Geochemical discrimination of volcanic rocks associated with borate deposits: an exploration tool?

The Miocene borate deposits of western Turkey are associated with extensive medium- to high-K calc-alkali ignimbritic volcanism and a differentiated comagmatic alkaline trachybasalt–trachydacite lava suite. Ignimbritic air-fall and reworked pumiceous clastic materials are intimately associated with lake sediments that host the borate deposits. Local ignimbritic volcanism is considered the primary source of the B for the Kirka borate deposit in this area. Comparison of the geochemical composition of Turkish ignimbrites associated with borates (`fertile' ignimbrites) with those that do not (`barren' ignimbrites), exhibit a number of features that might prove useful in the exploration for borates in similar volcanic domains. In particular, `fertile' ignimbrites are (a) generally a high-K calc-alkali suite, well-evolved and fractionated (K/Rb is low, <200) with a high-silica rhyolitic bulk composition, (b) exhibit a combined high content of B, As, F, Li and Pb, with high B/La (>1) and B/K (>0.001) ratios, and (c) a mildly fractionated REE pattern (La_N/Yb_N∼2) and large positive Eu anomaly (Eu/Eu^*∼0.1). Other apparent discriminants involving both compatible and incompatible elements (relative to major silicate phases) are largely a function of different degrees of partial melting and fractionation. It is suggested that the initial source of the B (and other associated elements) was from LIL-rich fluids released by the progressive dehydration of altered oceanic crust and pelagic sediments in a subduction zone. The absence or presence of sediments in a segmented subduction zone may influence the variable lateral distribution of borates in active margins on a global scale. Once the crust has become enriched in B via previous or contemporary subduction-related calc-alkali magmatism, the effect of tectonic environment, climate and hydrothermal activity influence the local development of the deposits.     

Electromagnetic heating of minor planets in the early solar system

Electromagnetic processes occurring in the primordial solar system are likely to have significantly affected planetary evolution. In particular, electrical coupling of the kinetic energy of a dense T-Tauri-like solar wind into the interior of the smaller planets could have been a major driver of thermal metamorphism. Accordingly a grid of asteroid models of various sizes and solar distances was constructed using dc transverse magnetic induction theory. Plausible parameterizations with no requirement for a high environmental temperature led to complete melting for Vesta (and others with sizes down to 50 km diameter and distance out to 2.8 AU thus approximately reproducing the observed distributions of S objects) with no melting for Pallas and Ceres. Fairly high temperatures were reached in the Pallas model, perhaps implying nonmelting thermal metamorphosis as a cause of its anomalous spectrum (somewhat similar to but distinct from C type). A reversal of this temperature sequence seems implausible, suggesting that the Ceres-Pallas-Vesta dichotomy is a natural outcome of the induction mechanism. Highly localized heating is expected to arise due to an instability in the temperature-controlled current distribution. Localized metamorphosis resulting from this effect may be relevant to the production and evolution of pallasites, the large presumed metal component of S object spectra, and the formation of the lunar magma ocean.     

Estimating the Mg <Emphasis Type="SmallCaps">ii</Emphasis> Index from 1961 Through 1981 Using Ca <Emphasis Type="SmallCaps">ii</Emphasis> K Images from the Mt Wilson Observatory

An empirical model of solar UV spectral irradiance has been developed that is based on observed spectral radiance measurements and full disk Ca ii K images. The Mg ii index is then calculated from the estimated spectra in a narrow wavelength range (180 Å) near the Mg ii doublet at 2800 Å. Our long term goal is to expand this wavelength range from 10 to 4000 Å in continuing studies based on spectral data covering this wavelength range (e.g. Skylab, UARS/SUSIM, TIMED/SEE, etc.). Our previous modeling effort produced spectra in this 180 Å range and the resulting Mg ii index values for the period from 1991 through 1995 and we have used observations during this time period to validate the model results. The current paper presents results from this model based on a 21-year portion of the recently digitized Ca ii K images from the Mt Wilson Observatory (MWO) film archive. Here we present details of the model, the required model modifications, and the resulting Mg ii index from 1961 through 1981. Since the NOAA Mg ii index did not begin until 1978, the present model results are compared to a Mg ii index estimated from the F_10.7 radio flux over this 21-year period. The NOAA Mg ii index, which is derived from measured UV spectra, is also included for comparison from late 1978 through 1981.     

Comparison of Solar UV Spectral Irradiance from SUSIM and SORCE

Knowledge of solar spectral irradiance (SSI) is important in determining the impact of solar variability on climate. Observations of UV SSI have been made by the Solar Ultraviolet Spectral Irradiance Monitor (SUSIM) on the Upper Atmosphere Research Satellite (UARS), the Solar-Stellar Irradiance Comparison Experiment (SOLSTICE), and the Solar Irradiance Monitor (SIM), both on the Solar Radiation and Climate Experiment (SORCE) satellite. Measurements by SUSIM and SORCE overlapped from 2003 to 2005. SUSIM and SORCE observations represent ～?20 years of absolute UV SSI. Unfortunately, significant differences exist between these two data sets. In particular, changes in SORCE UV SSI measurements, gathered at moderate and minimum solar activity, are a factor of two greater than the changes in SUSIM observations over the entire solar cycle. In addition, SORCE UV SSI have a substantially different relationship with the Mg ii index than did earlier UV SSI observations. Acceptance of these new SORCE results impose significant changes on our understanding of UV SSI variation. Alternatively, these differences in UV SSI observations indicate that some or all of these instruments have changes in instrument responsivity that are not fully accounted for by the current calibration. In this study, we compare UV SSI changes from SUSIM with those from SIM and SOLSTICE. The primary results are that (1) long-term observations by SUSIM and SORCE generally do not agree during the overlap period (2003?–?2005), (2) SUSIM observations during this overlap period are consistent with an SSI model based on Mg ii and early SUSIM SSI, and (3) when comparing the spectral irradiance for times of similar solar activity on either side of solar minimum, SUSIM observations show slight differences while the SORCE observations show variations that increase with time between spectra. Based on this work, we conclude that the instrument responsivity for SOLSTICE and SIM need to be reevaluated before these results can be used for climate-modeling studies.     

The Kwakshua Watersheds Observatory,central coast of British Columbia,Canada

The Kwakshua Watersheds Observatory (KWO) is an integrative watersheds observatory on the coastal margin of a rain-dominated bog-forest landscape in British Columbia (BC), Canada. Established in 2013, the goal of the KWO is to understand and model the flux of terrestrial materials from land to sea – the origins, pathways, processes and ecosystem consequences – in the context of long-term environmental change. The KWO consists of seven gauged watersheds and a network of observation sites spanning from land to sea and along drainage gradients within catchments. Time-series datasets include year-round measurements of weather, soil hydrology, streamflow, aquatic biogeochemistry, microbial ecology and nearshore oceanographic conditions. Sensor measurements are recorded every 5 min and water samples are collected approximately monthly. Additional observations are made during high-flow conditions. We used remote sensing to map watershed terrain, drainage networks, soils and terrestrial ecosystems. The watersheds range in size from 3.2 to 12.8 km², with varying catchment characteristics that influence hydrological and biogeochemical responses. Despite local variation, the overall study area is a global hotspot for yields of dissolved organic carbon, dissolved organic nitrogen and dissolved iron at the coastal margin. This observatory helps fill an important gap in the global network of observatories, in terms of spatial location (central coast of BC), climate (temperate oceanic), hydrology (very high runoff, pluvial regime), geology (igneous intrusive, glacially scoured), vegetation (bog rainforest) and soils (large stores of organic carbon).     

Lunar core detection using two surface magnetometers at very low frequency

A method of analysis is developed for combining the measurements of two surface magnetometers so as to deduce empirically the very low frequency electromagnetic transfer function of the Moon. The method is expected to be useful in determining the presence of a lunar metallic core by making usable for this purpose simultaneous magnetic field measurements by the Apollo 15 and 16 surface modules.     

Estimating Injury and Loss of Life in Floods: A Deterministic Framework

This paper presents an outline methodology and an operational framework for assessing and mapping the risk of death or serious harm to people from flooding, covering death and physical injuries as a direct and immediate consequence of deep and/or fast flowing floodwaters (usually by drowning), and deaths and physical injuries associated with the flood event (but occurring in the immediate aftermath). The main factors that affect death or injury to people during floods include flow velocity, flow depth, and the degree to which people are exposed to the flood. The exposure potential is related to such factors as the “suddenness” of flooding (and amount of flood warning), the extent of the floodplain, people’s location on the floodplain, and the character of their accommodation. In addition, risks to people are affected by social factors including their vulnerability and behaviour. A methodology is described for estimating the likely annual number of deaths/injuries. This is based on defining zones of different flood hazard and, for each zone, estimating the total number of people located there, the proportion that are likely to be exposed to a flood, and the proportion of those exposed who are likely to be injured or killed during a flood event. The results for each zone are combined to give an overall risk for each flood cell and/or community. The objective of the research reported here is to develop a method which could be applied using a map-based approach in which flood risks to people are calculated and displayed spatially for selected areas or communities. The information needed for each part of the process is described in the paper, and the further research to provide the required information is identified.