Thesis advisor: Rudolph Hon / Pleistocene-age terra rossa paleosols are situated on and are intercalated with eolianite and marine carbonate units across the Bermuda Islands. These clay-rich soils were originally thought to the derived from weathering of the volcanic seamount and/or from dissolution of the carbonate units, the paleosols are now believed to be primarily the result of atmospheric dust deposition from Saharan North Africa and the Sahel via long range transport, with some local inputs. If so, these soil units are mixtures of atmospheric deposition during one or more glacial- interglacial cycles. Previous investigations have been conducted on the paleosols to determine their provenance, age, and to identify unique characteristics for island wide mapping. We conducted comprehensive geochemical analyses to determine the degree of chemical weathering and diagenesis, and to identify processes responsible for their formation and development. The paleosols were found to be geochemically similar across all ages, and to show an increased degree of alteration with age rather than with their duration of subaerial exposure, indicating diagenesis by infiltrating meteoric waters as well subaerial weathering. Evidence of paleosol diagenesis suggests vadose flow across the island may not be limited to preferential pathways and that while flow through the limestones is complex, infiltrating waters appear to have allowed for additional alteration of the soils. In addition to the paleosols, clay-rich deposits with paleosol-like textures were identified during coring operations in Harrington Sound and Hungry Bay, beneath present-day sea level. The source and development histories of these materials were previously unknown. Since these clay deposits are situated beneath present-day sea level it is likely that they were deposited and chemically weathered exclusively during glacial low-sea level climate conditions. Geochemical analyses were conducted on the submarine clay samples to determine if they were related to the above-sea level paleosol and to identify their sources. Major and trace element signatures showed the submarine clay deposits to be chemically similar to the paleosols and to be derived from a similar upper continental crust-like parent. Trace element fingerprinting showed the samples to be derived from a parent similar to that of the paleosols; primarily atmospheric dust with some volcanic contributions. These findings provide additional evidence that trade wind vectors for dust transport were present during Pleistocene glacial climate conditions. Weathering indicators reveal the submarine clay samples to be somewhat less weathered than paleosols of similar age and comparable periods of exposure. Like the paleosols, the submarine clays underwent an initial period of rapid subaerial weathering which suggests warm humid climate conditions during glacial low sea level periods. However, the submarine clays did not experience extended periods of diagenesis, which may explain the somewhat lower degree of weathering. Evidence of inputs from the volcanic platform to the paleosols was limited, but comparisons with shallow volcanic rock and highly weathered volcanic residual known as the Primary Red Clay showed some similarities, suggesting that in-situ chemical weathering of the volcanic platform could produce a laterite with some characteristics similar to the Bermuda paleosols. Geochemical analysis of volcanic sands collected at Whalebone Bay showed the igneous fragments to be a result of mechanical weathering and sorting of heavy refractory minerals and we interpret these sediments to be best described as a beach placer deposit. These materials are enriched in insoluble trace elements and REE, and their contribution to the paleosols is limited. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

No description available.

Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) C-14 analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, USA. We find C-14 age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of C-14 measurements, despite different sources of carbon with likely disparate ages. Such age spectra have not previously been observed in the sedimentary record. Here they indicate vigorous soil carbon turnover prior to burial, which homogenized C-14 ages within SOM across the entire thermochemical spectrum. The weighted bulk C-14 ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate C-14 ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (<<300 years) of carbon in these soils relative to input of allochthonous carbon, indicating that the C-14 age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat C-14 ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea level rise.

The major goal of this study is to define the paleoclimatic conditions in Ankara region during Plio-Pleistocene period by evaluating the mineralogical and geochemical proxies carried from the paleosols and their calcretes. The field observations, mineralogical, micromorphological, geochemical and stable isotope investigations were all conducted to achieve a paleoclimatic approach. As pedogenic minerals in calcretes, presence of dolomite with palygorskite in the Karahamzali section and calcite with palygorskite in the Bala section together with high salinity and calcification values reveal the semi-arid and dry climatic conditions. The geochemical signatures of the paleosols are consistent with each other indicating low clastic input during the dry seasons favouring the formation of calcretes. The &delta / 13C and &delta / 18O values indicate the formation of calcretes from percolating soil-water under predominantly C4 to C3:C4 association type vegetation. Temperature calculations show that paleoclimatic conditions favouring the formation of calcretes in the region are semi-arid and seasonally dry with approximately 25&deg / C soil depositional temperature. This study is the first to give both a radiometric age data to the calcretes of Central Anatolia, Ankara and document their stable isotope compositions. Dated calcretes having ESR ages of 419&plusmn / 69ka and 761 &plusmn / 120ka point the formation during Middle Pleistocene when Mid-Brunches Event (MBE) was happened and the periodicity changed affecting the climatic control over the European continent. Like the Mediterranean calcretes, this study suggests that calcretes in the study area started to develop with MBE warmth between Marine Isotope Stages of 13- 11 and 19-17.

No description available.

Made available in DSpace on 2017-07-10T17:30:33Z (GMT). No. of bitstreams: 1 Andressa_Fachin.pdf: 7147263 bytes, checksum: c3f02dba66f39392f3087baf7f763360 (MD5) Previous issue date: 2013-12-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis presents the paleovalley head evolution in the Chopinzinho drainage basin inside Araucária Plateau (Planation Surface 2), aiming to understand the landscape evolution in the South Brazil during the Upper Quaternary. The stratigraphic record was characterized using the combined criteria of pedo-, litho-, allo-, and cronostratigraphic, for which chronology was establish by 14C (AMS) and thermoluminescence. As base these criteria was utilized following technical: field survey, laboratory analyses (textural, ten major oxides more zirconium oxide, clay mineralogy, and dating) and office work (cluster statistical analysis and organization of date). It has been done the reconstitution spatial distribution of the paleosol and paleogullies by drilling. The field survey showed stratigraphic section in the cutting rural road. Therein was identified paleosol with Ab horizon (27.36 + 0.14 Kyr BP 44.13 Kyr cal. BP), paleogullies field of colluvium (15 beds), colluvium-alluvial (4 beds) and alluvial (1 bed). The colluvium beds was divided into clogging faces and ramp faces. The paleogullies were generated in Last Glacial Maximum (< 24 Kyr to > 17 Kyr BP.) and in Medium Holocene (< 7 Kyr to > 4 Kyr BP). This last moment were generated two paleogullies generations promoting the larger erosion phenomenon in the paleovalley head. The paleovalley head happens to be clogging in the Upper Holocene (< 4 Kyr BP) and change of the morphology becoming colluvium ramp. The palleovalley head was eroded by spot drainage and becoming one convex mound in the end of period. This moment there was one inversion of the relief. / Esta dissertação apresenta a evolução de uma paleocabeceira de drenagem no Planalto das Araucárias (Superfície 2),buscando contribuir para o entendimento do Quaternário Tardio do Sul do Brasil. O registro estratigráfico foi caracterizado utilizando-se dos critérios conjugados da pedo-, lito-, alo- e cronoestratigrafia, cuja cronologia foi estabelecida pelo 14C (AMS) e termoluminescência (TL). Com base nesses critérios foram utilizadas as seguintes técnicas: levantamento de campo, análises laboratoriais (granulométrica, análise química dos 10 principais óxidos + Zircônio,mineralogia da fração argila e ainda datações por 14C e luminescência) e trabalho de gabinete (análise estatística por similaridade Cluster e organização dos dados). Foi feita a reconstituição da distribuição espacial do paleossolo e das paleovoçorocas por meio de sondagens. O levantamento de campo revelou seção estratigráfica exposta em corte de estrada. Nela identificou-se: paleossolo com horizonte A húmico (27.360 + 140 anos AP. 44.130 cal. AP.), paleovoçorocas colmatadas por colúvios (15 camadas), colúvio-alúvio (4 camadas) e alúvios (1 camada). As camadas colúviais foram subdivididas em fácies de colmatação e fácies de rampa.As paleovoçorocas foram geradas no Último Máximo Glacial (< 24.000 a> 17.000 anos AP) e no Holocêno Médio (< 7.000 anos a > 4.000 anos AP). Neste último período foram geradas duas gerações de paleovoçorocas, promovendo o maior fenômeno erosivo na cabeceira de drenagem. A paleocabeceira de drenagem passa a ser colmatada no Holoceno Superior (< 4.000 anos AP) e muda de morfologia para rampa de colúvio. No final desse período, a rampa de colúvio é dissecada pela drenagem local e torna-se uma colina convexa. Nessafasehouveumainversão de relevo.

Made available in DSpace on 2017-05-12T14:42:07Z (GMT). No. of bitstreams: 1 Andressa_Fachin.pdf: 7147263 bytes, checksum: c3f02dba66f39392f3087baf7f763360 (MD5) Previous issue date: 2013-12-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This thesis presents the paleovalley head evolution in the Chopinzinho drainage basin inside Araucária Plateau (Planation Surface 2), aiming to understand the landscape evolution in the South Brazil during the Upper Quaternary. The stratigraphic record was characterized using the combined criteria of pedo-, litho-, allo-, and cronostratigraphic, for which chronology was establish by 14C (AMS) and thermoluminescence. As base these criteria was utilized following technical: field survey, laboratory analyses (textural, ten major oxides more zirconium oxide, clay mineralogy, and dating) and office work (cluster statistical analysis and organization of date). It has been done the reconstitution spatial distribution of the paleosol and paleogullies by drilling. The field survey showed stratigraphic section in the cutting rural road. Therein was identified paleosol with Ab horizon (27.36 + 0.14 Kyr BP 44.13 Kyr cal. BP), paleogullies field of colluvium (15 beds), colluvium-alluvial (4 beds) and alluvial (1 bed). The colluvium beds was divided into clogging faces and ramp faces. The paleogullies were generated in Last Glacial Maximum (< 24 Kyr to > 17 Kyr BP.) and in Medium Holocene (< 7 Kyr to > 4 Kyr BP). This last moment were generated two paleogullies generations promoting the larger erosion phenomenon in the paleovalley head. The paleovalley head happens to be clogging in the Upper Holocene (< 4 Kyr BP) and change of the morphology becoming colluvium ramp. The palleovalley head was eroded by spot drainage and becoming one convex mound in the end of period. This moment there was one inversion of the relief. / Esta dissertação apresenta a evolução de uma paleocabeceira de drenagem no Planalto das Araucárias (Superfície 2),buscando contribuir para o entendimento do Quaternário Tardio do Sul do Brasil. O registro estratigráfico foi caracterizado utilizando-se dos critérios conjugados da pedo-, lito-, alo- e cronoestratigrafia, cuja cronologia foi estabelecida pelo 14C (AMS) e termoluminescência (TL). Com base nesses critérios foram utilizadas as seguintes técnicas: levantamento de campo, análises laboratoriais (granulométrica, análise química dos 10 principais óxidos + Zircônio,mineralogia da fração argila e ainda datações por 14C e luminescência) e trabalho de gabinete (análise estatística por similaridade Cluster e organização dos dados). Foi feita a reconstituição da distribuição espacial do paleossolo e das paleovoçorocas por meio de sondagens. O levantamento de campo revelou seção estratigráfica exposta em corte de estrada. Nela identificou-se: paleossolo com horizonte A húmico (27.360 + 140 anos AP. 44.130 cal. AP.), paleovoçorocas colmatadas por colúvios (15 camadas), colúvio-alúvio (4 camadas) e alúvios (1 camada). As camadas colúviais foram subdivididas em fácies de colmatação e fácies de rampa.As paleovoçorocas foram geradas no Último Máximo Glacial (< 24.000 a> 17.000 anos AP) e no Holocêno Médio (< 7.000 anos a > 4.000 anos AP). Neste último período foram geradas duas gerações de paleovoçorocas, promovendo o maior fenômeno erosivo na cabeceira de drenagem. A paleocabeceira de drenagem passa a ser colmatada no Holoceno Superior (< 4.000 anos AP) e muda de morfologia para rampa de colúvio. No final desse período, a rampa de colúvio é dissecada pela drenagem local e torna-se uma colina convexa. Nessafasehouveumainversão de relevo.

Ancient DNA (aDNA) is a useful tool for retrospective paleoenvironmental studies. Paleosols formed in Arctic environments constitute a potential archive of aDNA from terrestrial organisms living in past environments, given that the cold and dry climate prevailing at high latitudes favors DNA preservation and hamper post-depositional mobility of deposited fragments. However, to what extent aDNA is preserved in old buried soil layers (paleosol layers) are not well known. This study asses to what extent DNA older than 100 years is present in a paleosol profile from southwest Greenland. My main hypothesis was that aDNA from both plants and animals could be extracted from old buried soil layers. I found that oldest studied soil layers were more than 800 B.P. yr old. These old layers contained DNA from both plants and animals. The clean sampling protocol used showed no signs of contamination, suggesting that the DNA was from soil layers and not from modern contaminants. I conclude that my hypothesis seems valid and that a majority of the analyzed plant and animal DNA is ancient. Indeed, aDNA could be used to infer species presence in past paleoenvironments and widen our knowledge regarding how Arctic organism coped with climatic perturbations and thus, improve our understanding how they will respond to future climatic change.

Pleistocene loess-palaeosol sequences provide a unique proxy-record enabling detailed reconstruction of Quaternary palaeoenvironments. Environmental magnetic methods are often used to read the natural archives. The loess-palaeosol sequences exposed in two sections located in southern Moravia and a sequence from central Bohemia were studied in a frame of this Diploma Thesis. Variations of bulk magnetic susceptibility, measured in the sediments, show similar pattern as in the Chinese loess-palaeosol bodies - i.e. palaeosols reveal higher magnetic susceptibility in comparison with loess due to magnetic enhancement. The magnetic enhancement is driven by weathering during pedogenic processes related to the formation of ultra-fine magnetite particles. The magnetite content is controlling the sediment magnetic behavior. The magnetic enhancement rate indicates more intense pedogenic processes in the Moravia in comparison with Bohemia. Magnetic fabric in studied loess, represented by space orientation of anisotropy of magnetic susceptibility ellipsoid, indicates dominating glacial wind palaeocurrents across the southern Moravia blowing from W or SW, respectively. The magnetic fabric in the central Bohemian sequence has revealed a dominant control of running water and re-deposition of the loess material...

This diploma thesis deals with the research of primary and secondary magnetic fabric of aeolian loess sediments and paleosols on the cross-section temporary cropping out during the construction work in Prague 6. Magnetic enrichment - and the formation of magnetic nanoparticles in soil horizons - occurs during pedogenesis in warmer interglacials periods. The aim of this work is the interpretation of the paleoenvironment, weathering and pedogenic processes, by measuring the magnetic properties of sediments. Magnetic susceptibility, frequency-dependent magnetic susceptibility, anhysteresis remanent magnetization and natural remanent magnetization are used to detect the increased occurrence of magnetic particles, which indicate these pedogenic processes. The most developed paleosol horizon within the cross-section was the horizon of black soil and subsoil brown soil. Small signs of pedogenesis were revealed in the upper and lower loess part of the section. The magnetic fabric of loess, measured by means of anisotropy of magnetic susceptibility, reflects secondary sedimentary processes. This involves the displacement of clastic particles by flowing water and the redeposition of the material along the slope. The direction of movement of these sediments corresponds to the current geomorphology of the...