Taupo Volcanic Zone calc-alkaline tephras on the peralkaline Mayor Island volcano, New Zealand: identification and uses as marker horizons

Mayor Island is a peralkaline rhyolitic caldera volcano characterised by numerous, sector-confined pyroclastic deposits, together with lavas forming at least five composite shields. Correlation of sequences between sectors is difficult because of the scarcity of island-wide marker beds. However, eight distal calc-alkaline fall tephras (ca. 7.3 ¹⁴C ka to 64 ka) from Okataina and Taupo volcanic centres in the nearby Taupo Volcanic Zone (TVZ) have been identified on the island. These “foreign” TVZ tephras provide marker planes to correlate activity in different sectors of Mayor Island volcano, and refine an eruptive chronology. At least seventeen pyroclastic eruptions and fourteen lava-producing events (including multiple, shield-forming events) have occurred in the past ca. 64 ka. Age controls provided by the calc-alkaline tephras confirm the extremely local dispersal characteristics of many of the Mayor Island eruptives and show that K/Ar ages as young as 25–33 ka on obsidians with 4.2–4.4% K₂O are reliable.     

西藏羊八井热田地热流体成因及演化的惰性气体制约

地热流体中惰性气体的相对丰度和同位素组成，不仅可以揭露热田的热源性质，而且还能够揭示深，浅层地热流体的内在联系和演化过程等。在西藏羊八井热田的地热气体中，已检测出大量的^4He组分，3He/^4He值是大气的0．087－0．259倍，表明深部地壳物质的局部熔融为热田提供能量，浅层地热流体的3He/4He 值自西北向东南呈降低趋势，与热储温度的变化相一致，反映出侧向运移时补充了更多的壳源氦，热田北区深层地热流体具有稍高的3He/4He值，是浅层地热流体的母源，气体中氪和氙的相对丰度具有大气降水成因的特征，结合现有的实际资料，建立了热田地热流体的概念模型。     

Long-Term Landscape Evolution of the Northparkes Region of the Lachlan Fold Belt, Australia: Constraints from Fission Track and Paleomagnetic Data

Apatite fission track thermochronology (AFTT) and paleomagnetic (PM) results have been used to constrain the Late Paleozoic to Cenozoic landscape evolution of the Lachlan Fold Belt (LFB) around the Northparkes copper-gold deposit in east-central New South Wales. The present-day landscape of this region of the LFB is relatively flat with little expression of the underlying rock and has previously been interpreted to indicate long-term stability of the region since the end of LFB orogenesis in the Early Carboniferous. This was presumably borne out by PM analyses from thick weathered horizons within open pits at the mine, which suggested that significant periods of weathering, and hence relative landscape stability, prevailed during the Early to middle Carboniferous and at some time during the Cenozoic. Results from AFTT analyses, however, indicate that the region must have experienced significant episodes of cooling/denudation during the mid-Permian to mid-Triassic and during the early Cenozoic, as well as episodes of heating/burial during the Late Carboniferous to mid-Permian and during the late Mesozoic. When combined, the AFTT and PM results are in fact consistent and indicate that since the late Paleozoic the landscape of the LFB around the Northparkes deposit has evolved through multiple episodes of denudation and deposition as well as periods of relative stability during which the thick weathering horizons formed. Together these results establish a complementary chronological framework that constrains the Late Palaeozoic to Cenozoic landscape evolution of the Northparkes region and highlights the importance of using dual data sets in elucidating the long-term landscape evolution of similar "stable" terranes.     

Establishing Quaternary as a formal internationa Period/System

Despite being the most widely used unit infield mapping and having the greatest number of active researchers, the interval known as Quaternary is unique among the chronostratigraphic subdivisions of the Geological Time Scale （GTS） in having the most controversial definition and rank. After more than 100 years of debate, the base of the Quaternary is now widely recognized at -2.6 Ma, marking a dramatic and so-far irreversible shift to the ice-age-dominated world of oscillating glacial advances over the northern continents.     

Developing yellowtail kingfish (Seriola lalandi) and hāpuku (Polyprion oxygeneios) for New Zealand aquaculture

Two high value species, yellowtail kingfish (Seriola lalandi) and hāpuku (groper, Polyprion oxygeneios), have been identified as suitable new candidates for New Zealand aquaculture. This paper reviews the research by NIWA and collaborators conducted to test the biological, technological and economic feasibility of farming these two species. NIWA now has the capability to produce sufficient kingfish fingerlings per year to meet the needs of the early stages of an industry. Advances in hāpuku aquaculture have also been significant, from spawning in captivity through to the selection of juveniles for improved growth. Recently, the first spawning of captive hāpuku F1 broodstock and production of F2 eggs, larvae and juveniles was achieved. Although hāpuku larval survival remains variable, the ability to close the life cycle, and the availability of domesticated broodstock, provide a significant step forward and increase the chances of this species being commercially farmed.     

Quantifying the rate and depth dependence of bioturbation based on optically‐stimulated luminescence (OSL) dates and meteoric 10Be

Both the rate and the vertical distribution of soil disturbance modify soil properties such as porosity, particle size, chemical composition and age structure; all of which play an important role in a soil's biogeochemical functioning. Whereas rates of mixing have been previously quantified, the nature of bioturbation's depth dependence remains poorly constrained. Here we constrain, for the first time, the relationship between mixing rate and depth in a bioturbated soil in northeast Queensland, Australia using a novel method combining OSL (optically‐stimulated luminescence) ages and meteoric beryllium‐10 (¹⁰Be) inventories. We find that the best fit mixing rate decreases non‐linearly with increasing soil depth in this soil and the characteristic length scale of 0.28 m over which the mixing coefficient decays is comparable to reported rooting depth coefficients. In addition we show that estimates of surface mixing rates from OSL data are highly dependent on erosion rate and that erosion rate must be constrained if accurate mixing rates are to be quantified. We calculate surface diffusion‐like mixing coefficients of 1.8 × 10^?4 and 2.1 × 10^?4 m² yr^?1 for the studied soil for two different estimates of soil erosion. © 2014 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.     

Lake George revisited: New evidence for the origin and evolution of a large closed lake,Southern Tablelands,NSW, Australia

Lake George contains the longest continuous sedimentary record of any Australian lake basin, but previous age models are equivocal, particularly for the oldest (pre-Quaternary) part of the record. We have applied a combination of cosmogenic nuclide burial dating, magnetostratigraphy and biostratigraphy to determine the age of the basal (fluvial) unit in the basin, the Gearys Gap Formation. Within the differing resolutions achievable by the three dating techniques, our results show that (i) the Gearys Gap Formation, began accumulating at ca 4 Ma, in the early Pliocene (Zanclean), and (ii) deposition had ceased by ca 3 Ma, in the mid late Pliocene (Piacenzian). Whether the same age control provides an early Pliocene (Zanclean) age for the formation of the lake basin is uncertain. During the Piacenzian, the vegetation at the core site was a wetland community dominated by members of the coral fern family Gleicheniaceae, while the surrounding dryland vegetation was a mix of sclerophyll and temperate rainforest communities, with the latter including trees and shrubs now endemic to New Guinea–New Caledonia and Tasmania. Mean annual rainfall and temperatures are inferred to have been ～2000–3000 mm, although probably not uniformly distributed throughout the year, and within the mesotherm range (>14°C <20°C), respectively. Unresolved issues are: (1) Does the basal gravel unit predate uplift of the Lake George Range and therefore provide evidence that one of the proposed paleo-spillways of Lake George, that above Geary's Gap, has been elevated up to 100–200 m by neotectonic activity over the past 4 million years? (2) Did a shallow to deepwater lake exist elsewhere in the lake basin during the Pliocene?     

The Early-Middle Pleistocene Transition： characterization and proposed guide for the defining boundary

The mid-Pleistocene transition （MPT, c. 1.2 to 0.5 Ma） records fundamental changes in Earth＇s climate state, where low-amplitude 41-kyr obliquity-dominated cycles gave way progressively to the high-amplitude, quasiperiodic （c. 100-kyr） fluctuations that characterize the later Pleistocene and Holocene. We use wavelet analysis on the LR04 δ^l8O benthic foraminiferal stack to confirm low-frequency power as early as 1.25-1.20 Ma, determine the persistence of obliquity-dominated cyclicity through and beyond the MPT, and reveal new levels of complexity in climate evolution.     

Use of openly available occurrence data to generate biodiversity maps within the South African EEZ

Biodiversity maps are an important component of ecosystem-based management and conservation. In the past, biodiversity maps were largely generated using patchy occurrence data from a range of data sources. Currently, substantial species occurrence data are readily available for large parts of the world and are accessible programmatically. Considering both the observed and expected changes in species distributions, and hence biodiversity, in response to present and future climate change, it is important to utilise readily available species occurrence databases to generate temporal and spatial biodiversity maps. In this study biodiversity maps were generated for three generic functional groups within the exclusive economic zone of South Africa: zooplankton, fishes and benthos. This was achieved by stacking individual species-distribution maps. Freely available occurrence data from the Ocean Biogeographic Information System (OBIS) were accessed for this purpose. Ensemble species-distribution modelling, employing five widely used statistical methods, was used to generate species-distribution maps for each functional group. The resulting spatial patterns of biodiversity for the three functional groups were largely in agreement with known patterns. The results of this study highlight the value of open-source occurrence and environmental data to generate biodiversity maps that can potentially be used in future spatial prioritisation or planning for management of marine areas and in environmental-change studies.     

The effects of secular disequilibrium on (U-Th)/He systematics and dating of Quaternary volcanic zircon and apatite

The (U-Th)/He dating method applied to U-rich phases such as zircon and apatite has sufficient sensitivity and precision to be of potential use for dating relatively recent geologic events such as volcanic eruptions. However, in phases with crystallization ages less than ∼1 Ma, chemical fractionation within the ²³⁸U decay series may modify the He ingrowth rate, causing He ages computed from the secular equilibrium age equation to be incorrect. The resulting systematic error depends on the [²³⁰Th/²³⁸U] activity ratio of the dated phase when it is erupted, and on the eruption age. Zircons, which exclude Th relative to U, will likely have secular equilibrium He ‘ages’ that underestimate the eruption age by up to a few tens of %, decreasing with increasing eruption age. Apatites tend to accommodate U and Th with little fractionation, so apatite secular equilibrium He ages will be nearly concordant with eruption age. If minerals are erupted immediately after crystallization, the disequilibrium effect can be reasonably accounted for based on Th/U systematics. However, crystals are likely to reside for unknown but potentially long periods in a magma chamber, such that the degree of secular disequilibrium will be reduced prior to the onset of He accumulation. (U-Th)/He analyses of co-genetic phases that fractionate the U/Th ratio differently, like apatite and zircon, can be used to better constrain eruption age, as well as to provide insights into magma chamber residence time. We illustrate this approach with (U-Th)/He analyses of zircons and apatites of the Pleistocene-age Rangitawa Tephra, New Zealand.