Paleosols Research Papers - Academia.edu (original) (raw)

Olduvai Gorge, Tanzania is known for its fossil and cultural record of early hominins. The archaeological records are typically found within pedogenically modified sediments, thus the interpretation of paleosols provides important... more

Olduvai Gorge, Tanzania is known for its fossil and cultural record of early hominins. The archaeological records are typically found within pedogenically modified sediments, thus the interpretation of paleosols provides important paleoenvironmental context information. The Gorge contains a rich and diverse record of paleosols that vary spatially and temporally, however the stratigraphy can be divided into time slices using dated tuffs and studied in a paleolandscape context. Sediments were deposited in a semi-arid closed rift basin containing paleo Lake Olduvai, with volcanoes supplying volcaniclastic material to an alluvial fan system on the eastern side and quartzofeldspathic fluvial sediments derived from weathered basement rocks on the western side. The shallow saline-alkaline lake in the basin center and groundwater levels in the surrounding uplands fluctuated with Milankovitch-driven climatic (precession) cycles of w20,000 years. The rift basin paleolandscape (at w1.8 Ma) is reconstructed using sedimentology, stratigraphy and paleopedology. Standard field descriptions of physical and biogenic paleosol structures are combined with stable isotope ratios of carbonates, and whole rock geochemistry of sediments, to reveal diversity of paleosols within the basin. There are at least three distinct types of paleosols that record a paleocatena related to both landscape and drainage differences. Red tephra-rich Andisols developed on the volcaniclastic alluvial fan to the east of the paleolake, calcium-carbonate-rich, silty Aridisols developed on the interfluves and floodplain of the fluvial plain on the west, whereas clay-rich paleosols (Vertisols) developed on the lake margin and lake in the center of basin. Variances in geo-morphology, depositional environment, parent material, and depth to the water table are reflected in the development of distinctly different soil types that can provide key data needed for high-resolution reconstruction of the landscape known to be utilized by early hominins.

L’érosion du littoral aquitain favorise, sur les plages du Nord Médoc, l’affleurement d’anciens niveaux de sols (dits paléosols) pléistocènes et holocènes sous jacents au cordon dunaire. Ils sont connus depuis le XIXe siècle, à la fois... more

L’érosion du littoral aquitain favorise, sur les plages du Nord Médoc, l’affleurement d’anciens niveaux de sols (dits paléosols) pléistocènes et holocènes sous jacents au cordon dunaire. Ils sont connus depuis le XIXe siècle, à la fois par les géologues, mais aussi par les archéologues. Aujourd’hui encore, ils font l’objet d’une surveillance attentive de quelques chercheurs et de passionnés d’histoire, dans le cadre du programme de recherche interdisciplinaire LITAQ, dirigé par Florence Verdin (CNRS, Institut Ausonius) et Frédérique Eynaud (Université de Bordeaux).
C’est ainsi que fut repéré, le dimanche 19 avril 2015, au moment du plus bas niveau de la marée, les restes d’un squelette de cerf sur la plage de l’Amélie Nord (Soulac-sur-Mer). Le lendemain, dans le cadre du projet LITAQ, une fouille de sauvetage fut programmée avant que l’ensemble des données ne soit emporté par l’Océan Atlantique. Le matériel faunique recueilli et les interprétations liées à ce dernier sont présentés dans cet article.

Slope and lowland sediment systems throughout southern Africa are dominated by the presence of colluvium with interbedded palaeosols and hardground duricrusts. These sediments correspond to phases of land surface instability and... more

Slope and lowland sediment systems throughout southern Africa are dominated by the presence of colluvium with interbedded palaeosols and hardground duricrusts. These sediments correspond to phases of land surface instability and stability, respectively, during the late Quaternary. This study examines the stratigraphy and environmental interpretation of slope sediment records from specific sites in southern Africa for the period of marine isotope stages (MIS) 6 to 1 (~191 ka to present), informed by theoretical ideas of the dynamics of slope systems including sediment supply and accommodation space. Based on this analysis, phases of land surface instability and stability for the period MIS 6 to 1 are identified. The spatial and temporal patterns of land surface conditions are not a simple reflection of climate forcing, but rather reflect the workings of slope systems in response to climate in addition to the role of geologic, edaphic and ecological factors that operate within catchment-scale sediment systems. Considering these systems dynamics can yield a better understanding of the usefulness and limitations of slope sediment stratigraphies.

Although only recognized as a discrete stratigraphic unit since 1949, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This guidebook represents an... more

Although only recognized as a discrete stratigraphic unit since 1949, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This guidebook represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere.
Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

Paleosols are ancient soils that have been incorporated into the geological record. Soils form in response to interactions among the lithosphere, hydrosphere, biosphere, and atmosphere, so paleosols potentially record physical,... more

Paleosols are ancient soils that have been incorporated into the geological record. Soils form in response to interactions among the lithosphere, hydrosphere, biosphere, and atmosphere, so paleosols potentially record physical, biological, and chemical information about past conditions near Earth’s surface. As a result, paleosols are an important resource for terrestrial environmental and climatic reconstructions. Long-standing paleosol research topics include morphology, classification, and clay mineralogy, all of which provide information about pedogenic processes and local paleoenvironments. Paleosols are also used to infer processes involved in the development of
stratigraphic architecture and basin evolution. Recent paleosol research has introduced semiquantitative and quantitative measures for environmental and chronometric reconstructions that provide insight intomajor regional to global changes in temperature, precipitation, and atmospheric pCO2. These
new proxies focus on morphological and chemical transfer functions and stable isotope geochemistry to provide estimates of precipitation, temperature, pCO2, and productivity, as well as chronometric estimates of mineral crystallization in deep-time pedogenic systems. Looking forward, consensus must be reached on terminology that most effectively communicates paleosol characteristics and implies important processes. Proxy development will continue to improve as data sets become available across greater ranges of environments and timescales.

The Sausar belt on the southern flank of the Satpura Mountain Belt of Central India comprises several generations of granite gneisses and migmatites, and the metasedimentary rocks of the Sausar Group. A suite of ~3200-2450 Ma old rocks... more

The Sausar belt on the southern flank of the Satpura Mountain Belt of Central India comprises several generations of granite gneisses and migmatites, and the metasedimentary rocks of the Sausar Group. A suite of ~3200-2450 Ma old rocks comprising of an older Tonalite-Trondhjemite-Granodiorite (TTG) gneiss and younger quartz-monzonite plutons (Tirodi Gneiss-I) constitutes the basement complex for the Sausar Group. The contact of Tirodi Gneiss-I and the Sausar Group records the geological history at Archaean-Palaeoproterozoic boundary. A paleosol horizon at this contact contains unusual minerals such as siderite, ankerite, uraninite, and alumino-silicate minerals. The geochemical data of the paleosol indicate a reducing environment of formation and oxygen deficient conditions in the atmosphere at the time of development of this paleosol at the Archaean-Palaeoproterozoic boundary. The Sausar Group is reported to contain coarse clastics, volcanics, glaciogenic sediments, cap carbonates, and fine clastics with manganese ore deposits. Geochemical data from the cap carbonate horizon above the glaciogenic unit and manganese bearing horizons above the cap carbonate confirm presence of reducing environment in the shallow ocean.

In 1961, the late Marlin G. Cline wrote a remarkable essay entitled, “The Changing Model of Soil” for the 25th Anniversary Issue of the Soil Science Society of America Proceedings. Cline was most impressed with how geomorphology was... more

In 1961, the late Marlin G. Cline wrote a remarkable essay entitled, “The Changing Model of Soil” for the 25th Anniversary Issue of the Soil Science Society of America Proceedings. Cline was most impressed with how geomorphology was enriching pedology, and with the increasingly sophisticated views of soil time and of the processes of soil formation. We revisit Cline’s general objectives by re-evaluating the changing model of
soil from the perspective of the early 21st century, and by taking stock of the application of soil models to contemporary needs and challenges. Today, three ongoing changes in the genetic model of soil have far-reaching consequences for the future of soil science: (i) that soil is being transformed globally from natural to human-natural body, (ii) that the lower boundary of soil is much deeper than the solum historically confined to O to B horizons, and (iii) that most soils are a kind of pedogenic paleosol, archival products of soil-forming processes that have ranged widely over the life of most soils.
Together and each in their own way, these three changes in the model of soil impact directly human–soil relations and give structure and guidance to the science of anthropedology. In other words, human forcings represent a global wave of soil polygenesis altering fl uxes of matter and energy and
transforming the thermodynamics of soils as potentially very deep systems. Anthropedogenesis needs much better quantifi cation to evaluate the future of soil and the wider environment.

Many studies across the central and southern Maya Lowlands of Belize, Guatemala, Honduras, and Mexico have produced records of land degradation, mostly sedimentation and soil erosion, during the ancient Maya period from before 1000 BC to... more

Many studies across the central and southern Maya Lowlands of Belize, Guatemala, Honduras, and Mexico have produced records of land degradation, mostly sedimentation and soil erosion, during the ancient Maya period from before 1000 BC to the Maya Collapse of c. AD 900. This paper provides new data from two sites (Blue Creek and Cancuén), synthesizes more than a decade of the authors' research in Guatemala, Belize, and Mexico, and synthesizes other findings from this region. These research projects analyzed more than 100 excavations in upland and depression sites, cored lakes and wetland sediments, and studied sediments in the field and laboratory using radiocarbon dating, a battery of soil chemistry tests, stratigraphic analysis, magnetic susceptibility, elemental analyses, and artifact identification. Our objective was to date when sedimentation and soil erosion occurred, identify stable surfaces, and correlate them with the state of knowledge about past land use. These findings indicate three general epochs of accelerated soil erosion and identified two major paleosols. The three waves of soil erosion occurred in the Preclassic period (c. 1000 BC to AD 250), the Late Classic (AD 550 to 900), and in the last several decades. The major paleosol (‘Eklu'um’) in these sites is a well-developed Mollisol or Vertisol that started forming in the early Holocene and was buried in either the Preclassic or Classic periods (AD 250 to 900). At some sites the Eklu'um paleosol lies beneath sediments with a fainter paleosol, which in turn lies buried below Classic period and later sediments. This picture shows higher than expected soil erosion linked to the region's first pioneer farmers in the Preclassic and less than expected soil erosion in the Late Classic when population peaked and land use was the most intensive. In other regions like Cancuén, Guatemala, however, most soil erosion occurred during the Maya Late Classic (AD 550–830). Erosion here was intense but short-lived: depressions record 1–3 m of aggradation in two centuries. A third epoch of accelerated soil loss and aggradation arose with the rapid land use changes brought by new pioneers during the last several decades.

A B S T R A C T The middle Eocene Koluel-Kaike Formation, located in the San Jorge Basin, Patagonia, Argentina, is a strongly pedogenically modified succession associated with volcaniclastic input in an aggrading distal eolian-dominated... more

A B S T R A C T The middle Eocene Koluel-Kaike Formation, located in the San Jorge Basin, Patagonia, Argentina, is a strongly pedogenically modified succession associated with volcaniclastic input in an aggrading distal eolian-dominated fluvial system, located ∼400 km downwind of the Eocene Andean volcanic arc. The coordinated study of sediments and paleosols of this unit allows (1) reconstruction of environmental conditions and landscape evolution , and (2) determination of the interplay of the main forcing factors in the evolution of the Kokuel-Kaike Formation. The landscape reconstruction attests to the existence of a loessic rolling plain drained by a subordinate fluvial system, composed of both unconfined and confined flows, with locally ponded areas. Over these, thick stacked cumulative paleo-Ultisols and vertic paleo-Ultisols developed with scarce simple and stacked compound vitric Entisols analogues and compound Inceptisols equivalents. This high-resolution sedimentolo-gical-pedological analysis of the Kokuel-Kaike Formation indicates that the interplay between episodic volca-niclastic supply and cyclic climate controlled landscape evolution and soil development.

2008.04 Abstract: The stratigraphic and regional distributions of paleosol morphology in latest Pennsylvanian through Early Permian strata in Colorado, Utah, Arizona, New Mexico, Texas, and Oklahoma are presented in this paper. This... more

2008.04 Abstract: The stratigraphic and regional distributions of paleosol morphology in latest Pennsylvanian through Early Permian strata in Colorado, Utah, Arizona, New Mexico, Texas, and Oklahoma are presented in this paper. This regional extent corresponds to a paleolatitudinal gradient spanning approximately 5 degrees S to 10 degrees N. Morphological trends from this region delineate significant and systematic temporal and spatial changes in Permian-Carboniferous paleoenvironment and paleoclimate. The inferred latest Pennsylvanian (Virgilian) through early Early Permian environmental pattern is complex, but it indicates persistently dry, semiarid to arid conditions in Colorado, Utah, and Arizona, at paleolatitudes north of approximately 2 degrees N, whereas lower paleolatitude (approximately 2 degrees S to 2 degrees N) tropical regions in New Mexico exhibit a stepwise shift from subhumid to semiarid and variably seasonal conditions throughout late Pennsylvanian and the first half of Early Permian (Virgilian through Wolfcampian) time, followed by a subsequent shift to more arid conditions during the latter part of the Early Permian (Leonardian). Notably, strata from the southernmost paleosites, in Texas and Oklahoma, exhibit the most significant and abrupt climate changes through this period; they show a rapid transition from nearly ever-wet latest Pennsylvanian climate (at approximately 5 degrees S) to drier and seasonal climate across the Permian-Carboniferous system boundary, and finally to arid and seasonal climate by Leonardian time (at approximately 2-4 degrees N). The inferred climate patterns show no robust long-term correlation with the high-latitude Gondwanan records of glaciation. Rather, the long-term record of Permian-Pennsylvanian climate indicators from the southwestern United States is most simply explained by an approximately 8 degrees northward tectonic drift through (essentially) static climate zones over western tropical Pangea during the interval of study. However, the relatively rapid perturbations to climate recorded by these pedogenic archives appear to be too rapid for tectonic forces and might correspond to changes in climate drivers, such as atmospheric pCO (sub 2) , atmospheric circulation, and glacial-interglacial cycles.

Study of the pedogenic features of the Upper Jurassic Morrison Formation in western Colorado, USA, shows a clear difference in the types of paleosols between the strata of the lower and upper Brushy Basin Member. Lower Brushy Basin... more

Study of the pedogenic features of the Upper Jurassic Morrison Formation in western Colorado, USA, shows a clear difference
in the types of paleosols between the strata of the lower and upper Brushy Basin Member. Lower Brushy Basin paleosols are mostly calcareous
Aridisols with Stage I through Stage III calcrete Bk horizons, abundant root traces, occasional vertic features, but only rarely with
ochric epipedons. Upper Brushy Basin paleosols are mainly thicker and commonly display ochric epipedons and well-developed Bt and
Bw horizons. We assign these paleosols to the order Inceptisol. Limestones occur in the Brushy Basin Member and include both uniformly
micritic limestones and limestones with strongly brecciated textures. The former contain sparse body fossils and charophyte debris, while
the latter are characterized by clotted-peloidal fabrics with circumgranular cracking and silica replacement. We interpret these limestones
as the deposits of carbonate in small water bodies on a low-gradient flood plain, with the textures resulting from pedogenic reworking of
the carbonate sediment. We find no evidence for the presence of extensive lacustrine or wetlands (Lake T’oo’dichi’) deposits in the study
area. The paleoclimate suggested by all of these features is strongly seasonal, but subject to variations on orbital (precessional and higher)
timescales causing intervals of semi-aridity during weaker monsoons, to alternate with sub-humid periods during stronger monsoons.
The apparent long-term change in climate during Brushy Basin deposition potentially resulted from northward drift of North America.
1 Department

Archaeological investigations undertaken by the Proyecto Arqueológico Tlajinga Teotihuacán are focused on understanding urban expansion and household economies in this southern district of the city. Our geoarchaeological research... more

Archaeological investigations undertaken by the Proyecto Arqueológico Tlajinga Teotihuacán are focused on understanding urban expansion and household economies in this southern district of the city. Our geoarchaeological research addresses similar topics through examination of relevant microstratigraphic and botanical signatures as well as those relevant to reconstructing paleoenvironment. We investigated four different contexts at Tlajinga: the southern extension of the Street of the Dead, an obsidian working area outside Compound 17:S3E1, anthropogenic and natural layers below Compound 18:S3E1, and a soil profile at the San Lorenzo river. We employed micromorphological, pollen, and phytolith analyses as well as standard soil analytics to study the various deposits in these contexts. Our analysis demonstrates artificial lowering of the tepetate for continuing the axis of the Street of the Dead, microdebitage from obsidian working outside Compound 17:S3E1, and the preservation of in situ burning activities at Compound 18:S3E1. Further, we reconstruct alluvial infilling of the Street of the Dead with pedogenetic overprinting and present further evidence on the occurrence and variability of the Black San Pablo Paleosol and its agricultural significance.

A B S T R A C T As an important geological archive, paleosols have been widely used in reconstruction of paleoenvironmental and paleoclimatic conditions. In this study, we undertook detailed analyses of the clay mineralogy and carbon and... more

A B S T R A C T As an important geological archive, paleosols have been widely used in reconstruction of paleoenvironmental and paleoclimatic conditions. In this study, we undertook detailed analyses of the clay mineralogy and carbon and oxygen isotopic compositions of pedogenic carbonates in a series of 13 paleosol horizons within a fluvial section of the Eocene (~52–44 Ma) Lulehe Formation in the Qaidam Basin. Pedogenic smectite and illite/ smectite (I/S) mixed-layer minerals are the predominant clay minerals in the paleosols, suggesting that the early Eocene paleoclimate of the Qaidam Basin was strongly seasonal with warm-wet summers. The high levels of pedogenic smectite production and high atmospheric pCO 2 reconstructed from soil carbonate nodule δ 13 C (mean −7.1 ± 0.8‰) are consistent with elevated temperatures during the Early Eocene Climatic Optimum (EECO). Coeval paleosol carbonate nodules yield estimated paleo-surface water compositions (δ 18 O psw) of −7.9‰ to −5.0‰ (VSMOW), which are significantly higher than the δ 18 O value of modern summer precipitation in the Qaidam Basin. The estimated temperature difference (~5.0 °C cooling) implies uplift of the study area by nearly 1000 m to its current average elevation of ~3000 m above sea level. This paleoelevation estimate agrees with modern meteoric water isotopes of Global Network of Isotopes in Precipitation (GNIP) sites in Asia in the same elevation range.

Upper Permian and Lower Triassic palaeosols from northeastern Tethyan localities exposed within the Bogda Mountains, NW China, provide a wealth of information regarding long-term palaeoclimatic and palaeoenvironmental variations.... more

Upper Permian and Lower Triassic palaeosols from northeastern Tethyan localities exposed within the Bogda Mountains, NW China, provide a wealth of information regarding long-term palaeoclimatic and palaeoenvironmental variations. Wuchiapingian palaeosols are characterized by intense redoximorphy, accumulation of vascular plant matter, accumulation of clay minerals and Fe-oxides, slickensides, and clastic dikes, suggesting a soil moisture regime that ranged from perennially wet to distinctly seasonal in soil moisture budget. Changsinghian to early Induan palaeosols include subsurface accumulations of clay and carbonate as well as surficial accumulations of organic matter, indicative of sub-humid to sub-arid soil moisture and variable soil moisture regimes. Induan to Olenekian palaeosols contain pedogenic CaCO3 accumulations and gypsum pseudomorphs, indicating a drier environment characterized by net soil moisture deficiency. Elemental composition of palaeosol matrix was used to estimate palaeoprecipitation through the chemical index of alteration minus Potassium (CIA-K) proxy. Estimates from various Wuchiapingian strata indicate relatively stable palaeoprecipitation. During the late Changsinghian and early Induan, palaeoprecipitation appears to have decreased from 1100 to 230 (±180)mm/year over less than 100 m of vertical stratigraphic section. In the Induan and Olenekian, palaeoprecipitation appears much less stable than in Wuchiapingian, with values vacillating from 290 to 1014 mm/year. The transition to a relatively unstable precipitation state coincides generally with the Permian–Triassic boundary, and may reflect climatic disturbances associated with the end-Permian extinction event in addition to altered atmospheric circulation patterns resulting from regional tectonics, moisture availability, and expansion of the subtropical high pressure belt.

Floodplain deposits in the valley of the Moskva-river contain a series of buried soils of the Holocene age, which can be an important source of palaeoecological information. These soils are aged: Soil 1 - last 4 centuries, Soil 2 - cal... more

Floodplain deposits in the valley of the Moskva-river contain a series of buried soils of the Holocene age, which can be an important source of palaeoecological information. These soils are aged: Soil 1 - last 4 centuries, Soil 2 - cal 1200 AD-500 BC, Soil 3 - 900-2700 BC, Soil 4 - 3500-5000 BC. Archaeological monuments attributed to these soils are dated: Neolithic (Soil 4), Early Bronze Age (Soil 3), the Iron Age and the Middle Ages (Soil 2). Buried soils have well developed profiles and diagnostic features. Buried soils of the Sub-Atlantic period (Soil 2) are usually referred to Luvisols and Albeluvisols. Dark-colored soils of the Atlantic period (Soil 4) in most cases refer to Phaeozems; pollen analysis shows that these soils were formed under forest-steppe communities. Buried soils of Subboreal period (Soil 3) are traced in rare cases and have no clear diagnostic features; pollen analysis shows that this soil could be developed under mixed forests dominated by spruce. Radiocarbon dating suggests that the landscapes of the lower levels of the valley have changed dramatically between 5000 and 4500 cal BP. The forest-steppe communities, typical for the Atlantic period, were replaced by dense spruce forests due to early Subboreal climate change. Some traces of human impact on the floodplain vegetation from the Neolithic and Bronze Age were revealed. The maximum anthropological transformation was noted in the beginning of Middle Ages.

Interpretive cross sections based on detailed descriptions of 33 outcrops and cores are used to better understand the relative effects of tectonics, eustasy, tides, and climate on Upper Mississippian (middle Chesterian) stratigraphy in... more

Interpretive cross sections based on detailed descriptions
of 33 outcrops and cores are used to better understand the relative
effects of tectonics, eustasy, tides, and climate on Upper Mississippian
(middle Chesterian) stratigraphy in the tectonically active, tide-dominated
Illinois basin. The cross sections show that five mixed carbonate–
siliciclastic, high-frequency sequences in the Bethel through Glen Dean
formations can be correlated around the outcrop belt through areas
with very different subsidence histories.
The sequence boundaries are marked by paleosols and incised valleys
and can be correlated basin-wide within a framework of distinctive
marker beds. Because of its updip position, lowstand systems tracts are
not preserved in the Illinois basin. The transgressive systems tracts
generally consist of one or two parasequences that are typically composed
of tidally influenced quartz sandstone filling incised valleys at
the base overlain by open-marine skeletal limestone, shallow-marine
shale, and heterolithic siliciclastic tidal-flat deposits. The maximum
flooding surface (MFS) for the sequences is picked at the base of the
deepest water limestone facies. Highstand systems tracts are composed
of 1 to 6 regressive parasequences that consist of basal offshore skeletal
limestone capped by laterally extensive shale and heterolithic siliciclastic
tidal-flat facies.
The basin-wide extent of the sequence boundaries and maximum
flooding surfaces across tectonic highs and lows suggests that the sequences
were produced by eustatic sea-level changes rather than local
tectonics or autogenic processes. The sequences were likely produced
by moderate- to high-amplitude (30–100 m) fourth-order (; 400 ky)
glacio-eustatic sea-level changes driven by the transition from the
greenhouse conditions of the Early Mississippian to the ‘‘icehouse’’
conditions of the late Paleozoic. The lateral extent and frequency of
component parasequences suggests that they were likely produced by
fifth-order sea-level changes (10–100 ky). The sequences may be bundled
into third-order composite sequences, but the third-order signal
is obscured by the magnitude of the fourth-order sea-level changes a
feature typical of ice-house stratigraphies.
The sequences can be used as time slices to identify spatial and temporal
variations in differential subsidence between the Cincinnati Arch
and the more rapidly subsiding Basin Interior. Episodes of high and
low differential subsidence occurred every two to three sequences.
These subsidence variations had a major impact on lithofacies distribution
and onlap and offlap geometries in sequences and parasequences.
The occurrence of some widespread seismically disturbed
beds suggests that active faulting occurred during deposition. Normal
faulting appears to have occurred during periods of high differential
subsidence and reverse faulting during periods of low differential subsidence.
Differential subsidence and related normal and reverse faulting
may have occurred in response to phases of thrust loading and
quiescence in the Appalachian orogenic belt to the east. Even in this
tectonically active setting, however, it is the eustatic signal that generates basin-wide, mappable stratigraphic sequences.

Although there is general consensus that a global greenhouse climate characterized the mid-Cretaceous, details of the climate state of the mid-Cretaceous Southern Hemisphere are less clearly understood. In particular, continental... more

Although there is general consensus that a global greenhouse climate characterized the mid-Cretaceous, details of the climate state of the mid-Cretaceous Southern Hemisphere are less clearly understood. In particular, continental paleoclimate reconstructions are scarce and exclusively derived from paleontological records. Using paleosol-derived climofunction studies of the mid-to Upper Cretaceous Mata Amarilla Formation, southern Patagonia, Argentina, we present a reconstruction of the mid-Cretaceous climate of southern South America. Our results indicate that at ~60° south paleolatitude during the Cenomanian–Santonian stages, the climate was subtropical temperate–warm (12 °C ± 2.1 °C) and humid (1404 ± 108 mm/yr) with marked rainfall seasonality. These results are consistent with both previous estimations from the fossil floras of the Mata Amarilla Formation and other units of the Southern Hemisphere, and with the previous observations of the displacement of tropical and subtropical floras towards the poles in both hemispheres. The data presented here show a more marked sea-sonality and slightly lower mean annual precipitation and mean annual temperature values than those recorded at the same paleolatitudes in the Northern Hemisphere.

The Lower Permian (Wolfcampian) Abo Formation of south-central New Mexico was deposited by a silt-dominated fluvial system along the western half of the Orogrande basin a few degrees north of the equator in western Pangaea. Fluvial... more

The Lower Permian (Wolfcampian) Abo Formation of south-central New Mexico was deposited by a silt-dominated fluvial system along the western half of the Orogrande basin a few degrees north of the equator in western Pangaea. Fluvial channel deposits consist primarily of: (1) inclined siltstone stratasets up to 4.5 m thick and 25 m wide interpreted as point bar deposits, and (2) symmetrically infilled siltstone stratasets up to 2.4 m thick and 14 m long that may represent avulsion crevasse channels. Both types of channels are dominated by climbing ripple cross-laminae and plane bed laminae, but trough cross-beds are also present, as are several types of soft-sediment deformation structures and desiccation cracks. Red silty mudstones interpreted as floodplain deposits comprise up to 70% of the formation and are interbedded with thin (<2 m) tabular siltstone beds of crevasse-splay/levee origin, as well as rare lacustrine carbonates (∼0.5 m thick) and structureless siltstones (<1 m thick) interpreted as loessites.Common pedogenic features in floodplain strata and on the tops of some fluvial channel beds include root traces, peds, and calcic nodules/tubules, whereas gypsum, gley colour mottling, and translocated clay and/or iron oxides are rare. Also present is an ichnofauna dominated by opportunistic arthropods that colonized the moist upper surfaces of recently deposited crevasse-splay/levee beds and the uppermost surfaces of fluvial channels following avulsion.The relative abundance of channel and crevasse-splay/levee deposits increases eastward in response to moderate asymmetrical subsidence of the basin, whereas calcic paleosols are more numerous on the more slowly subsiding western margin of the basin. A semi-arid to sub-humid palaeoclimate with seasonal precipitation favoured relatively deep rivers whose point bars were seasonally exposed, the formation of calcic and vertic soils, a sparse ichnofauna and flora, periodic desiccation of small carbonate lakes, and perhaps reworking of loess from the floodplain and/or upstream catchments.

Petrographic and calcrete carbon isotope data from seasonally waterlogged Upper Silurian (Přídolí) to Lower Devonian (Pragian) palaeo-V ertisols of the Old Red Sandstone, South Wales, UK, are presented. The δ13C values mostly range from... more

Petrographic and calcrete carbon isotope data from seasonally waterlogged Upper Silurian (Přídolí) to Lower Devonian (Pragian) palaeo-V ertisols of the Old Red Sandstone, South Wales, UK, are presented. The δ13C values mostly range from -9 to -12‰ (VPDB), suggesting the soils were inhabited by abundant vegetation that when oxidised (perhaps with microbial assistance) resulted in CO2-rich soils. Such soils would favour calcrete precipitation through equilibration of soil zone CO2 with the relatively lower atmospheric pCO2. However, reliably estimating palaeoatmospheric pCO2 calculated from these carbon isotope data is a challenge.

Se presentan los resultados del estudio parcial de los conjuntos de fitolitos localizados en dos paleosuelos rubefactados de la Isla de Tenerife (Canarias), donde tales partículas constituyen un depósito de microfósiles vegetales,... more

Se presentan los resultados del estudio parcial de los conjuntos de fitolitos localizados
en dos paleosuelos rubefactados de la Isla de Tenerife (Canarias), donde tales partículas
constituyen un depósito de microfósiles vegetales, desarrollados a nivel interno y
externo por antiguas plantas, cuya identificación y valoración permite conocer parte de
la paleoflora local en base a sus propiedades de diagnóstico taxonómico. Tal cualidad
deriva en la posibilidad de conocer las condiciones ambientales vinculadas a la
edafogénesis de este tipo de suelos. Las muestras fueron tomadas en dos perfiles de
suelos y sus registros de fitolitos nos han permitido valorar una metodología básica de
estudio paleoedáfico, aplicándola sobre los restos microscópicos depositados en este
tipo de suelos.
Las tareas de recogida de muestras, tratamientos de laboratorio y gabinete microscópico
verificaron la presencia de fitolitos en el perfil de la costa del Puerto de La Cruz (Los
Roques, 5 m.s.n.m.) y en el de las medianías de La Laguna (DECA-1, 400 m.s.n.m.).
Pese a no existir dataciones absolutas para ambos, trabajos anteriores permiten
enclavarlos en secuencias pleistocénicas de Würm II-IV, relacionándose con
condiciones climáticas propuestas como diferentes a las actuales, que propiciarían una
edafogénesis intercalada en la secuencia eruptiva aérea del edificio insular, bajo un
clima con mayores valores de humedad y temperatura. Los resultados confirman que
estos materiales pueden también calificarse como paleosuelos desde su contenido en
fitolitos, presentes en todos los niveles analizados (superficial, medio y profundo) y en
algunos casos en elevadas concentraciones (DECA-1). Dentro de los morfotipos
seleccionados como indicadores paleoambientales destacan las concentraciones de
fitolitos de células cortas Poaceae, donde prevalecen las gramíneas de tipo C3 frente a
C4 (familias Pooideae y Panicoideae respectivamente). Lo cual indica condiciones
climáticas más templadas y contrastadas que en la actualidad, al menos en las medianías
representadas por DECA-1 donde apenas existe rastro de palmáceas, como sí es habitual
en contextos edáficos holocénicos de Canarias. En el paleosuelo de Los Roques la
concentración de fitolitos de gramíneas es netamente inferior, aunque con mayor
representación de palmáceas e igual predominio de las gramíneas C3.

Plant fossils are rarely preserved within the Upper Permian of western Europe as the majority of continental deposits consists of siliciclastic redbeds. Because organic matter such as plant debris and palynomorphs is destroyed by... more

Plant fossils are rarely preserved within the Upper Permian of western Europe as the majority of continental deposits consists of siliciclastic redbeds. Because organic matter such as plant debris and palynomorphs is destroyed by oxidizing conditions, these red sedimentary facies were often considered as “devoid of life”. This paper presents new palaeobotanical data from the Upper Permian strata of Minorca (Balearic Islands, Spain). In addition, a rich and diverse “Thuringian” palynoflora was recovered from the Permian sediments, and several megafloral taxa are recorded. Additionally, a detailed sedimentological analysis of the studied section is provided. The Permian succession shows a general evolution from a ponded floodplain environment to sand-sheet rivers flowing across a semi-arid alluvial plain. Additionally, new palaeobotanical elements, added to the study of palaeosols, allow reconstruction of Late Permian plant growth within the terrestrial environment, as well as a palaeoenvironment reconstruction of the preserved sedimentary interval. At the transition between ponds and alluvial plain deposits, root systems surprisingly similar to those known in extant mangroves are described for the first time within Permian deposits. As there are no other palaeobotanical remains preserved in association, the type of plant that inhabited this environment remains conjectural.

A 50 m thick stratigraphic section at Ngira, near Karungu on the shore of Lake Victoria in western Kenya, documents the early Miocene paleoenvironments of the area. The basal Ngira paleosol is a 7.6 m thick, oxisolic Vertisol that formed... more

A 50 m thick stratigraphic section at Ngira, near Karungu on the shore of Lake Victoria in western Kenya, documents the early Miocene paleoenvironments of the area. The basal Ngira paleosol is a 7.6 m thick, oxisolic Vertisol that formed during a prolonged period of pedogenesis; it began as a smectite-dominated Vertisol that was later overprinted through polypedogenesis to become a kaolinitic paleosol highly depleted of all base cations, with abundant Fe concentrations and depletions, and complexly variegated color mottle patterns that reflect extensive ferruginization. Paleoenvironmental reconstructions using bulk geochemistry indicate warm and wet conditions during development of the Ngira paleosol that probably supported a tropical seasonal forest on a stable upland surface for 10s to 100s of thousands of years. Following this long-lived stable landscape, rapid subsidence, perhaps associated with slip on a high-angle fault associated with the onset or progression of the Nyanza Rift and/or the development and eruptive history of the nearby Kisingiri volcano, buried the paleosol and formed a nascent lake basin that experienced multiple transgressions and regressions. During one interval of regression, fluvial sandstones and conglomerates were deposited along with fluvio-lacustrine sandstones and claystones that include weakly developed paleosols. These weakly-developed paleosols indicate a relatively dry paleoenvironment with seasonal precipitation, and probably a shrubland/bushland or riparian forest habitat. Important terrestrial and aquatic vertebrate fossils are primarily preserved within fluvial and fluvio-lacustrine deposits, indicating that the terrestrial Karungu fauna lived in a relatively dry and open habitat. This study demonstrates polypedogenesis and inferences regarding onset of abrupt tectonic activity in the early Miocene in equatorial eastern Africa, and emphasizes the contrasts between landscape stability of the Ngira paleosol and the poorly developed soils in the fluvio-lacustrine facies.

While it is generally accepted that the initial Pleistocene human colonizers of the Americas likely entered the continents via the Pacific coast, formal models of their entry and dispersion into the continental interior are scarce. The... more

While it is generally accepted that the initial Pleistocene human colonizers of the Americas likely entered the continents via the Pacific coast, formal models of their entry and dispersion into the continental interior are scarce. The ability to identify colonizer period archaeological sites for development of such models requires that researchers identify landforms of appropriate age and depositional character to target for large-scale archaeological survey. Well-preserved Upper Pleistocene and Early Holocene landforms are present across the Pacific Northwest. From coastal environs to the Palouse, these landforms represent a remnant landscape which initial colonizers explored at some point subsequent to the last glacial maximum. The types of landforms suitable for deposition and preservation of colonizer period archaeological sites include a broad array of settings, including: Coastal environments, characterized by relict Pleistocene-age landscape features shoreward of the submerged continental shelf; Continental ice-marginal and ice-distal depositional environments, where a variety of glaciomarine and long-standing glacial lakes formed behind the retreating Puget Lobe of western Washington State; Interior Scablands where cataclysmic outburst floods created scoured topographic lows that acted as local depositional basins—often holding paleo-lakes and marshes; and the Palouse loess within the Columbia Basin province, where eolian deposition has buried and preserved the Pleistocene and early Holocene landscape. Along the major drainageways, Upper Pleistocene to Early Holocene alluvial chronologies vary locally, but overall regional trends indicate that climate-controlled aggradation initiated between 12.0 to 11.0KBP, forming distinct terraces in the major river systems and their tributaries. Regional soil formation is evidenced by the Bishop Geosol which dates between 13.5KBP and 11.2KBP, present in a broad variety of depositional environments. Upper Pleistocene archaeology is sparse but present across the region; initial colonizers were broad-spectrum foragers whose toolkit included distinctive stemmed and shouldered bifaces, macroblade tools and crescents.

In this study, a multidisciplinary approach was used for a detailed characterization of sediments from the archaeological site Vinča-Belo Brdo, Serbia, one of the most important Neolithic settlements in Europe. This research aimed to... more

In this study, a multidisciplinary approach was used for a detailed characterization of sediments from the archaeological site Vinča-Belo Brdo, Serbia, one of the most important Neolithic settlements in Europe. This research aimed to determine the paleoenvironmental conditions during Pleistocene and Early Holocene sedimentation prior to Early Neolithic settlement (~5800 cal BC) and provide novel insight into the interaction between humans and the environment during the Middle and Late Neolithic (5300-4550 cal BC). For the first time, organic geochemical characterization, combined with organic petrography, grain size, mineralogy, and inorganic analysis were done on sediment samples from geological and archaeological sections of the Vinča-Belo Brdo site. In the archaeological section, the layer with remains of the burned house and the overlaying leveling layer were particularly interesting. The samples from the oldest geological layers were characterized by the relatively high content of carbonates, the largest amount of soluble organic matter (OM), predominance of liptinite macerals, along with the prevalence of short and mid-chain n-alkanes indicating a marsh-lake depositional environment. The sedimentation of overlaying geological layers continued in an oxbow lake, followed by a shallow depositional environment with stronger input of vascular plants. This was indicated by an increase of the terrigenous component, a high amount of huminite maceral, especially textinite, the predominance of odd long-chain n-alkanes, as well as the presence of diterpanes, pimarane, and 16α(H)-phyllocladane. Quartz was the most abundant mineral in paleosol, while the OM had a mixed origin with a major input of microorganism in the precursor biomass. Estimated average paleosol temperature around 12-16°C and mean annual precipitation of 938 mm/yr were favorable for ancient civilization settlement. In archaeological samples, the OM was predominantly formed by microorganisms, with a certain contribution of terrestrial plants. Their occurrence was substantiated by the presence of telohuminite, detrohuminite, resinite, and sporinite. The prevalence of n-alkane C 18 , along with the occurrence of inertinite macerals, semifusinite and fusinite, in the layer with the burned house remains confirmed the incomplete combustion of woody biomass at temperatures < 500°C. Organic and inorganic geochemical parameters for the leveling layer covering the destroyed buildings showed analogous composition as the lowest geological layers. This proved that Vinča inhabitants excavated material for leveling at a site in their vicinity, and used it for covering the burnt debris, clearing the areas for a new settlement. In this context, the decades long archaeological dilemma of the origin of the leveling material was resolved.

The Messak Settafet is a wide plateau located in the Libyan central Sahara (SW Fezzan); it is cut into the Nubian sandstone and interpreted as relic of a Tertiary peneplain, heavily affected by aeolian deflation. Notwithstanding... more

The Messak Settafet is a wide plateau located in the Libyan central Sahara (SW Fezzan); it is cut into the Nubian sandstone and interpreted as relic of a Tertiary peneplain, heavily affected by aeolian deflation. Notwithstanding degradation phenomena, discontinuous, thin soil bodies are locally preserved below the hamada. Several profiles, located in correspondence of different geomorphological units (the hamada, the endorheic depressions, and the southern escarpment), were described and sampled for micropedological analyses. Micromorphology outlined that the main characteristics of the residual B horizons from each geomorphological units are (i) high concentration of ferruginous nodules, (ii) multiple generations of clay illuviation, (iii) fragmentation and deformation of textural pedofeatures, and (iv) calcite mobilization and redeposition. According to horizon macro- and micromorphological characteristics, these pedologic bodies do not seem to be in equilibrium with the present-day climatic conditions and should be regarded as paleosols generated by processes regulated by large water availability and warm temperature, such as rubification, clay translocation, and calcite redistribution. The development of horizons acted mainly since the Early/Middle Pleistocene during subsequent pluvial periods and was interrupted by several erosional and aeolian input phases (arid periods). Pedological processes ended at the onset of the severe dry environmental conditions at the Mid-Late Holocene transition. The development of this kind of paleosols in the central Sahara is also discussed in comparison with pedogenetic processes occurring in temperate regions during interglacial and interstadial intervals.

Resumen: Se presenta el resultado de la investigación geoarqueológica conducida en el valle de Teotihuacan, con el objeto de establecer la distribución de asentamientos en diferentes periodos (Formativo, Clásico y Post-clásico) y su... more

Resumen: Se presenta el resultado de la investigación geoarqueológica conducida en el valle de Teotihuacan, con el objeto de establecer la distribución de asentamientos en diferentes periodos (Formativo, Clásico y Post-clásico) y su dinámica en la degradación ...

Climate models indicate increased desertification in the continental interior of Pangea during the Permian, which would have affected the composition of the flora and fauna. We present a multi-proxy paleoenvironmental reconstruction of a... more

Climate models indicate increased desertification in the continental interior of Pangea during the Permian, which would have affected the composition of the flora and fauna. We present a multi-proxy paleoenvironmental reconstruction of a terrestrial ecosystem in central Pangea of Lopingian age. The reconstruction is based on biological and physical data from the Moradi Formation, located in the Tim Mersoi Basin, northern Niger. Paleosols and sedimentological evidence indicate that the prevailing climate was semi-arid to very arid with marked intervals of high water availability. Carbon stable isotope data from organic matter and paleosols suggest that both the soil productivity and actual evapotranspiration were very low, corresponding to arid conditions. Histological analysis of pareiasaur bones shows evidence of active metabolism and reveals distinct growth marks. These interruptions of bone formation are indicative of growth rhythms, and are considered as markers for contrasting seasonality or episodic climate events. The macrofossil floras have low diversity and represent gymnosperm-dominated woodlands. Most notable are ovuliferous dwarf shoots of voltzian conifers, and a 25-m long tree trunk with irregularly positioned branch scars. The combined biological and physical evidence suggests that the Moradi Formation was deposited under a generally arid climate with recurring periods of water abundance, allowing for a well-established ground water-dependent ecosystem. With respect to its environment, this system is comparable with modern ecosystems such as the southern African Namib Desert and the Lake Eyre Basin in Australia, which are discussed as modern analogues.

Fluvial, alluvial, lacustrine, and debris flow sedimentary rocks from the Keweenaw Peninsula (Michi-gan, USA) are geochemically characterized to examine weathering processes and provenance. These sedimentary rocks result from the erosion,... more

Fluvial, alluvial, lacustrine, and debris flow sedimentary rocks from the Keweenaw Peninsula (Michi-gan, USA) are geochemically characterized to examine weathering processes and provenance. These sedimentary rocks result from the erosion, weathering, and redistribution of effusive and plutonic igneous lithologies during periods of volcanic quiescence associated with the failed 1.1 Ga North Ameri-can Midcontinental Rift. Three units comprising the sedimentary/igneous-mixed Portage Lake Volcanics, coarseness and source-varied Copper Harbor Conglomerate, and the quartz-rich post-rift fill unit of the Jacobsville Sandstone were studied over a geographically-wide and lithologically-varied range of localities across the Keweenaw Peninsula, Michigan. Provenance indicators such as Ti/Zr and Ti/Al ratios and LaTh -Sc ternary diagrams reveal that the Portage Lake Volcanic conglomerates are near-source, and that the Copper Harbor Conglomerate is primarily derived from felsic uplifted basement and recycled orogen lithologies to the east. The Jacobsville Sandstone is a combination of pulses of sources from the top to the bottom of the stratigraphic section: (1) felsic arkosic arenites sourced from the erosion and uplift of basement orogenic volcanic and plutonic rocks (top), (2) felsic arkosic-subarkosic arenites sourced from the erosion of uplifted basement, recycled orogeny and reworking of primary sedimentary and metased-imentary rocks (middle), and (3) quartz arenites eroded from the cratonic interior (highly mature). This work can consequently aid in structuring a stratigraphic nomenclature for the Jacobsville Sandstone. Both petrographic data and weathering indices such as the chemical index of alteration (CIA) and the pale-osol hydrolysis metric (Al/Ca+Na+Mg+K) indicate low degrees of weathering during syn-rift deposition at 1.1 Ga, but increases with evolution of the rift in post-rift units toward the Late Mesoproterozoic/Early Neoproterozoic. Values for the CIA throughout the Mesoproterozoic from this and other localities have the same trend to that of proposed atmospheric CO 2 concentrations derived from paleosol data, demonstrating that characterizing the weathering trends of floodplain deposits can be a useful addition to deciphering past paleoclimatic conditions in the Precambrian geologic record.