Private rights,public benefits: Industry-driven seabed protection

New Zealand has a large exclusive economic zone (EEZ) that contains a variety of marine habitats and commercially-important species. The commercial fishing industry operating within New Zealand's EEZ is of significant value to the economy and fisheries resources are managed through the extensive use of Individual Transferable Quotas (ITQs). One of the benefits of ITQs has been to better align some of the private incentives of quota owners with the public interest. These incentives contributed to an initiative proposed by the fishing industry to close large areas of New Zealand's EEZ to protect the seabed from trawling. These closed areas are termed benthic protection areas (BPAs) and protect the benthic biodiversity of about 1.1 million square kilometres of seabed—approximately 30% of New Zealand's EEZ. A significant proportion of New Zealand's known seamounts and active hydrothermal vents are protected by these closed areas. We describe and discuss the criteria used to select BPAs and some of the criticism of this marine protection initiative. We argue that the assignment of strong property rights in fishing resources was an important precondition to an industry initiative that has a significant public benefit. Where private and public interests are well aligned, government can adopt an enabling and facilitation role, ceding direct control of processes in order to get the results the align with the public interest.     

墨西哥湾南部晚侏罗纪主力烃源岩的形成条件

通过对墨西哥湾不同时代可采储量的分布特征和油源对比资料的分析认为,晚侏罗纪烃源岩是墨西哥湾南部最主要的烃源岩。资料显示,晚侏罗纪优质烃源岩形成的主控因素是稳定的构造和沉积条件以及超咸的还原环境,其中,"世界顶级"的晚侏罗纪提塘阶烃源岩主要形成于超咸的碳酸盐岩和/或蒸发岩沉积环境,属半深海还原环境,有机质以藻类为主,推测烃源岩中的有机质可能与极端干旱气候条件下的藻类勃发有关。     

High‐ to ultrahigh‐temperature metamorphism in the lower crust: An example resulting from Hikurangi Plateau collision and slab rollback in New Zealand

Lower crustal xenoliths erupted from an intraplate diatreme reveal that a portion of the New Zealand Gondwana margin experienced high‐temperature (HT) to ultrahigh‐temperature (UHT) granulite facies metamorphism just after flat slab subduction ceased at c. 110–105 Ma. P–T calculations for garnet–orthopyroxene‐bearing felsic granulite xenoliths indicate equilibration at ~815 to 910°C and 0.7 to 0.8 GPa, with garnet‐bearing mafic granulite xenoliths yielding at least 900°C. Supporting evidence for the attainment of HT and UHT conditions in felsic granulite comes from re‐integration of exsolution in feldspar (~900–950°C at 0.8 GPa), Ti‐in‐zircon thermometry on Y‐depleted overgrowths on detrital zircon grains (932°C ± 24°C at aTiO₂ = 0.8 ± 0.2), and correlation of observed assemblages and mineral compositions with thermodynamic modelling results (≥850°C at 0.7 to 0.8 GPa). The thin zircon overgrowths, which were mainly targeted by drilling through the cores of grains, yield a U–Pb pooled age of 91.7 ± 2.0 Ma. The cause of Late Cretaceous HT‐UHT metamorphism on the Zealandia Gondwana margin is attributed to collision and partial subduction of the buoyant oceanic Hikurangi Plateau in the Early Cretaceous. The halt of subduction caused the fore‐running shallowly dipping slab to rollback towards the trench position and permitted the upper mantle to rapidly increase the geothermal gradient through the base of the extending (former) accretionary prism. This sequence of events provides a mechanism for achieving regional HT–UHT conditions in the lower crust with little or no sign of this event at the surface.     

Subduction and back-arc activity at the Hikurangi convergent Margin,New Zealand

The Hikurangi Margin is a region of oblique subduction with northwest-dipping intermediate depth seismicity extending southwest from the Kermadec system to about 42°S. The current episode of subduction is at least 16–20 Ma old. The plate convergence rate varies along the margin from about 60 mm/a at the south end of the Kermadec Trench to about 45 mm/a at 42°S. The age of the Pacific lithosphere adjacent to the Hikurangi Trench is not known.The margin divides at about latitude 39°S into two quite dissimilar parts. The northern part has experienced andesitic volcanism for about 18 Ma, and back-arc extension in the last 4 Ma that has produced a back-arc basin onshore with high heaflow, thin crust and low upper-mantle seismic velocities. The extension appears to have arisen from a seawards migration of the Hikurangi Trench north of 39°S. Here the plate interface is thought to be currently uncoupled, as geodetic data indicate extension of the fore-arc basin, and historic earthquakes have not exceededM _s=7.South of 39°S there is no volcanism and a back-arc basin has been produced by downward flexure of the lithosphere due to strong coupling with the subducting plate. Heatflow in the basin is normal. Evidence for strong coupling comes from historic earthquakes of up to aboutM _s=8 and high rates of uplift on the southeast coast of the North Island.The reason for this division of the margin is not known but may be related to an inferred increase, from northeast to southwest, in the buoyancy of the Pacific lithosphere.     

Classification and distribution of Oligocene Aetiocetidae (Mammalia; Cetacea; Mysticeti) from western North America and Japan

Abstract Fossil whales in the very rare, primitive, extinct cetacean family Aetiocetidae are small, relict, toothed mysticetes that persisted into Late Oligocene time after more highly derived baleen-bearing mysticetes had already evolved. No known aetiocetid could be ancestral to baleen-bearing mysticetes, but aetiocetid morphology is in many ways intermediate between archaeocetes and baleen-bearing mysticetes, demonstrating the probable transitional steps passed through in the evolution of baleen-bearing mysticetes. Their discovery indicates that mysticetes evolved from Archaeocetes, and supports theories of the monophyly of Cetacea. Late Oligocene aetiocetids have been found on both sides of the North Pacific Ocean: on Vancouver Island, British Columbia, Canada; in Oregon and Washington, USA; in Baja California Sur, México; and the islands of Kyushu and Hokkaido, Japan. The most primitive North American aetiocetid, Chonecetus sookensis Russell, 1968, is from the early Late Oligocene Hesquiat Formation on Vancouver Island, British Columbia, Canada. A more derived, Late Oligocene species, Chonecetus goedertorum Barnes and Furusawa, new species, from the Late Oligocene Pysht Formation, Olympic Peninsula, Washington, has the primitive placental mammalian tooth count of 11/11. The type genus of the family, Aetiocetus Emlong, 1966, has as its type species, A. cotylalveus Emlong, 1966, known only from the Late Oligocene Yaquina Formation on the coast of Oregon. It has 11 upper teeth on each side of the rostrum. A more derived species, Aetiocetus weltoni Barnes and Kimura, new species, from a higher stratigraphic level in the Yaquina Formation, has a more posteriorly positioned cranial vertex and a tooth count of 11/12. We describe four new species of aetiocetids in three genera from the Late Oligocene Morawan Formation near Ashoro, Hokkaido, Japan. The most primitive, Ashorocetus eguchii Barnes and Kimura, new genus and species, has a primitive stage of cranial telescoping, and is closely related to Chonecetus Russell, 1968. Another, Morawanocetus yabukii Kimura and Barnes, new genus and species, in some ways intermediate between Chonecetus and Aetiocetus, has a suite of unique derived characters, including a much foreshortened brain case. The third, Aetiocetus tomitai Kimura and Barnes, new species, is the most primitive species of Aetiocetus yet discovered. The fourth, Aetiocetus polydentatus Sawamura, new species, the most derived species of Aetiocetus known, has a highly telescoped cranium, homodonty, polydonty and a dental count of 13–14/14–15. The fossil record now indicates considerable diversity in the family, with several different contemporaneous lineages in three new subfamilies: Chonecetinae, Morawanocetinae and Aetiocetinae. Aetiocetids are not known outside the North Pacific. Many Recent mysticetes are essentially cosmopolitan, and aetiocetids might have also been relatively widely dispersed. We suspect that with time their remains will be found around other ocean basins also. If so, then they may be potentially useful in trans-oceanic geological correlations.     

Seismic activity related to the 1991 eruption of Colima Volcano,Mexico

Ten years after the last effusive eruption and at least 15 years of seismic quiescence, volcanic seismic activity started at Colima volcano on 14 February 1991, with a seismic crisis which reached counts of more than 100 per day and showed a diversity of earthquake types. Four other distinct seismic crises followed, before a mild effusive eruption in April 1991. The second crisis preceded the extrusion of an andesitic scoriaceous lava lobe, first reported on 1 March; during this crisis an interesting temporary concentration of seismic foci below the crater was observed shortly before the extrusion was detected. The third crisis was constituted by shallow seismicity, featuring possible mild degassing explosion-induced activity in the form of hiccups (episodes of simple wavelets that repeat with diminishing amplitude), and accompanied by increased fumarolic activity. The growth of the new lava dome was accompanied by changing seismicity. On 16 April during the fifth crisis which consisted of some relatively large, shallow, volcanic earthquakes and numerous avalanches of older dome material, part of the newly extruded dome, which had grown towards the edge of the old dome, collapsed, producing the largest avalanches and ash flows. Afterwards, block lava began to flow slowly along the SW flank of the volcano, generating frequent small incandescent avalanches. The seismicity associated with the stages of this eruptive activity shows some interesting features: most earthquake foci were located north of the summit, some of them relatively deep (7–11 km below the summit level), underneath the saddle between the Colima and the older Nevado volcanoes. An apparently seismic quiet region appears between 4 and 7 km below the summit level. In June, harmonic tremors were detected for the first time, but no changes in the eruptive activity could be correlated with them. After June, the seismicity decreasing trend was established, and the effusive activity stopped on September 1991.     

Last interglacial sea levels on the south coast of New South Wales

Remnants of the Last Interglacial shoreline occur at Middle Lagoon on the far south coast of New South Wales. Relict beach sediments can be traced to a height of at least +4.8 m and are indicative of a former mean sea level of about +3 m. Thermoluminescence (TL) ages of 126 ± 13 ka and 114 ± 15 ka were determined for beach and aeolian facies respectively. Sands in the lower part of an exposure on the adjacent Gillards Beach gave TL ages of 108 ± 13 ka, but sands in the upper part of that exposure gave an age of 19.9 ± 3.5 ka. This chronological evidence of a stratigraphic unconformity in what was initially taken as pedogenic differentiation at Gillards Beach is supported by contrasting electron traps and colour centres in crystal lattices of quartz grains in these two samples. No tectonic displacement is apparent. This site provides the first evidence of the Last Interglacial sea level for 1000 km along the coast between Gippsland and Newcastle.     

Interpretation of210Pb profiles and verification of the CRS dating model in PIRLA project lake sediment cores

This paper reports results and analysis of²¹⁰Pb-activity measurements in 51 lake-sediment cores from 32 lakes in the four PIRLA (Paleoecological Investigations of Recent Lake Acidification) project regions (Adirondack Mountains [New York], Northern New England, Northern Florida, and the Northern Great Lakes States). General application of the Constant Rate of Supply (Constant Flux) model for²¹⁰Pb dating is valid for lakes in the PIRLA study, although application of the model is equivocal in a few lakes.²¹⁰Pb inventories and profiles are replicable among closely spaced cores within a lake. Specific²¹⁰Pb activity in surface sediments is negatively correlated with bulk sediment accumulation rate in seepage lakes, but not in drainage lakes. Drainage lakes with lower pH have lower unsupported²¹⁰Pb inventories in sediments, but the relationship does not occur in seepage lakes.²¹⁰Pb profiles in only seven of the cores, all from either the Adirondacks or the northern Great Lakes states, exhibit exponential decay curves. Deviations from an exponential profile include a flattening of the profile in the top few cm or excursions of one or a few measurements away from an exponential curve.²¹⁰Pb dates typically agree with other chronostratigraphic markers, most of which are subject to greater uncertainty. Several hypotheses, including sediment mixing, hydrologic regime, sediment focusing, and acidification, are proposed to explain variation of²¹⁰Pb distribution among lakes and regions. Hydrologic factors exert control on unsupported²¹⁰Pb inventories in PIRLA lakes, and there is a strong focusing effect in drainage lakes but a weak focusing effect in seepage lakes.This is the third of a series of papers to be published by this journal following the 20^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P. G. Appleby is guest editing this series.     

第20届国际大地测量学与地球物理学联合会维也纳大会地震地质类成果交流简介

根据作者参加大会收集到的资料和考察体会，介绍了在会上交流的地震地质类成果，对某些前缘研究领域的新进展作了重点介绍。