Comment on: Mass Fractions of Forty‐Six Major and Trace Elements,Including Rare Earth Elements,in Sediment and Soil Reference Materials Used in Environmental Studies. Fiket et al. (2017), Geostandards and Geoanalytical Research, 41, 123–135     

Vibor Roje 《Geostandards and Geoanalytical Research》2019,43(2):317-327

This paper is intended to be a constructive discussion of Fiket et al. (2017, Geostandards and Geoanalytical Research , 41 , 123–135), who dealt with the determination of major, trace and rare earth elements in several sediment and soil certified reference materials. In the present author's view, the paper by Fiket et al. (2017) suffers from a lack of reference to several publications in which somewhat similar results had already been reported. The present contribution therefore provides a comparison of previously published results with those of Fiket et al. for the CRMs soil NCS DC 77302 (GBW 07410), stream sediment NCS DC 73309 (GBW 07311), marine sediments MESS‐3 and NCS DC 75301 (GBW 07314) and estuarine sediment IAEA‐405. It is argued that this fuller consideration (a) allows critical evaluation of the quality of the results presented by Fiket et al. and (b) highlights the advantages of their work. Finally, attention is drawn to the (possible or real) problems that can arise during simultaneous determination of multiple trace elements.  相似文献   

Tectonic evolution of the West Kunlun Orogenic Belt along the northern margin of the Tibetan Plateau:Implications for the assembly of the Tarim terrane to Gondwana   总被引：2，自引：0，他引：2  

Chuan-Lin Zhang  Hai-Bo Zou  Xian-Tao Ye  Xiang-Yan Chen 《地学前缘(英文版)》2019,10(3):973-988

The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneous rocks and ophiolites distributed mostly along the Xinjiang-Tibet road and the China-Pakistan road, and have constructed a preliminary tectonic model for this orogenic belt. However, few studies have focused on the so-called Precambrian basement in this area. As a result, the tectonic affinity of the individual terranes of the WKOB and their detailed evolution process are uncertain. Here we report new field observations, zircon and monazite U-Pb ages of the "Precambrian basement" of the South Kunlun terrane(SKT) and the Tianshuihai terrane(TSHT), two major terranes in the WKOB. Based on new zircon U-Pb age data, the amphibolite-facies metamorphosed volcanosedimentary sequence within SKT was deposited during the late Neoproterozoic to Cambrian(600-500 Ma), and the flysch-affinity Tianshuihai Group, as the basement of the TSHT, was deposited during the late Neoproterozoic rather than Mesoproterozoic. The rock association of the volcano-sedimentary sequence within SKT suggests a large early Paleozoic accretionary wedge formed by the long-term lowangle southward subduction of the Proto-Tethys Ocean between Tarim and TSHT. The amphibolitefacies metamorphism in SKT occurred at ca. 440 Ma. This ca. 440 Ma metamorphism is genetically related to the closure of the Proto-Tethys Ocean between Tarim and the Tianshuihai terrane, which led to the assembly of Tarim to Eastern Gondwana and the final formation of the Gondwana. Since the late Paleozoic to early Mesozoic, the northward subduction of the Paleo-Tethys Ocean along the HongshihuQiaoertianshan belt produced the voluminous early Mesozoic arc-signature granites along the southern part of NKT-TSHT. The Paleo-Tethys ocean between TSHT and Karakorum closed at ca. 200 Ma, as demonstrated by the monazite age of the paragneiss in the Kangxiwa Group. Our study does not favor the existence of a Precambrian basement in SKT.  相似文献   

An integrated ore prospecting model for the Nyasirori gold deposit in Tanzania     

《China Geology》2019,2(4):407-421

The Nyasirori gold deposit, located in the middle-western end of the Musoma-Mara Archean greenstone belt in Tanzania, is a tectonic altered rock type gold deposit controlled by shear tectonic zone. This work conducted high-precision ground magnetic measurements to delineate fault structures and favorable prospecting targets, utilized induced polarization (IP) intermediate gradient to roughly determine the distribution and extension of the tectonic altered zone and gold ore (mineralized) bodies, and further carried out IP sounding and magnetotelluric sounding to locate the tectonic altered zone and gold ore (mineralized) bodies. The anomalous gradient belt of the combination of positive and negative micromagnetic measurements reflects the detail of shallow surface tectonic alteration zone and gold mineralization body. Micromagnetic profile anomalies indicate the spatial location and occurrence of concealed tectonic alteration zone and gold (mineralized) ore bodies. Soil geochemical measurements indicate that the ore-forming element Au correlates well with As and Sb, and As and Sb anomalies have a good indication to gold orebodies. Based on the multi-source geological-geophysical-geochemical information of the Nyasirori gold deposit, this work established an integrated prospecting model and proposed a set of geophysical and geochemical methods for optimizing prospecting targets.  相似文献   

Growth rate is temperature‐dependent,but the proportion of resource allocation between the growth and gonads is not,in early adult stage of the lancelet branchiostoma japonicum     

Fumio Takeshita  Takumi Maekawa  Yasuhisa Henmi 《Marine Ecology》2021,42(1):e12628

The pattern of resource allocation into multiple life‐history traits can vary with the environment; for example, high temperatures generally facilitate growth. Changes in investment in growth due to temperature may alter the allocation to other traits that are in trade‐off with that. Here, we investigated the trade‐off between growth and reproduction and whether the proportion of allocation to these varies with increasing seawater temperature in the lancelet Branchiostoma japonicum. We reared the lancelets of early adult stage under three different temperature treatments (control, + 1°C and + 2°C treatments) for 427 days in the laboratory. Although the total body length at initiation did not differ between treatments, the length was influenced by the interaction between elapsed days and temperature treatments, suggesting that growth rate was temperature‐dependent; the lancelets under higher temperature conditions showed a more rapid growth rate than did those under the control conditions. The frequency of individuals with gonads did not differ between treatments throughout their reproductive season. The monthly growth increments were also not significantly affected by the interaction between the presence/absence of gonads and temperature treatments, although the presence of gonads caused the growth increments to decrease. In addition, the effect of temperature treatments was significant. These results suggest that changes in temperature did not alter the pattern of allocation between growth and reproduction that were in a trade‐off, whereas high temperature would solely result in an increase in resource intake, at least in the early adult stage of this species.  相似文献   

Meltwater discharge during the Holocene from the Wilkes subglacial basin revealed by beryllium isotope analysis of marine sediments     

Bethany Behrens  Yosuke Miyairi  Adam D. Sproson  Masako Yamane  Yusuke Yokoyama 《第四纪科学杂志》2019,34(8):603-608

Understanding Antarctic Ice Sheet dynamics related to global climate change is of scientific and societal interest as the future behaviour of the ice sheet under the currently changing climate is unknown. We present beryllium‐10 (¹⁰Be) analysis of a high‐resolution marine sediment core from the Adélie Basin near the eastern Wilkes Land margin, which is susceptible to marine ice sheet instability due to the low‐lying nature and down‐sloping trough of the Wilkes Subglacial Basin. Combined with a newly constructed age model using compound specific radiocarbon dates, the data reveal three events associated with high meteoric ¹⁰Be at ca. ~10 ka, ca. ~6.5 ka and from ca. ~4 ka. We interpret these high meteoric ¹⁰Be events to be derived from the deposition of ¹⁰Be released from the ice sheet during meltwater discharge. In particular, the shift to higher meteoric ¹⁰Be concentration at~4 ka may correspond to changes in climate patterns at this time. Copyright © 2019 John Wiley & Sons, Ltd.  相似文献   

Late Holocene changes in vegetation and atmospheric circulation at Lake Uddelermeer (The Netherlands) reconstructed using lipid biomarkers and compound‐specific δD analysis          下载免费PDF全文

《第四纪科学杂志》2018,33(1):100-111

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Single subduction zone for the generation of Devonian ophiolites and high‐P metamorphic belts of the Variscan Orogen (NW Iberia)     

Rubn Díez Fernndez  Ricardo Arenas  Sonia Snchez Martínez  Irene Novo‐Fernndez  Richard Albert 《地学学报》2020,32(4):239-245

Within the Variscan Orogen, Early Devonian and Late Devonian high‐P belts separated by mid‐Devonian ophiolites can be interpreted as having formed in a single subduction zone. Early Devonian convergence nucleated a Laurussia‐dipping subduction zone from an inherited lithospheric neck (peri‐Gondwanan Cambrian back‐arc). Slab‐retreat induced upper plate extension, mantle incursion and lower plate thermal softening, favouring slab‐detachment within the lower plate and diapiric exhumation of deep‐seated rocks through the overlying mantle up to relaminate the upper plate. Upper plate extension produced mid‐Devonian suprasubduction ocean floor spreading (Devonian ophiolites), while further convergence resulted in plate coupling and intraoceanic ophiolite imbrication. Accretion of the remaining Cambrian ocean heralded Late Devonian subduction of inner sections of Gondwana across the same subduction zone and the underthrusting of mainland Gondwana (culmination of NW Iberian allochthonous pile). Oblique convergence favoured lateral plate sliding, and explained the different lateral positions along Gondwana of terranes separated by Palaeozoic ophiolites.  相似文献   

Spatial patterns and driving mechanisms of mid‐Holocene hydroclimate in western North America          下载免费PDF全文

Nicholas Wayne Hermann  Jessica Leigh Oster  Daniel Enrique Ibarra 《第四纪科学杂志》2018,33(4):421-434

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The 1‐million‐year‐old quartz assemblage from Pont‐de‐Lavaud (Centre,France) in the European context          下载免费PDF全文

Jackie Despriée  Marie‐Hélène Moncel  Marta Arzarello  Gilles Courcimault  Pierre Voinchet  Jean‐Jacques Bahain  Christophe Falguères 《第四纪科学杂志》2018,33(6):639-661

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The recognition of former melt flux through high‐strain zones          下载免费PDF全文

Catherine A. Stuart  Sandra Piazolo  Nathan R. Daczko 《Journal of Metamorphic Geology》2018,36(8):1049-1069

High‐strain zones are potential pathways of melt migration through the crust. However, the identification of melt‐present high‐strain deformation is commonly limited to cases where the interpreted volume of melt “frozen” within the high‐strain zone is high (>10%). In this contribution, we examine high‐strain zones in the Pembroke Granulite, an otherwise low‐strain outcrop of volcanic arc lower crust exposed in Fiordland, New Zealand. These high‐strain zones display compositional layering, flaser‐shaped mineral grains, and closely spaced foliation planes indicative of high‐strain deformation. Asymmetric leucosome surrounding peritectic garnet grains suggest deformation was synchronous with minor amounts of in situ partial melting. High‐strain zones lack typical mylonite microstructures and instead display typical equilibrium microstructures, such as straight grain boundaries, 120° triple junctions, and subhedral grain shapes. We identify five key microstructures indicative of the former presence of melt within the high‐strain zones: (a) small dihedral angles of interstitial phases; (b) elongate interstitial grains; (c) small aggregates of quartz grains with xenomorphic plagioclase grains connected in three dimensions; (d) fine‐grained, K‐feldspar bearing, multiphase aggregates with or without augite rims; and (e) mm‐ to cm‐scale felsic dykelets. Preservation of key microstructures indicates that deformation ceased as conditions crossed the solidus, breaking the positive feedback loop between deformation and the presence of melt. We propose that microstructures indicative of the former presence of melt, such as the five identified above, may be used as a tool for recognising rocks formed during melt‐present high‐strain deformation where low (<5%) volumes of leucosome are “frozen” within the high‐strain zone.  相似文献