Mussels as sentinels

Mussel Watch II, ‘Chemical changes in the coastal zone’, Honolulu, Hawaii, 7–11 November 1983     

The JPL deep-well mid-infrared array camera

We describe the development of a mid-infrared camera intended for use at the Palomar 5-m telescope and at the NASA Infrared Telescope Facility. The camera is based on Rockwell's HF-16 128×128 Si:As BIB array. This array is unusual in that it has a well depth of approximately 30 million electrons; this will allow the use of traditional broadband astronomical filters (N and Q) while keeping a reasonable field-of-view. Measured array performance indicates that it has a read noise of 1100 electrons and shows non-linearities of <1% up to 65% of full well. In this paper, we discuss the array and its operating characteristics and we give a brief overview of the camera design.National Research Council research associate at JPLSummer Undergraduate Research Fellow at JPL     

Re-inventing government: Emerging geographies in the aftermath of the 1984 reforms in New Zealand

Introduction

Re-inventing government: Emerging geographies in the aftermath of the 1984 reforms in New Zealand     

End-member ferrian kanonaite: an andalusite phase with one Al fully replaced by (Mn,Fe)<Superscript>3+</Superscript> in a quartz vein from the Ardennes mountains,Belgium, and its origin

Kanonaite, with compositions plotting on the join Mn³⁺AlSiO₅–Fe³⁺AlSiO₅, was discovered in a late quartz vein of the Le Coreux metamorphic manganese deposit. A typical structural formula is (Mn³⁺_3.69Fe³⁺_0.36)Al_3.95Si_4.00O₂₀, representing maximum solid solution within the system Al₂SiO₅–Mn₂SiO₅–Fe₂SiO₅. Refractive indices are =1.777; =1.855. The end-member compositions form the outermost, latest products in zoned crystals ranging to less manganiferous kanonaite. A crystal structure determination of a Mn-rich kanonaite confirms that about 96% of all the Mn³⁺ present is located in the strongly Jahn-Teller-distorted octahedron of the andalusite-type structure. Combining all relevant mineral-chemical and petrological data available on the deposit, a speculative model is presented in which kanonaite crystals with successively higher Mn³⁺ contents form during decreasing temperatures in the course of the anticlockwise PTt path of extensional metamorphism. Kaolinite occurring in zones within composite kanonaite porphyroblasts of adjacent phyllites is regarded here as by-product of a continuous retrograde breakdown reaction of less manganiferous kanonaite. In places, kanonaite was peripherally replaced by muscovite and Mn- and Fe-oxides.Editorial responsibility: J. HoefsDedicated to the late Dr. H.S. Yoder, Jr.     

Die Kupfervererzung vom Gaskasjavri in Troms (Norwegen)

Zusammenfassung Aus den nordnorwegischen Kaledoniden wird ein neues Kiesvorkommen vom Gaskasjavri in der Provinz Troms beschrieben, das sich durch Gangarten auszeichnet, die unter stärkeren Metamorphosebedingungen gebildet wurden und die Mineralisation skarnähnlich erscheinen lassen. Die hochtemperiert angelegte Vererzung wird von Magnetit und einigen Sulfiden gebildet, wobei Pyrit, Kupferkies und Magnetkies die Hauptmasse bilden, die anderen Erze finden sich nur noch akzessorisch. Die Gangart besteht hauptsächlich aus Epidot, Pyroxen. Granat und Hornblende. Quarz sowie andere Gangartminerale treten nur untergeordnet auf. Neben den primären Verwachsungen werden auch eingehend die deszendenten Bildungen, hauptsächlich die Umbildung von Magnetkies, beschrieben. Abschließend wird auf die Entstehung des Vorkommens und eine eventuelle Deutung als Skarn eingegangen.

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Summary A new sulphide deposit in the Caledonides of Northern Norway is described from Gaskasjavri in Troms. The deposit and surrounding rocks have been formed under high metamorphosis, and are skarn-like. Magnetite, chalcopyrite, pyrite and pyrrhotite are the main products of the high-temperature mineralization, other sulphides occur only in small quantities. The gangue consists mainly of epidote, pyroxene, garnet and amphibole with small amounts of quartz and other gangue-minerals. This primary mineral association is described as well as the secondary formations due to descending water, especially those of pyrrhotite. Finally, the genesis of the deposit, and its possible interpretation as a skarn is discussed.

     

Conditional use of mangrove habitats by fishes: Depth as a cue to avoid predators

The flooded intertidal zone in coastal estuarine systems (e.g., mangroves and salt marshes) is thought to provide nekton with both food and refuge from predators. The primary aim of this study was to identify the relative contribution of root structure, shading, and leaf litter, all characteristic features of mangrove forests, in shaping the intertidal distribution of tidally migrating fishes. We manipulated the structure and shade in 9-m² sample plots in a shallow, mangrove-fringed, intertidal embayment in Tampa Bay, Florida. In a separate field experiment, we compared fish association with standing mangrove leaf litter and bare sand substrate. Shade and leaf litter had a water depthdependent effect on the distribution of the fish; no effect was associated with the presence of mangrove roots. In shallow water (<45 cm), fish were captured primarily in plots without shade, but this distribution shifted progressively with increasing water depth, so that when water was greater than 55 cm most fish were captured in shaded plots. Fish were more frequently associated with, and feeding in, plots covered in leaf litter than bare sand plots. This relationship did not persist at depths greater than 15 cm because fish abundance declined gratly. Tethering experiments usingCyprinodon variegatus demonstrated that predation pressure was quadratically correlated with water depth (inflexion point approximately 60 cm). Our results suggest that small fishes will abandon well-lighted foraging grounds in favor of the potential refuge of shaded waters as water depth increases. We suggest that studies of intertidal nekton should be carefully interpreted in the context of water depth.     

Conversion of carbonaceous material to graphite within the Greywacke Zone of the Eastern Alps

Morphology and reflectance of carbonaceous material (CM) in Late Carboniferous metasediments of the eastern Greywacke Zone (Eastern Alps) indicate a mixture of vitrinite, grainy textured and lamellar shaped particles. As imaged by high-resolution atomic-force microscopy, vitrinite and the grainy textured particles show mesophase structures which can be described as facetted nanocrystals within the carbon matrix. High-resolution transmission electron microscopy has revealed two types of microtextures representing different degrees of graphitization. The first type is characterized by elongated ring-shaped microtextures, whereas the second type is characterized by graphite lamellae and polygonal flakes with long-range ordered aromatic layers. In spite of the heterogeneity of the CMs, the geographical distribution of quantitative metamorphic parameter (Raman spectra parameter, X-ray diffraction pattern, microscopic reflectance) suggests a graphitization process which is promoted by advective heat transport during post-collisional processes. In a tentative pressure-time path, Late Cretaceous thrusting results in a turbostratic ordering of the aromatic layer. Ordering to long-range ordered aromatic layers was achieved during the Late Cretaceous-Paleogene exhumation of mid-crustal rocks beneath the eastern Greywacke Zone.     

Introductory perspective on the COREF Project

Abstract Coral reefs are tropic to subtropic, coastal ecosystems comprising very diverse organisms. Late Quaternary reef deposits are fossil archives of environmental, tectonic and eustatic variations that can be used to reconstruct the paleoclimatic and paleoceanographic history of the tropic surface oceans. Reefs located at the latitudinal limits of coral‐reef ecosystems (i.e. those at coral‐reef fronts) are particularly sensitive to environmental changes – especially those associated with glacial–interglacial changes in climate and sealevel. We propose a land and ocean scientific drilling campaign in the Ryukyu Islands (the Ryukyus) in the northwestern Pacific Ocean to investigate the dynamic response of the corals and coral‐reef ecosystems in this region to Late Quaternary climate and sealevel change. Such a drilling campaign, which we call the COREF (coral‐reef front) Project, will allow the following three major questions to be evaluated: (i) What are the nature, magnitude and driving mechanisms of coral‐reef front migration in the Ryukyus? (ii) What is the ecosystem response of coral reefs in the Ryukyus to Quaternary climate changes? (iii) What is the role of coral reefs in the global carbon cycle? Subsidiary objectives include (i) the timing of coral‐reef initiation in the Ryukyus and its causes; (ii) the position of the Kuroshio current during glacial periods and its effects on coral‐reef formation; and (iii) early carbonate diagenetic responses as a function of compounded variations in climate, eustacy and depositional mineralogies (subtropic aragonitic to warm‐temperate calcitic). The geographic, climatic and oceanographic settings of the Ryukyu Islands provide an ideal natural laboratory to address each of these research questions.