Double Dating Research Articles

Changing exhumation patterns during Cenozoic growth and glaciation of the Alaska Range: Insights from detrital thermochronology and geochronology

Cenozoic growth of the Alaska Range created the highest topography in North America, but the space-time pattern and drivers of exhumation are poorly constrained. We analyzed U/Pb and fission-track double dates of detrital zircon and apatite grains from 12 catchments that span a 450 km length of the Alaska Range to illuminate the timing and extent of exhumation during different periods. U/Pb ages indicate a dominant Late Cretaceous to Oligocene plutonic provenance for the detrital grains, with only a small percentage of grains recycled from the Mesozoic and Paleozoic sedimentary cover. Fission-track ages record exhumation during Alaska Range growth and incision and reveal three distinctive patterns. First, initial Oligocene exhumation was focused in the central Alaska Range at ~30 Ma and expanded outward along the entire length of the range until 18 Ma. Oligocene exhumation, coeval with initial Yakutat microplate collision >600 km to the southeast, suggests a far-field response to collision that was localized by the Denali Fault within a weak Mesozoic suture zone. Second, the variable timing of middle to late Miocene exhumation suggests independently evolving histories influenced by local structures. Time-transgressive cooling ages suggest successive rock uplift and erosion of Mounts Foraker (12 Ma) through Denali (6 Ma) as crust was advected through a restraining bend in the Denali Fault and indicate a long-term slip rate ~4 mm/yr. Third, Pliocene exhumation is synchronous (3.7–2.7 Ma) along the length of the Alaska Range but only occurs in high-relief, glacier-covered catchments. Pliocene exhumation may record an acceleration in glacial incision that was coincident with the onset of Northern Hemisphere glaciation.

Exhumation history of the West Kunlun Mountains, northwestern Tibet: Evidence for a long-lived, rejuvenated orogen

How and when the northwestern Tibetan Plateau originated and developed upon pre-existing crustal and topographic features is not well understood. To address this question, we present an integrated analysis of detrital zircon U–Pb and fission-track double dating of Cenozoic synorogenic sediments from the Kekeya and Sanju sections in the southwestern Tarim Basin. These data help establishing a new chronostratigraphic framework for the Sanju section and confirm a recent revision of the chronostratigraphy at Kekeya. Detrital zircon fission-track ages present prominent Triassic–Early Jurassic (∼250–170 Ma) and Early Cretaceous (∼130–100 Ma) static age peaks, and Paleocene–Early Miocene (∼60–21 Ma) to Eocene–Late Miocene (∼39–7 Ma) moving age peaks, representing source exhumation. Triassic–Early Jurassic static peak ages document unroofing of the Kunlun terrane, probably related to the subduction of Paleotethys oceanic lithosphere. In combination with the occurrence of synorogenic sediments on both flanks of the Kunlun terrane, these data suggest that an ancient West Kunlun range had emerged above sea level by Triassic–Early Jurassic times. Early Cretaceous fission-track peak ages are interpreted to document exhumation related to thrusting along the Tam Karaul fault, kinematically correlated to the Main Pamir thrust further west. Widespread Middle–Late Mesozoic crustal shortening and thickening likely enhanced the Early Mesozoic topography. Paleocene–Early Eocene fission-track peak ages are presumably partially reset. Limited regional exhumation indicates that the Early Cenozoic topographic and crustal pattern of the West Kunlun may be largely preserved from the Middle–Late Mesozoic. The Main Pamir–Tam Karaul thrust belt could be a first-order tectonic feature bounding the northwestern margin of the Middle–Late Mesozoic to Early Cenozoic Tibetan Plateau. Toward the Tarim basin, Late Oligocene–Early Miocene steady exhumation at a rate of ∼0.9 km/Myr is likely related to initial thrusting of the Tiklik fault and reactivation of the Tam Karaul thrust. Thrusting together with upper crustal shortening in the mountain front indicates basinward expansion of the West Kunlun orogen at this time. This episode of exhumation and uplift, associated with magmatism across western Tibet, is compatible with a double-sided lithospheric wedge model, primarily driven by breakoff of the Indian crustal slab. Accelerated exhumation of the mountain front at a rate of ∼1.1 km/Myr since ∼15 Ma supports active compressional deformation at the margins of the northwestern Tibetan Plateau. We thus propose that the West Kunlun Mountains are a long-lived topographic unit, dating back to Triassic–Early Jurassic times, and have experienced Middle–Late Mesozoic to Early Cenozoic rejuvenation and Late Oligocene–Miocene expansion.

Loosely Coupled Transformer Structure and Interoperability Study for EV Wireless Charging Systems

As the wireless power transfer (WPT) technology has been proved to be a convenient and reliable charging method to plug-in hybrid electric vehicles and electric vehicles, the loosely coupled transformer structure and size are the primary and fundamental concern to design an efficient WPT system. In this paper, a double D (DD) coil and a unipolar coil are selected to conduct the study. We focus on the coil structure design to achieve the maximum coupling coefficient as well as efficiency with two situations: 1) with no misalignment, and 2) with a 75-mm door-to-door and 100-mm front-to-back misalignment at which the maximum operating capability can still be achieved. A coil size optimization process is proposed for both the DD coil and the unipolar coil configurations. The relationship between the size of the secondary (receiving) coil, which determines the weight of the pad on the vehicle, and achievable maximum efficiency is studied for both coil topologies. The interoperability between the two coil topologies is studied. The proposed transformer structures with aluminum shielding meet human exposure regulations of the International Commission on Non-Ionizing Radiation Protection guidelines as a foundation. Finally, experiments validated the analyses.

On the Syntactic Structure of Double Object and Dative Constructions in English

On the Syntactic Structure of Double Object and Dative Constructions in English

Hierarchical optimization with double due dates on an unbounded parallel-batching machine to minimize maximum lateness

This paper studies a hierarchical optimization problem on an unbounded parallel-batching machine, in which two objective functions are maximum lateness induced by two sets of due dates, representing different purposes of two decision-makers. By a hierarchical optimization problem, we mean the problem of optimizing the secondary criterion under the constraint that the primary criterion is optimized. A parallel-batching machine is a machine that can handle several jobs in a batch in which all jobs start and complete respectively at the same time. We present an $$O(n\log P)$$ -time algorithm and an $$O(n^3)$$ -time algorithm for this hierarchical scheduling problem, where P is the total processing time of all jobs.

Doubled Haploids Technology in Plants

Doubled Haploids Technology in Plants

Evidence of a full West Antarctic Ice Sheet back to the early Oligocene: insight from double dating of detrital apatites in Ross Sea sediments.

AbstractThe West Antarctic Ice Sheet is the most unstable component of the Antarctic cryosphere. Its fluctuations are well documented since the Pliocene, but its behaviour over the last 35 Ma is more controversial, particularly during periods of past high global pCO2 values similar to those predicted in future global climate scenarios. Here, we present new U–Pb dating of detrital apatite grains (previously dated by the fission‐track method) from Cape Roberts Project Oligocene to Pliocene marine sediments in the Ross Sea. Two past ice‐flow patterns were identified: one formed by outlet glaciers sourcing short‐travelled apatites and one, northerly directed, bringing far‐travelled apatite grains. The latter provides the first robust physical evidence for the presence and repeated expansion of an Oligocene West Antarctic Ice Sheet.

Anatomy of collision-type orogen Himalaya by means of U-Pb and FT double dating of zircons

Anatomy of collision-type orogen Himalaya by means of U-Pb and FT double dating of zircons

Basically Doubled: Expecting...and the Unexpected with Diabetes

Kristina and Jonathan Rosa, a couple expecting their second child, provide us with their thoughts on what life is like dealing with pregnancy and diabetes. They were able to share a lot of insights and advice, and leave us with a much better picture of what pregnancy and diabetes is like for both moms and dads.

Detrital zircon U-Pb-He double dating: A method of quantifying long- and short-term exhumation rates in collisional orogens

A U-Pb-He double-dating method is applied to detrital zircons with core-rim structure from the Ganges River in order to determine average short- and long-term exhumation rates for the Himalayas. Long-term rates are calculated from the U/Pb ages of metamorphic rims of the grains that formed during the Himalayan orogeny and their crystallization temperatures, which are calculated from the Ti-in-zircon thermometer. Short-term rates are calculated from (U-Th)/He ages of the grains with appropriate closure temperatures. The results show that short-term rates for the Himalayas, which range from 0.70 ± 0.09 to 2.67 ± 0.40 km/Myr and average 1.75 ± 0.59 (1 σ) km/Myr, are higher and more varied than the long-term rates, which range from 0.84 ± 0.16 to 1.85 ± 0.35 km/Myr and average 1.26 ± 0.25 (1 σ) km/Myr. The differences between the long-term and short-term rates can be attributed to continuous exhumation of the host rocks in different mechanisms in continental collision orogen. The U/Pb ages of 44.0 ± 3.7 to 18.3 ± 0.5 Ma for the zircon rims indicate a protracted episode of ∼25 Myr for regional metamorphism of the host rocks at deeper crust, whereas the (U-Th)/He ages of 42.2 ± 1.8 to 1.3 ± 0.2 Ma for the zircon grains represent a protracted period of ∼40 Myr for exposure of the host rocks to shallower crustal level. In particular, the oldest (U-Th)/He ages of the zircon grains are close to the oldest U/Pb ages for the rims, indicating that some parcels of the rocks that contain zircons were rapidly exhumed from deep to shallow levels in the stage of collisional orogeny. On the other hand, some parcels of the rocks may have been carried upwards by thrust faults in the post-collisional stage. The parcels could be carried upwards by the thrust faults that steepen as they near the surface, or by transient movement faults so that areas of rapid exhumation became areas of slow exhumation and visa versa on a time scale of a few Myr in order to maintain the continuous exhumation. In this regard, the Ganges River must be preferentially sampling areas that are currently undergoing above average rates of uplift.

Determining the Physical Size of Inductive Couplers for IPT EV Systems

Due to increasing environmental concerns and decreasing fossil fuel supplies, electric vehicles (EVs) are fast becoming attractive alternatives to conventional fossil-fuel driven vehicles. Inductive power transfer (IPT) is a method that can be used to transfer power to EVs over an air-gap and can dramatically increase the range, convenience, and safety of EV battery charging. One of the major difficulties is determining the physical sizes of the primary IPT coupler, buried in the roadway, and the EV mounted secondary coupler. This is mainly due to the variation in vehicle classes and charging locations that may be encountered. This paper seeks to determine if suitably sized couplers can be selected, which can realize all these demands. A recently proposed EV charging coupler, known as the Double-D (DD), which has been shown to provide the best power to size ratio over typical expected air gaps is selected. As such a method to select the best design from eight approximately square DD couplers ranging from 300 to 1000 mm in length to meet the challenge of delivering high power over large air-gaps is presented. The performance of these couplers, or power pads, is simulated and the results can be used to select couplers for EV charging systems. A practical design example is presented involving the IPT charging of sedans and SUVs in multiple practical charging locations. The proposed pad sizes and systems are capable of transferring 10 kW to the EVs for realistic horizontal misalignments (±200 mm) and air-gaps (100-400 mm).

Exhumation of the North American Cordillera revealed by multi-dating of Upper Jurassic–Upper Cretaceous foreland basin deposits

New low-temperature thermochronology and geochronology data from Upper Jurassic–Upper Cretaceous strata from the North American Cordilleran foreland basin in Utah, Colorado, Wyoming, and South Dakota document rapid exhumation rates of the adjacent Cordilleran orogenic belt to the west. Both zircon (U-Th-[Sm])/He (zircon He) and apatite fission track (AFT) thermochronology were applied to proximal and distal synorogenic deposits in order to identify a thermochronometer suitable to record source exhumation during the North America Cordilleran orogeny. AFT lag times from Upper Jurassic–Upper Cretaceous deposits are 0–5 m.y. and indicate a relatively steady-state to slightly increasing exhumation rate between 118 Ma and 66 Ma. These lag-time measurements are consistent with active shortening and rapid exhumation rates of ∼0.9–>1 km/m.y. of the North American Cordillera throughout the Cretaceous. Double dating of the detrital AFT samples was performed on apatites with young AFT cooling ages, in order to test whether or not the young cooling ages represent a signal related to exhumation rather than volcanic activity. Maximum depositional ages using detrital zircon U-Pb geochronology match existing ages on basin stratigraphy. This study indicates that AFT is the most effective thermochronometer to resolve source exhumation from Lower to Upper Cretaceous foreland stratigraphy in the central Cordilleran foreland, and indicates that source material was exhumed from 4 to 5 km depths but was never buried more than a few kilometers ( 8–9 km. Double dating of apatites (with AFT and U-Pb) shows that volcanic contamination is a significant issue that can, however, be addressed by double dating.

Motivation and expectancy influences in placebo responding: the mediating role of attention.

Drawing upon research in perception and motivation, the current study proposes a motivation-attention model of placebo in which more motivated persons pay greater attention to placebo-related stimuli, directly influencing placebo response. We manipulated both motivation to respond to placebo and expectations of placebo response in a 2 × 2 design. Participants (N = 152) evaluated a series of placebo pheromones (slightly scented water) of potential romantic dates and made desirability ratings. Consistent with hypotheses, more highly motivated participants demonstrated greater placebo responses, as evidenced by higher desirability ratings of the "pheromone" and greater variability among ratings, when compared to less motivated participants. Moreover, the relation between motivation and placebo response was mediated by attention. Contrary to expectations, we found no effect for expectancy. These findings highlight the importance of motivation and the mediating factor of attention in placebo and support goal-oriented models of placebo.

My Personal Tribute to Dr. Mary Ellen Avery

Because my husband was planning to pursue a fellowship in adolescent medicine at Boston Children’s Hospital, I was set to interview there in July of 1974 for a third year of pediatric training. I was just starting my second year of pediatrics in Los Angeles and had been focusing more on the mechanics of completing pediatric training than on choosing a fellowship. Dr. Mary Ellen Avery had just become Children’s Physician-in-Chief. In fact, she was still finding her way about the place, both physically and professionally. It was my second interview, the first resulting in less than positive news about the possibility of my obtaining a senior pediatric residency for the coming year. She did not let me be discouraged, made it known that she would welcome me there, and suggested I could pursue the start of a fellowship before completing my full pediatric training. What type of fellowship? I certainly hadn’t spent much time contemplating this. How about neonatology, she suggested, and immediately arranged for me to see Dr. Bill Taeusch, newly appointed Neonatology Division Director. So serendipity, and more importantly, Dr. Mel Avery are responsible for my career in neonatology: I joined the first official JPN fellows’ group that started training in July of 1975. Dr. Avery was a pioneering researcher in the field of neonatology and a great research motivator as well. She had overseen a recent publication associating an increased risk of hyaline membrane disease in infants of diabetic mothers (1). She “shepherded” me into examining this further, thus leading me both to the delivery room to collect infants’ cord blood for C-peptide measurements (2) and into the animal lab with alloxan-diabetic pregnant rabbits and the lung development of their offspring (3–7). I remember her delight when I presented my findings at research meetings and had my first peer-reviewed publications in the New England Journal of Medicine (2) and Journal of Applied Physiology (3). In fact, when I moved on to University of Miami, I continued the line of research looking at lung development in the animal model of the IDM, this time examining pulmonary antioxidant enzyme development in offspring of streptozotocin-treated rats (8). She opened her heart to me not just professionally but socially and personally as well. I remember a cozy Thanksgiving evening when just she, my husband, and I sat by the fire in her Wellesley condo and dined on delicious leftovers from the day. She hosted the two of us to a very special Boston evening: a “double date” with Dr. Fred Rosen for dinner at the Harvard Club and then to hear the Boston Symphony. When I was about to have my first child, she was glowing when I came to her with the news. She wanted to make sure I would be nursing him which of course I was. When he was born, she presented us with a beautifully framed print of a mother rabbit and her pups (how appropriate!) which we hung above his changing table. And once I had successfully established nursing and returned to work, she invited me to write an article with her on the benefits of breast feeding for the Harvard Medical School Health Letter (9). My respect and admiration for Dr. Mary Ellen Avery are without bounds. There is no doubt that Mel brought me into neonatology, fostered my career, and opened her intellect and heart to me many years ago. For this I am eternally grateful.

Late proterozoic A-type granites of the chernorechenskii massif in the Yenisei ridge: New geochemical and geochronological data

The problems in estimation of the geochronologi� cal boundaries in the history of the breakup of the Rodinia Supercontinent are mostly far from their final solution. This is explained by the lack of precise dat� ings, which limits significantly the possibilities of age correlations for global geological processes. Because of this, the problem of geochemical specifics and dat� ing of Neoproterozoic granitoid complexes, i.e., the main components of the continental crust and indica� tors of geodynamic environments of key significance for reconstruction of events in the lithosphere evolu� tion, is still important. Recently new results on the geochemistry and geo� chronology of granitoids from the Yenisei Ridge formed under contrasting geotectonic environments were obtained (1). These crystalline massifs are located in the axial part of the Central cratonic block, mostly in the Tatarsko-Ishimbinskaya suture zone. In this relation, the western part of the Central block composed of rocks of the Garevka metamorphic com� plex (GMC), the oldest in Transangaria, is the least studied. It consists of a number of intrusive massifs located within the Yenisei regional suture zone (YRSZ), the large deformational metamorphic struc� ture of the lineament type separating the Central cra� tonic block and the Isaakovskii islandarc terrane (2). This zone is a continuation of the Baikal-Yenisei fault and located on the left side of the Yenisei River along the western margin of the Siberian Craton for more than 200 km at a width from 50 to 70 km. Because of the absence of reliable geochemical and geochrono� logical data, the problem of the age and tectonic set� ting of these intrusions is debatable. This is especially important for rocks of the Chernorechenskii massif occurring in the composition of the Posol'nenskii and Ayakhtinskii magmatic complexes of various age and origin (3). To resolve these contradictions, we obtained new data on the geochemistry, age, and nature of these granitoids formed under the environment of extension along the western margin of the Siberian Craton. The Chernorechenskii massif (CM) is located in the GMC, on the western flange of the YRSZ charac� terized by contrast metamorphism, intense foliation, and dynamic recrystallization of rocks (4). This massif occurs on the right side of the Yenisei River, in the Raz� gromnaya River basin, and is located in the same tec� tonic zone as small massifs of rapakivitype granites (5) and bimodal complex of granite and basic dykes (2). The intrusive body of a lenslike shape and an area of ≈140 km 2 occurs at large submeridional faults. With account for the geophysical data (3), it is suggested that the massif has subvertical dipping, a "platelike" shape, and tectonic contacts with host rocks. Three main stages with different thermodynamic regimes and values of geothermal gradients are distin� guished in the evolution of western areas of the YRSZ (6). At the first stage related to the Grenville orogeny (1050-850 Ma), zoned lowpressure metamorphic complexes with a gradient of dT/dH = 20-30°C/km typical of orogenesis were formed. At the second stage in the nappe zone, these rocks underwent Late Riph� ean (801-793 Ma) collisional metamorphism of mod� erate pressures with low dT/dH ≤ 10°С/km. The last stage was accompanied by synexhumation metamor� phism (785-776 Ma) with dT/dH ≤ 12°С/km reflect� ing the tectonic environments of rapid uplift in the dis� location-thrust zones of the crust. The final stages of the orogen evolution in the region include the forma� tion of the bimodal dyke belt with an age of 797- 785 Ma intruding gneiss and crystalline schist of the GMC (2). These events are controlled by the processes of extension along the western margin of the Siberian Craton and consistent with the beginning of breakup of the Rodinia Supercontinent. Later a number of rif� togenic troughs and grabens filled by Neoproterozoic

Application of apatite U–Pb and fission-track double dating to determine the preservation potential of magnetite–apatite deposits in the Luzong and Ningwu volcanic basins, eastern China

The Cretaceous Luzong and Ningwu volcanic basins in eastern China contain numerous magnetite–apatite deposits with similar geological characteristics and mineralization ages (~130Ma). These deposits, however, occur at distinctly different burial depths. To explain this difference, LA-ICP-MS apatite U–Pb and fission track double dating of five samples were carried out to establish the thermal histories from crystallization to the exhumation of four representative deposits: the deeply buried Nihe (665–1065m underground) and Luohe deposits (425–856m underground) from the Luzong basin; the shallow Meishan deposit (40–530m underground) and the exposed Dongshan deposit from the Ningwu basin. The cooling histories of the four deposits could be divided into rapid cooling for the Dongshan deposit and slow continuous cooling for the Nihe, Luohe, and Meishan deposits. Combined with geological evidence, it can be determined that the Dongshan and Meishan deposits formed at shallow depths with the Dongshan deposit emplaced at a very high level while the Meishan deposit was emplaced relatively deeper. The Nihe and Luohe deposits were emplaced deeper than the Dongshan and Meishan deposits and the burying of the Shuangmiao volcanic cycle after mineralization increased the burial depth. However, this burial event did not occur in the Ningwu basin. All of these resulted in the different burial of the magnetite–apatite deposits between the two basins prior to 120Ma while the exhumation after 120Ma among these deposits was similarly slow and continuous. The metallogenic conditions of both basins were similar but the smaller number and gross reserve of magnetite–apatite deposits in the Luzong basin, we believe that the Luzong basin has better preservation potential for the magnetite–apatite deposits.

Bias in detrital zircon geochronology and thermochronometry

Detrital studies that utilize zircon U–Pb geochronology and fission-track (FT) thermochronometry are subject to a range of potential sources of bias that should be properly evaluated and minimized. Some of them are common to any single-grain mineral analysis (e.g., variable bedrock mineral fertility, hydraulic sorting during transport, selective grain loss during sample processing), whereas others are intrinsic to zircon, and are related to radiation damage and age discordance. In this article, we quantify the impact of intrinsic bias on detrital studies thanks to the analysis of modern detritus shed from the European Alps, and illustrate the general implications on geological interpretations.We show that detrital zircon U–Pb age distributions based on statistically robust datasets are highly reproducible and representative of the parent bedrock ages in the catchment. Arbitrary or selective removal of discordant grain ages can be minimized by using the Kolmogorov–Smirnov test to identify an appropriate cutoff level. Loss of metamict (α-damaged) zircon has a minor impact on data representativeness, and is mainly controlled by regional metamorphism rather than by mechanical abrasion during river transport. Zircon FT grain-age distributions were found to have poor reproducibility, although age spectra are consistent with bedrock data. However, unlike the U–Pb datasets, U-rich zircon grains (>1000ppm) are systematically missed, and undatable grains may exceed 50%. We identify two major sources of distribution bias specific to zircon FT datasets: (i) sediment sources dominated by U-rich zircon grains are markedly underrepresented in the detrital record, because such grains often have uncountable high densities of fission tracks (“U concentration bias”); (ii) sediment sources that shed zircon grains with high levels of α-damage are underrepresented, because these grains are lost during chemical etching for FT revelation (“etching bias”). In the case of multimethod dating on the same grains (e.g., FT and U–Pb double dating), bias affecting detrital zircon FT dating propagates to the entire dataset. These effects may not impact on exhumation-rate studies that utilize the youngest grain ages (i.e., lag-time approach). However, they represent a limiting factor for conventional provenance studies, and generally preclude application of zircon FT dating to sediment budget calculations.

Erratum: U–Pb and Hf isotopic data from Franklinian Basin strata: insights into the nature of Crockerland and the timing of accretion, Canadian Arctic Islands

New detrital zircon uranium-lead (U-Pb) ages and initial epsilon hafnium (eHf(i)) data from the Devonian clastic succession of the Canadian Arctic Islands refines the provenance of strata within the Franklinian Basin and provides constraints on the geologic evolution of the landmass responsible for the Ellesmerian Orogen. This study contributes more than 500 U-Pb ages and 32 eHf(i) values from the Blackley Formation and the Parry Islands Formation. The Middle Devonian Blackley Formation represents the onset of clastic sedimentation into the Franklinian Basin during the Devonian period. Detrital zircon from two samples yield U-Pb age populations of 380 - 470, 500 -700, 900 -2100, and 2550 -3000 Ma. The population of 500 -700 Ma U-Pb ages indicates a source exotic to the northern Laurentian margin and is attributed to a continental landmass located north of the present Canadian Arctic Islands (often referred to as Crockerland). This is some of the earliest evidence of 500 -700 Ma detrital zircon deposition onto the northern Laurentian margin and indicates this northern landmass is at least partially accreted to Laurentia by early-Eifelian time. The Late Devonian Parry Islands Formation is the uppermost succession of Ellesmerian Orogen foreland basin sedimentation in the Franklinian Basin. Detrital zircon from four samples yield U-Pb age populations of 370 - 450, 470 -750, 930 -2100, and 2300 -3200 Ma. The U-Pb ages suggest the Parry Islands Formation is derived from the northern source terrane (Crockerland) and indicate this landmass contains rocks similar to that of the east Greenland Caledonides, Pearya, and northeastern Baltica. Rim and core U-Pb double dates from the 500 -700 Ma detrital zircon population and eHf(i) values from the 380 - 450, 520 -550, and 650 -710 Ma detrital zircon populations help constrain magma generation processes within Crockerland and suggest the zircons are derived from a juvenile lithosphere.

Short-lived, fast erosional exhumation of the internal western Alps during the late early Oligocene: Constraints from geothermochronology of pro- and retro-side foreland basin sediments

Apatite and zircon fission-track analysis and single zircon fission-track–U/Pb double dating of Oligocene to Miocene pro- and retro-side foreland basin sedimentary rocks provide evidence for short-lived but fast erosional exhumation of at least 1.5–2 km/m.y. in the internal western Alps between ca. 30 and 28 Ma. This period of fast erosion is seen as a result of rapid surface uplift coupled with increasing orographic precipitation during this phase of orogenesis. Surface uplift may have been caused and sustained by different plate-tectonic processes such as a change in convergence direction, intermediate-depth slab breakoff, and emplacement of the Ivrea body during continental collision. The occurrence of contemporaneous volcanic activity on the pro-side of the western Alps on the subducting European plate between ca. 36 Ma and 30 Ma is seen in connection with slab rollback of the Apennine slab and upwelling of hot mantle material beneath the western Alps. Single zircon double dating shows that the exhumational signal in the detrital thermochronologic data is not compromised by volcanically derived zircons, as volcanic grains can be identified and removed from the zircon fission-track data set to obtain a pure exhumational signal. The signal of fast exhumation is observed in the zircon fission-track data of the pro-side foreland basin and in the apatite fission-track data and published 40Ar-39Ar data in the retro-side foreland basin. During late Oligocene times, erosion rates slowed down to rates similar to present-day erosion rates in the western Alps.

Development of a Single-Sided Flux Magnetic Coupler for Electric Vehicle IPT Charging Systems

Inductive power transfer is a practical method for recharging electric vehicles because it is safe, convenient, and reliable. The performance of the magnetic couplers that transfer power determines the overall feasibility of a complete system. Circular couplers are the most common topology in the literature; however, they have fundamentally limited coupling. Their flux patterns necessarily limit the operational air gap as well as tolerance to horizontal misalignment. A new polarized coupler topology [referred to as a double D (DD)] is presented, which overcomes these difficulties. DDs provide a charge zone five times larger than that possible with circular pads for a similar material cost and are smaller. A 0.31-m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> DD enables 2 kW of power transfer over an oval area measuring 540 mm × 800 mm with a 200-mm air gap. Leakage magnetic fields have been investigated and show that circular and DD couplers operating under similar power transfer conditions produce similar levels. Both topologies can be designed and operated to ensure compliance with international guidelines.