title: Sub-millennial eruptive recurrence in the silicic Mangaone Subgroup tephra sequence, New Zealand, from Bayesian modelling of zircon double-dating and radiocarbon ages

authors: Danišík, Martin

subjects: Zircon double-dating

abstract: Accurate dating of young (<1 Ma) volcanic eruptions has long been a challenge for modern geochronology given the scarcity of datable mineral phases and low quantities of radiogenic daughter products. Combined U-Th-Pb and (U-Th)/He dating of zircon (i.e., zircon double-dating, ZDD) is a relatively new dating approach that offers a viable option for dating zircon-bearing volcanic and pyroclastic deposits as young as ca. 3 ka, and has a great potential for application in many fields within the Quaternary sciences, including volcanology, palaeoclimatology, and archaeology. In our study, a stratigraphically and spatially well-defined sequence of 13 rhyodacitic to rhyolitic tephra beds e the Mangaone Subgroup (MSg) erupted from the Okataina Volcanic Centre (OVC), is used as a natural laboratory to conduct a crossvalidation experiment in which the ZDD eruption ages are compared with published and new radiocarbon (¹⁴C) eruption ages. These ZDD and ¹⁴C ages are then used together to underpin a Bayesian age model developed (using ChronoModel) to provide new ages for the entire MSg sequence. New ZDDeruption ages of 36.1 ± 4.4, 31.5 ± 5.2, 30.9 ± 5.6, 31.2 ± 4.4 ka BP for four MSg tephras (Units D, I, J, and K, respectively) are statistically indistinguishable from ¹⁴C-based eruption ages. These results validate the feasibility of ZDD to date late Quaternary eruptions accurately. The Bayesian age sequence model provides provides an eruptive geochronology eruptive geochronology for all 13 MSg tephra beds for the first time (and for the stratigraphically-interbedded Taupo-volcano-derived Tahuna tephra, 38.4 ⁺¹.⁷ ₋₁.₄ ka BP), and constrains the beginning of the MSg eruption period to 42.7 ⁺³.⁷₋₃.₅ ka BP (Unit A) and the end to 30.6 ⁺⁰.⁶₋₁.₅ ka BP (Unit L). Thus, the entire MSg sequence was emplaced in ~12,100 years, representing an eruption frequency of one event per ~930 years on average. Our study demonstrates the efficacy of ZDD to yield accurate eruption ages on pyroclastic deposits, highlighting its potential for dating young (<1 Ma) magmatic and eruption events that are difficult to date by other geochronological methods, and also shows that ZDD dates can be integrated with ¹⁴C ages using Bayesian modelling to develop new age models for long sequences of tephra beds, in this case those of the MSg tephras that were deposited during MIS 3. In addition, the U-Th zircon crystallization data revealed distinct U-Th model age spectra for older and younger MSg tephras, providing geochronological evidence for decreasing degree of interconnectedness within the OVC magma reservoir during the MSg eruption period that followed caldera collapse associated with the pre-MSg Rotoiti (Rotoehu) eruption at ca. 45 ka BP.

text: Sub-millennial eruptive recurrence in the silicic Mangaone Subgroup tephra sequence, New Zealand, from Bayesian modelling of zircon double-dating and radiocarbon ages Accurate dating of young (<1 Ma) volcanic eruptions has long been a challenge for modern geochronology given the scarcity of datable mineral phases and low quantities of radiogenic daughter products. Combined U-Th-Pb and (U-Th)/He dating of zircon (i.e., zircon double-dating, ZDD) is a relatively new dating approach that offers a viable option for dating zircon-bearing volcanic and pyroclastic deposits as young as ca. 3 ka, and has a great potential for application in many fields within the Quaternary sciences, including volcanology, palaeoclimatology, and archaeology. In our study, a stratigraphically and spatially well-defined sequence of 13 rhyodacitic to rhyolitic tephra beds e the Mangaone Subgroup (MSg) erupted from the Okataina Volcanic Centre (OVC), is used as a natural laboratory to conduct a crossvalidation experiment in which the ZDD eruption ages are compared with published and new radiocarbon (¹⁴C) eruption ages. These ZDD and ¹⁴C ages are then used together to underpin a Bayesian age model developed (using ChronoModel) to provide new ages for the entire MSg sequence. New ZDDeruption ages of 36.1 ± 4.4, 31.5 ± 5.2, 30.9 ± 5.6, 31.2 ± 4.4 ka BP for four MSg tephras (Units D, I, J, and K, respectively) are statistically indistinguishable from ¹⁴C-based eruption ages. These results validate the feasibility of ZDD to date late Quaternary eruptions accurately. The Bayesian age sequence model provides provides an eruptive geochronology eruptive geochronology for all 13 MSg tephra beds for the first time (and for the stratigraphically-interbedded Taupo-volcano-derived Tahuna tephra, 38.4 ⁺¹.⁷ ₋₁.₄ ka BP), and constrains the beginning of the MSg eruption period to 42.7 ⁺³.⁷₋₃.₅ ka BP (Unit A) and the end to 30.6 ⁺⁰.⁶₋₁.₅ ka BP (Unit L). Thus, the entire MSg sequence was emplaced in ~12,100 years, representing an eruption frequency of one event per ~930 years on average. Our study demonstrates the efficacy of ZDD to yield accurate eruption ages on pyroclastic deposits, highlighting its potential for dating young (<1 Ma) magmatic and eruption events that are difficult to date by other geochronological methods, and also shows that ZDD dates can be integrated with ¹⁴C ages using Bayesian modelling to develop new age models for long sequences of tephra beds, in this case those of the MSg tephras that were deposited during MIS 3. In addition, the U-Th zircon crystallization data revealed distinct U-Th model age spectra for older and younger MSg tephras, providing geochronological evidence for decreasing degree of interconnectedness within the OVC magma reservoir during the MSg eruption period that followed caldera collapse associated with the pre-MSg Rotoiti (Rotoehu) eruption at ca. 45 ka BP.

year: 2020

title: Recent progress in remanufacturing technologies using metal additive manufacturing processes and surface treatment

authors: Kahhal, Parviz

subjects: additive manufacturing

abstract: Remanufacturing has emerged as an effective strategy to promote sustainability, reduce waste, and enhance resource efficiency in modern manufacturing processes. However, traditional remanufacturing methods have limitations in producing complex geometries and restoring parts to their original condition, leading to reduced performance and durability. Metal additive manufacturing (AM) methods have shown significant potential in overcoming these limitations and enhancing the quality and reliability of remanufactured parts. Metal AM enables the production of replacement parts with high geometrical complexity and tight tolerances. On the other hand, surface treatment techniques, such as polishing and coating, can improve the surface properties of additively manufactured parts. Recent advancements in metal AM have led to significant progress in manufacturing technologies, including the development of hybrid methods combining metal AM with a surface treatment to achieve superior surface finish and accuracy while reducing production time and cost. Despite progress, challenges such as the need for cost-effective and scalable processing methods, the development of new materials, and the optimization of process parameters for specific applications still need to be addressed. Moreover, although surface modification techniques suitable for metal components fabricated through additive manufacturing can be employed for remanufactured parts, their adoption needs to be improved and necessitates additional advancement. This paper provides an overview of recent progress in manufacturing and remanufacturing technologies using metal additive manufacturing processes and surface treatments, highlighting their potential to significantly improve the quality and reliability of remanufactured parts. The paper concludes with a discussion of the future prospects of this field and the need for continued research and development to fully realize the potential of remanufacturing technologies.

text: Recent progress in remanufacturing technologies using metal additive manufacturing processes and surface treatment Remanufacturing has emerged as an effective strategy to promote sustainability, reduce waste, and enhance resource efficiency in modern manufacturing processes. However, traditional remanufacturing methods have limitations in producing complex geometries and restoring parts to their original condition, leading to reduced performance and durability. Metal additive manufacturing (AM) methods have shown significant potential in overcoming these limitations and enhancing the quality and reliability of remanufactured parts. Metal AM enables the production of replacement parts with high geometrical complexity and tight tolerances. On the other hand, surface treatment techniques, such as polishing and coating, can improve the surface properties of additively manufactured parts. Recent advancements in metal AM have led to significant progress in manufacturing technologies, including the development of hybrid methods combining metal AM with a surface treatment to achieve superior surface finish and accuracy while reducing production time and cost. Despite progress, challenges such as the need for cost-effective and scalable processing methods, the development of new materials, and the optimization of process parameters for specific applications still need to be addressed. Moreover, although surface modification techniques suitable for metal components fabricated through additive manufacturing can be employed for remanufactured parts, their adoption needs to be improved and necessitates additional advancement. This paper provides an overview of recent progress in manufacturing and remanufacturing technologies using metal additive manufacturing processes and surface treatments, highlighting their potential to significantly improve the quality and reliability of remanufactured parts. The paper concludes with a discussion of the future prospects of this field and the need for continued research and development to fully realize the potential of remanufacturing technologies.

year: 2024

title: Community Based Coastal Monitoring: Developing Tools For Sustainable Management

authors: Rickard, Darcel

subjects: Science

abstract: Burgeoning coastal development, recreational use, and the future affects of climate change are placing increasing strain on regulators to manage risk associated with coastal hazards.  Low-lying coastal communities in particular are vulnerable to a range of natural hazards including coastal erosion, storm surge inundation, tsunami and water safety that come with varying levels of risk to life and property. New Zealand's coastal hazard monitoring network is patchy and resources are limited. As a consequence there is considerable potential for coastal communities are going to need to take a more active role in monitoring their environment and building data bases and knowledge that can be used to better manage their coast. This paper describes simple methodologies based on the needs of various community groups and sound science principles that can be used to monitor beaches and the coastal environment. By employing these tools councils, technical experts and community groups will be able to make better-informed decisions for managing activities in the coastal environment. 
One of the keys to the successful uptake of a monitoring programme by a community group is its relevance to the group. The programme and the tools provided must fit the interests, needs, capability and resources of the group. This project develops tools for coastal monitoring and targets coastal community groups such as Coast Care, Coastal Hapu, Secondary Schools, and Surf Life Saving Clubs. The monitoring methodologies have been developed in consultation with Tainui ki Whaingaroa hapu, Raglan Area School, and the Waikato Beach Care and Coast Care Bay of Plenty.
Successful methodologies for measuring changes on the coast are also those that are matched to the type of beach, use appropriate equipment, collect structured data, provide data to which analysis can be applied, incorporate local knowledge of the environment, and feed results back to the community and other interested parties such as councils and science organisations. This project provides the target groups with simple monitoring methodologies, field forms/checklists, and appropriate survey and measurement equipment (which have undergone field trials) to carry out coastal monitoring.  A web-based facility has been developed to input, check and store data; and provide immediate feedback using graphs and images. It also provides background information on coastal processes relevant to monitoring programmes.  In this manner, a scientifically robust data set is collected and stored within a secure and future proofed archive, providing valuable information to coastal groups for years to come.
Although the primary objective of this research is to develop a means for coastal communities to monitor changes in their environment, there are additional benefits associated with engaging communities in the study of their environment. These benefits include increasing awareness of coastal hazards, capacity building, providing valuable educational resources, and improving the temporal and spatial data coverage of information for the New Zealand coastline.

text: Community Based Coastal Monitoring: Developing Tools For Sustainable Management Burgeoning coastal development, recreational use, and the future affects of climate change are placing increasing strain on regulators to manage risk associated with coastal hazards.  Low-lying coastal communities in particular are vulnerable to a range of natural hazards including coastal erosion, storm surge inundation, tsunami and water safety that come with varying levels of risk to life and property. New Zealand's coastal hazard monitoring network is patchy and resources are limited. As a consequence there is considerable potential for coastal communities are going to need to take a more active role in monitoring their environment and building data bases and knowledge that can be used to better manage their coast. This paper describes simple methodologies based on the needs of various community groups and sound science principles that can be used to monitor beaches and the coastal environment. By employing these tools councils, technical experts and community groups will be able to make better-informed decisions for managing activities in the coastal environment. 
One of the keys to the successful uptake of a monitoring programme by a community group is its relevance to the group. The programme and the tools provided must fit the interests, needs, capability and resources of the group. This project develops tools for coastal monitoring and targets coastal community groups such as Coast Care, Coastal Hapu, Secondary Schools, and Surf Life Saving Clubs. The monitoring methodologies have been developed in consultation with Tainui ki Whaingaroa hapu, Raglan Area School, and the Waikato Beach Care and Coast Care Bay of Plenty.
Successful methodologies for measuring changes on the coast are also those that are matched to the type of beach, use appropriate equipment, collect structured data, provide data to which analysis can be applied, incorporate local knowledge of the environment, and feed results back to the community and other interested parties such as councils and science organisations. This project provides the target groups with simple monitoring methodologies, field forms/checklists, and appropriate survey and measurement equipment (which have undergone field trials) to carry out coastal monitoring.  A web-based facility has been developed to input, check and store data; and provide immediate feedback using graphs and images. It also provides background information on coastal processes relevant to monitoring programmes.  In this manner, a scientifically robust data set is collected and stored within a secure and future proofed archive, providing valuable information to coastal groups for years to come.
Although the primary objective of this research is to develop a means for coastal communities to monitor changes in their environment, there are additional benefits associated with engaging communities in the study of their environment. These benefits include increasing awareness of coastal hazards, capacity building, providing valuable educational resources, and improving the temporal and spatial data coverage of information for the New Zealand coastline.

year: 2008