explosive volcanism during the holocene in the upper limay river basin the effects of ashfalls on human societies northern patagonia argentina abstract in order to understand human response to holocene ashfall events tephra layers found in archaeological sites along the upper limay river basin northern patagonia argentina were bracketed with radiocarbon dates and correlated with tephra from a lacustrine sediment core and from outcrops and the archaeological evidence was analyzed a dark tephra associated with seismic activity was identified in the el trebol rockshelter filling interstices between fallen blocks together with remains of human activity and bones of extinct fauna marking a seismo volcanic event occurring between 11 758 and 12 866 cal yr bp this same seismic event affected the cuyin manzano site where the roof collapse made the site uninhabitable for a time a white tephra present in epullan grande epullan chica and traful i caves is correlated with nahuel huapi tephra nht equivalent to laya s rio blanco and rio pereyra members rio pireco formation nht is considered to have been derived from the same eruptive event with dates ranging between ca 1950 2500 cal yr bp a dark tephra from ortega s cave and several tephra from puerto tranquilo i rockshelter ranging between 521 and 2069 cal yr bp show how the mobile hunters gatherers of northern patagonia were able to cope with the changing circumstances

taphonomic differentiation of acropora palmata facies in cores from campeche bank reefs gulf of mexico a common assumption in the geological analysis of modern reefs is that coral community zonation seen on the surface should also be found in cores from the reef interior such assumptions not only underestimate the impact of tropical storms on reef facies development but have been difficult to test because of restrictions imposed by narrow diameter cores and poor recovery that assumption is tested here using large diameter cores recovered from a range of common zones across three campeche bank reefs it is found that cores from the reef front crest flat and rubble cay zones are similar in texture and coral composition making it impossible to recognize coral assemblages that reflect the surface zonation taphonomic signatures imparted by variations in encrustation bioerosion and cementation however produce distinct facies and delineate a clear depth zonation cores from the reef front zone 2 10 m depth are characterized by sections of acropora palmata cobble gravel interspersed with sections of in place but truncated a palmata stumps upper surfaces of truncated colonies are intensely bioeroded by traces of entobia isp and gastrochaenolites isp and encrusted by mm thick crustose corallines before colony regeneration and therefore indicate punctuated growth resulting from a hurricane induced cycle of destruction and regeneration cores from the reef crest flat 0 2 m depth are also characterized by sections of hurricane derived a palmata cobble gravels as well as in place a palmata colonies in contrast to the reef front however these cobble gravels are encrusted by cm thick crusts of intergrown coralline algae low relief homotrema and vermetids bored by traces of entobia isp and trypanites isp and coated by a dense peloidal micrite cement cores from the inter to supratidal rubble cay zone 0 5 m are only composed of a palmata cobble gravels and although clasts show evidence of subtidal encrustation and bioerosion these always represent processes that occurred before deposition on the cay instead these gravels are distinguished on the basis of their limited bioerosion and marine cements which exhibit fabrics formed in the intertidal zone these results confirm that hurricanes have a major influence on facies development in campeche bank reefs instead of reflecting the surface coral zonation each facies records a distinctive depth related set of taphonomic processes which reflect colonization alteration and stabilization following the production of new substrates by hurricanes

alpine faunas from the white mountains california adaptive change in the late prehistoric great basin abstract high elevation archaeological sites in the white mountains of eastern california document the establishment of small villages at elevations above 3100 m at about ad 800 replacing occupations that lacked substantial structures storage facilities and abundant plant processing equipment previllage faunas are far more tightly focused on large artiodactyls than on smaller mammals but do not differ significantly from village faunas in richness or diversity these differences do not provide strong support for the bettinger baumhoff 1982 model of late prehistoric adaptive change in the great basin but adequate testing of more subtle versions of such hypotheses may require a massive research effort

taphonomic signatures of turbid zone reef development examples from paluma shoals and lugger shoal inshore central great barrier reef australia numerous coral reefs and coral communities occur along the nearshore regions of the central great barrier reef australia coastline these develop under conditions of episodically high wave induced sediment resuspension and turbidity and terrigenoclastic sediment accumulation cores recovered from two such reefs at paluma shoals and lugger bay are used to assess the taphonomic features and processes associated with framework development in such settings reef framework development is dominated by the accumulation of mainly rubble coral and isolated in situ coral colonies the reef fabric varies from clast to matrix supported in character and the matrix comprises poorly sorted mixed terrigenoclastic carbonate sediments taphonomic signatures from the different reef sites and facies show little variability and thus a distinct suite of taphonomic criteria indicative of nearshore turbid zone reef development are delineated the degree of both calcareous encrustation and internal bioerosion exhibits a high degree of between clast variability and many clasts are preserved in near pristine condition where present calcareous encrustation is restricted to thin isolated crusts comprising mainly of the coralline algae lithoporella or lithothamnion and isolated serpulid worms and cemented bivalves no biological binding of framework constituents occurs bioerosion is dominated by traces of entobia sp sponge borings and locally gastrochaenolites sp bivalve traces although only a limited suite of bioerosion trace morphologies is present there is little or no cementation of the reef framework and only isolated acicular aragonite or peloidal micrite cements occur within intra skeletal cavities significant occlusion of primary and secondary skeletal porosity by uncemented fine grained mainly terrigenous sediment is however common throughout the reef sequence the taphonomic criteria identified all have good preservation potential and should be readily identifiable within core sections such criteria thus have potential for aiding the recognition of reefs that either developed under similar environmental conditions of high turbidity and terrigenous sediment accumulation or which were subject to similar conditions during more short lived phases of reef accretion

holocene coral reef development under windward and leeward locations at ishigaki island ryukyu islands japan abstract coral reef growth is largely controlled by the wave energy associated with ocean swells and local winds this growth has responded to changes in wave conditions that evolved in concert with holocene sea level changes we analyzed holocene facies of the ibaruma and fukido reefs of ishigaki island southern ryukyu islands in the context of temporal and spatial changes in wave conditions by comparing present day coral assemblages and internal fossil reef facies four major coral assemblages that developed under different wave energy conditions were recognized six cores recorded a holocene reef sequence consisting of four sedimentary facies that differed in the relative volumes of four coral taxa acropora digitifera and acropora hyacinthus and lesser amounts of favia stelligera and montastrea curta holocene windward reef growth began at 7820 cal years bp after flooding of the pleistocene reef limestone surface the ensuing reef growth kept up with the rapid sea level rise a vertical growth rate of 7 5 m 1000 years during reef nucleation and early growth stages decreased to 3 5 m 1000 years during the main stage of reef framework development the uppermost part of the windward reef consisted of a very robust framework unlike the open framework of the leeward reef ages indicated that the uppermost leeward reef was ca 3000 years younger than the uppermost windward reef these variations in facies development and timing were caused by differences in local wind driven wave conditions

holocene development of the belize barrier reef previously knowledge of the holocene development of the belize barrier reef bbr the largest reef system in the atlantic ocean was limited to one location carrie bow cay we present new data from 11 rotary drill cores taken at 9 locations and 36 radiometric ages that indicate that the bbr was established from 8 26 to 6 68 ky bp on pleistocene reef limestones presumably deposited during oxygen isotope stage 5 the nonsynchronous start of holocene reef growth was a consequence of variation in elevation of antecedent topography largely controlled by underlying nne trending structures from north to south pleistocene elevation decreases along these structural trends probably reflecting differential subsidence and variations in karst topography reef anatomy is characterized by three facies in order of decreasing abundance these facies are represented by corals mainly acropora palmata and members of the montastraea annularis group by unconsolidated sand and rubble and by well cemented coral grainstones rudstones holocene reef accumulation rates average 3 25 m ky the degree of reef consolidation is negatively correlated with holocene thicknesses indicating that slowly growing reefs are better cemented than fast growing ones we present a holocene sea level curve for belize based on 36 dates from this study and 33 dates from our previous studies in the area

holocene sea level changes and barrier reef formation on an oceanic island palau islands western pacific abstract internal facies and development of an oceanic island s barrier reef were revealed by the stratigraphical study of six drill cores in palau islands western pacific the holocene reef development is primarily constrained at its foundation by the antecedent topography of pleistocene substratum holocene barrier reef is an increment on the pleistocene barrier reef which had been subaerially exposed during glacial stages about 8300 cal year bp calibrated calendar years b p branching acropora facies initially formed a bank on the seaward side of a pleistocene limestone surface with a vertical accumulation rate as high as 30 m ka ka 1000 years after 7200 cal year bp when the sea level rise rate decreased reef crest facies caught up with the sea surface with an accumulation rate of less than 2 2 m ka corals found in the reef crest facies are similar to the present day reef crest corals dominated by acropora digitifera and a humilis after the reef crest was formed bioclastic sand and gravel facies prograded lagoonward of the reef crest and consisted mostly of reef derived materials the construction of patch reefs post dated the barrier reef formation the mature barrier reef provided calm conditions inside the lagoon which then led to the construction of patch reefs and fringing reefs sea level changes deduced from the accumulation curves show rapid rise before 7200 cal year bp followed by a slight rise of 4 m at its maximum this change in sea level rise rate inspired the change in reef facies from branching acropora to reef crest

late glacial to post glacial sea levels in the western indian ocean late glacial to post glacial sea level changes provide direct evidence of the progress of melting of large ice sheets during the last deglaciation but although the correlation between ice and ocean volumes is incontrovertible the causal link is commonly obscured local effects including tectonics isostatic and hydroisostatic responses and equatorial ocean syphoning impose additional signals that hide the true picture a detailed regional study of the western indian ocean based on the analysis of drill cores carried out through modern reefs in combination with observations and sampling of reef foreslopes and investigations of outcrops provides a comprehensive data base sites from a range of tectonic settings include the microcontinental margins of madagascar the granitic seychelles and the isolated volcanic islands of reunion mauritius and the comoros in which the effects of subsidence can be shown to be small these cover a range of latitudes and comparisons with adjacent sites on continental margins allow the construction of sea level curves that closely reflect the eustatic response and disengage this from the effects of other mechanisms the mayotte foreslope in the comoro islands provides the first coral reef record of sea level change during the early deglaciation in the indian ocean 110 115 m below present sea level between 18 000 and 17 000 yr bp two distinctive reef terraces at 90 and 60 m water depth are dated at 13 600 yr bp and partly attributed to the younger dryas period 12 700 11 600 cal yr bp reef drowning at around 13 500 yr bp may correspond to meltwater pulse 1a and although there were surges in the rate of sea level rise most notably between 11 950 and 11 350 yr bp there is little evidence to support a well defined meltwater pulse 1b reconstructed holocene sea level curves are in good agreement and reflect a rapid sea level rise of about 6 mm yr 1 between 10 000 and 7500 yr bp followed by a clear inflection around 7500 yr bp when the rate fell to 1 1 mm yr 1 modern reefs started to grow 8000 9000 years ago in the post glacial period the rate of sea level rise was 1 1 5 mm yr 1 before stabilization at its present level 3000 2500 years ago curves for the 10 000 6000 yr 1 bp interval correspond closely with those predicted by theoretical models but lie below these in the subsequent period in particular and with the exception of the margins of the madagascar microcontinent influenced by hydroisostatic processes they do not reflect predicted higher sea level stands during the late holocene

relationship between species diversity and reef growth in the holocene at ishigaki island pacific ocean abstract coral reefs are influenced by global and local factors and living corals are currently faced with a potential loss of species diversity knowledge of the relationship between species diversity and reef growth during the holocene is important in terms of accurately reconstructing natural conditions prior to recent disturbances e g human impact pollution and over harvesting and in predicting future scenarios e g abrupt sea level rise coastal change and economic services this study seeks to characterize the holocene and present day reef at ishigaki island in the ryukyu islands focusing on spatial and temporal variations in the relationship between species diversity and reef growth the analysis is based on a drilling core obtained for the holocene reefs and quantitative species diversity data shannon and weaver s diversity index h obtained for the present day reef h was calculated for four coral communities surveyed at the ibaruma and fukido reefs the holocene sequence was dominated by the corymbose coral community e g acropora digitifera a hyacinthus goniastrea retiformis and platygyra ryukyuensis yielding an h value of 1 6 the encrusting coral community e g echinopora lamellose and pachyseris rugosa showed the highest diversity at the reef h 2 2 however this community was not one of the main reef builders during the holocene the massive coral community e g porites lutea and favites chinensis showed the lowest diversity h 0 6 it also made a minor contribution to reef building this community appeared in a shallow lagoon once sea level had stabilized the arborescent coral community e g a formosa and a nobilis was one of the main reef builders although yielding an h value of much less than 1 0 species diversity is not a prerequisite in terms of holocene reef growth thus a few species e g a digitifera a hyacinthus a formosa a nobilis g retiformis and p ryukyuensis from two main reef building communities are important for reef growth these corals that act as reefs are characterized by high growth rates having an upward reef growth rate of 2 12 m kyr 1 in the indo pacific during the holocene

quaternary glaciations of the southern andes abstract the southern andes comprise the southernmost portion of the andean cordillera beginning at the edge of the puna altiplano lat 27 s and ending at isla de los estados lat 55 s the late cainozoic glacial record of these mountains spans the interval from the late miocene to the present and is one of the most complete to be found anywhere in the world this has arisen for several reasons i the conterminous mountain ice cap extended to the piedmont zone on both flanks of the range where the sedimentary and morphological record has been well preserved ii periodic volcanism mainly from monogenetic fissure eruptions of basalt east of the range and from central tephra producing cones along the mountain crest has provided opportunity for the preservation and radiometric dating of interbedded glacial deposits iii a tectonically induced interval of stream incision in the mid pleistocene and simultaneous uplift has preserved glacial sediments on interfluves iv in the chilean lakes region west of the mountains late quaternary glaciers terminated in a well vegetated landscape thus creating scope for radiocarbon dating of interbedded and incorporated organic materials consequently the last glaciation in the llanquihue area of chile is one of the best dated sequences in south america thus the llanquihue glaciation is proposed as the south american equivalent of the wisconsin and weichsel glaciations of north america and north west europe respectively

small mammal remains from cueva huenul 1 northern patagonia argentina taphonomy and paleoenvironments since the late pleistocene abstract small mammal samples from the archaeological sequence of cueva huenul 1 ch1 36 56 45 s 69 47 32 w neuquen province argentina are described and taphonomic and paleoenvironmental conditions assessed this site is located near the steppe monte ecotone in the northernmost patagonia small mammal remains nisp 1426 mne 1409 mni 87 were recovered from late pleistocene 13 800 11 800 14 c bp early holocene 9500 14 c bp and late holocene layers 1400 14 c bp taphonomic analysis indicates that the ch1 assemblage is an archaeofaunistic owl pellet accumulation it has a good post depositional preservation since it was rapidly incorporated in the sedimentary matrix although it previously experienced trampling action from latest pleistocene to late holocene the assemblages are mainly composed by the sigmodontines eligmodontia spp and phyllotis xanthopygus and the caviomorphs microcavia australis and ctenomys sp suggesting in overall terms a marked ecological stability chl is one of the few sites where the pleistocene holocene transition is represented by faunal evidence the latest pleistocene sample spanning 13 800 and 11 800 14 c bp indicate scrub steppe with substantial open ground and rocky exposition one early holocene sample 9500 14 c bp suggests a more heterogeneous environment as evidenced by the first occurrence of akodon iniscatus and euneomys chinchilloides in this context ch1 assemblages do not reflect the small mammal community reworking that putatively accompanied the pleistocene holocene transition

response of reef coral communities to sea level rise a holocene model from mauritius western indian ocean the fringing reef at pointe au sable mauritius indian ocean was used to examine the effects of holocene sea level rise on coral growth this reef is about 1000 m wide and comprises a forereef slope 30 m maximum depth a narrow reef crest and a very shallow backreef 1 5 m maximum depth four major coral communities were recognized which developed within relatively narrow depth ranges a pachyseris oulophyllia community deeper than 20 m an acropora tabulate faviid community 20 6 m a robust branching acropora community less than 6 m and a pavona community less than 10m three high recovery cores show the holocene reef sequence is a maximum of 19 3 m thick and comprises four coral biofacies which are similar to counterparts identified in modern communities robust branching tabular branching robust branching domal and foliaceous coral facies a minimum sea level curve for the past 7500 years was constructed using distribution patterns of coral biofacies and radiocarbon dates from corals reconstruction of reef growth history indicates that both offshore and onshore reef zones were developing coevally aggrading at rates of 4 3 mm year 1 from 6900 years b p the reef caught up with sea level only after sea level stabilized changes in coral community and reef growth rates were driven principally by increasing water agitation due to the decrease in accommodation space based on the composition of the successive coral assemblages the reef appears to have grown through successive equilibrium stages

differential burning recrystallization and fragmentation of archaeological bone abstract this paper presents research on the conditions under which progressive levels of burning may occur to archaeological bone and how burning damage changes bones crystal structure and susceptibility to fragmentation a k a friability experiments were conducted to simulate common patterns of high temperature bone diagenesis and fragmentation previously documented in paleolithic shelter sites bones buried up to 6 cm below the coal beds of the experimental fires were carbonized but calcination occurred only with direct exposure to live coals analysis by infra red spectroscopy reveals that marked changes in crystallinity accompany the macroscopic transformations in colour and friability of modern fire altered bone specifically a monotonic non linear decrease in mean fragment length across six colour categories was observed when samples were agitated or trampled and a concordant decline in bone identifiability first with respect to skeletal element and ultimately the recognizability of bone tissue itself these findings help qualify the behavioural and taphonomic implications of fragmented burned bones in archaeological sites especially with regard to potential stratigraphic associations between artefacts and hearth features in sites and the intensity of space use by human occupants the identification of burning damage on archaeological bone is a separate issue however it was found that the molecular signatures of recrystallization in modern burned bones partly overlap with recrystallization caused by weathering after only 1 to 2 years of exposure in an arid setting and by partial fossilization of archaeological bones over the long term while infra red and x ray diffraction techniques effectively describe heat induced changes in modern bone mineral and are an important aid for modelling diagenetic processes these techniques did not reliably identify burning damage to archaeological bones cross referencing readily visible colour phases with hcl insoluble fraction data proves much more effective and economically feasible for the latter purpose

postglacial growth history of a french polynesian barrier reef tract tahiti central pacific bthe internal structure and growth pattern of tahiti reefs over the last 14 ka is reconstructed using sedimentological morphological and palaeobiological data coupled with radiometric dates in drill cores through the modern barrier reef flooding of the volcaniclastic deposits or the karst surface of a pleistocene reef started at 14 ka bp and coral growth began shortly after inundation the sequence in the tahiti barrier reef edge has formed predominantly through long term keep up growth controlled by stable environmental conditions while the adjacent backreef deposits did not start to accumulate before sea level stabilization around 6 ka the dominance of porites communities and the coeval occurrence of branching gracile lithophyllum in the lowermost part of the postglacial reef sequence 14 11 ka suggest the prevalence of uniformly moderate to low energy conditions and or growth in slightly deeper waters all over the drflled area during the early reef stages during the last 11 ka the reef frameworks developed in a high energy environment at maximum water depths of 5 6 m and were dominated by an acropora robusta danaihydrolithon onkodes association the local interlayering of other coralgal assemblages dominated by tabular acropora or domal porites reflects distinct diversification stages resulting either from the palaeotopographic control of the substrate or from slight and episodic environmental changes

the hydrodynamic and sedimentary setting of nearshore coral reefs central great barrier reef shelf australia paluma shoals a case study the great barrier reef gbr shelf contains a range of coral reefs on the highly turbid shallow inner shelf where interaction occurs with terrigenous sediments the modern hydrodynamic and sedimentation regimes at paluma shoals a shore attached turbid zone coral reef and at phillips reef a fringing reef located 20 km offshore have been studied to document the mechanisms controlling turbidity at each reef waves currents and near bed turbidity were measured for a period of 1 month bed sediments were sampled at 135 sites on the inner shelf muddy sands are widespread with admixed terrigenous and carbonate gravel components close to the reefs and islands except on their relatively sheltered sw side where sandy silty clays occur at paluma shoals the coral assemblage is characteristic of inner shelf or sheltered habitats on the gbr shelf dominated by galaxea fascicularis up to 50 coral cover and is broadly similar to that at phillips reef further offshore and in deeper water the sediments of the paluma shoals reef flats consist of mixed terrigenous and calcareous gravels and sands with intermixed silts and clays whereas the reef slope is dominated by gravelly quartz sands the main turbidity generating process is wave driven resuspension and turbidity ranges up to 175 nephelometric turbidity units ntu in contrast at phillips reef turbidity is 40 ntu probably occurs for a total of 40 days each year and relatively little time is spent at intermediate turbidities 15 50 ntu the extended time spent at either low or high turbidities is consistent with the biological response of some species of corals to adopt two alternative mechanisms of functioning autotrophy and heterotrophy in response to different levels of turbidity sedimentation rates over periods of hours may reach the equivalent of 10 000 times the mean global background terrigenous flux btf of sediment to the sea floor i e 10 000 btf over three orders of magnitude greater than the holocene average for halifax bay of 3 btf as elsewhere along the nearshore zone of the central gbr dry season hydrodynamic conditions form a primary control upon turbidity and the distribution of bed sediments the location of modern nearshore coral reefs is controlled by the presence of suitable substrates which in halifax bay are pleistocene and early holocene coarse grained and relatively stable alluvial deposits

postglacial vegetation climate and fire history along the east side of the andes lat 41 42 5 s argentina abstract the history of the low elevation forest and forest steppe ecotone on the east side of the andes is revealed in pollen and charcoal records obtained from mid latitude lakes prior to 15 000 cal yr bp the vegetation was characterized by steppe vegetation with isolated stands of nothofagus the climate was generally dry and the sparse vegetation apparently lacked sufficient fuels to burn extensively after 15 000 cal yr bp a mixture of nothofagus forest and shrubland steppe developed fire activity increased between 13 250 and 11 400 cal yr bp contemporaneous with a regionally defined cold dry period huelmo mascardi cold reversal the early holocene period was characterized by an open nothofagus forest shrubland mosaic and fire frequency was high in dry sites and low in wet sites the data suggest a sharp decrease in moisture eastward from the andes a shift to a surface fire regime occurred at 7500 cal yr bp at the wet site and at 4400 cal yr bp at the dry site preceding the expansion of austrocedrus by 1000 1500 yr the spread of austrocedrus is explained by a shift towards a cooler and wetter climate in the middle and late holocene the change to a surface fire regime is consistent with increased interannual climate variability and the onset or strengthening of enso the present day mixed forest dominated by nothofagus and austrocedrus was established in the last few millennia

anatomy of a modern coral reef flat a recorder of storms and uplift in the late holocene abstract cores from kabira reef ishigaki island southwest japan reveal the internal structure and temporal changes in sedimentary process of a complete coral reef flat the reef crest caught up with sea level at about 4000 yr bp since then it expanded oceanward and the reef pavement has grown landward the backreef structure is composed of bioclasts derived from the reef framework of all the bioclasts corals and coralline algae are most abundant coral fragments coarser than 3 0 o have dominated the backreef sediments since about 2000 yr bp benthic foraminiferal tests first occurred at about 4000 yr bp and their abundance increased significantly starting around 2000 yr bp shallowing of the reef crest is also indicated by the presence of the shallow water benthic foraminifera baculogypsina sphaerulata tests after 2000 yr bp the date 2000 yr bp is coincident with tectonic uplift at kabira reef kawana 1989 we consider this uplift to have caused a relative sea level fall that aided the deposition of coral fragments transported from the reef pavement by storms the relative sea level fall also caused subaerial exposure of the reef crest during low tides and the transition of reef building organisms from corals to shallow water species of benthic foraminifera resulting in a change noticeable in the constituents of backreef sediments the results of this study suggest that the coral reef flat and especially the backreef can be a faithful recorder of relative sea level changes

1200 year paleoecological record of coral community development from the terrigenous inner shelf of the great barrier reef increased terrestrial sediment and nutrient yields are regarded as significant threats to coral reef health within the central great barrier reef lagoon where water quality has reportedly declined since european settlement since ca a d 1850 inner shelf reef conditions have purportedly deteriorated however the link between reef decline and water quality change remains controversial primarily because of a lack of pre european period ecological baseline data against which to assess contemporary ecological states here we present a high resolution record of reef accretion and coral community composition from a turbid zone nearshore reef on the inner shelf of the great barrier reef the record is based on six radiocarbon date constrained cores and extends back to ca 1200 calibrated yr b p results demonstrate not only the potential for coral communities to initiate and persist in settings dominated by fine grained terrigenous sediment accumulation but also that a temporally persistent but low diversity suite of corals has dominated the reef building community at this site for at least the past millennium furthermore the coral assemblages exhibit no evidence of community shifts attributable to post european water quality changes while extrapolation of these findings to other turbid zone reefs must remain tentative the study raises important questions about the resilience of inner shelf reefs that are under terrestrial sediment influence and subject to elevated turbidity conditions and demonstrates the potential to develop detailed millennial time scale coral community records from holocene reef systems

interstadial coral reef terraces and relative sea level changes during marine oxygen isotope stages 3 4 kikai island central ryukyus japan abstract coral reef terraces are one of the best recorders of relative sea level changes during the last glacial cycle thus far knowledge of relative sea level record based on coral reefs during the marine oxygen isotope stage ois 3 has been limited to studies of the huon peninsula papua new guinea high precision a spectrometric 230 th 234 u dating demonstrated an offlapping sequence of five coral reef complexes ages of which are 66 64 62 55 and 52 ka in the northern part of kikai island central ryukyus of japan interstadial reefs characterized by deepening upward sequences of coral assemblages recorded three hemicycles from transgression to highstand at 52 62 and 66 ka during which these reefs were drowned these highstands in the relative sea level record can be correlated with the eustatic record reconstructed from the huon reef terraces and with the interstadials 14 18 and 19 of the gisp 2 oxygen isotope record this consistency confirms the huon sea level record of ois 3 and implies that the eustatic sea level responded to the millennial scale climate changes even during the glacial period of ois 4

holocene lagoonal sedimentation at the latitudinal limits of reef growth lord howe island tasman sea abstract the southernmost limit to coral reef growth occurs on lord howe island 33 30 s 159 05 e where a discontinuous fringing reef flanks the western side of the island coring and radiocarbon dating indicate that carbonate sediments were first deposited within the lagoon around 6500 radiocarbon years bp coincident with sea level reaching close to its modern level high energy conditions dominated the reef with robust branching corals dominating the developing reef growth of the reef crest between 6000 and 5000 yr bp is inferred to have caused a reduction in the energy conditions within the lagoon resulting in mud deposition during this period sedimentation occurred at average rates of around 5 mm yr though locally up to 10 mm yr which infilled almost all the available accommodation space in the lagoon by 4000 yr bp most of the lagoon had accreted to a level very close to the modern lagoon floor having accumulated over 11 m of sediment in the northern part of the lagoon and possibly up to 30 m in the south sediments younger than 3000 yr bp form a thin veneer over these older units with the main deposition being confined to embayments the coastal plain and the infilling of blue hole depressions the reef and lagoon fringing lord howe island appear to have developed their present form primarily during a phase of luxuriant growth in the mid holocene

small mammal taphonomy of gran dolina atapuerca burgos spain abstract the middle pleistocene sequence at the atapuerca burgos complex of caves is most completely represented at gran dolina eleven stratigraphic units are distinguished seven of which contain abundant small mammal fossils these seven units are analysed in order to determine the taphonomic processes present during the accumulation of their faunal remains the fossil bones are extensively broken both before and after burial fossils from six of the units show evidence of localized pre depositional acid corrosion which occurred both before and after breakage in the upper levels there is also evidence of post depositional corrosion both from alkaline and from acid environments of deposition and in the top level some fossil bones also show evidence of weathering and root marks images of these modifications by means of the scanning electron microscope and their comparison with a large comparative data base of recent modifications from known causal agents permits the identification of the agents responsible for many of the modifications and consequently the reconstruction of the sequence of events leading to the accumulation and preservation of the fossil assemblages predators are implicated for some of the breakage and all of the pre depositional corrosion which is the result of digestion in the predators stomachs in all cases the category of predator can be identified and at three stratigraphic levels the actual species can be identified with moderate degrees of reliability post depositional corrosion is linked with observations on local acidity alkalinity of different levels and the incidence of weathering is linked with evidence for roof collapse over parts of the cave taking account of the effects of these processes particularly the selectivity resulting from predator hunting methods allows estimates to be made of the degree of bias in the faunal composition and the palaeoecology thereby indicated

holocene sea level change and tectonic uplift deduced from raised reef terraces kikai jima ryukyu islands japan abstract kikai jima kikai island is surrounded by four holocene raised coral reef terraces which are thought to be an offlapping sequence of reef deposits caused by combined effects of seismic uplift and holocene sea level change many studies in this region have investigated holocene sea level changes and reef growth but there are relatively few in which reliable sea level indicators are given we have found that pocillopora verrucosa one of the most abundant coral species on the upper reef slopes of fringing reefs in the ryukyus has its peak abundance at a depth of 1 5 m therefore this species is considered ideal for the analysis of relative sea level change and can be used as a dipstick for the holocene reef deposits in this area based on the distribution of p verrucosa on the four holocene raised terraces we calculate relative paleo mean sea levels to be 10 8 11 1 and 8 5 8 9 m for terrace i 5 0 5 3 m for terrace ii 4 0 4 3 m for terrace iii and 1 9 2 5 m for terrace iv these results combined with hitherto known and newly measured radiometric dates 103 total clearly show that the four terraces formed in response to repeated seismic uplifts at 6 3 4 1 3 1 and 1 4 ka and that sea level was higher than present between 7 0 and 6 3 ka

reef coralgal assemblages as recorders of paleobathymetry and sea level changes in the indo pacific province the coralgal framework within the outer reef margin of many indo pacific reefs exhibits three main shallow water communities the environmental significance of which can be inferred by comparison with their modern counterparts a community dominated by tabular acropora gr hyacinthus cytherea with branching pocillopora damicornis p eydouxi montipora digitata occasional domal faviids and mm thick crusts of the coralline algae lithophyllum and mesophyllum mainly typical of the 6 15 m paleodepth range a community including robust branching acropora gr danai robusta a humilis a digitifera and subordinate favia stelligera echinopora gemmacea associated to vermetid gastropods and thick coralline crusts of hydrolithon cf onkodes and neogoniolithon cf fosliei flourishing in depths less than 6 m in medium to high water energy settings a community composed of domal porites cf lutea and p cf lobata with occasional acropora gr danai robusta and cm thick crusts of coralline algae in sheltered habitats in depths less than 10 m these biological assemblages allow us to determine relationships between reef growth and paleobathymetry and consequently to reconstruct regional relative sea level curves high water energy reefal assemblages provide stronger evidence for reconstructing sea level curves than low energy buildups because they have generally been controlled by a keep up growth mode subsiding reef sites seem to be more reliable indicators of sea level variations because they usually present expanded reef sequences

late quaternary structure and development of the northern ningaloo reef australia ningaloo reef situated on the central west coast is australia s largest fringing reef system extending southward from 22 s for over 200 km its narrow lagoon is backed by a coastal plain which is largely composed of an emergent last interglacial reef on the flank of folded tertiary limestones the west facing reef is exposed to strong oceanic swells across a narrow 8 km continental shelf climatic aridity cyclones tsunamis and the poleward flowing leeuwin current all influence the reef system seismic profiling and a coring and dating program along a transect through a reef pass indicate two periods of reef development in the northern part of the reef holocene and last interglacial seaward of the crest the holocene reef forms either a prominent 500 m wide bulge with 10 m of relief and an abrupt seaward slope or a series of discrete patch reefs holocene reef development is limited to depths of less than 30 m and reaches a maximum thickness of ca 10 15 m below the reef crest u th tims dates from distal parts of the last interglacial section between 18 and 36 m give ages toward the end of the high stand 120 115 ka last interglacial reef growth was more extensive of the two filling much of the available accommodation space perhaps as a result of a stronger leeuwin current this substrate subsequently provided an antecedent foundation for holocene reef development

postglacial reef development in the south west pacific case studies from new caledonia and vanuatu abstract analysis of reef development in the south west pacific provides valuable information on climatic variations and environmental changes during the past 20 ka here i compare fringing reef development from two sites in different geotectonic settings in new caledonia located on a stable passive margin a lag in reef development is observed and postglacial reefs initiated late between 7 2 and 4 ka in vanuatu located in an uplifting island arc reef development was continuous from 24 to 6 ka and there was no lag with the reef initiating as soon as substrate was available the initiation lag in new caledonia can be attributed to a lack of suitable substrate or to unfavorable oceanographic conditions such as cold sea surface temperature sst which did not allow reef initiation in vanuatu although sst during much of the postglacial sea level rise was probably cooler than present the reef was still able to develop as soon as the substrate was flooded

human subsistence and environmental stability during the last 2200 years in epullan chica cave northwestern patagonia argentina a perspective from the zooarchaeological record abstract the faunal content from epullan chica archaeological site ech thereafter a small cave located in northwestern patagonia argentina was studied from taphonomic and paleoenvironmental points of view this cave is placed in the ecotone between monte desert and the patagonian steppe in the middle limay river basin was occupied since the end of the late holocene zooarchaeological evidence retrieved from ech is diverse including fresh water mollusk shells diplodon chilensis eggshell and bone fragments of rheidae bones and teeth of large lama guanicoe medium e g chaetophractus villosus conepatus chinga and micro sized several species of sigmodontine and caviomorph rodents mammals most of the recorded taxa were the result of human exploitation however owl pellets preserved in the sediments and other taphonomic signatures clearly indicate that avian predators are responsible for part of the micromammal record micromammal abundances during the last 2 2 ka bp are suggestive of a relative environmental stability around ech at least until the beginning of the last century in this sense late holocene landscapes were dominated by open steppe areas and large rocky outcrops with minor changes in humidity and temperature during this period

holocene stability and recent dramatic changes in micromammalian communities of northwestern patagonia abstract micromammalian fossil sequences of two classical archaeological sites cueva traful i cti and cueva epullan grande ll both in the province of neuquen northwestern patagonia argentina were studied these sequences cover the entire holocene with assemblages mainly composed by rodent and marsupial remains accumulated by owls both sites are located near the ecotone fringes of the major vegetation units currently present in patagonia forest patagonian steppe cti and patagonian steppe monte desert ll comparisons between fossil and recent owl pellet samples in a regional approach indicated that micromammal communities remained stable over the major part of the last 10 ka with some minor expansion of desert adapted taxa to the west since the middle holocene and a dramatic change in the assemblages during the last 100 150 years two alternative but not contradictory explanations can be presented to interpret the stable period first climate environmental changes were not of sufficient magnitude to produce a clear reorganization of micromammal communities forest did not invade cti surroundings and monte did not reach around ll second the basic structure of northwestern patagonian steppe micromammal communities was resilient to minor or moderate climate environmental changes the strong shift depicted in the studied sequences in very recent times 100 150 years can be linked to human impact on the regional environment this change involves a deep restructuration of small mammal communities ranging from virtual extirpations of some species to dramatic increments of opportunistic taxa a century of sheep overgrazing coupled with the introduction of exotic shrubs was the main factor driving the configuration of present small mammal assemblages in northwestern patagonia