direct determination of the timing of sea level change during termination ii an outcrop within the last interglacial terrace on barbados contains corals that grew during the penultimate deglaciation or termination ii we used combined 230th and231pa dating to determine that they grew 135 8 0 8 thousand years ago indicating that sea level was 18 3 meters below present sea level at the time this suggests that sea level had risen to within 20 of its peak last interglacial value by 136 thousand years ago in conflict with milankovitch theory predictions orbital forcing may have played a role in the deglaciation as may have isostatic adjustments due to large ice sheets other corals in the same outcrop grew during oxygen isotope 18o substage 6e indicating that sea level was 38 5 meters below present sea level about 168 0 thousand years ago when compared to the 18o signal in the benthic v19 30 v19 28 record at that time the coral data extend to the previous glacial cycle the conclusion that deep water temperatures were colder during glacial periods

evidence from u th dating against northern hemisphere forcing of the penultimate deglaciation milankovitch proposed that summer insolation at mid latitudes in the northern hemisphere directly causes the ice age climate cycles1 this would imply that times of ice sheet collapse should correspond to peaks in northern hemisphere june insolation but the penultimate deglaciation has proved controversial because june insolation peaks 127 kyr ago whereas several records of past climate suggest that change may have occurred up to 15 kyr earlier2 3 4 5 6 7 8 there is a clear signature of the penultimate deglaciation in marine oxygen isotope records but dating this event which is significantly before the 14c age range has not been possible here we date the penultimate deglaciation in a record from the bahamas using a new u th isochron technique after the necessary corrections for recoil mobility of 234u and 230th and a small age correction for sediment mixing the midpoint age for the penultimate deglaciation is determined to be 135 2 5 kyr ago this age is consistent with some coral based sea level estimates but it is difficult to reconcile with june northern hemisphere insolation as the trigger for the ice age cycles potential alternative driving mechanisms for the ice age cycles that are consistent with such an early date for the penultimate deglaciation are either the variability of the tropical ocean atmosphere system or changes in atmospheric co2 concentration controlled by a process in the southern hemisphere

mapping the piute mountains california with thermal infrared multispectral scanner tims images thermal infrared multispectral scanner tims data were acquired in 1990 over the piute mountains california to evaluate their usefulness for lithologic mapping in an area of metamorphosed structurally complex igneous and sedimentary rocks the data were calibrated and atmospherically corrected and emissivity variations in the form of alpha residuals were extracted from which color composite images were made there was an excellent visual correlation between the units revealed in the color composite image and the lithologic units mapped in the eastern side of the area it was also possible to correct improve and extend the recent map for example several areas mapped as granodioritic gneiss had tims alpha residual spectra consistent with mafic rocks and were subsequently mapped as amphibolite the presence of a swarm of mafic dikes of which only a few had previously been identified was also revealed the images also showed color variations in granitoid plutons that correlated with compositional variations previously determined by extensive field and geochemical work the western piute mountains is an area that has proven to be especially difficult to map with field and air photographic methods due to heterogeneous nature of certain units and various levels of desert varnish the images permitted the extremely heterogeneous proterozoic schists gneisses and granites to be easily mapped because the small scale compositional variability was averaged to the tims pixel size 12 m 12 m square areal measurements from the images show that the proterozoic rocks in the piute mountains consist of granitoids 50 biotite gneiss 15 pelitic gneiss 15 quartzite 10 and amphibolite 10 tims data can dramatically increase the efficiency and the quality of geologic mapping in well exposed heterogeneous areas with minimal vegetation cover where detailed mapping of lithologic contacts by traditional methods is unusually difficult

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

evidence for obliquity forcing of glacial termination ii variations in the intensity of high latitude northern hemisphere summer insolation driven largely by precession of the equinoxes are widely thought to control the timing of late pleistocene glacial terminations however recently it has been suggested that changes in earth s obliquity may be a more important mechanism we present a new speleothem based north atlantic marine chronology that shows that the penultimate glacial termination termination ii commenced 141 000 2500 years before the present too early to be explained by northern hemisphere summer insolation but consistent with changes in earth s obliquity our record reveals that terminations i and ii are separated by three obliquity cycles and that they started at near identical obliquity phases

potential of sentinel 2 data for alteration extraction in coal bed methane reservoirs abstract this study illustrates the potential of alteration extraction in coal bed methane cbm reservoirs using the recently available sentinel 2 data this study then evaluates the capabilities for mapping the altered minerals and vegetation in the alteration mapping process we separately analyzed the key remote sensing signatures of altered minerals and geobotanical anomalies based on the hydrocarbon micro seepage theory the diagnostic spectral characteristics of irons clays and altered vegetation were concentrated and demonstrated the distribution of hydrocarbon micro seepage in the bare soil region the altered minerals including irons and clays were extracted through band math and principal component analysis pca methods in the vegetation area mapping the diagnostic spectral feature parameters such as the locations and slopes of three feature edges were calculated in addition the mapping accuracy was assessed based on the extraction results of hyperion data through full spectral profile matching method and the x ray diffraction xrd analysis results the results show that 1 compared with band math and pca methods the different extraction methods were suitable for different minerals 2 the extraction results of iron and clay minerals were most accurate 78 33 and 76 67 respectively with xrd analysis 3 the highest rate of change of the feature edge slope was up to 39 with a reference spectrum and 4 the distribution of alteration information was consistent with the hudi coal mining area in jincheng shanxi province the potential geological application of sentinel 2 data was revealed to identify the direction of cbm exploration in a large scale highly efficient convenient and inexpensive way

four climate cycles of recurring deep and surface water destabilizations on the iberian margin centennial climate variability over the last ice age exhibits clear bipolar behavior high resolution analyses of marine sediment cores from the iberian margin trace a number of associated changes simultaneously proxies of sea surface temperature and water mass distribution as well as relative biomarker content demonstrate that this typical north south coupling was pervasive for the cold phases of climate during the past 420 000 years cold episodes after relatively warm and largely ice free periods occurred when the predominance of deep water formation changed from northern to southern sources these results reinforce the connection between rapid climate changes at mediterranean latitudes and century to millennial variability in northern and southern polar regions

expert system based mineral mapping in northern death valley california nevada using the airborne visible infrared imaging spectrometer aviris abstract integrated analysis of imaging spectrometer data and field spectral measurements were used in conjunction with conventional geologic field mapping to characterize bedrock and surficial geology at the northern end of death valley california and nevada a knowledge based expert system was used to automatically produce image maps showing the principal surface mineralogy from airborne visible infrared imaging spectrometer aviris data linear spectral unmixing of the aviris data allowed further determination of relative mineral abundances and identification of mineral assemblages and mixtures the imaging spectrometer data show the spatial distribution of spectrally distinct minerals occurring both as primary rockforming minerals and as alteration and weathering products field spectral measurements were used to verify the mineral maps and field mapping was used to extend the remote sensing results geographically referenced image maps produced from these data form new base maps from which to develop improved understanding of the prosesses of deposition and erosion affecting the present land surface

lithologic mapping in the mountain pass california area using advanced spaceborne thermal emission and reflection radiometer aster data abstract evaluation of an advanced spaceborne thermal emission and reflection radiometer aster image of the mountain pass california area indicates that several important lithologic groups can be mapped in areas with good exposure by using spectral matching techniques the three visible and six near infrared bands which have 15 m and 30 m resolution respectively were calibrated by using in situ measurements of spectral reflectance calcitic rocks were distinguished from dolomitic rocks by using matched filter processing in which image spectra were used as references for selected spectral categories skarn deposits and associated bright coarse marble were mapped in contact metamorphic zones related to intrusion of mesozoic and tertiary granodioritic rocks fe muscovite which is common in these intrusive rocks was distinguished from al muscovite present in granitic gneisses and mesozoic granite quartzose rocks were readily discriminated and carbonate rocks were mapped as a single broad unit through analysis of the 90 m resolution five band surface emissivity data which is produced as a standard product at the eros data center three additional classes resulting from spectral angle mapper processing ranged from 1 a broad granitic rock class 2 to predominately granodioritic rocks and 3 a more mafic class consisting mainly of mafic gneiss amphibolite and variable mixtures of carbonate rocks and silicate rocks

imaging spectroscopy earth and planetary remote sensing with the usgs tetracorder and expert systems 1 imaging spectroscopy is a tool that can be used to spectrally identify and spatially map materials based on their specific chemical bonds spectroscopic analysis requires significantly more sophistication than has been employed in conventional broadband remote sensing analysis we describe a new system that is effective at material identification and mapping a set of algorithms within an expert system decision making framework that we call tetracorder the expertise in the system has been derived from scientific knowledge of spectral identification the expert system rules are implemented in a decision tree where multiple algorithms are applied to spectral analysis additional expert rules and algorithms can be applied based on initial results and more decisions are made until spectral analysis is complete because certain spectral features are indicative of specific chemical bonds in materials the system can accurately identify and map those materials in this paper we describe the framework of the decision making process used for spectral identification describe specific spectral feature analysis algorithms and give examples of what analyses and types of maps are possible with imaging spectroscopy data we also present the expert system rules that describe which diagnostic spectral features are used in the decision making process for a set of spectra of minerals and other common materials we demonstrate the applications of tetracorder to identify and map surface minerals to detect sources of acid rock drainage and to map vegetation species ice melting snow water and water pollution all with one set of expert system rules mineral mapping can aid in geologic mapping and fault detection and can provide a better understanding of weathering mineralization hydrothermal alteration and other geologic processes environmental site assessment such as mapping source areas of acid mine drainage has resulted in the acceleration of site cleanup saving millions of dollars and years in cleanup time imaging spectroscopy data and tetracorder analysis can be used to study both terrestrial and planetary science problems imaging spectroscopy can be used to probe planetary systems including their atmospheres oceans and land surfaces

glacial variability over the last two million years an extended depth derived agemodel continuous obliquity pacing and the pleistocene progression abstract an agemodel not relying upon orbital assumptions is estimated over the last 2 ma using depth in marine sediment cores as a proxy for time agemodel uncertainty averages 10 ka in the early pleistocene 2 1 ma and 7 ka in the late pleistocene 1 ma to the present twelve benthic and five planktic 18 o records are pinned to the agemodel and averaged together to provide a record of glacial variability major deglaciation features are identified over the last 2 ma and a remarkable 33 out of 36 occur when earth s obliquity is anomalously large during the early pleistocene deglaciations occur nearly every obliquity cycle giving a 40 ka timescale while late pleistocene deglaciations more often skip one or two obliquity beats corresponding to 80 or 120 ka glacial cycles which on average give the 100 ka variability this continuous obliquity pacing indicates that the glacial theory can be simplified an explanation for the 100 ka glacial cycles only requires a change in the likelihood of skipping an obliquity cycle rather than new sources of long period variability furthermore changes in glacial variability are not marked by any single transition so much as they exhibit a steady progression over the entire pleistocene the mean variance skewness and timescale associated with the glacial cycles all exhibit an approximately linear trend over the last 2 ma a simple model having an obliquity modulated threshold and only three adjustable parameters is shown to reproduce the trends timing and spectral evolution associated with the pleistocene glacial variability

geometrical and fractal analysis of a three dimensional hydrothermal vein network in a fractured granite abstract a three dimensional study of a fracture network has been performed on a 0 66 m 3 block of fine grained granite from la peyratte deux sevres france the block was sawn in nine parallel plates the fractures associated with altered haloes were mapped for each plate using a photographic method the nine fracture sets were subjected to an analysis of the percolated network based on a measurement of the width of altered haloes developed around fractures hydrothermal alteration is created by circulation of a certain amount of fluid flow in the rock we assume that the alteration zone width is proportional to fluid mass flow the width of alteration zones will give a good idea of the path preferentially followed by fluids the relation between fracture length and width of the alteration zone shows that the total fracture network consists in fact of two sorts the largest fractures surface 0 1 m 2 create a loose and poorly interconnected pattern in the block however they have developed wide alteration zones 3 mm and have then had a great role in fluid conduction they represent only 10 of the fractures but are responsible for 47 of alteration in volume approximately 80 of these fractures with wide alteration zones are oriented in the same direction this main network is linked to a more dense highly interconnected system made of shorter fractures with narrower altered zones fractal analysis has also been performed on pictures of the fracture patterns using the linear cantor s dust method fractal dimension values d indicate an anisotropy of fracture distribution on each plane moreover when the planes are compared to one another in succession variations of d values can be noticed indicating an inhomogeneity in the third dimension the study of such a three dimensional fracture set shows that fluids follow preferential paths within a fracture network and helps the understanding of fracture distribution

automated lithological mapping using airborne hyperspectral thermal infrared data a case study from anchorage island antarctica the thermal infrared portion of the electromagnetic spectrum has considerable potential for mineral and lithological mapping of the most abundant rock forming silicates that do not display diagnostic features at visible and shortwave infrared wavelengths lithological mapping using visible and shortwave infrared hyperspectral data is well developed and established processing chains are available however there is a paucity of such methodologies for hyperspectral thermal infrared data here we present a new fully automated processing chain for deriving lithological maps from hyperspectral thermal infrared data and test its applicability using the first ever airborne hyperspectral thermal data collected in the antarctic a combined airborne hyperspectral survey targeted geological field mapping campaign and detailed mineralogical and geochemical datasets are applied to small test site in west antarctica where the geological relationships are representative of continental margin arcs the challenging environmental conditions and cold temperatures in the antarctic meant that the data have a significantly lower signal to noise ratio than is usually attained from airborne hyperspectral sensors we applied preprocessing techniques to improve the signal to noise ratio and convert the radiance images to ground leaving emissivity following preprocessing we developed and applied a fully automated processing chain to the hyperspectral imagery which consists of the following six steps 1 superpixel segmentation 2 determine the number of endmembers 3 extract endmembers from superpixels 4 apply fully constrained linear unmixing 5 generate a predictive classification map and 6 automatically label the predictive classes to generate a lithological map the results show that the image processing chain was successful despite the low signal to noise ratio of the imagery reconstruction of the hyperspectral image from the endmembers and their fractional abundances yielded a root mean square error of 0 58 the results are encouraging with the thermal imagery allowing clear distinction between granitoid types however the distinction of fine grained intermediate composition dykes is not possible due to the close geochemical similarity with the country rock

southern ocean origin for the resumption of atlantic thermohaline circulation during deglaciation during the two most recent deglaciations the southern hemisphere warmed before greenland at the same time the northern atlantic ocean was exposed to meltwater discharge which is generally assumed to reduce the formation of north atlantic deep water yet during deglaciation the atlantic thermohaline circulation became more vigorous in the transition from a weak glacial to a strong interglacial mode here we use a three dimensional ocean circulation model to investigate the impact of southern ocean warming and the associated sea ice retreat on the atlantic thermohaline circulation we find that a gradual warming in the southern ocean during deglaciation induces an abrupt resumption of the interglacial mode of the thermohaline circulation triggered by increased mass transport into the atlantic ocean via the warm indian ocean and cold pacific ocean water route this effect prevails over the influence of meltwater discharge which would oppose a strengthening of the thermohaline circulation a southern ocean trigger for the transition into an interglacial mode of circulation provides a consistent picture of southern and northern hemispheric climate change at times of deglaciation in agreement with the available proxy records

rapid determination of coalbed methane exploration target region utilizing hyperspectral remote sensing abstract this study reveals the common surface mineral characteristics over coalbed methane cbm enrichment regions from spaceborne hyperion images and the possibility of hyperspectral remote sensing for prospecting coalbed methane exploration target region with an inexpensive large scale rapid and convenient way for this study a typical scheme including bands removal atmospheric correction snr estimation minimum noise fraction mnf pixel purity index ppi and n dimensional visualization was applied on hyperion image in qinshui basin china to accurately extract mineral endmembers the endmember spectra of carbonate and clay mineral were identified based on the diagnostic absorption feature while no endmember of ferrous iron mineral was found the absorption feature parameters of carbonate absorption position and especially asymmetric factor and clay mineral absorption position left and right shoulder positions were quantitatively estimated which showed the endmember spectra of carbonate and clay mineral from hyperspectral images in this paper were correct in addition this study proposed an interesting research direction measuring the asymmetric absorption factor to facilitate the identification of carbonates furthermore spectral angle mapper sam and spectral feature fitting sff were used to map carbonates and clay minerals two assessment methods visual interpretation based on field spectra and x ray diffraction xrd analysis were utilized to evaluate the mapping accuracy which showed total agreements of 84 03 and 72 58 respectively the results in this paper suggested that both carbonates and clay minerals were rich while there was hardly any ferrous iron mineral on the surface of cbm enrichment regions in addition another similar experiment was carried out in ordos basin and also showed similar surface mineral characteristics on cbm enrichment region

the classic marine isotope substage 5e since its identi cation nearly fty years ago marine iso tope stage 5 mis 5 has been placed onto absolute time scaleson the basis of three independent approaches cesare emiliani who set up the isotope stages emiliani 1955 depended onuranium series dating of the sediments a method that today isregarded as not generally capable of yielding useful precisionor accuracy broecker and van donk 1970 pioneered the ap proach of correlating to radiometrically dated marine coral ter races thishasbeenmuchaidedinrecentyearsbyimprovementsin the precision and accuracy of these age determinations thathave owed from the development of thermal ionization massspectrometry tims for uranium series dating edwards

integrating visible near infrared and short wave infrared hyperspectral and multispectral thermal imagery for geological mapping at cuprite nevada this study investigated the potential value of integrating hyperspectral visible near infrared and short wave infrared imagery with multispectral thermal data for geological mapping two coregistered aerial data sets of cuprite nevada were used airborne visible infrared imaging spectrometer aviris hyperspectral data and modis aster airborne simulator master multispectral thermal data four classification methods were each applied to aviris master and a combined set confusion matrices were used to assess the classification accuracy the assessment showed in terms of kappa coefficient that most classification methods applied to the combined data achieved a marked improvement compared to the results using either aviris or master thermal infrared tir data alone spectral angle mapper sam showed the best overall classification performance minimum distance classification had the second best accuracy followed by spectral feature fitting sff and maximum likelihood classification the results of the study showed that sff applied to the combination of aviris with master tir data are especially valuable for identification of silicified alteration and quartzite both of which exhibit distinctive features in the tir region sam showed some advantages over sff in dealing with multispectral tir data obtaining higher accuracy in discriminating low albedo volcanic rocks and limestone which do not have unique distinguishing features in the tir region

palaeoclimatic implications of the growth history and stable isotope delta o 18 and delta c 13 geochemistry of a middle to late pleistocene stalagmite from central western italy the age structure and stable isotope composition of a stalagmite cc i from an upland cave in central western italy were studied to investigate regional response to global climatic changes four growth phases are constrained by 28 thermal ionization and multi collector inductively coupled plasma mass spectrometry th u ages and reveal intermittent deposition through the period between marine isotope stage mis 11 and 3 similar to380 and similar to43 kyr most of the growth took place between similar to380 and similar to280 kyr a period punctuated briefly by a hiatus in deposition through the glacial maximum of mis 10 growth was terminated abruptly at 280 kyr just prior to the mis 8 glacial maximum with a present day chamber temperature of 7 5 degreesc the timing of hiatuses close to these glacial maxima point to freezing conditions at the time no deposition was recorded through the entirety of mis 7 and most of mis 6 whilst two minor growth phases occurred at similar to141 125 and similar to43 kyr growth at 141 kyr indicates temperatures 0 degreesc at a time when mis 6 ice volumes were close to their maximum high stable carbon isotope delta 13 c values similar to2 8parts per thousand to 3 1parts per thousand throughout the stalagmite s growth reflect a persistently low input of biogenic co2 indicating that the steep barren and alpine like recharge area of today ha s been in existence for at least the last similar to380 kyr during mis 9 the lowest delta 13 c values occur well after maximum interglacial conditions suggesting a lag in the development of post glacial soils in this high altitude karst the stable oxygen isotope delta 18 o trends match the main structural features of the major climate proxy records specmap vostok and devils hole suggesting that the delta 18 o of cc1 has responded to global scale climate changes whilst remarkable similarity exists between cc1 delta 18 o and regional sea surface temperature reconstructions from north atlantic core odp980 and southwest pacific marine core md97 2120 through the most detailed part of the cc1 record mis 9 8 the results suggest that cc1 and other stalagmites from the cave have the potential to capture a long record of regional temperature trends particularly in regards to the relative severity of pleistocene glacial stages c 2004 elsevier b v all rights reserved

abrupt temperature changes in the western mediterranean over the past 250 000 years a continuous high resolution western mediterranean sea surface temperature sst alkenone record spanning the past 250 000 years shows that abrupt changes were more common at warming than at cooling during marine isotope stage mis 6 sst oscillated following a stadial interstadial pattern but at lower intensities and rates of change than in the dansgaard oeschger events of mis 3 some of the most prominent events occurred over miss 5 and 7 after prolonged warm periods of high stability climate during the whole period was predominantly maintained in interglacial interstadial conditions whereas the duration of stadials was much shorter

mapping white mica alteration associated with the jiama porphyry skarn cu deposit central tibet using field swir spectrometry abstract field measurement of the short wave infrared swir reflectance from drill hole samples proved to be an effective method to map variations in white mica composition tschermak substitution associated with hydrothermal alteration zonation of the jiama porphyry skarn cu deposit tibetan plateau china this swir mineral spectral information provides geological insights into a the possible nature of the related magmatic intrusions b the physicochemistry of the associated hydrothermal fluids c the interactions between these fluids and country rocks and d potential vectors to economic mineralization the results suggest that the al oh band wavelength of white mica can used as an indicator in the subsequent steps of prospecting

stalagmite evidence for the precise timing of north atlantic cold events during the early last glacial evidence of millennial scale cold events following the last interglacial are well preserved in north atlantic marine cores greenland ice and pollen records from europe however their timing was previously undetermined by radiometric dating we report the first precise radiometric ages for two such events c23 105 1 0 9 ka to 102 6 0 8 ka and c24 112 0 0 8 ka and 108 8 1 0 ka based on stable carbon and oxygen isotope measurements on a stalagmite from italy cc28 in addition to providing new information on the duration of these events in southern europe the age data provide invaluable tuning points for the melisey i c24 and montaigu c23 pollen zones identified in western europe the former event is of particular significance because it represents the end of the eemian interglacial forest phase in western europe the new age data will also allow fine tuning of the timing and duration of greenland stadial 24 equivalent to c23 in the north greenland ice core project ice core and via a common gasage chronology tuning of the vostok and epica european project for ice coring in antarctica ice cores

deconstructing terminations i and ii revisiting the glacioeustatic paradigm based on deep water temperature estimates benthic and planktonic oxygen isotope 18occ and mg ca analyses in two cores from the northeast atlantic have permitted the reconstruction of surface and deep water temperature tdw and 18o 18ow variations across the last two deglaciations these records allow the timing of de glacial melt water pulses reaching the northeast atlantic to be compared with the evolution of local deep water tdw 18ow conditions although each glacial termination is unique in detail a similar pattern of hydrographic change is reconstructed for both deglaciations with the first major decrease in deep water 18ow due to sea level and or purely local deep water change occurring in parallel with the onset of intensely cold glacial surface water temperatures and prior to a terminal ice rafting and melt water event the evolution of deep water across both de glaciations involved two transient incursions of cold low 18o water into the deep northeast atlantic the second of which was particularly pronounced each time these pulses of cold deep water are interpreted to reflect the incursion of water directly analogous to modern antarctic bottom water aabw and containing a significant component of brine rejected during sea ice formation the results presented here show that the same type of transient changes in deep water circulation that occurred across termination i also occurred across termination ii and that as a result of these deep ocean changes the timing of each benthic 18o termination cannot precisely reflect the timing of de glacial sea level change as many palaeoceanographic interpretations and some controversies are prone to assume such imprecision in timing especially may well extend to marine isotope stage mis boundaries in general as a principle of hydrographic variability and its expression in the geological record

rapid fluctuations in sea level recorded at huon peninsula during the penultimate deglaciation about 140 000 years ago the breakup of large continental ice sheets initiated the last interglacial period sea level rose and peaked around 135 000 years ago about 14 meters below present levels a record of last interglacial sea levels between 116 000 years to 136 000 years ago is preserved at reef vii of the uplifted coral terraces of huon peninsula in papua new guinea however corals from a cave situated about 90 meters below the crest of reef vii are 130 000 2000 years old and appear to have grown in conditions that were 6 c cooler than those at present these observations imply a drop in sea level of 60 to 80 meters after 130 000 years sea level began rising again in response to the major insolation maximum at 126 000 to 128 000 years ago the early about 140 000 years ago start of the penultimate deglaciation well before the peak in insolation is consistent with the devils hole chronology

sea level reversal during termination ii the termination of the penultimate glacial period tii shows both similarities and differences to the last termination ti both terminations show significant cold reversals in the postglacial warming trend ti consists of a continuously increasing sea level trend whereas tii may demonstrate a sea level reduction midway through the termination we present a new continuous sea level record for tii derived from red sea 18 o records that supports the existence of the tii sea level reversal the record gives an unprecedented look at the structure of the tii sea level reversal which consists of an early highstand lasting several millennia in duration followed by a 30 12 m to 40 12 m reduction in sea level and a stillstand of several millennia before the final sea level rise to the marine oxygen isotope stage mis 5e interglacial we suggest that there is a link between the sea level reversal and internal millennial scale variability in the climate system

airborne imaging spectrometer data of the ruby mountains montana mineral discrimination using relative absorption band depth images abstract airborne imaging spectrometer data collected in the near infrared 1 2 2 4 m wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the ruby mountains of southwestern montana the data were analyzed by using a new data enhancement procedure the construction of relative absorption band depth rbd images rbd images like bandratio images are designed to detect diagnostic mineral absorption features while minimizing reflectance variations related to topographic slope and albedo differences to produce an rbd image several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum rbd images are both highly specific and sensitive to the presence of particular mineral absorption features further the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods by using rbd images a number of rock and soil units were distinguished in the ruby mountains including weathered quartz feldspar pegmatites marbles of several compositions and soils developed over poorly exposed mica schists the rbd technique is especially well suited for detecting weak near infrared spectral features produced by soils which may permit improved mapping of subtle lithologic and structural details in semiarid terrains the observation of soils rich in talc an important industrial commodity in the study area also indicates that rbd images may be useful for mineral exploration

first use of an airborne thermal infrared hyperspectral scanner for compositional mapping in may 1999 the airborne thermal infrared hyperspectral imaging system spatially enhanced broadband array spectrograph system sebass was flown over mormon mesa nv to provide the first test of such a system for geological mapping several types of carbonate deposits were identified using the 11 25 m band however massive calcrete outcrops exhibited weak spectral contrast which was confirmed by field and laboratory measurements because the weathered calcrete surface appeared relatively smooth in hand specimen this weak spectral contrast was unexpected here we show that microscopic roughness not readily apparent to the eye has introduced both a cavity effect and volume scattering to reduce spectral contrast the macroroughness of crevices and cobbles may also have a significant cavity effect the diminished spectral contrast is important because it places higher signal to noise ratio snr requirements for spectroscopic detection and identification this effect should be factored into instrumentation planning and interpretations especially interpretations without benefit of ground truth sebass had the required high snr and spectral resolution to allow us to demonstrate for the first time the ability of an airborne hyperspectral thermal infrared scanner to detect and identify spectrally subtle materials

quantitative estimation of granitoid composition from thermal infrared multispectral scanner tims data desolation wilderness northern sierra nevada california we have produced images that quantitatively depict modal and chemical parameters of granitoids using an image processing algorithm called minmap that fits gaussian curves to normalized emittance spectra recovered from thermal infrared multispectral scanner tims radiance data we applied the algorithm to tims data from the desolation wilderness an extensively glaciated area near the northern end of the sierra nevada batholith that is underlain by jurassic and cretaceous plutons that range from diorite and anorthosite to leucogranite the wavelength corresponding to the calculated emittance minimum min varies linearly with quartz content sio2 and other modal and chemical parameters thematic maps of quartz and silica content derived from min values distinguish bodies of diorite from surrounding granite identify outcrops of anorthosite and separate felsic intermediate and mafic rocks