Publications by authors named "Joshua M Feinberg"

11 Publications

  • Page 1 of 1

The effects of dislocations on crystallographic twins and domain wall motion in magnetite at the Verwey transition.

Earth Planets Space 2019 15;71(1). Epub 2019 Jan 15.

5Marine, Earth, and Atmospheric Sciences, North Carolina State University at Raleigh, 2800 Faucette Drive, Raleigh, NC 27695 USA.

Pure magnetite experiences a first-order phase transition (the Verwey transition) near 120-125 K wherein the mineral's symmetry changes from cubic to monoclinic. This transformation results in the formation of fine-scale crystallographic twins and is accompanied by a profound change in magnetic properties. The Verwey transition is critical to a variety of applications in environmental magnetism and paleomagnetism because its expression is diagnostic for the presence of stoichiometric (or nearly stoichiometric) magnetite and cycling through the Verwey transition tends to remove the majority of multidomain magnetic remanence. Internal and external stresses demonstrably affect the onset of the Verwey transition. Dislocations create localized internal stress fields and have been cited as a possible source of an altered Verwey transition in deformed samples. To further investigate this behavior, a laboratory-deformed magnetite sample was examined inside a transmission electron microscope as it was cooled through the Verwey transition. Operating the microscope in the Fresnel mode of Lorentz microscopy enabled imaging of the interactions between dislocations, magnetic domain walls, and low-temperature crystallographic twin formation during the phase transition. To relate the observed changes to more readily measurable bulk sample magnetic behavior, low-temperature magnetic measurements were also taken using SQUID magnetometry. This study allows us, for the first time, to observe the Verwey transition in a defect-rich area. Dislocations, and their associated stress fields, impede the development of monoclinic magnetite twin structures during the phase transition and increase the remanence of a magnetite sample after cooling and warming through the Verwey transition.
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http://dx.doi.org/10.1186/s40623-018-0981-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6383955PMC
January 2019

Atmospheric C/C changes during the last glacial period from Hulu Cave.

Science 2018 12;362(6420):1293-1297

Institute of Global Environmental Change, Xi'an Jiaotong University, China.

Paired measurements of C/C and Th ages from two Hulu Cave stalagmites complete a precise record of atmospheric C covering the full range of the C dating method (~54,000 years). Over the last glacial period, atmospheric C/C ranges from values similar to modern values to values 1.70 times higher (42,000 to 39,000 years ago). The latter correspond to C ages 5200 years less than calibrated ages and correlate with the Laschamp geomagnetic excursion followed by Heinrich Stadial 4. Millennial-scale variations are largely attributable to Earth's magnetic field changes and in part to climate-related changes in the oceanic carbon cycle. A progressive shift to lower C/C values between 25,000 and 11,000 years ago is likely related, in part, to progressively increasing ocean ventilation rates.
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http://dx.doi.org/10.1126/science.aau0747DOI Listing
December 2018

Speleothem record of geomagnetic South Atlantic Anomaly recurrence.

Proc Natl Acad Sci U S A 2018 12 10;115(52):13198-13203. Epub 2018 Dec 10.

Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455.

The diminishing strength of the Earth's magnetic dipole over recent millennia is accompanied by the increasing prominence of the geomagnetic South Atlantic Anomaly (SAA), which spreads over the South Atlantic Ocean and South America. The longevity of this feature at millennial timescales is elusive because of the scarcity of continuous geomagnetic data for the region. Here, we report a unique geomagnetic record for the last ∼1500 y that combines the data of two well-dated stalagmites from Pau d'Alho cave, located close to the present-day minimum of the anomaly in central South America. Magnetic directions and relative paleointensity data for both stalagmites are generally consistent and agree with historical data from the last 500 y. Before 1500 CE, the data adhere to the geomagnetic model ARCH3K.1, which is derived solely from archeomagnetic data. Our observations indicate rapid directional variations (>0.1°/y) from approximately 860 to 960 CE and approximately 1450 to 1750 CE. A similar pattern of rapid directional variation observed from South Africa precedes the South American record by 224 ± 50 y. These results confirm that fast geomagnetic field variations linked to the SAA are a recurrent feature in the region. We develop synthetic models of reversed magnetic flux patches at the core-mantle boundary and calculate their expression at the Earth's surface. The models that qualitatively resemble the observational data involve westward (and southward) migration of midlatitude patches, combined with their expansion and intensification.
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http://dx.doi.org/10.1073/pnas.1809197115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6310861PMC
December 2018

Response of pedogenic magnetite to changing vegetation in soils developed under uniform climate, topography, and parent material.

Sci Rep 2017 12 14;7(1):17575. Epub 2017 Dec 14.

Department of Soil, Water, and Climate, University of Minnesota, Saint Paul, MN, 55108, USA.

Pedogenesis produces fine-grained magnetic minerals that record important information about the ambient climatic conditions present during soil formation. Yet, differentiating the compounding effects of non-climate soil forming factors is a nontrivial challenge that must be overcome to establish soil magnetism as a trusted paleoenvironmental tool. Here, we isolate the influence of vegetation by investigating magnetic properties of soils developing under uniform climate, topography, and parent material but changing vegetation along the forest-prairie ecotone in NW Minnesota. Greater absolute magnetic enhancement in prairie soils is related to some combination of increased production of pedogenic magnetite in prairie soils, increased deposition of detrital magnetite in prairies from eolian processes, or increased dissolution of fine-grained magnetite in forest soils due to increased soil moisture and lower pH. Yet, grain-size specific magnetic properties associated with pedogenesis, for example relative frequency dependence of susceptibility and the ratio of anhysteretic to isothermal remanent magnetization, are insensitive to changing vegetation. Further, quantitative unmixing methods support a fraction of fine-grained pedogenic magnetite that is highly consistent. Together, our findings support climate as a primary control on magnetite production in soils, while demonstrating how careful decomposition of bulk magnetic properties is necessary for proper interpretation of environmental magnetic data.
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http://dx.doi.org/10.1038/s41598-017-17722-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5730611PMC
December 2017

Holocene ENSO-related cyclic storms recorded by magnetic minerals in speleothems of central China.

Proc Natl Acad Sci U S A 2017 01 17;114(5):852-857. Epub 2017 Jan 17.

Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an 710049, China.

Extreme hydrologic events such as storms and floods have the potential to severely impact modern human society. However, the frequency of storms and their underlying mechanisms are limited by a paucity of suitable proxies, especially in inland areas. Here we present a record of speleothem magnetic minerals to reconstruct paleoprecipitation, including storms, in the eastern Asian monsoon area over the last 8.6 ky. The geophysical parameter IRM represents the flux of soil-derived magnetic minerals preserved in stalagmite HS4, which we correlate with rainfall amount and intensity. IRM exhibits relatively higher values before 6.7 ky and after 3.4 ky and lower values in the intervening period, consistent with regional hydrological changes observed in independent records. Abrupt enhancements in the flux of pedogenic magnetite in the stalagmite agree well with the timing of known regional paleofloods and with equatorial El Niño-Southern Oscillation (ENSO) patterns, documenting the occurrence of ENSO-related storms in the Holocene. Spectral power analyses reveal that the storms occur on a significant 500-y cycle, coincident with periodic solar activity and ENSO variance, showing that reinforced (subdued) storms in central China correspond to reduced (increased) solar activity and amplified (damped) ENSO. Thus, the magnetic minerals in speleothem HS4 preserve a record of the cyclic storms controlled by the coupled atmosphere-oceanic circulation driven by solar activity.
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http://dx.doi.org/10.1073/pnas.1610930114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5293094PMC
January 2017

Pre-Clovis occupation 14,550 years ago at the Page-Ladson site, Florida, and the peopling of the Americas.

Sci Adv 2016 05 13;2(5):e1600375. Epub 2016 May 13.

Aucilla Research Institute Inc., 555 North Jefferson Street, Monticello, FL 32344, USA.

Stone tools and mastodon bones occur in an undisturbed geological context at the Page-Ladson site, Florida. Seventy-one radiocarbon ages show that ~14,550 calendar years ago (cal yr B.P.), people butchered or scavenged a mastodon next to a pond in a bedrock sinkhole within the Aucilla River. This occupation surface was buried by ~4 m of sediment during the late Pleistocene marine transgression, which also left the site submerged. Sporormiella and other proxy evidence from the sediments indicate that hunter-gatherers along the Gulf Coastal Plain coexisted with and utilized megafauna for ~2000 years before these animals became extinct at ~12,600 cal yr B.P. Page-Ladson expands our understanding of the earliest colonizers of the Americas and human-megafauna interaction before extinction.
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http://dx.doi.org/10.1126/sciadv.1600375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4928949PMC
May 2016

Middle Palaeolithic toolstone procurement behaviors at Lusakert Cave 1, Hrazdan valley, Armenia.

J Hum Evol 2016 Feb 31;91:73-92. Epub 2015 Dec 31.

Department of Anthropology, Old World Archaeology Program, University of Connecticut, 354 Mansfield Road, Unit 1176, Storrs, CT 06269, United States.

Strategies employed by Middle Palaeolithic hominins to acquire lithic raw materials often play key roles in assessing their movements through the landscape, relationships with neighboring groups, and cognitive abilities. It has been argued that a dependence on local resources is a widespread characteristic of the Middle Palaeolithic, but how such behaviors were manifested on the landscape remains unclear. Does an abundance of local toolstone reflect frequent encounters with different outcrops while foraging, or was a particular outcrop favored and preferentially quarried? This study examines such behaviors at a finer geospatial scale than is usually possible, allowing us to investigate hominin movements through the landscape surrounding Lusakert Cave 1 in Armenia. Using our newly developed approach to obsidian magnetic characterization, we test a series of hypotheses regarding the locations where hominins procured toolstone from a volcanic complex adjacent to the site. Our goal is to establish whether the cave's occupants procured local obsidian from preferred outcrops or quarries, secondary deposits of obsidian nodules along a river, or a variety of exposures as encountered while moving through the river valley or across the wider volcanic landscape during the course of foraging activities. As we demonstrate here, it is not the case that one particular outcrop or deposit attracted the cave occupants during the studied time intervals. Nor did they acquire obsidian at random across the landscape. Instead, our analyses support the hypothesis that these hominins collected obsidian from outcrops and exposures throughout the adjacent river valley, reflecting the spatial scale of their day-to-day foraging activities. The coincidence of such behaviors within the resource-rich river valley suggests efficient exploitation of a diverse biome during a time interval immediately preceding the Middle to Upper Palaeolithic "transition," the nature and timing of which has yet to be determined for the region.
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http://dx.doi.org/10.1016/j.jhevol.2015.10.008DOI Listing
February 2016

Planetary science. Low-altitude magnetic field measurements by MESSENGER reveal Mercury's ancient crustal field.

Science 2015 May 7;348(6237):892-5. Epub 2015 May 7.

Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA.

Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data.
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http://dx.doi.org/10.1126/science.aaa8720DOI Listing
May 2015

The Buttermilk Creek complex and the origins of Clovis at the Debra L. Friedkin site, Texas.

Science 2011 Mar;331(6024):1599-603

Center for the Study of the First Americans, Departments of Anthropology and Geography, Texas A&M University, College Station, TX 77843-4352, USA.

Compelling archaeological evidence of an occupation older than Clovis (~12.8 to 13.1 thousand years ago) in North America is present at only a few sites, and the stone tool assemblages from these sites are small and varied. The Debra L. Friedkin site, Texas, contains an assemblage of 15,528 artifacts that define the Buttermilk Creek Complex, which stratigraphically underlies a Clovis assemblage and dates between ~13.2 and 15.5 thousand years ago. The Buttermilk Creek Complex confirms the emerging view that people occupied the Americas before Clovis and provides a large artifact assemblage to explore Clovis origins.
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http://dx.doi.org/10.1126/science.1201855DOI Listing
March 2011

Localized magnetic fields in arbitrary directions using patterned nanomagnets.

Nano Lett 2010 May;10(5):1549-53

Cavendish Laboratory, University of Cambridge, Cambridge, U.K.

Control of the local magnetic fields desirable for spintronics and quantum information technology is not well developed. Existing methods produce either moderately small local fields or one field orientation. We present designs of patterned magnetic elements that produce remanent fields of 50 mT (potentially 200 mT) confined to chosen, submicrometer regions in directions perpendicular to an external initializing field. A wide variety of magnetic-field profiles on nanometer scales can be produced with the option of applying electric fields, for example, to move a quantum dot between regions where the magnetic-field direction or strength is different. We have confirmed our modeling by measuring the fields in one design using electron holography.
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http://dx.doi.org/10.1021/nl902949vDOI Listing
May 2010

Geochronology: age of Mexican ash with alleged 'footprints'.

Nature 2005 Dec;438(7068):E7-8

Berkeley Geochronology Center, Berkeley, California 94709, USA.

A report of human footprints preserved in 40,000-year-old volcanic ash near Puebla, Mexico (http://www.royalsoc.ac.uk/exhibit.asp?id=3616&tip=1), was the subject of a press conference that stirred international media attention. If the claims (http://www.mexicanfootprints.co.uk) of Gonzalez et al. are valid, prevailing theories about the timing of human migration into the Americas would need significant revision. Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30+/-0.03 million years old. We conclude that either hominid migration into the Americas occurred very much earlier than previously believed, or that the features in question were not made by humans on recently erupted ash.
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http://dx.doi.org/10.1038/nature04425DOI Listing
December 2005