Relative Dating Technique Research Articles

A humification-based method toward refining Holocene radiocarbon chronologies: Wetland records from southeastern China

Holocene paleoclimate reconstructions and comparisons largely rely on accurate age-depth modeling. However, uncertainties in chronology, such as those caused by sparse radiocarbon dates, will hamper inter-core comparisons and correlations, and might result in misleading “cause and consequence” conclusions. This study aimed to find a solution to increase the comparability and minimize the uncertainty of wetland chronology as much as possible. Sediment cores were recovered and radiocarbon dated from the Lianhuachi wetland located in Southeastern China. Humification degree and loss-on-ignition (LOI) were determined using colorimetric and combustion methods respectively. Our data were compared with previously published datasets obtained in the same wetland. The results show that independent humification profiles from the Lianhuachi wetland displayed high similarities. This high similarity between the humification profiles allowed us to transfer radiocarbon ages from one core to another using sequence slotting correlation. Applying the humification-based chronology refinement method to all sediment cores resulted in an improvement in the correlation coefficients between the same but independently measured proxy sequences from the wetland, which suggests both the inter- and intra-core comparability was improved. Because determining peat humification degree is easy, inexpensive, and time-saving, we suggest that humification can serve as a tool that can be used to correlate different cores and to transfer published radiocarbon ages within the same wetland (peatland) or in a comparable geological setting, to establish a more robust chronology of these comparable cores. The degree of peat humification can thus serve as a relative dating technique to refine the chronology of wetland (including peatland) records.

A test of the pseudo-Thellier technique for determining relative palaeointensity in the Tirna Basin, Osmanabad, Maharashtra, India

Abstract A relative palaeointensity determination was obtained using the pseudo-Thellier technique on sediment from Ther, Tirna Basin, Latu-Osmanabad District, Maharashtra, India. The stability of the natural remanent magnetization was investigated by alternating field (AF) demagnetization. Rock magnetic studies suggest that the main carriers of magnetization are ferrimagnetic minerals, predominantly pseudo-single-domain magnetite. To varying degrees, the smoothed palaeoinclination and palaeodeclination patterns of the Tirna Basin are similar to other Asian palaeosecular variation records CALS3k.4, CALS10k.1 and SED3k.1, with an age offset. Measurements of intensity of the natural remanent magnetization left after AF demagnetization v. intensity of anhysteric remanent magnetization gained at the same peak were carried out on a set of samples. A jackknife re-sampling scheme provides error estimates for the palaeointensity. A good agreement pattern can be observed between the Tirna Basin relative palaeointensity proxy and other global curves with an age shift. Although some temporal offsets of palaeointensity features between different records have been recognized, their similar shape suggests that the palaeointensity can give a globally coherent signal and may be used as a relative dating technique. For the first time, relative palaeointensity data for the past 2 kyr from India is presented here, which complement the existing archaeological records but with an additional input.

A new method for enamel amino acid racemization dating: A closed system approach

Abstract Analysis of the predictable breakdown of proteins and amino acids in ancient biominerals enables age estimation over the Quaternary. We postulate that enamel is a suitable biomineral for the long-term survival of endogenous amino acids. Analysis of multiple amino acids for geochronological studies is typically achieved using a RP-HPLC method. However, the low concentrations of amino acids coupled with high concentrations of inorganic species make accurate determination of amino concentrations challenging. We have developed a method for the routine preparation of multiple enamel samples using biphasic separation. Furthermore, we have shown that amino acids that exhibit effectively closed system behaviour can be isolated from enamel through an exposure time of 72 h to bleach. Elevated temperature experiments investigating the processes of intra-crystalline protein degradation (IcPD) do not appear to match the patterns from fossil samples, reinforcing the need for a comprehensive understanding of the underlying mechanisms of protein degradation. This novel preparative method isolates intra-crystalline amino acids suitable for the development of mammalian geochronologies based on enamel protein degradation. The lower rates of racemization in enamel (cf. Bithynia opercula) suggest that the enamel AAR may be able to be used as a relative dating technique over time scales >2.8 Ma. Enamel AAR has the potential to directly date mammalian remains past the limit of all other current direct dating methods, providing an invaluable tool for geochronological studies.

Re-evaluation of the ages of 40Ar/39Ar sanidine standards and supereruptions in the western U.S. using a Noblesse multi-collector mass spectrometer

The rewards from resolving the tempo of magmatic, paleobiologic, paleoclimatic, and tectonic processes at better than the per mil level of precision have spurred a quest within the geochronology community to improve the precision, accuracy, and calibration of several chronometers, including the 40Ar/39Ar variant of the K-Ar clock. A new generation of multi-collector mass spectrometers for 40Ar/39Ar geochronology provides the means to address these issues, as well as to evaluate the ages of 40Ar/39Ar standards and key marker horizons deposited by large volume, caldera-forming supereruptions in the western U.S. at unprecedented temporal resolution. We highlight the utility of a 5-collector Noblesse mass spectrometer that has a sufficiently high mass resolving power to distinguish 36Ar+H35Cl from a 36Ar+H35Cl+12C3 sum peak at m/e 36, maintains a remarkably low and stable background, and thus yields 40Ar/39Ar dates of exceptionally high precision. We have calibrated a reference gas and developed a simple analytical routine involving one peak hop, both of which are used to evaluate detector-bias correction factors. Because the 40Ar/39Ar chronometer is a relative dating technique that relies on calibration against mineral standards of known age, precise and accurate determination of the ages of these standards, and verification of isotopic composition and homogeneity, is essential. We present results from both total fusion and incremental heating experiments on single crystals of the widely used Alder Creek (ACs) and Fish Canyon (FCs) sanidine standards. Several recent, independent, measurements of ACs using multi-collector mass spectrometers, including those presented herein, favor an age of 1.1864±0.0003/0.0012Ma (95% confidence analytical/full external uncertainty), that is >1% younger than the widely used value obtained by Nomade et al. (2005) using a single collector mass spectrometer. Incremental-heating experiments on single crystals of FCs most commonly do not yield plateau ages, instead many crystals appear to be affected by Ar loss or excess Ar. Our findings, obtained using ion counters, independently confirm those recently obtained using a multiple-Faraday detectors or a combination of Faraday and ion counting detectors. Thus, careful consideration must be given to using FCs in future high-precision 40Ar/39Ar calibrations of the geologic timescale. Notwithstanding, 40Ar/39Ar dating of sanidine using the 5- collector Noblesse can now provide leverage critical to interpreting the large range of U–Pb zircon dates commonly found in rhyolitic lavas and tuffs.

Application of the Handysurf E-35B electronic profilometer for the study of weathering micro-relief in glacier forelands in SE Iceland

AbstractThis article presents the results of weathering micro-roughness measurements performed with the use of a Handy-surf E-35B electronic profilometer, a new tool in geomorphological studies. Measurements were performed on glacially abraded basaltic surfaces within the Little Ice Age (LIA) glacial forelands of Hoffelsjökull, Fláajökull, Skálafellsjökull and Virkisjökull in Iceland. Results show a statistical increase in micro-roughness in a direction from the glacial termini to LIA moraines. However, a major change in the micro-roughness of basaltic surfaces only occurs during the first 80 to 100 years since the onset of subaerial weathering. Increase in rock surface micro-roughness is accompanied by an increase in weathering rind thickness and a decrease in Schmidt hammer R-values. Micro-roughness measurements with the use of the Handysurf E-35B can provide insights into initial rates of rock surface micro-relief development. The use of this instrument as a relative dating technique is limited to fine-grained rocks and decadal time-scales of weathering because of the limited range of measureable micro-relief amplitude.

Viable paleosol microorganisms, paleoclimatic reconstruction, and relative dating in archaeology: a test case from Hell Gap, Wyoming, USA

Living soil microorganisms are ubiquitous and could provide unrealized contributions to paleoenvironmental, dating, and other archaeological research. We evaluated the effectiveness of a previously proposed microbiological technique for paleoclimatic reconstruction (which has been applied but not adequately verified), and also introduced and tested a preliminary method of using soil microbe density for relative dating. Soils from a sample column representing a complete chronosequence at Hell Gap, Locality I, Wyoming, were cultured on three different solid media. To test the paleoclimatic reconstruction method, trophic group data were tested for serial correlation and compared to soil and phytolith analyses formerly completed at the site. Microbial trophic group composition significantly correlated to soil pH, but not to prior precipitation reconstructions. Further refinement is required before the paleoclimatic reconstruction method can be implemented with confidence. Additionally, microbial density decreased with age, suggesting a temporal signature within the sample column and that density could potentially be used as a relative dating technique.

Further Evaluation of Fluoride Dating by Ion Selective Electrode Analysis

Fluoride dating by ion selective electrode (ISE) analysis is a viable relative dating technique for dense cortical bone from archaeological sites. The fluoride content of cortical bone and rate of absorption is directly related to the porosity and microstructure of the sample and post-depositional environmental variables including the CaF2 content of the bedrock, soil, and changes in groundwater levels, flow rates, and chemical composition. Dense diaphyseal cortical bone from homogenous sediment contexts exposed to consistent groundwater chemistry through time is the best sample for fluoride dating by the ISE technique. Teeth should not be used as samples for fluoride dating because differences in the porosity and permeability of enamel can produce wide variations in composition.

A Comparison of Radiocarbon and Archaeomagnetic Dating from an Archaeological Site in Spain

Reference archaeomagnetic secular variation (SV) curves recently have been proposed for the Iberian Peninsula and may now be used for archaeomagnetic dating. Archaeomagnetic dating is a relative dating technique that is strongly dependent on the age control of the data used to construct the reference curves. In order to test the method, an archaeological structure from central Spain has been studied. Samples have been taken for both archaeomagnetic and radiocarbon dating, and the results are compared. Close agreement is observed between both techniques, with the archaeomagnetic age of AD 603–999 overlapping the calibrated age of AD 770–890. These results demonstrate the reliability of the proposed reference curves as a dating tool within the Iberian Peninsula during this archaeological period.

Geomagnetic field intensity changes in Sweden between 9000 and 450 cal BP: extending the record of “archaeomagnetic jerks” by means of lake sediments and the pseudo-Thellier technique

The pseudo-Thellier technique was applied to recover relative palaeointensity (PT-RPI) estimates from four piston cores retrieved from a Holocene lake sediment sequence in the province of Småland, central southern Sweden. A time–depth model between 11,000 and 450 cal BP was based on a combination of calibrated radiocarbon ages and the ages of established palaeomagnetic secular variation (PSV) features that were transferred from a varve-dated regional master curve. In Fennoscandia, significant peaks in geomagnetic field intensity occurred at ∼8400, ∼6400, 3900 and 2800 cal BP. The maximum field intensity at 2800 cal BP was associated with the most rapid change in the direction of the geomagnetic vector. While the high-resolution sedimentary data show that significant century scale increases and decreases in relative field intensity between 4000 and 2000 cal BP were associated with abrupt changes (jerks) in the direction of the geomagnetic vector, archaeomagnetic jerks younger than 2000 years were not reproduced in this multiple sediment core study. On the other hand, the PT-RPI reconstructions display century to millennial scale trends between 5000 and 450 cal BP that are coherent with archaeomagnetic data sets from western Europe and Central Asia. This agreement indicates that palaeointensity may be used as a relative dating technique across this region. Fennoscandian PSV and RPI records for the earlier Holocene do not show the same rapid style of vector movement, which suggests that northern Europe has been affected by a more turbulent geodynamo since ∼4000 cal BP.

Magnetic susceptibility applied as an age–depth–climate relative dating technique using sediments from Scladina Cave, a Late Pleistocene cave site in Belgium

Here we demonstrate that magnetic susceptibility (MS) data from Scladina Cave, Belgium, provide a time–depth–climate relationship that is correlated to the marine oxygen isotopic record and thus yields a high-resolution relative dating method for sediments recovered from many archaeological sites. This methodology will help resolve one of the major problems facing archaeologists, namely the difficulty of acquiring absolute dates with reasonable precision for the period from 40,000 to 400,000 years or so. The problem is that dating techniques applicable to most materials within this age range are subject to significant errors. Relative dating techniques, such as magnetic secular variation or stable isotope methods, offer the potential to improve this precision, but both methods suffer from problems that make broad application to many sites impossible. However, for most archaeological cave sites, MS measurements of cave sediments offers the potential for intra-site correlation and paleoclimate estimation. This is possible in protected cave environments because the MS of cave sediments results from climate processes active outside caves, which cause variations in magnetic properties of the sediments that ultimately accumulate inside caves. Once deposited, these materials are often preserved and their stratigraphy provides a time–depth–climate signal that can be identified. Therefore MS data can be used as an independent methodology, alongside conventional methods such as sedimentology and palynology, for relative age dates, and correlation within and between sites by tracing evidence of paleoclimatic change. This correlation has been used to infer an age of 90,000±7000 years for Neanderthal skeletal remains recovered from Scladina Cave, an important Middle Paleolithic archaeological site in Belgium.

Archaeological Evidence for the Origin of the Plank Canoe in North America

Advanced maritime technology associated with long-distance exchange and intensified resource acquisition has been linked to the development of stratification and greater sociopolitical complexity in the Pacific Rim region. One such example is the emergence of hereditary chiefs among the Chumash Indians of southern California. Plank boats owned by an elite group of wealthy individuals and chiefs were an integral part of an elaborate economic system that was based on maritime exchange. An artifact assemblage associated with the construction, maintenance, and use of this watercraft was identified and analyzed. It included wooden planks, asphaltum plugs, asphaltum caulking, and chipped stone drills. Radiocarbon dates and other relative-dating techniques provide strong evidence that the plank canoe originated at least 1,300 years ago in southern California. This represents the earliest use of this type of watercraft in North America and probably in the New World. The timing of this innovation provides evidence that sociopolitical complexity developed in the region at least 500 years earlier than previously proposed.

Relative Dating of Terraces of the Owens River, Northern Owens Valley, California, and Correlation with Moraines of the Sierra Nevada

In the northern Owens Valley, the Owens River has cut and preserved three terraces uplifted above its modern floodplain. We have analyzed soils and used other relative-dating techniques in order to differentiate the terrace surfaces, to correlate from the terraces to moraines of the eastern Sierra Nevada, and to test the effects of relief and climatic differences on relative-dating results. Most of the relative-dating techniques attempted were successful in differentiating the terraces of the Owens River sequence. In addition, weathering rinds, soil descriptions, and an early Holocene 14 C date for the youngest terrace support correlation of the three terrace levels with the three post-Sherwin-age glacial stages (Tioga, Tahoe, and pre-Tahoe) found in nearby canyons of the Sierra Nevada. Other relative-dating techniques that are commonly employed, however, suggest distinct differences between the terrace and moraine sequences. These differences probably reflect the difference in relief, such that slow erosion of the moraine crests may have retarded soil development relative to the flat terrace surfaces and altered surface-weathering processes. Use of relative-dating analyses to correlate between dissimilar geomorphic systems requires caution but use of a broad range of techniques and absolute-age calibration may make correlation possible.

Phosphate Fractionation of Soils at Agroal, Portugal

Eidt (1973, 1977, 1984a) suggested that the analysis of soil phosphate fractions (I-III) could be used to identify land-use areas on archaeological sites as well as serve as a relative-dating technique. He noted that the total inorganic phosphate value (I + II + III) reflects the type and intensity of land-use practice, and he hypothesized that the ratio of Fraction II/I correlates with the time elapsed since soil enrichment. A test of these propositions was carried out in conjunction with the excavations at the settlement of Agroal (Portugal), which was occupied during the Bronze Age (2000-1000 B.C.) and Middle Ages (A.D. 1300-1640). Samples were taken from all archaeological levels of the site as well from soils with known land-use histories in the area of Agroal. Results of this study support Eidt"s two principal hypotheses. First, there was a strong correspondence in the control soils between total phosphate values and the nature of land-use activities. Second, the ratio of Fraction II/I in the archaeological samples did, in fact, correlate with the relative age of the associated artifacts. A model of the site"s land-use history, based on the total inorganic phosphate and the Fraction II/I values, suggests a significant alteration and degradation of the soil landscape during the Bronze Age, as a consequence of agriculture, herding, and refuse disposal, followed by less-intensive use during the Middle Ages.

A Re-Evaluation of Boulderflow as A relative Dating technique For surficial Boulder features

(1988). A Re-Evaluation of Boulderflow as A relative Dating technique For surficial Boulder features. Plains Anthropologist: Vol. 33, No. 119, pp. 113-118.

Reevaluation of Multiparameter Relative Dating Techniques and their Application to the Glacial Sequence Along the Eastern Escarpment of the Sierra Nevada, California

Four valleys, recently studied by other workers, were examined along the eastern Sierra Nevada to refine relative-dating techniques. A variety of weathering parameters and soil properties fail to delineate more than two major post-Sherwin Pleistocene glaciations. We correlate these two glaciations with the Tahoe and Tioga Glaciations. Type Mono Basin Till, usually considered to be pre-Tahoe, exhibits the following weathering similarities with Tahoe Till, if both are under sagebrush: (1) grusification of subsurface granitic boulders; (2) degree of pitting, mineral relief, and rind development on surface granitic boulders; and (3) very slight clay increase in the B horizon. Type Casa Diablo Till also has weathering characteristics similar to Tahoe Till, except a slightly more developed Bt horizon is present. Hence, dates on basalt of 0.126 ± 0.025 and 0.062 ± 0.013 my Casa Diablo Till also has weathering characteristics similar to Tahoe Till, except a slightly more developed Bt horizon is present. Hence, dates on basalt of 0.126 ± 0.025 and 0.062 ± 0.013 my (Bailey et al. 1976), which bracket type Casa Diablo, may provide age control on the Tahoe glaciation. In addition, we are unable to demonstrate that the Tenaya is a separate glaciation. In three of the four valleys studied our weathering data for Tenaya Till are equivalent with those for Tioga Till, but with those for Tahoe Till in the fourth valley. We were not satisfied with our ability to differentiate the Casa Diablo, Mono Basin, and Tenaya as separate glaciations even though data were collected in the type areas for two of these deposits. Reasons for suggesting a change back to a two-fold Tahoe-Tioga glacial sequence, rather than the present five-fold sequence, are that we have measured a greater number of parameters than has been done previously, soils were submitted to detailed laboratory analyses, and surface weathering features were studied under consistent present vegetation cover to avoid possible problems induced by ancient forest fires. Nevertheless our relative-dating scheme does not rule out the possibility of a more detailed glacial sequence.

Effect Of Boulderflow On Soil Transformation Under Tipi Rings

To examine the effect of boulderflow on soil transformation under tipi rings on the prairies, two sites were located with rings of at least two different diameters. Boulderflow, defined as water flowing over a boulder, decreased the pHCaCl2 C and N contents, cation exchange capacity, and exchangeable Ca, and increased extractable C of the soil under the ring boulders. Depth to effervescence with dilute HCI proved to be an excellent and simple relative dating technique to. c?r:npare relative time of being in situ for boulders of t1p1 nngs of various diameters.