due to a more southern position of the polar front alkenone based sst reached absolute maxima of about 19 c during mis 11 3 and absolute minima of 10 c during mis 12 and 10 within mis 11 prominent cooling events mis 11 22 and 11 24 occurred the absolute sst minima recorded directly before and after the glacial maxima mis 10 2 and 12 2 are related to heinrich like event meltwater pulses as supported by the coincidence of sst minima and maxima in c37 4 alkenones and dolomite these sudden meltwater pulses especially during terminations iv and v probably caused a collapse of phytoplankton productivity as indicated by the distinct drop in alkenone concentrations ice sheet disintegration and subsequent surges and outbursts of icebergs and meltwater discharge may have been triggered by increased insolation in the northern high latitudes

orbital forcing of continental climate during the pleistocene a complete astronomically tuned climatic record from lake baikal se siberia abstract a new composite bdp 96 biogenic silica record over the entire pleistocene was generated by splicing bdp 96 1 and bdp 96 2 drill cores from lake baikal crosschecked against a similar record from a nearby bdp 98 drill core a new astronomically tuned age model is proposed based on correlating peak biogenic silica responses with the timing of september perihelia this target is derived from analysis of regional climate proxy responses during the holocene the last interglacial and around paleomagnetic reversals by resolving virtually every precessional cycle during the pleistocene the new age model represents a major improvement compared with previously reported lake baikal timescales the astronomically tuned ages of the pleistocene paleomagnetic reversals are consistent with published dates the minimal tuning approach we used precession only has also aligned high signal power in a narrow obliquity band confirming the strong presence of orbital forcing there are also strong ca 100 ka scale cycles but these are not aligned with the orbital eccentricity despite the location of lake baikal in a continental interior that is highly sensitive to insolation forcing the tuned biogenic silica record reveals a consistent phase difference of 32 ca 4 ka relative to insolation in the obliquity band an inherent lag embedded in a continental proxy record not driven by global ice volume is an intriguing finding another new observation is that long term changes in sedimentation rates in lake baikal appear to be related to the amplitude of orbital forcing both amplitudes and sedimentation rates undergo significant changes during mis 24 mis 19 interval corresponding to the middle pleistocene transition with potential for linking continental and marine climato stratigraphies the new baikal record serves a new benchmark correlation target in continental eurasia as an alternative to june 65 n insolation and odp correlated timescales

the lunar gruithuisen silicic extrusive domes topographic configuration morphology ages and internal structure abstract the gruithuisen domes situated on the western portion of the imbrium basin rim form three tall mountains nw gamma delta totaling 780 km3 in volume the shapes of the domes are significantly different from that of mare type domes elsewhere on the moon we use data from the lunar reconnaissance orbiter lro and kaguya missions lro lunar orbiter laser altimeter lunar reconnaissance orbiter camera diviner and the kaguya imager to characterize the domes and assess models for their origin the configuration of the domes steep slopes up to 18 20 and their specific remote sensing characteristics strong downturn in the uv and results from the m3 and diviner instruments suggest that the domes formed by eruptions of highly viscous lava the estimated surface volumes of the domes vary from 20 km3 nw dome to 290 km3 gamma dome to 470 km3 delta dome the domes occur on the portion of the imbrium basin rim that is overlain by ejecta from the post imbrium iridum crater in some areas relatively high albedo smooth volcanic plains are seen within the iridum ejecta near the gruithuisen domes and low albedo mare deposits surround and embay the domes and iridum crater dating of different units and features by crater counts indicates that impact melts from the iridum basin are 3 9 ga old the domes gamma and delta are 3 8 ga and the ages of the plains near the domes vary from 2 3 to 3 6 ga a fresh impact crater exposes the internal structure of the gamma dome the most prominent features on the wall of the crater are rough blocky layers that are typical of volcanic plains in the highlands and maria around the domes the layers are interleaved with fine grained materials of higher and lower albedo and the visible orientation of the layers changes over short a few hundred meters distances these characteristics of the internal structure of the dome are consistent with eruptions of high viscosity lava rough layers that alternated with possible explosive activity fine grained materials the spatial association of the gruithuisen domes with the highland lava plains resembles the situation in which bimodal volcanism occur on earth the terrestrial association can be due to either fractional crystallization in basaltic magma reservoirs or remelting of high silica crustal materials in the first case the evolved melts appear in later stages of volcanic activity and in the second case these melts are formed near the beginning of evolution of the magmatic systems the age estimates of the gruithuisen domes and the surrounding volcanic plains are more consistent with the crustal remelting scenario however remelting of primary anorthositic crust cannot readily produce the silica rich melts and requires the presence of pre existing granite like materials formation of the domes by fractional crystallization avoids this difficulty but requires explanation of the older age of the domes relative to the volcanic plains in the surroundings a third option is that the domes are unrelated genetically to the mare deposits

the asian monsoon over the past 640 000 years and ice age terminations oxygen isotope records from chinese caves characterize changes in both the asian monsoon and global climate here using our new speleothem data we extend the chinese record to cover the full uranium thorium dating range that is the past 640 000 years the record s length and temporal precision allow us to test the idea that insolation changes caused by the earth s precession drove the terminations of each of the last seven ice ages as well as the millennia long intervals of reduced monsoon rainfall associated with each of the terminations on the basis of our record s timing the terminations are separated by four or five precession cycles supporting the idea that the 100 000 year ice age cycle is an average of discrete numbers of precession cycles furthermore the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands and is nearly in anti phase with summer boreal insolation these observations indicate that insolation in part sets the pace of the occurrence of millennial scale events including those associated with terminations and unfinished terminations records of the asian monsoon have been extended to 640 000 years ago and confirm both that the 100 000 year ice age cycle results from integral numbers of precessional cycles and that insolation influences the pacing of major millennial scale climate events prior records of the asian monsoon have revealed cyclic variations over hundreds of thousands of years probably driven by variations in insolation caused by the precession of earth s orbit hai cheng and colleagues now provide a speleothem record from chinese cave samples that extends earlier records to 640 000 years ago close to the maximum age possible with uranium thorium dating this spectacular record confirms that the characteristic 100 000 year ice age cycle corresponds to an integral number four or five of precession cycles and that insolation influences millennial scale variations in monsoon strength

reconstructing the western boundary variability of the western pacific subtropical high over the past 200 years via chinese cave oxygen isotope records cave oxygen isotope 18o records have been important in characterizing asian monsoon variations on a wide range of timescales the climatic significance of the 18o proxy of the cave records and its main control factors however remain hotly debated especially with respect to annual to decadal timescales in particular while the spatial and intensity variations of the western pacific subtropical high wpsh affects the east asian monsoon remarkably on annual to decadal timescales cave records up to present do not show clear evidence of the wpsh signal here we report a new high resolution average of 1 5 months 18o record from dongshiya cave qinling mountain central china the region is highly sensitive to variations in the position of the wpsh western boundary which in turn regulates the alternation of dominant moisture sources between the proximal pacific ocean and the remote indian ocean together with another cave record near the wpsh western boundary we established a new index to reconstruct variations of the wpsh western boundary over the past 200 years our new data revealed two significant periodicities 12 and 2 7 years respectively that can be causally linked to solar and enso variances correspondingly

stress and displacement distributions around pyrite grains abstract photomicrographs from two sulfide mineralized areas in scandinavia show fragments of pyrite in a relatively homogeneous ground mass at the extremities of the fragments quartz segregations are common in order to understand the stress and displacement in the development of these mineral segregations the finite element method has been used models have been constructed in order to simulate angular fragments or crystals in an incompetent ground mass which have been subjected to a differential pressure several models have been deformed iteratively simulating viscous behaviour the results indicate that the magnitude of deformation depends on the viscosity contrast the magnitude of external pressure and the orientation of the inclusion the stress distribution is governed by the viscosity contrast and the form of the inclusion the tensile stress areas in the models are comparable to the areas of mineral segregation in the samples

a new greenland ice core chronology for the last glacial termination 1 we present a new common stratigraphic timescale for the north greenland ice core project ngrip and grip ice cores the timescale covers the period 7 9 14 8 kyr before present and includes the bolling allerod younger dryas and early holocene periods we use a combination of new and previously published data the most prominent being new high resolution continuous flow analysis cfa impurity records from the ngrip ice core several investigators have identified and counted annual layers using a multiparameter approach and the maximum counting error is estimated to be up to 2 in the holocene part and about 3 for the older parts these counting error estimates reflect the number of annual layers that were hard to interpret but not a possible bias in the set of rules used for annual layer identification as the grip and ngrip ice cores are not optimal for annual layer counting in the middle and late holocene the timescale is tied to a prominent volcanic event inside the 8 2 kyr cold event recently dated in the dye 3 ice core to 8236 years before a d 2000 b2k with a maximum counting error of 47 years the new timescale dates the younger dryas preboreal transition to 11 703 b2k which is 100 150 years older than according to the present grip and ngrip timescales the age of the transition matches the gisp2 timescale within a few years but viewed over the entire 7 9 14 8 kyr section there are significant differences between the new timescale and the gisp2 timescale the transition from the glacial into the bolling interstadial is dated to 14 692 b2k the presented timescale is a part of a new greenland ice core chronology common to the dye 3 grip and ngrip ice cores named the greenland ice core chronology 2005 gicc05 the annual layer thicknesses are observed to be log normally distributed with good approximation and compared to the early holocene the mean accumulation rates in the younger dryas and bolling periods are found to be 47 2 and 88 2 respectively

lunar mare volcanism stratigraphy eruption conditions and the evolution of secondary crusts abstract lunar mare basalt deposits cover 17 of the lunar surface occur preferentially in topographic lows on the nearside and have a total volume estimated at 1 107 km3 analysis of returned samples and photogeologic and remote sensing studies shows that mare volcanism began prior to the end of heavy bombardment the period of cryptomare formation in pre nectarian times and continued until the copernican period a total duration approaching 3 5 4 ga stratigraphic analyses show that the flux was not constant but peaked in early lunar history during the imbrian period which spans the period 3 85 3 2 ga average volcanic output rate during this peak period was about 10 2 km 3 a very low relative to the present global terrestrial volcanic output rate and comparable to the present local output rates for individual volcanoes such as vesuvius and kilauea hawaii volcanic landforms indicate that many eruptions were of high volume and long duration some eruptions associated with sinuous rules may have lasted of the order of a year and emplaced 103 km3 of lava representing the equivalent in one year of about 70 000 years at the average flux shallow magma chambers were uncommon the nearsidefarside mare deposit asymmetry can be readily explained by differences in crustal thickness magma ascending from the mantle or from a buoyancy trap at the base of the crust should preferentially extrude to the surface on the nearside but should generally stall and cool in dikes in the farside crust extruding only in the deepest basins the occurrence of farside maria within craters whose diameter is generally near to or less than the thickness of the crust may be accounted for by the difference between local and regional compensation dikes that establish pathways to the surface on the nearside should have very high volumes comparable to the volumes associated with many observed flows and sinuous rilles an abundance of dikes should exist in the lower crust of the moon many more than those feeding surface eruptions the upper limit is 37 50 of the crust by volume the presence and abundance of such dike swarms have important implications for the interpretation of the average composition of the lunar crust and the composition of basin and crater ejecta the interplay between thermal contraction and differentiation leads to net cooling and ultimate contraction of the outer portions of the moon resulting in a regional horizontal compressive stress acting on the lunar crust in addition overall cooling and deepening of sources require the production of ever larger volumes of magma in order to reach the surface with time stresses became high enough so that few dikes could open to the surface causing eruptive activity to be severely diminished in the eratosthenian and perhaps to cease in the copernican period lower stress levels are required to terminate eruptive activity on the lunar farside consistent with the imbrian age of the farside maria and the nearside location of the youngest maria lunar mare deposits provide an example of the transition from primary crusts to secondary crusts and illustrate the significance of several factors in the evolution of secondary crusts such as crustal density variations in crustal thickness presence of impact basins state and magnitude of stress in the lithosphere and general thermal evolution these factors are also responsible for the extremely low volcanic flux even during periods of peak extrusion

ages of mare basalts on the lunar nearside the chronology of lunar volcanism is based on radiometric ages determined from apollo and luna landing site samples regional stratigraphic relationships and crater degradation and size frequency distribution data for units largely defined prior to the end of the apollo program here we report on new crater size frequency distribution data for 139 spectrally and morphologically defined basalt units which are exposed in six nearside impact basins australe tranquillitatis humboldtianum humorum serenitatis and imbrium crater size frequency distribution measurements are a statistically robust and accurate method to derive absolute model ages of unsampled regions of the moon compared to crater degradation ages crater size frequency ages performed on spectrally defined units offer significant improvements in accuracy our investigation showed that 1 in the investigated basins lunar volcanism was active for at least 1 5 2 0 b y starting at about 3 9 4 0 b y and ceasing at 2 0 b y 2 most basalts erupted during the late imbrian period at about 3 6 3 8 b y 3 significantly fewer basalts were emplaced during the eratosthenian period 4 basalts of copernican age were not found in any of the investigated basins 5 lunar basin filling volcanism probably started within 100 m y after the formation of the individual basins we also assessed the relationship between impact basin age and the history of mare basalt emplacement in these basins we found that 1 in all pre nectarian basins australe and tranquillitatis as well as in the humboldtianum basin which is of nectarian age the distribution of surface ages is clearly dominated by only a single peak in the number of erupted units at 3 6 3 8 b y 2 in the younger basins humorum serenitatis and imbrium a second peak at 3 3 3 5 b y is observed 3 basalt eruptions younger than 2 6 b y occur only intermittently and 4 in the youngest basins serenitatis and imbrium we see an extended period of active basin filling volcanism 1 5 1 6 b y which is 500 m y longer than in the australe and humorum and even 1 0 b y longer than in tranquillitatis and humboldtianum

structure and origin of holocene cold events abstract the present interglacial the holocene spans the period of the last 11 700 years it has sustained the growth and development of modern society the millennial scale decreasing solar insolation in the northern hemisphere summer lead to northern hemisphere cooling a southern shift of the intertropical convergence zone itcz and a weakening of the northern hemisphere summer monsoon systems on the multidecadal to multicentury scale periods of more stable and warmer climate were interrupted by several cold relapses at least in the northern hemisphere extra tropical area based on carefully selected 10 000 year long time series of temperature and humidity precipitation as well as reconstructions of glacier advances the spatiotemporal pattern of six cold relapses during the last 10 000 years was analysed and presented in form of a holocene climate atlas hoclat see http www oeschger unibe ch research projects holocene atlas a clear cyclicity was not found and the spatiotemporal variability of temperature and humidity precipitation during the six specific cold events 8200 6300 4700 2700 1550 and 550 years bp was very high different dynamical processes such as meltwater flux into the north atlantic low solar activity explosive volcanic eruptions and fluctuations of the thermohaline circulation likely played a major role in addition internal dynamics in the north atlantic and pacific area including their complex interaction were likely involved

geology tectonism and composition of the northwest imbrium region abstract the objective of this study is to explore the regional geology of the northwest imbrium region in which the chang e 3 ce 3 landing site is located ce 3 successfully landed on december 14 2013 on the unsampled eratosthenian basalts whose study is important for understanding the evolution of the moon new geologic and structural maps of the research area were produced through the integrated analysis of diverse datasets the highlands surrounding imbrium differ from typical farside highlands terrain fht the iridum highland region as well as the surrounding imbrium region exhibits elevated concentrations of fe and abundant local exposures of low ca pyroxene and olivine bearing lithologies in this study these highlands are named as mafic highlands mh our dating results using crater size frequency distributions csfds show that the iridum basin hosting sinus iridum was formed 3 8 ga shortly following the imbrium basin formation and before the last large multiringed basin orientale the eratosthenian period of lunar basalt eruptions which lasted longer than other stratigraphic units is suggested to divide into the lower eratosthenian mare lem and upper eratosthenian mare uem units this subdivision is based on whether lava fronts can be clearly seen or not and the age separating the units is 2 35 ga the mafic mineralogy of the mare basalts in imbrium is characterized by abundant olivine in the eratosthenian aged basalts and average pyroxene compositions near pigeonite to sub calcic augite in the imbrian and em1 units the thickness of individual lava for uem units is 8 11 m indicative of high effusion rates the thickness of the em3 unit ranges from 17 m to 45 m with lesser thickness to the west and greater thickness in the interior and to the east the estimated volume and average flux of the eratosthenian aged basalts are greater than previously thought the presence of these youngest basalts in the procellarum kreep terrain pkt is hypothesized to be a causal relationship with the pkt terrain reducing the thickness of the lithosphere and permitting preferential dike emplacement and extrusion there we speculate that high ti and olivine rich composition in late stage basalts may be consistent with low si and high ti and low degrees of partial melting large numbers of sinuous rilles and small ridges are identified and mapped many young ridges were found inside imbrium suggesting a very extended period at least as young as the last 50 ma of the moon s tectonic activity the distinct compositions of both highlands and mare basalts and extended tectonism emphasize how the imbrium basin is an important area for understanding the moon

computer experiments to investigate complex fibre patterns in natural antitaxial strain fringes antitaxial non deforming strain fringes from lourdes france show complex quartz calcite and chlorite fibre patterns that grew around pyrite in a slate during non coaxial progressive deformation development of these fringes was modelled using a computer program fringe growth 2 0 which can simulate incremental growth of crystal fibres around core objects of variable shape it uses object centre paths as input which are obtained from fibre patterns in thin section the numerical experiments produced fibre patterns that show complex intergrowth of displacement controlled face controlled and intermediate fibres similar to those in the natural examples the direction of displacement controlled growth is only dependent on the relative movement between core object and fringe so that core object rotation with respect to the fringe influences the fibre patterns and produces characteristic asymmetric fibre curvature object centre paths should be used for kinematic analysis of strain fringes instead of single fibres since these paths represent the fringe as a whole the length along the path can be interpreted in terms of finite strain and path curvature in terms of rigid body rotation of fringes with respect to an external reference frame

improved chandrayaan 1 m3 data a northwest portion of the aristarchus plateau and contiguous maria abstract we provide and test a method to obtain significant improvement of available chandrayaan 1 m3 data the advance is achieved using the gaussian convolution of spectra and fourier filtration of images the main result is imagery of the reflectance across different wavelengths as well as parameters of 1 m and 2 m absorption bands with unprecedented quality this approach can be particularly useful for further investigations using m3 data since it produces improved imagery of various lunar surface characteristics we studied a region comprising a portion of the aristarchus plateau montes agricola and a small part of the mare surface in ocean procellarum to the north of montes agricola we found that the lava flows in the area between the aristarchus plateau and montes agricola have a chemical mineral composition different in comparison with mare areas to the northwest of the ridge montes agricola we also identified distinct spectral properties of morphologically young craters located on the plateau and mare surface a correlation diagram for positions of the minima of the 1 m and 2 m bands allows a cluster analysis of the region and we map areas associated with a cluster corresponding to pyroclastic glasses relationships between geologic and spectral parameter maps were established

east asian hydroclimate modulated by the position of the westerlies during termination i speleothem oxygen isotope records have revolutionized our understanding of the paleo east asian monsoon yet there is fundamental disagreement on what they represent in terms of the hydroclimate changes we report a multiproxy speleothem record of monsoon evolution during the last deglaciation from the middle yangtze region which indicates a wetter central eastern china during north atlantic cooling episodes despite the oxygen isotopic record suggesting a weaker monsoon we show that this apparent contradiction can be resolved if the changes are interpreted as a lengthening of the meiyu rains and shortened post meiyu stage in accordance with a recent hypothesis model simulations support this interpretation and further reveal the role of the westerlies in communicating the north atlantic influence to the east asian climate

gruithuisen domes region a candidate for an extended nonmare volcanism unit on the moon small lunar areas known as red spots are thought to represent good candidates for nonmare volcanic units predating or contemporaneous with the period of mare volcanism in this study we present imaging telescopic and orbital clementine multispectral surveys of the gruithuisen region located in the northwestern border of mare imbrium which contains imbrian age domical features of likely viscous volcanic origin with spectral characteristics of red spot areas a rather spectrally homogeneous unit having typical characteristics of red spots is found to coincide with the material within the morphological boundaries of the gruithuisen delta gamma and northwest domes an extended dome like unit is identified spectrally and surrounds and extends to the west and the north of the domes this unit shows spectral characteristics close to those of the domes suggesting the presence of a significant amount of dome material extending many kilometers away from the domes themselves both the spectral characteristics of the dome and the dome like unit are clearly different from those of highlands and the surrounding mare basalts the spectral identification of a widespread dome like unit suggests that the specific style of eruption that is inferred for the formation of the domes i e viscous flows of possible more silicic composition might have occurred on a regional scale in this part of the moon prior to the iridum event about 3 8 gyr ago this volcanic style appears to be more widespread in the early part of lunar history than previously thought

lunar red spots stratigraphic sequence and ages of domes and plains in the hansteen and helmet regions on the lunar nearside 1 basaltic mare materials extruded between 4 ga and 1 2 ga ago and formed large expanses on the lunar nearside in contrast to the maria volcanic shields domes and cones also occur but cover only a small area of the total lunar surface one specific type of dome is characterized 1 by steep slopes 2 by a high albedo similar to lunar highlands and 3 by a strong absorption in the ultraviolet because of this latter feature they appear spectrally red and therefore were termed red spots their morphology suggests that these domes were created by much more viscous silica rich lava also red spots which are believed to be possibly volcanic in origin are associated with light plains materials in order to constrain the formation of these presumed volcanic features in context with the formation of the surrounding mare and highland materials we carried out 1 geologic and morphologic mapping of high resolution lunar orbiter iv and apollo 16 frames and 2 measurements of superimposed crater frequencies on geologic units in order to assess stratigraphy and geological history in the following two volcanic provinces in which red spots occur 1 the hansteen region dominated by the dome hansteen also known as the arrowhead and 2 the helmet region dominated by light plains possibly of volcanic origin such as the feature called the helmet and darney and the southern montes riphaeus in the hansteen region the dome hansteen postdates craters billy 3 88 ga and hansteen 3 87 ga but predates most of the mare materials 3 51 ga cratering model ages of the dome range from 3 74 to 3 65 ga placing its major activity as extending into the late imbrian in the helmet region presumed highland volcanism associated with red spots started in the nectarian with darney 3 94 ga cratering model ages measured on the helmet light plains range from 3 8 to 2 08 ga the origin of these light plains and local resurfacing processes in this unit however highland volcanism or impact remains an open question locally younger processes of eratosthenian or even copernican age such as emplacement of mare materials or mass wasting deposits could be dated in the higher resolution apollo 16 frame

lunar gruithuisen and mairan domes rheology and mode of emplacement characteristics of the domes to estimate the yield strengths 10 5 pa plastic viscosities 10 9 pa s and effusion rates 50 m 3 s of the magmas which formed them these values are similar to those of terrestrial rhyolites dacites and basaltic andesites and support the hypothesis that these domes are an unusual variation of typical highlands and mare compositions the dikes which formed them are predicted to have had widths of 50 m and lengths of about 15 km the magma rise speed implied by this geometry is very low 7 10 5 m s and the reynolds number of the motion is 2 10 8 implying a completely laminar flow regime estimates of emplacement duration range from one to several decades these new calculations confirm the unusual nature of these features and support previous qualitative suggestions that they were formed from magmas with significantly higher viscosity than those typical of mare basalts index terms 5480 planetology solid surface planets volcanism 8450 5410 planetology solid surface planets composition 5460 planetology solid surface planets physical properties of materials 8429 volcanology lava rheology and morphology keywords moon volcanism domes

the relationship between radar scattering and surface roughness of lunar volcanic features lunar roughness measurements derived from the lunar orbiter laser altimeter are compared to 12 6 cm wavelength radar data collected by the miniature radio frequency instrument and 70 cm wavelength radar data collected by the arecibo observatory these data are compared to assess how surface and subsurface roughness are correlated and affected by parameters including age and composition at length scales between 0 1 and 100 m a range of features are analyzed including volcanic domes marius hills rumker hills gruithuisen and mairan domes mare imbrium serenitatis and oceanus procellarum pyroclastic dark mantle deposits sinus aestuum sulpicius gallus and mare vaporum and two young craters copernicus and tycho statistically significant positive correlations exist between topographic roughness and both p and s band circular polarization ratios the strongest correlation is observed at the longest length scales correlations weaken as length scales become less similar potentially due to distinct processes controlling surface modification roughness is not significantly correlated with local slope although the marius hills are compositionally distinct from the gruithuisen and mairan domes they are indistinguishable in roughness characteristics conversely the rumker hills mare and dark mantle deposits are smoother at the length scales examined possibly due to fine grained mantling of regolith or pyroclastic deposits the floor and ejecta of tycho are the roughest surfaces measured in this study while the floor and ejecta of copernicus overlap the roughness distribution of the volcanic features this study shows that many factors control the evolution of roughness over time on various length scales

applications of stalagmite laminae to paleoclimate reconstructions comparison with dendrochronology climatology abstract laminated stalagmites observed in either ultra violet or visible light or recognized via trace elements are now widely recognized as a common deposition form annually laminated stalagmites should be expected in caves which have an overlying climate that has a strong seasonality similar climate zones to where trees grow with distinct annual rings continuous laminated stalagmite chronologies up to several thousand years should be expected where some mixing of stored water occurs such stalagmites can be used to reconstruct climate particularly through variations in lamina width such climate records would be relatively damped by mixing of event water with stored groundwater constraining the amount of high frequency climate signals contained in the stalagmite but relatively long continuous lamina sequences permit the preservation of low frequency centennial scale climate signals this contrasts with numerous tree ring climate records which are frequently limited in preserving multi centennial trends due to the necessary removal of age related noise from relatively short tree segments laminated stalagmites and tree rings should therefore to some degree provide complementary climate information appropriate methods for compiling stalagmite layer chronologies and climatologies are presented

kinematics of crystal growth in syntectonic fibrous veins abstract detailed observations of a set of fibrous antitaxial calcite veins in a slate reveal that some of the calcite fibres do not connect material markers on both sides of the vein and can therefore not have tracked the full opening trajectory during vein growth this calls for a better understanding of the mechanisms of fibre formation and reliable criteria to test the tracking hypothesis based on surface roughness characteristics of the vein wall we develop a simple model for shape growth of crystals in a crack seal environment which can account for both tracking and non tracking behaviours and propose a set of tracking criteria for antitaxial veins finally we discuss ways by which the model can be tested against natural examples

a high resolution absolute dated late pleistocene monsoon record from hulu cave china oxygen isotope records of five stalagmites from hulu cave near nanjing bear a remarkable resemblance to oxygen isotope records from greenland ice cores suggesting that east asian monsoon intensity changed in concert with greenland temperature between 11 000 and 75 000 years before the present yr b p between 11 000 and 30 000 yr b p the timing of changes in the monsoon as established with 230th dates generally agrees with the timing of temperature changes from the greenland ice sheet project two gisp2 core which supports gisp2 s chronology in this interval our record links north atlantic climate with the meridional transport of heat and moisture from the warmest part of the ocean where the summer east asian monsoon originates

a high resolution absolute dated holocene and deglacial asian monsoon record from dongge cave china abstract we present a continuous record of the asian monsoon over the last 16 ka from 18o measurements of stalagmite calcite over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230th dates 18o and therefore asian monsoon intensity generally follows changes in insolation although changes in 18o are generally accommodated in abrupt shifts in contrast to smoothly varying insolation indicating that threshold effects may be important 18o decreased dramatically 3 at the start of the holocene 11 5 ka and remained low for 6 ka four positive 18o events centered at 11225 97 yr bp 1 05 10880 117 yr bp 1 15 9165 75 yr bp 1 4 and a double event centered at 8260 64 yr bp 1 1 and 8080 74 yr bp 1 0 punctuated this period of high monsoon intensity all four events correlate within error with climate changes in greenland ice cores thus the relationship between the asian monsoon and the north atlantic observed during the glacial period appears to continue into the early holocene in addition three of the four events correlate within error with outburst events from lake agassiz the decline of monsoon intensity in the mid late holocene is characterized by an abrupt positive shift in 18o which occurs at 3550 59 yr bp 1 1 in 100 yr in addition the holocene is punctuated by numerous centennial and multi decadal scale events amplitudes 0 5 to 1 up to half the amplitude of the glacial interstadial events seen in the last glacial period thus holocene centennial and multi decadal scale monsoon variability is significant although not as large as glacial millennial scale variability the monsoon shows a strong connection with northern south american hydrological changes related by changes in itcz position spectral analysis of the 18o record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing however there are numerous other significant peaks including peaks at el nino frequencies observed for high resolution portions of the record between 8110 and 8250 yr which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling holocene monsoon climate in addition for this high resolution portion we observe a distinctive biennial oscillation of the asian monsoon which has been associated with the tropospheric biennial oscillation tbo

the pyrite type strain fringes from lourdes france indicators of alpine thrust kinematics in the pyrenees a new method is developed to reconstruct polyphase deformation histories from pyrite grains with displacement controlled fibrous strain fringes it decomposes the relative displacement between a pyrite grain and a fringe into incremental rotations and pull apart directions application to a classic specimen from lourdes france shows that the rotations determine the fibre curvature sense and strongly depend on local strain parameters as well as the initial orientation and shape of pyrite grains in contrast pull apart directions appear to be relatively constant and straight although curved pull apart trajectories were expected from the heterogeneous non coaxial deformation in the matrix the discrepancy is due to the localization of shear strain components around pyrite fringe complexes the complexes themselves represent ellipsoidal domains of relatively coaxial strain that parallel a regional crenulation cleavage even in zones lacking this cleavage due to stretching and shearing of a pre existing foliation s1 thus strain fringes consistently record bulk shortening orientations regardless of local variations in strain parameters and microstructural development the analysed pyrite fringe complexes from lourdes were previously considered as classic shear sense indicators but yield hook shaped pull apart trajectories in the new method this indicates two deformation events that can be related to a sub horizontal s2 and steep regional crenulation cleavage s3 the recorded polyphase deformation history is tentatively interpreted in terms of a change from gravitational spreading to a compressive emplacement of a thrust sheet in the north pyrenean foreland

timing and structure of the 8 2 kyr b p event inferred from δ18o records of stalagmites from china oman and brazil oxygen isotope records of stalagmites from china and oman reveal a weak summer monsoon event with a double plunging structure that started 8 21 0 02 kyr b p an identical but antiphased pattern is also evident in two stalagmite records from eastern brazil indicating that the south american summer monsoon was intensifi ed during the 8 2 kyr b p event these records demonstrate that the event was of global extent and synchronous within dating errors of 50 years in comparison with recent model simulations it is plausible that the 8 2 kyr b p event can be tied in changes of the atlantic meridional overturning circulation triggered by a glacial lake draining event this in turn affected north atlantic climate and latitudinal position of the intertropical convergence zone resulting in the observed low latitude monsoonal precipitation patterns

delayed build up of arctic ice sheets during 400 000 year minima in insolation variability an east asian winter monsoon proxy record using grain size variations in chinese loess over the past 900 000 years shows that for up to 20 000 years after the interglacials at 400 000 year intervals the weak monsoon winds maintain a mild non glacial climate at high northern latitudes qingzhen hao and colleagues present a record of grain size variations in the chinese loess plateau a proxy of variations in the strength of the east asian winter monsoon and show that relatively high insolation at 400 000 year intervals held off the inception of the subsequent ice age for about 20 000 years relative to other glacial inceptions mechanistically the extension of warm conditions was probably linked to a weak siberian high pressure system associated with a delayed build up of northern ice and snow the authors speculate that these observations imply that arctic climate may remain in non glacial mode for more than 40 000 years even in the absence of anthropogenic greenhouse gases knowledge of the past variability of climate at high northern latitudes during astronomical analogues of the present interglacial1 may help to inform our understanding of future climate change unfortunately long term continuous records of ice sheet variability in the northern hemisphere only are scarce because records of benthic 18o content represent an integrated signal of changes in ice volume in both polar regions2 however variations in northern hemisphere ice sheets influence the siberian high3 an atmospheric pressure system so variations in the east asian winter monsoon eawm as recorded in the aeolian dust deposits on the chinese loess plateau can serve as a useful proxy of arctic climate variability before the ice core record begins here we present an eawm proxy record using grain size variations in two parallel loess sections representative of sequences across the whole of the chinese loess plateau over the past 900 000 years the results show that during periods of low eccentricity and precessional variability at approximately 400 000 year intervals the grain size inferred intensity of the eawm remains weak for up to 20 000 years after the end of the interglacial episode of high summer monsoon activity and strong pedogenesis in contrast there is a rapid increase in the eawm after the end of most other interglacials we conclude that for both the 400 000 year interglacials the weak eawm winds maintain a mild non glacial climate at high northern latitudes for much longer than expected from the conventional loess and marine oxygen isotope records during these times the less severe summer insolation minima at 65 n ref 4 would have suppressed ice and snow accumulation leading to a weak siberian high and consequently weak eawm winds

orientation history and rheology in slates kodiak and afognak islands alaska abstract theoretical and experimental studies have shown that slates have a roughly parabolic yield curve in and space where is the orientation of cleavage relative to the maximum compressive stress is the orientation of cleavage relative to the incremental shortening direction and is the deviatoric stress deformation mechanisms that operate in low grade rocks such as diffusive mass transfer in a grain boundary fluid dislocation creep and frictional grain boundary sliding may have stress strain rate relationships that depend on during a progressive strain history and may vary as a function of the strain path thus the sequence of dominant deformation mechanisms as well as the stress strain history may depend on the orientation history or variations in as strain accumulates in the kodiak formation a slate belt in southwest alaska the orientation history and deformation mechanisms were evaluated using incremental strain indicators and microstructures there are four successive textural events 1 development of a slaty cleavage s2 with antitaxial growth of fibrous quartz and mica in pressure shadows fi2 2 static growth of siderite and chlorite porphyroblasts 3 10 70 rotation of porphyroblasts relative to s2 with growth of curved syntaxial siderite fibers and 4 antitaxial growth of fibrous quartz and micas with local development of a crenulation cleavage s3 cumulative incremental strain and progressive finite strain histories were determined in 23 samples from syntectonic fibers and orientation histories were reconstructed from information provided by cumulative incremental strain histories textural and strain analyses indicate that 1 the strain history of nearly all samples can be approximated by two coaxial strain accumulations separated by a rigid rotation 2 development of crenulation cleavages was dependent on the orientation history and the magnitude of the early strain accumulation i e the degree of mica alignment at the completion of d2 3 unstable behavior or buckling occurred when suggesting that the angle of internal friction was close to 0 i e basal slip in micas may have been more important than frictional grain boundary sliding and 4 diffusive mass transfer was accompanied by anisotropic plastic deformation so the orientation history could be used to reconstruct the history

timing and characteristics of the latest mare eruption on the moon unraveling the timing and duration of mare volcanism on the moon is essential for understanding its thermal evolution the end of mare volcanism is poorly constrained because mare basalts are incompletely sampled in this study employing selene kaguya high resolution images we performed new crater size frequency measurements for 49 young mare units 3 0 ga in the procellarum kreep terrane pkt in which the latest magma eruption of the moon occurred mare volcanism in this region continued until 1 5 ga suggesting that volcanic activity in this region ceased 1 0 ga after the magma eruption had globally ceased 2 5 3 0 ga volcanic activity may have peaked 1 8 2 2 ga ago the youngest basalts occur around the aristarchus plateau and the kepler crater which are located in the central region of the pkt it is likely that heating in the crust due to the concentration of heat producing elements in the pkt delayed cooling of a partial melting zone in the underlying mantle in contrast with previous basalt dating in this region our results indicate a higher correlation between ages and spectral types of mare basalts the young mare units in the pkt tend to have spectral types corresponding to high titanium contents while low titanium basalts occur mainly in the early stage the titanium variation in mare basalts may reflect vertical heterogeneity in tio2 content in the upper mantle beneath the pkt

the determination of progressive deformation histories from antitaxial syntectonic crystal fibres abstract antitaxial syntectonic crystal fibres are modelled here as mechanically passive features the fibres representing displacement paths forming within a homogeneously deforming material evidence that many fibres develop in this way is widespread asymptotic curvature thinning of fibres and strained old fibres a measuring technique is proposed by which the complete deformation history excluding translation may be determined the method involves the iterative unstraining of two complete fibres whose development began and ended simultaneously a source of error is introduced by assuming that each of the two fibres developed at constant proportional rates although synthetic examples suggest this error to be minimal it is suggested that the kinematics of non passive fibres are unobtainable since the rheologies and boundary conditions of the material involved are relatively unknown and cannot be determined from geometry alone analysis of natural fibres found within the ordovician slates in new jersey u s a indicates that volume losses of up to 50 may occur during the formation of some slates general constraints concerning the geometrical analysis of syntectonic crystal fibres are briefly discussed and it is concluded that deformation histories must be interpreted with some modicum of caution

sixty year quasi period of the asian monsoon around the last interglacial derived from an annually resolved stalagmite δ18o record abstract the 60 year quasi periodic variability of the asian monsoon in the mid late holocene has been found to be widespread in instrumental and various terrestrial records however whether this period exists in the older interglacial periods remains to be further studied this paper is based on an 1840 mm long stalagmite with clear annual laminae with a growth rate of about 1 mm yr from yongxing cave china that allows for the reconstruction of the asian monsoon evolution sequence during the period 123 20 121 21 kyr bp the stalagmite record closely tracks the 65 n solar insolation changes as a whole indicating the dominant control of solar insolation on the asian summer monsoon after removing the solar insolation signal from the yx108 record the 18o residuals 18o show 28 multidecadal monsoon cycles the average amplitude of these fluctuations is larger than 0 8 with a duration typically ranging from 50 to 80 yr about 64 yr on average which is very similar to the mid late holocene asian monsoon variability further wavelet analysis displays a significant quasi periodicity of 60 years throughout the studied period providing further evidence for assessing whether the 60 year quasi periodic variability of the asian monsoon found in the holocene exists in older periods our study thus suggests that this quasi periodic variability not only occurred during the modern period but also existed in the last interglacial and their influence may even be an intrinsic characteristic of the asian monsoon system during glacial interglacial cycles we manifested that the interactions between solar activity and the atlantic multidecadal oscillation may be the main reason for the 60 year quasi period of the asian monsoon

geology and scientific significance of the rumker region in northern oceanus procellarum china s chang e 5 landing region the rumker region 41 45 n 49 69 w is located in northern oceanus procellarum of the moon mons rumker is the most distinctive geological feature in the area the region is characterized by prolonged lunar volcanism late imbrian period to eratosthenian period forming multiple geologic units in the area including very low ti to low ti mare basalts high ti mare basalts and volcanic complexes each geologic unit has distinct element composition and mineral assemblages the rumker region overlying the procellarum kreep terrain was selected as the landing region for china s chang e 5 lunar sample return mission prelanding analyses of the geologic context and scientific potential are reported in this contribution we conducted detailed geological mapping using image spectral and altimetry data fourteen geological units were defined a geologic map was constructed and the geologic history was outlined the western mare units im1 im2 and im3 are imbrian aged 3 4 3 5 ga representing the major stage of lunar mare eruptive volcanism the eastern young mare units em3 and em4 2 ga are among the youngest mare basalts on the moon they have never been explored in situ or studied in the laboratory we suggest that samples returned from the eastern mare unit em4 could answer many fundamental questions and that this unit should be listed as the top priority landing site for chang e 5 sample return mission

crack seal fibre growth mechanisms and their significance in the development of oriented layer silicate microstructures abstract an analysis of crack seal fibre growth mechanisms has shown two important implications of the crack seal process for the interpretation of microstructures in low grade metamorphic rocks 1 1 the ability of fibre growth to track the incremental separation history of crack walls depends on details of the nucleation and growth mechanisms 2 2 fibrous crystals may develop cristallographic preferred orientations in certain crack seal situations the microstructures of layer silicates and associated phases developed in several examples of syntectonic intragranular microfracture sites and veins indicates that layer silicate 001 and grain shape preferred orientation can develop during crack seal deformation by oriented growth mechanisms during successive crack seal increments preferred orientation may develop in response to an interaction between anisotropic growth kinetics and the displacement history resulting in preferential rejoining by syntaxial overgrowth of pulled apart grains having fast growth directions parallel to the incremental displacement direction across a microcrack preferred orientation may also be developed and enhanced in crack seal growth sites by overgrowth of previously oriented layer silicates in the microcrack walls in this case the crystallographic preferred orientation need not be simply related to the displacement history during crack seal fibre growth since crack seal processes may operate on all scales down to the minimum size of a microfracture in a deforming rock such mechanisms of layer silicate preferred orientation development are expected to be very significant in developing and enhancing foliation during deformation involving microfracture and solution transfer processes

galileo imaging observations of lunar maria and related deposits the galileo spacecraft imaged parts of the western limb and far side of the moon in december 1990 ratios of 0 41 0 56 gin filter images from the solid state hnaging ssi experiment provided information on the titanium content of mare deposits ratios of the 0 76 0 99 gm images indicated 1 gin absorptions associated with fe 2 in mafic minerals mare ages were derived froin crater statistics obtained from lunar orbiter images results on mare coinpositions in western oceanus procellarum and the humorurn basin are consistent with previous earth based observations thus providing confidence in the use of galileo data to extract compositional information mare units in the grimaldi and riccioli basins range in age froin 3 25 to 3 48 ga and consist of medium to medium high titanium 4 to 7 tio2 content lavas the schiller zucchius basin shows a higher 0 76 0 99 gm ratio than the surrounding highlands indicating a potentially higher mafic mineral content consistent with previous interpretations that the area includes mare deposits blanketed by highland ejecta and light plains materials the oldest mare materials in the orientale basin occur in south central mare orientale and are 3 7 ga old youngest mare materials are in lacus autumni and are 2 85 ga old these units are medium to medium high titanium 4 to 7 tio2 basalts thus volcanism was active in orientale for 0 85 ca but lavas were relatively constant in composition galileo data suggest that mendel rydberg mare is similar to mare orientale cryptomare are present as well thus the mare lavas on the western limb and far side to 178oe are remarkably uniform in coinposition being generally of medium to medium high titanium content and having relatively low 0 76 0 99 gin ratios this region of the moon is between two postulated large impact structures the procellarum and the south pole aitken basins and may have a relatively thick crust in areas underlain by an inferred thinner crust i e zones within large basins as at apollo titanium content is often higher however no mare deposits with titanium abundances approaching those of the high titanium 9 to 14 tio2 apollo 11 and 17 basalts nor of the high titanium regions of central oceanus procellarum are seen on the western limb or eastern far side light plains deposits are generally indistinct froin the surrounding highlands in the ssi data and are inferred to be derived primarily from the same material that forins the highlands some of the light plains are too young to be related to basin forming impacts suggesting possible volcanic origin dark mantle deposit compositions derived from ssi data are consistent with earth based observations of similar near side deposits and are interpreted to be pyroclastic materials however the modernitc albedo and 1 gin absorption of the dark mantle deposit on the southwest margin of the orientale basin suggest it is a local pyroclastic deposit contaminated with underlying highland materials from the orientale impact

the mons rumker volcanic complex of the moon a candidate landing site for the chang e 5 mission mons rumker is a large volcanic complex in oceanus procellarum on the moon and is a candidate landing site for china s chang e 5 sample return mission we conducted a comprehensive study of the topography geomorphology composition and stratigraphy of the mons rumker region with multi source remote sensing data in order to better understand the geology of the region and provide further support for the chang e 5 mission the results show that the rumker plateau stands 200 1300 m above the surrounding mare surface and 75 of the plateau has a slope of less than 3 at a baseline length of 30 m domes are the most prominent volcanic landforms in mons rumker and a total of 22 domes were identified and divided into two types that may represent different stages of volcanic activity spectral analyses indicated that mons rumker is covered by low ti basalt and the dominant mafic mineral is high calcium pyroxene though signs of mixing of highland materials and basalt have been found mons rumker has three main basalt units and their absolute model ages are 3 71 ga 3 58 ga and 3 51 ga respectively steep sided domes could be the youngest volcanic features on the plateau with indications that they were active until the eratosthenian a new geologic map of the study region was produced and used to interpret and discuss the geologic evolution of the region finally we propose two candidate landing sites for the chang e 5 mission

glacial interglacial indian summer monsoon dynamics the modern indian summer monsoon ism is characterized by exceptionally strong interhemispheric transport indicating the importance of both northern and southern hemisphere processes driving monsoon variability here we present a high resolution continental record from southwestern china that demonstrates the importance of interhemispheric forcing in driving ism variability at the glacial interglacial time scale as well interglacial ism maxima are dominated by an enhanced indian low associated with global ice volume minima in contrast the glacial ism reaches a minimum and actually begins to increase before global ice volume reaches a maximum we attribute this early strengthening to an increased cross equatorial pressure gradient derived from southern hemisphere high latitude cooling this mechanism explains much of the nonorbital scale variance in the pleistocene ism record