Geology topics

S. Honjo

Publications and source records attributed to S. Honjo.

3 recordsLinked to original sources

USGS1988

Sediment deposition in the Late Holocene abyssal Black Sea with climatic and chronological implications

The temporal sedimentary patterns in the Late Holocene central eastern and western Black Sea are very similar. The sedimentary history was most visibly affected by the coccolithophorid species Emiliania huxleyi which briefly invaded the Black Sea for the first time (“First Invasion Period”), nearly disappeared again shortly afterwards (“Transition Sapropel”), but returned permanently several centuries later (“Final Invasion Period”). The temporary near-disappearance of E. huxleyi was probably caused by a temporary drop in salinity. Accumulation of E. huxleyi was on average about 40% higher in the western than in the eastern Black Sea. Highest coccolithophorid production occurred basin-wide during part of the Little Ice Age. The accumulation of terrigenous matter was generally higher in the eastern than in the western Black Sea by about 20%.

Deep Sea Research Part A, Oceanographic Research P↗

USGS1982

Sedimentation of lithogenic particles in the deep ocean

Investigation of lithogenic particles collected by sediment traps in open-ocean stations revealed that the sediment flux increased linearly with depth in the water column. This rate of increase decreased with distance of the station from the continent; it was largest at the Panama Basin station and almost negligible at the E. Hawaii Abyssal Plain station. At the Panama Basin station, smectite flux increased with depth. We suggest that smectite resuspended from bottom sediments of the continental slope west of the sediment-trap station is advected by easterly deep currents, and the suspended particles are then possibly entrapped by large settling particles. On the other hand, the flux of hemipelagic clay particles, kaolinite and chlorite, was nearly constant at all depths; this can be explained by incorporation of these particles in fecal pellets which then settle from the surface water. At the Demerara Abyssal Basin Station, flux of illite and chlorite particles increased with depth and the flux of smectite was constant. A sudden increase of the flux of illite and chlorite was observed near the bottom traps at the So??hm Abyssal Plain station. The flux of quartz and feldspar was 10 to 15% of the clay flux.

Marine Geology↗

USGS1972

Microcrystalline sphalerite in resin globules suspended in Lake Kivu, East Africa

The origin and chemical nature of micron-sized spheres found as suspended particles in Lake Kivu are examined. It can be shown that the hollow spheres, with a wall thickness of 500 Å, consist of a complex polymeric resinous material which has little functionality, except for hydroxyl groups. The spheres arise in the process of degassing of water samples at depth. Tiny gas bubbles, about 1 micron in size, act as scavengers of dissolved resinous material. The newly created resinous membrane promotes the selective coordination of zinc dissolved in the water column. In the prevailing H 2 S regime, formation of sphalerite crystals in induced. The size range of the crystals, 5 to 50 Å, corresponds to 1 to 10 unit cells and suggests that the resinous membrane also acts as a template in sphalerite growth processes. The sources of the zinc and dissolved gases (CO 2 , CH 4 , H 2 S) are hydrothermal springs seeping from the lake bottom into the basin. Water discharge is substantial; about 100 years are required to fill the lake to its present level (ca. 550 km 3 water). The average Kivu water contains 2 ppm zinc. Thus, 1 million tons of zinc are contained in Lake Kivu in the form of sphalerite.

Lake Kivu↗