Papers by Strasser Andreas
History of Geo- and Space Sciences, Apr 1, 2022
The archetype of a cycle has played an essential role in explaining observations of nature over t... more The archetype of a cycle has played an essential role in explaining observations of nature over thousands of years. At present, this perception significantly influences the worldview of modern societies, including several areas of science. In the Earth sciences, the concept of cyclicity offers simple analytical solutions in the face of complex events and their respective products, in both time and space. Current stratigraphic research integrates several methods to identify repetitive patterns in the stratigraphic record and to interpret oscillatory geological processes. This essay proposes a historical review of the cyclic conceptions from the earliest phases in the Earth sciences to their subsequent evolution into current stratigraphic principles and practices, contributing to identifying opportunities in integrating methodologies and developing future research mainly associated with quantitative approaches.
Bulletin de la Société Géologique de France, 1991
Les dépôts littoraux du Pléistocène supérieur de Sardaigne ont été étudiés depuis le siècle derni... more Les dépôts littoraux du Pléistocène supérieur de Sardaigne ont été étudiés depuis le siècle dernier, mais n'ont jamais été abordés sous l'angle de la sédi mentologie et de la stratigraphie séquentiel.le. Co travail concerne un affleurement complexe situé sur la côte occidentale de la Sardaigne à proximité de San Giovanni di Sinis, affleurement dans lequel troi s séquences de dépôts peuvent être identifiées. La séquence inférieure surmonte une surface d'érosion entaillée dans le s marnes messiniennes. Un conglomérat de base recouvert par des sables à rides de courant et laminations de plage témoigne d'un environnement marin littoral. L'essentiel de celle première séquence est cependant constitué de dunes éoliennes localement pédogénisées e t de colluvions. Une imponante surface d'érosion marque la lim.ite supérieure de cette séquence. Le conglomérai de base de la deuxième séquence qui renferme des galets pédogé. nisés passe à des sablés .11 laminarions de plage. Ces faciès sont surmonrés par une lumachelle :1 Mytiltt.< et pur des va.se.s biorurbécs à ostrneodes qui correspondent à des dépôts lugunaircs. La présence localisée de charophy tes e1 de rhi-z-olithes traduiL l 'inOuence d 'eau• douces ci un débu1 de p&iogenèse. A nouveau, une importante surface d'émersion en111ille ces dépôts. La troisième séquence débute avec des facills de plage et d'avant-plage très riches en corallinacées et s'achève avec des dépôts éoliens qui progradenr par place directement sur des dépôts d'avanL-pfoge et des dépôts de chenal de marée. L'examen sédimentologique détaillé de celle derQière séquence suggère que les concepts de la stratigraphie séquentielle sont applicables à l'analyse de systèmes sédi mentuires lit1 omux de dimension réduite. Les principales .surfaces d'érosion se son t formées durnnt des phases d'abaissement important du niveau marin et correspondent à des limites de séquences. Les conglomém1s pourraient représen ter les dépôts de• l ' i.ntervalle transgressif, tandis que les successions «bathydécroissantes» pourraient correspondre au prisme de haut niveau marin. li es t probable que les trois séquences identifiées, imputables à des variations eustatiques importantes, représentent 1 'enregistrement sédimentaire des trois cycles climatiques majeurs qui ont marqué le dernier interglaciaire entre 130 000 et 70 000 ans.
Geologica Carpathica, 2018
Sedimentary facies and cycles of the Triassic continental–marine transition of NW Bulgaria are do... more Sedimentary facies and cycles of the Triassic continental–marine transition of NW Bulgaria are documented in detail from reference sections along the Iskar river gorge between the villages of Tserovo and Opletnya. The depositional environments evolved from anastomosing and meandering river systems in the Petrohan Terrigenous Group to mixed fluvial and tidal settings in the Svidol Formation, and to peritidal and shallow-marine conditions in the Opletnya Member of the Mogila Formation. For the first time, the palynostratigraphic data presented here allow for dating the transitional interval and for the precise identification of a major sequence boundary between the Petrohan Terrigenous Group and the Svidol Formation (Iskar Carbonate Group). This boundary most probably corresponds to the major sequence boundary Ol4 occurring in the upper Olenekian of the Tethyan realm and thus enables interregional correlation. The identification of regionally traceable sequence boundaries based on bio...
Geologica Carpathica, 2019
A cyclostratigraphic interpretation of peritidal to shallow-marine ramp deposits of the early Mid... more A cyclostratigraphic interpretation of peritidal to shallow-marine ramp deposits of the early Middle Triassic (Anisian) Opletnya Member exposed in outcrops along the Iskar River gorge, NW Bulgaria, is presented. Based on facies trends and bounding surfaces, depositional sequences of several orders can be identified. New biostratigraphic data provide a time frame of the studied succession with placement of the boundaries of the Anisian substages and show that the Aegean (early Anisian) substage lasted about 1.6 Myr. In the corresponding interval in the two studied sections, 80 elementary sequences are counted. Five elementary sequences compose a small-scale sequence. The prominent cyclic pattern of the Opletnya Member can thus be interpreted in terms of Milankovitch cyclicity: elementary sequences represent the precession (20-kyr) cycle and small-scale sequences the short eccentricity (100-kyr) cycle in the Milankovitch frequency band. Medium-scale sequences are defined based on lith...
Proceedings of the Ocean Drilling Program, 143 Scientific Results, 1995
Hole 866A on Resolution Guyot, in the Mid-Pacific Mountains, recorded a 1619-m-thick Hauterivian ... more Hole 866A on Resolution Guyot, in the Mid-Pacific Mountains, recorded a 1619-m-thick Hauterivian to Albian shallow-water carbonate sequence above volcanic basement, and overlain by a thin late Cretaceous to Cenozoic pelagic cap. Facies organization, geophysical log examination, and sequence stratigraphy interpretation give rise to a detailed history of the interplay of sedimentation and relative sea-level changes, and a comparison with that from other Lower Cretaceous platforms of the northern and southern margins of the Tethys. The Hauterivian to Aptian sequence consists of 19 depositional sequences, each characterized by transgressive systems tract, maximum flooding, and highstand systems tract. Four depositional sequence sets are distinguished. The first one corresponds to the Hauterivian sequences 1 through 4. It is characterized by oolitic and oncoidal open-marine sediments, massive dolomitization, and a cyclic evolution, where the deepest water environments occur at the bottom and at the top of this sequence set (Hauterivian transgressions). Above an emersion horizon, which is probably related to a local uplift, the second set of eight Hauterivian to Barremian depositional sequences (sequences 5 through 12) is characterized by restricted subtidal to intertidal facies that display a general evolution grading from progradation to aggradation and a thickening-upward trend possibly related increased subsidence rate toward the top. The third sequence set consists of four Aptian sequences (sequences 13 through 16) characterized by open-marine facies, and a general deepening up to the lower/upper Aptian boundary. Two major maximum flooding surfaces could be identified. The upper one correlates with the Goguel level of southeastern France and the Selli level of central Italy. The fourth sequence set includes upper Aptian to Albian sequences 17 through 19, which are characterized by the abrupt return to restricted facies, implying a monotonous aggradation of swamp, marsh, and shallow-lagoonal sediments. The middle to upper Albian series correspond to an aggradational, then retrogradational, succession of sequences. However, owing to low recovery, this latter series could not be studied in detail. A comparison of the sequence stratigraphic record is attempted between those at Resolution Guyot and other Lower Cretaceous platforms of the Tethys. Correlations are well constrained for the Aptian section. However, they are more tenuous for the Hauterivian and Barremian sections. The general sedimentary evolution at Hole 866A is similar to that of Tethyan platforms, as the same number of depositional sequences and maximum flooding events could be identified. This indicates that sedimentation on Resolution Guyot was influenced more by global sea-level changes than by local variations in subsidence rates. LITHOLOGY Using combined microfossil and macrofossil biostratigraphy, visual core descriptions, physical properties, and downhole logs, eight
International Journal of Earth Sciences, 2008
The Middle Berriasian deposits of the Jura platform in Switzerland and France have already been w... more The Middle Berriasian deposits of the Jura platform in Switzerland and France have already been well studied in terms of high-resolution sequence stratigraphy and different orders of depositional sequences (large-, medium-, and small-scale) have been defined. The hierarchical stacking pattern of the sequences and the time span represented by the investigated interval imply that sea-level fluctuations in the Milankovitch frequency band as well as differential subsidence caused the observed changes of accommodation on the Jura platform. The present study focuses on three small-scale sequences within the transgressive interval of a large-scale sequence. The initial flooding of the platform is marked by a facies change from supra-and intertidal (Goldberg Formation) to shallowmarine subtidal deposits (Pierre Châtel Formation). Detailed logging and facies analysis of 11 sections allow recognizing small environmental changes that define elementary sequences within the well-established small-scale sequences and distinguishing between autocyclic and allocyclic processes in sequence formation. It is concluded that the small-scale sequences correspond to the 100-ka orbital eccentricity cycle, while allocyclic elementary sequences formed in tune with the 20-ka precession cycle. Based on the correlation of elementary and small-scale sequences it can be shown that the Jura platform has been flooded stepwise by repeated transgressive pulses. Differential subsidence and pre-existing platform morphology further controlled sediment accumulation and distribution during the transgression. The combination of high-resolution sequence stratigraphy and cyclostratigraphy then enables the reconstruction of hypothetical palaeogeographic maps in time increments of a few ten thousand years.
Cyclostratigraphy: Approaches and Case Histories, 2004
The Berriasian Pierre-Châtel Formation in the Swiss and French Jura Mountains is dominated by sha... more The Berriasian Pierre-Châtel Formation in the Swiss and French Jura Mountains is dominated by shallow-marine carbonates that overlie lacustrine and marginal-marine sediments with a major transgressive surface. Detailed facies analysis of five sections allows the definition of elementary and small-scale depositional sequences, which commonly exhibit deepening-shallowing trends. Benthic foraminifera and rare ammonites on the platform, as well as a sequence-stratigraphic correlation with a well-dated deeper-water section, furnish the biostratigraphic framework. Thus, the large-scale sequence boundaries below and at the top of the Pierre-Châtel Formation can be correlated with dated boundaries in other European basins. This time constraint and the hierarchical stacking pattern on the platform as well as in the basin suggest that the sea-level fluctuations influencing the formation of the depositional sequences were controlled, at least partly, by Milankovitch cycles. The elementary sequences correspond to the 20 ky precession cycle, and the small-scale sequences to the 100 ky eccentricity cycle. Uncertainties in the definition of sequences exist if facies contrasts are too low to develop clearly marked sequence boundaries or maximum-flooding intervals. Nevertheless, a best-fit solution for the correlation of the small-scale sequences between the studied sections can be proposed. The lowermost three small-scale sequences of the Pierre-Châtel Formation are analyzed in detail. They are decompacted and correlated on the level of the elementary sequences. Within this relatively precise time frame, the flooding of the Jura platform (following the early Berriasian sea-level lowstand) can be monitored. It is seen that the transgression occurred stepwise: every 20 ky, a transgressive pulse established marine facies farther towards the platform interior. This study demonstrates that the cyclostratigraphical approach makes it possible to construct a narrow time frame, within which the rates of sedimentary, ecological, and diagenetic processes can be evaluated, phases of differential subsidence identified, and the durations of stratigraphic gaps estimated. The complex and dynamic evolution of an ancient carbonate platform can thus be studied with a time resolution of 20 to 100 ky.
Perspectives in Carbonate Geology, 2012
Modern shallow-water carbonate systems commonly display a complex pattern of juxtaposed depositio... more Modern shallow-water carbonate systems commonly display a complex pattern of juxtaposed depositional environments with a patchy facies distribution (facies mo saics). On ancient carbonate platforms, the reconstruction of lateral facies distribution is often hampered not only by discontinuous outcrop but also by lack of suffi ciently high time resolution. This case study from the Oxfordian (Late Jurassic) of the Swiss Jura Mountains demonstrates a way to improve the temporal and spatial resolution for the interpretation of carbonate rocks. Sequence-stratigraphic and cyclostratigraphic analyses have been performed that provide a basis for defi ning depositional sequences, which formed through sea-level changes that were induced by the 400-, 100-and 20-kyr orbital cycles. On the 100-kyr scale, sequence boundaries are well developed and can be correlated between sections. However, identifi cation and correlation of sequences related to the 20-kyr cycle may be diffi cult if local processes overprinted the record of orbitally controlled sea-level changes. The reconstruction of facies distribution along selected time lines gives a dynamic picture of platform evolution with time steps of a few ten thousand years and helps to interpret the controlling factors such as differential subsidence, low-amplitude eustatic sea-level fl uctuations, climate and ecology of the carbonate-producing organisms. Reefs and ooid shoals developed preferentially on topographic highs and thus accentuated platform morphology. Siliciclastics were shed onto the platform during sea-level falls and increased rainfall in the hinterland; their distribution was controlled by platform morphology. Siliciclastics and associated nutrients hindered carbonate production and thus indirectly infl uenced platform morphology. In addition to these controls, random processes acted on the smaller-scale facies relationships. Sedimentation rates can be estimated for each facies type over time spans of 10-20 kyr. They can thus be compared more easily with Holocene rates than if averaged over millions of years. This study shows that the Oxfordian platform in the Swiss Jura was as complex and dynamic as Holocene carbonate systems.
Newsletters on Stratigraphy, 2011
The recurrence of the same types of sequence stratigraphic surface through geologic time defines ... more The recurrence of the same types of sequence stratigraphic surface through geologic time defines cycles of change in accommodation or sediment supply, which correspond to sequences in the rock record. These cycles may be symmetrical or asymmetrical, and may or may not include all types of systems tracts that may be expected within a fully developed sequence. Depending on the scale of observation, sequences and their bounding surfaces may be ascribed to different hierarchical orders. Stratal stacking patterns combine to define trends in geometric character that include upstepping, forestepping, backstepping and downstepping, expressing three types of shoreline shift: forced regression (forestepping and downstepping at the shoreline), normal regression (forestepping and upstepping at the shoreline) and transgression (backstepping at the shoreline). Stacking patterns that are independent of shoreline trajectories may also be defined on the basis of changes in depositional style that can be correlated regionally. All stratal stacking patterns reflect the interplay of the same two fundamental variables, namely accommodation (the space available for potential sediment accumulation) and sediment supply. Deposits defined by specific stratal stacking patterns form the basic constituents of any sequence stratigraphic unit, from sequence to systems tract and parasequence. Changes in stratal stacking patterns define the position and timing of key sequence stratigraphic surfaces. Precisely which surfaces are selected as sequence boundaries varies as a function of which surfaces are best expressed within the context of the depositional setting and the preservation of facies relationships and stratal stacking patterns in that succession. The high degree of variability in the expression of sequence stratigraphic units and bounding surfaces in the rock record means ideally that the methodology used to analyze their depositional setting should be flexible from one sequence stratigraphic approach to another. Construction of this framework ensures the success of the method in terms of its objectives to provide a process-based understanding of the stratigraphic architecture. The purpose of this paper is to emphasize a standard but flexible methodology that remains objective.
Swiss Journal of Geosciences, 2009
Sedimentology, 2005
During the Late Jurassic, accelerated ocean-floor spreading and associated sealevel rise were res... more During the Late Jurassic, accelerated ocean-floor spreading and associated sealevel rise were responsible for a worldwide transgression, which reached its maximum in the Late Kimmeridgian. In many Western European basins, this major sea-level rise led to the formation of marly and condensed sections. In the Swiss Jura, however, a shallow carbonate platform kept growing and only subtle changes in the stratigraphic record suggest an increasingly open-marine influence. Field observations and thin-section analyses reveal that the central Swiss Jura was at that time occupied by tidal flats and by more or less open marine lagoons where shoals and bioherms developed. The evolution through time of sedimentary facies and bed thicknesses permits the definition of small-, medium-, and large-scale depositional sequences. The diagnostic features of these sequences are independent of scale and seem largely controlled by the Kimmeridgian second-order transgression. A high-resolution sequencestratigraphic correlation with biostratigraphically well-dated hemipelagic and pelagic sections in the Vocontian Basin in France reveals that: (i) The most important increase in accommodation recorded in the Kimmeridgian of the central Swiss Jura occurs in the Eudoxus ammonite zone (Late Kimmeridgian) and corresponds to the second-order maximum flooding recognized in many sedimentary basins. (ii) The small-and medium-scale sequences have time durations corresponding to the first and second orbital eccentricity cycle (i.e. 100 and 400 ka, respectively), suggesting that sedimentation on the platform and in the basin was at least partly controlled by cyclic environmental changes induced by insolation variations in the Milankovitch frequency band. The comparison of the high-resolution temporal framework defined in the Swiss Jura and Vocontian Basin with the sequencestratigraphic interpretation realized in other Western European basins shows that the large-scale sequence boundaries defined in the Kimmeridgian of the Swiss Jura appear in comparable biostratigraphic positions in most Western European basins. Discrepancies that occur are probably because of local or regional tectonics.
Sedimentology, 2011
Recent global change occurs within decades and leaves a significant imprint on shallow carbonate ... more Recent global change occurs within decades and leaves a significant imprint on shallow carbonate platforms. To what extent can rate and synchronicity of environmental changes in the past be evaluated in order to allow comparisons with the processes and products of today? Sections of a carbonate-dominated platform of Late Oxfordian age have been logged in detail in the Swiss Jura Mountains. The time frame, based on ammonite biostratigraphy and the hierarchical stacking of the sedimentary sequences, suggests that these formed by low-amplitude, high-frequency sea-level changes in tune with the orbital cycles. The smallest unit, the elementary sequence, can thus be attributed to the 20 kyr precession cycle. By identifying sequence-stratigraphic elements such as maximum-flooding surfaces within an elementary sequence, an even higher time resolution can be obtained and reconstructions of changes in water depth and sea-level are attempted. Sedimentation rates were highly irregular and discontinuity surfaces are common. Correlation of such surfaces from one section to the other is tentative because they could also have formed locally and are not necessarily synchronous. On the scale of elementary sequences, the vertical facies evolution permits interpretation of changes in water depth, which were produced by eustatic sea-level changes (allocyclic) and/or by autocyclic processes. The distribution of clay minerals indicates changes of sea-level, as well as of rainfall in the hinterland. Biotic changes were controlled by water depth and water quality, and also by nutrient and clay input. Carbon and oxygen isotopes do not show significant shifts within the elementary sequences. The original ecological, mineralogical and geochemical signals have partly been homogenized because of time-averaging through bioturbation and through reworking by storms, and because of diagenetic modifications. Consequently, there is potential to interpret environmental changes on the studied carbonate platform but the time resolution is not better than a few thousand years. The rates and the synchronicity of the processes leading to the observed environmental changes can thus be estimated only within this time frame.
Sedimentary Geology, 2000
The late Pleistocene stratigraphic record from the Bahamas and Bermuda archipelagoes includes pec... more The late Pleistocene stratigraphic record from the Bahamas and Bermuda archipelagoes includes peculiar V-shaped coastal ridges and wedges of seaward-dipping planar beds showing fenestral porosity up to 40 m above present sea level. Judging from this porosity, these landforms were till now interpreted as resulting from the action of giant waves during a period of climatic instability at the end of the last interglacial period. The occurrence of widespread mm-thick laminae of aeolian origin (subcritically climbing translatent stratification) throughout these deposits does not agree with this hypothesis. It rather suggests that the V-shaped ridges and seaward-dipping beds represent fossil parabolic and climbing aeolian dunes, respectively. The occurrence of fenestrae high above the intertidal zone could be related to both wave splashing and rainfall action. Parabolic dunes are restricted to the NW Bahamas. They were probably formed during a time interval (ca. 500-5000 yr), when regional climatic conditions were dryer than today, and characterized by persistently blowing NE trade winds.
Sedimentary Geology, 2002
... Pascal Kindler a , Corresponding Author Contact Information , E-mail The Corresponding Author... more ... Pascal Kindler a , Corresponding Author Contact Information , E-mail The Corresponding Author and André Strasser b. ... we suspect that the waves were generated by a local high-energy event such as a hurricane impact or partial collapse of the bank margin (Mullins and Hine ...
Palaeogeography, Palaeoclimatology, Palaeoecology, 2003
When quantifying sedimentary processes on shallow carbonate platforms, it is important to know th... more When quantifying sedimentary processes on shallow carbonate platforms, it is important to know the highfrequency accommodation changes through time. Accommodation changes in cyclic successions are often analysed by simply converting cycle thickness to Fischer plots. This approach is not satisfactory, because it does not account for differential compaction, possible erosion, sea-level fall below the depositional surface, or subtidal cycles. An attempt is made here to reconstruct a realistic, high-frequency accommodation and sea-level curve based on a detailed facies and cyclostratigraphical analysis of Middle Berriasian to Lower Valanginian sections in the French Jura Mountains. The general depositional environment was a shallow-marine carbonate platform on a passive margin. Our approach includes the following steps: (1) facies interpretation; (2) cyclostratigraphical analysis and identification of Milankovitch parameters in a well-constrained chronostratigraphic framework ; (3) differential decompaction according to facies; (4) estimation of depth ranges of erosion and vadose zone; (5) estimation of water-depth ranges at sequence boundaries and maximum flooding intervals; (6) estimation of mean subsidence rate; (7) classification of depositional sequences according to types of facies evolution: 'catch-up', 'catch-down', 'give-up', or 'keep-up'; (8) classification of depositional sequences according to long-term sea-level evolution: 'rising', 'stable', 'falling'; (9) calculation of 'eustatic' sea-level change for each depositional sequence using the parameters inferred from these scenarios, assuming that sea-level cycles were essentially symmetrical (which is probable in Early Cretaceous greenhouse conditions); (10) calculation of a sea-level curve for each studied section; (11) comparison of these curves among each other to filter out differential subsidence; (12) construction of a 'composite eustatic' sea-level curve for the entire studied platform; (13) spectral analysis of the calculated sea-level curves. Limitations of the method are those common to every stratigraphic analysis. However, the method has the potential to improve the original cyclostratigraphical interpretations and to better constrain the high-frequency sea-level changes that control carbonate production and sediment fluxes.
Palaeogeography, Palaeoclimatology, Palaeoecology, 2013
Lagoonal carbonates of Kimmeridgian age in NW Switzerland formed in a tropical epeiric sea and ex... more Lagoonal carbonates of Kimmeridgian age in NW Switzerland formed in a tropical epeiric sea and exhibit indicators of subaerial emergence such as tidal biolaminites, desiccation cracks, flat pebble conglomerates, and fenestral structures. Additionally, 30 dinosaur tracksites from at least six stratigraphic intervals indicate repeated formation of land bridges between the platform and adjacent massifs. Populations of herbivorous and carnivorous dinosaurs necessitate substantial vegetation and consequently a soil cover, but no striking evidence of paleosols have been found within the track bearing sequences. However, two stratigraphic levels exposed in nine outcrops exhibit distinctive hardgrounds that experienced early meteoric diagenesis during times of emergence. Initial induration began with the precipitation of thin micritic meniscus cements. Contemporaneously meteoric waters completely dissolved all aragonite leaving large voids. Iron-hydroxides were precipitated in the uppermost 7-10 cm where they impregnated the porous micrite and constituted a separate cement generation, which caused a penetrative dark red staining. These aspects are suggestive of the formation of Mediterranean-type red soils on the emerged platform. During transgression, the soil was eroded and wavecut hardgrounds were superimposed on the hardgrounds formed during regression. Erosion is evidenced by micro-karst, truncated Gastrochaenolites isp. borings and the physical removal of steinkerns. The eroded material including floral remains provided surplus nutrients leading to eutrophication. This food-rich environment supported the mass-occurrence of gastropods in the nerineoid limestones and oysters (Nanogyra sp.) in the Virgula Marls.
Ichnos, 2009
This study concerns the formation, taphonomy, and preservation of human footprints in microbial m... more This study concerns the formation, taphonomy, and preservation of human footprints in microbial mats of present-day tidal-flat environments. Due to differences in water content and nature of the microbial mats and the underlying sediment, a wide range of footprint morphologies was produced by the same trackmaker. Most true tracks are subjected to modification due to taphonomic processes, leading to modified true tracks. In addition to formation of biolaminites, microbial mats play a major role in the preservation of footprints on tidal flats. A footprint may be consolidated by desiccation or lithification of the mat, or by ongoing growth of the mat. The latter process may lead to the formation of overtracks. Among consolidated or (partially) lithified footprints found on present-day tidal flats, poorly defined true tracks, modified true tracks, and overtracks were most frequently encountered while unmodified and well-defined true tracks are rather rare. We suggest that modified true tracks and overtracks make up an important percentage of fossil footprints and that they may be as common as undertracks. However, making unambiguous distinctions between poorly defined true tracks, modified true tracks, undertracks, and overtracks in the fossil record will remain a difficult task, which necessitates systematic excavation of footprints combined with careful analysis of the encasing sediment.
Geology, 1997
Rapid and abrupt relative sea-level changes within the last interglacial (substage 5e) are record... more Rapid and abrupt relative sea-level changes within the last interglacial (substage 5e) are recorded in the island geology of the tectonically stable Bahamas. From 132 to 118 ka, reef growth reached a maximum elevation near ؉2 m, as indicated by fossil reef elevation across the platform, whereas bioeroded notches are incised in coastal cliffs as high as ؉6 m. The end of the interval is characterized by voluminous eolianites exhibiting palm tree and frond impressions. It is inferred that sea level for most of the interval remained near ؉2 m, restraining reef growth, and that the notch at ؉6 m represents a rapid and brief excursion just before the close of the substage. The subsequent fall must have been rapid in order to leave the notch profile intact and mobilize windward lagoon ooids into dunes before cementation could anchor them. In order to explain the rapid rise to ؉6 m, glacial surging is invoked. The subsequent fall, also rapid, may be a consequence of the surge flooding high latitudes and providing enough moisture to initiate reglaciation and drawdown.
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Papers by Strasser Andreas