The Amplifier - v. 7, no. 7

In this issue...Len Waters, Circle K Club, Max Kert, Air Force, Stanley Eugene Bosch, Wesley Club, Engineer's week, toboggan party, Butte Central, Anaconda High School

Sediment dynamics in the subaquatic channel of the Rhone delta (Lake Geneva, France/Switzerland)

bstract With its smaller size, well-known boundary conditions, and the availability of detailed bathymetric data, Lake Geneva’s subaquatic canyon in the Rhone Delta is an excellent analogue to understand sedimentary pro- cesses in deep-water submarine channels. A multidisciplinary research effort was undertaken to unravel the sediment dynamics in the active canyon. This approach included innovative coring using the Russian MIR sub- mersibles, in situ geotechnical tests, and geophysical, sedimentological, geochemical and radiometric analysis techniques. The canyon floor/levee complex is character- ized by a classic turbiditic system with frequent spillover events. Sedimentary evolution in the active canyon is controlled by a complex interplay between erosion and sedimentation processes. In situ profiling of sediment strength in the upper layer was tested using a dynamic penetrometer and suggests that erosion is the governing mechanism in the proximal canyon floor while sedimen- tation dominates in the levee structure. Sedimentation rates progressively decrease down-channel along the levee structure, with accumulation exceeding 2.6 cm/year in the proximal levee. A decrease in the frequency of turbidites upwards along the canyon wall suggests a progressive confinement of the flow through time. The multi-proxy methodology has also enabled a qualitative slope-stability assessment in the levee structure. The rapid sediment loading, slope undercutting and over-steepening, and increased pore pressure due to high methane concentrations hint at a potential instability of the proximal levees. Fur- thermore, discrete sandy intervals show very high methane concentrations and low shear strength and thus could cor- respond to potentially weak layers prone to scarp failures.

Timing of Tertiary Extension in the Railroad Valley Pioche Transect, Nevada: Constraints from Ar-40/Ar-39 Ages of Volcanic Rocks

Time-space relations of extension and volcanism place critical constraints on models of Basin and Range extensional processes. This paper addresses such relations in a 130-km-wide transect in the eastern Great Basin, bounded on the east by the Ely Springs Range and on the west by the Grant and Quinn Canyon ranges. Stratigraphic and structural data, combined with 40Ar/39Ar isotopic ages of volcanic rocks, document a protracted but distinctly episodic extensional history. Field relations indicate four periods of faulting. Only one of these periods was synchronous with nearby volcanic activity, which implies that volcanism and faulting need not be associated closely in space and time. Based on published dates and the analyses reported here, the periods of extension were (1) prevolcanic (pre-32 Ma), (2) early synvolcanic (30 to 27 Ma), (3) immediately postvolcanic (about 16 to 14 Ma), and (4) Pliocene to Quaternary. The break between the second and third periods is distinct. The minimum gap between the first two periods is 2 Ma, but the separation may be much larger. Temporal separation of the last two periods is only suggested by the stratigraphic record and cannot be rigorously demonstrated with present data. The three younger periods of faulting apparently occurred across the entire transect. The oldest period is recognized only at the eastern end of the transect, but appears to correlate about 150 km northward along strike with extension in the Northern Snake Range-Kern Mountains area. Therefore the oldest period also is regional in extent, but affected a different area than that affected by younger periods. This relation suggests that distinct extensional structures and master detachment faults were active at different times. The correlation of deformation periods of a few million years duration across the Railroad Valley-Pioche transect suggests that the scale of active extensional domains in the Great Basin may be greater than 100 km across strike.

Into the abyss of Lake Geneva: the elemo interdisciplinary field investigation using the MIR submersibles

In summer 2011, the two Russian MIR sub- mersibles were brought to Switzerland to perform deep water dives in Lake Geneva. Research teams from several environmental science institutes, both national and inter- national, participated in this interdisciplinary effort to investigate the deeper parts of Lake Geneva. Using the MIRs allowed the scientists to see and precisely select the sites where they could extract specific sediment cores and carry out detailed in situ measurements at the sediment– water boundary. One focus site was the surrounding of the outlet of the wastewater treatment plant of the City of Lausanne, which discharges into the Vidy Bay. The investigations concentrated on the pollution of the local sediments, pollution-related ecotoxicological risks, micro- bial activity and spreading and removal of the effluents from the bay to the open waters of the lake. The other focus site was the Rhoˆne River delta and its subaquatic canyons, which formed as a result of the long-term interplay of the deposition of river-borne sediments and flood-triggered canyon erosion events.

Na 1 Nachlass Max Horkheimer, 17 - Korrespondenzen u.a. mit M. Gosling (p. I 9, 1-159)

11 Briefe zwischen M. Gosling und Max Horkheimer, 1935-1938; 1 Brief von Ellen Gottschalk an 04.08.1936; 1 Brief von Brill an Max Horkheimer, 15.08.1936; 2 Briefe zwischen Louise Gottschalk und Max Horkheimer, 06.12.1937, 19.04.1937; 3 Briefe zwischen Max Gottschalk und Max Horkheimer, 1941, 23.01.1941; 2 Briefe zwischen Nemes Gottschalk und Max Horkheimer, 29.03.1939, 03.04.1939; 2 Briefe zwischen Lawrence Gould und Max Horkheimer, 12.01.1947, 04.01.1947; 4 Briefe zwischen Isaeque Graeber und Max Horkheimer, 20.07.1941, 1941; 4 Briefe zwischen Malborne W. Graham und Max Horkheimer, 17.10.1940, 1940; 1 Brief von Max Horkheimer an J. A. C. Grant, 23.10.1940; 2 Briefe zwischen dem Grant Grove Lodge Kings Canyon National Park California und Max Horkheimer, 30.09.1946, 04.10.1946; 4 Brefe zwischen Liesel Gras und Max Horkheimer, 1948, 02.04.1948; 2 Briefe zwischen Claire F. Gravel und 23.03.1942, 26.03.1942; 1 Brief und 4 Briefentwürfe von Max Horkheimer an Edward S. Greenbaum, 20.06.1940; 13 Briefe zwischen B. Groethuysen und Max Horkheimer, 1935-1937; 1 Hochzeitsanzeige von Isabelle Grossen, 26.11.1938; 1 Brief von Max Horkheimer an Isabelle Grossen, 17.12.1938; 1 Brief von Kurt Grossmann an Max Horkheimer, 29.12.1939; 3 Briefe von Eva Grosz an Max Horkheimer, 1937; 5 Briefe zwischen Franz M. Groedel und Max Horkheimer, 1939, Oktober 1939; 7 Briefe zwischen Emil Grünberg und Max Horkheimer, 1935-1940; 1 Brief von B. M. Telders an Max Horkheimer, 27.09.1938; 3 Briefe zwischen dem Academic Assistance Council London und Max Horkheimer, 1935, 29.03.1935; 1 Briefentwurft von Max Horkheimer an Karl Grünberg, 07.02.1936; 1 Brief von Juliette Favez an Max Horkheimer, 07.02.1936; 3 Briefe zwsichen Martin Grünberg und Max Horkheimer, November 1938, 18.11.1938; 3 Briefe zwischen Alfred Grünebaum und Max Horkheimer, 10.01.1939, 1939; 2 Briefe zwischen D. E. Grünebaum und Max Horkheimer, 24.11.1940, 02.12.1940; 3 Briefe zwischen Richard Güldenstein und Max Horkheimer, August 1937, 17.08.1937; 1 Brief von Daniel Guérin an Max Horkheimer, 13.07.1947; 1 Brief von Max Horkheimer an Guerro, 08.09.1936;

(Table 2) Geochemistry of ore minerals and magnetization properties at the DSDP Leg 73 Holes

The samples investigated in this study come from DSDP Leg 73 Drill Holes 519A, 522B, and 524, all of which are in the South Atlantic. A general petrographic description of the basalts is given by Carman et al. (1984; doi:10.2973/dsdp.proc.73.120.1984).

Paleomegnetic and geochemistry of sediments from the early Aptian Oceanic Anoxic Event

The early Aptian Oceanic Anoxic Event (OAE1a, 120 Ma) represents a geologically brief time interval in the mid-Cretaceous greenhouse world that is characterized by increased organic carbon accumulation in marine sediments, sudden biotic changes, and abrupt carbon-isotope excursions indicative of significant perturbations to global carbon cycling. The brevity of these drastic environmental changes (< 10**6 year) and the typically 10**6 year temporal resolution of the available chronologies, however, represent a critical gap in our knowledge of OAE1a. We have conducted a high-resolution investigation of three widely distributed sections, including the Cismon APTICORE in Italy, Santa Rosa Canyon in northeastern Mexico, and Deep Sea Drilling Project (DSDP) Site 398 off the Iberian margin in the North Atlantic Ocean, which represent a range of depositional environments where condensed and moderately expanded OAE1a intervals are recorded. The objectives of this study are to establish orbital chronologies for these sections and to construct a common, high-resolution timescale for OAE1a. Spectral analyses of the closely-spaced (corresponding to ~5 to 10 kyr) measurements of calcium carbonate content of the APTICORE, magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) of the Santa Rosa samples, and MS, ARM and ARM/IRM, where IRM is isothermal remanent magnetization, of Site 398 samples reveal statistically significant cycles. These cycles exhibit periodicity ratios and modulation patterns similar to those of the mid-Cretaceous orbital cycles, suggesting that orbital variations may have modulated depositional processes. Orbital control allows us to estimate the duration of unique, globally identifiable stages of OAE1a. Although OAE1a had a duration of ~1.0 to 1.3 Myr, the initial perturbation represented by the negative carbon-isotope excursion was rapid, lasting for ~27-44 kyr. This estimate could serve as a basis for constraining triggering mechanisms for OAE1a.