Journal of the Sedimentological Society of Japan

Tide-dominated deltaic deposits of the Upper Cretaceous Frontier Formation, Wyoming, USA

Ryoichi Matsui

1997 Volume 46 Issue 46 Pages 1-2
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.1

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Alluvial fan sedimentation in the Cretaceous Athgarh Gondwana basin, Orissa, India

B. Mishra, K. L. Pandya, Wataru Maejima

1997 Volume 46 Issue 46 Pages 3-14
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.3

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The Athgarh Formation forms an important stratigraphic unit of Upper Gondwana sediments of Peninsular India. The regional palaeocurrent indicates a consistent southeasterly dispersal of clastics from the Archaean source terrain located to the northwest of the basin. The Athgarh Formation represents deposition in an alluvial fan environment with the development of proximal, mid-, and distal fan subenvironments and the distal part of the fan merging into a lake. The buildup of the Athgarh alluvial fan system occurred in a humid climate. Stream-flow processes dominated and a fan was drained by braided channels. Debris flow processes also operated, but were prominent only in the proximal fan zone. Several fans coalesced along the basin margin, forming a southeasterly sloping, broad and extensive alluvial plain terminating to a lake in the center of the basin. Aggradation of fans along the subsiding margin of the basin resulted in the Athgarh succession showing a remarkable lateral facies change in the down-slope direction. The proximal fan conglomerates pass into the sandstone-dominated mid-fan deposits, which, in turn, grades into the cyclic sequences of sandstones and mudstones of a distal fan origin. Further down slope, thick sequence of lacustrine shales occurs.

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Thenardite and gypsum precipitated in wall of brick building in campus of University of the Ryukyus, Okinawa

Satoshi Yamamoto, Youhai Zhu

1997 Volume 46 Issue 46 Pages 15-21
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.15

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Fine-grained white sulphates were precipitated in wall of brick building in the campus of the University of the Ryukyus, Okinawa. The sulphate samples scratched by knife were investigated by X-ray diffraction analysis (XRD), optical microscopy, and scanning electron microscopy (SEM). The precipitated sulphates are thenardite and gypsum. These minerals were precipitated by evaporitic reaction between sulphate (SO₄^2-) in acid rain and cations. Sodium (Na⁺) would be supplied from salt (NaCl) dissolved in rain and calcium (Ca²⁺) would be leached from the brick. Accidentally, we found massive precipitation of gypsum and taylorite along the brick wall under the agricultural fertilizer, laid on a shelf-like place in the building, which had supplied SO₄^2-, K⁺ and NH₄²⁺ during raining.

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Comparison between a lazer diffraction-scattering method and a hydrometer method in the grain size analysis for fine-grained sediments

Hajime Katayama

1997 Volume 46 Issue 46 Pages 23-30
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.23

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Grain size distributions analyzed by a laser diffraction-scattering method have been compared with those by a conventional hydrometer method. The laser method shows coarser shifts of grain size distribution for all samples. For the reason, it is pointed out that the difference of the physical meaning of the grain size measured by these two methods, and the effects of hindered settling, turbulence of the liquid and Brownian motions to the Stokes velocity for the hydrometer method.

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Physical properties of sea bottom surface sediments

Development of a bulk density and porosity profiler using gamma- and neutron-ray for an undisturbed sediment core and the preliminary results

Ken Ikehara

1997 Volume 46 Issue 46 Pages 31-42
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.31

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A bulk density and porosity profiler using gamma- and neutron-ray attenuation was developed for profiling the detailed figure of their changes near the sediment-water interface. Because of dissolution and decomposition of particulate matters sinking through the water column, the sea floor is an important interface in material cycle in the ocean. Preliminary results for the East China Sea sediments and the south Pacific deep-sea sediments indicated that surface sediments were deviled into several sections on the basis of density and porosity changes. That is, both values decreased rapidly with increasing sub-bottom depth at the uppermost 0.5-1cm (Section A). As compared with porosity, bulk density increased largely at Section B with sub-bottom depth of 0.5 to 2cm. Between 2 and 6cm deep, the rate of porosity decreasing was larger than that of bulk density increasing. Below 6cm deep, both of bulk density and porosity showed no significant change. These changes might be occurred by initial compaction of sediments and selective dissolution and decomposition of the lighter grains near the sediment-water interface.

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Organic components of the sediment core samples from the Ross Sea continental shelf, Antarctica

Masatoshi Komiya, Akira Nishimura

1997 Volume 46 Issue 46 Pages 43-48
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.43

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Organic components of the core sediment from the Ross Sea continental shelf, Antarctica are analyzed. The relation between the late Quaternary sedimentary environments and characteristics of organic elemental composition is discussed. The variations in the contents of organic carbon and nitrogen reflect the lithological change. The Holocene siliceous muds which were widely distributed on the continental shelf, are characterized by high organic carbon contents and low carbon/nitrogen (TOC/TN) ratios, suggesting a high productivity environment. The consolidated sandy silts which were influenced by the last glacial ice sheet inducing reworked coarse sediments, have low carbon contents and high TOC/TN ratios. The sandy sediments, which were deposited at the continental shelf edge in the last glacial time, are characterized by high inorganic carbon contents and a distinctive low TOC/TN ratios. Organic components in these sediments are considered to be the mixture of two different types. One is the organic matter which is derived from planktonic organisms in the ocean, such as diatoms, and its TOC/TN ratio is ca. 5. The other is the organic matter which is derived from kerogen in the continental rocks, and its TOC/TN ratio is≥8.

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A note on the functions of accommodation and sediment supply

Tetsuji Muto

1997 Volume 46 Issue 46 Pages 49-58
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.49

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Report on the Deltas Industrial Associates field trip “Lowstand Deltas in the Late Cretaceous Frontier Formation of central Wyoming”

Ryoichi Matsui

1997 Volume 46 Issue 46 Pages 71-76
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.71

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Report on the 2nd annual meeting of IGCP-396 “Continental Shelves in the Quaternary”

Yoshiki Saito

1997 Volume 46 Issue 46 Pages 77-82
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.77

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Report from ODP Leg 172 (Northwest Atlantic Sediment Drift)

Miwa Yokokawa, Leg 172 Scientific Party

1997 Volume 46 Issue 46 Pages 83-90
Published: November 25, 1997
Released on J-STAGE: May 27, 2010

DOIhttps://doi.org/10.4096/jssj1995.46.83

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