IV RECENT RESEARCH BY IGCP 299 PARTICIPANTS
IV1 WORLD KARST CORRELATION
K. A. GORBUNOVA , Reader ,
Perm University , Perm , 614600 , Russia
The Perm Region territory of 160.6 km2 is situated within three large geostructures:the eastern margin of the Eastern European platformm , Pre-Urals foredeep and the folded belt of the Urals zone. The karstic rocks:Paleozoic limestones , dolomites , gypsums , anhydrites , salts are exposed or occur not deep from the surface on the area of about 30 thousand km2.
In the east part of the platform on the boundary with Pre-Urals foredeep , the karst is developed in the arches and on the limbs of tectonic swells. In the Ufa swell arch there are karstified flat-pitching Artinskian and partially Kungurian limestones and dolomites. The plateau is karstic waters' catchment area. Along its margins there flow out karstic springs. The western and eastern limbs and the northern plunge of Ufa swell are composed of gypsums , anhydrites , limestones and dolomites of Iren horizon of the Kungurian stage of the Lower series of the Perm system .To the north these deposits are spread in the arch of the Krasnokamsk-Polasna swell. Upon all this area karstic breccia is found. The karstic forms are represented with numerous sinkholes , basins, karstic ravines and karstic lakes. In the Kungur area there is Kungur ice cave (5.6 km).
The Solikamsk and the southern part of the Pechora tectonic basin of thePre-Urals foredeep are characterized with karst in the salts of Kungurianstage. In places of salts leaching there have been formed considerable in area closed lows with great thickness of loose Quaternary deposits. Saline springs open onto the surface.
In the Urals folded belt the karst are mainly in the limestones and dolomites of the Devonian , Carboniferous , Permian , to a lesser degree Ordovician and Silurian system. The karstified rocks occur in the form of anticline and syncline folds accompanied with fracture dislocations. Typical are sinkholes , basins , lost rivers , springs , caves andblind creeks.
Various kinds of the human activities ,being called as technogenic impact change karstic processes course. These changes have various trends. In most cases the technogenic impact lead to activization of karstic processes as a result of the environment components deformation which determine the basic conditions and factors of karst formation.The karst activization has a negative impact on engineering geological constructions and may cause hazardous situations.
K. G. GRIMES
Regolith Mapping , PO Box 362 , HAMILTON , Victoria , 3300.
The South-East Karst Province of South Australia is an extensive area oflow relief with dolines , cenotes , uvalas and a variety of cave types developed in the soft , porous ,flat- lying Tertiary ( Miocene) Gambier Limestone , and also as syngenetic karst in the overlying calcarenite dunes of the Pleistocene Bridgewater Formation (Marker , 1975; Lewis , 1984) . Shallow swampy dolines and subjacent and covered karst depressions occur in superficial Quaternary sediments. There are some similarities with the Nullarbor Karst Region (also developed on extensive soft flat-lying Tertiarylimestone) but the climate is wetter and the younger dune ridges and surficial sediments complicate the karst development in this region.
Systematic variations within the province reflect , in particular , differences in the parent rock types, the extent and nature of the cover and the hydrology - in particular the depth to the water table and its gradient (Marker , 1975).
The most spectacular surface karst features are the collapse dolines , especially those that extend below the water table to form cenotes. These have formed above large phreatic caverns. More numerous are the many small shallow swampy hollows that appear on the flat plains between the dune ridges in the northern two-thirds of the region. The hollows are of two maintypes: normal karst ‘dolines' developed in the calcareous coastal flat deposits , but limited in vertical range by the shallow water tables; and small subjacent or covered karst subsidence dolines where quartzose dunes and sheets overlie the older limestone. The larger shallow lakes with lunettes may not be karst , but rather primary coastal lagoons that have been modified by the wind since the sea withdrew from the flats.
The caves are dominantly phreatic in origin and vadose features are extremely rare. Both joint and bedding plane control can be seen , but solution at temporary water-table levels can make the latter hard to recognize in this area of flat- bedded limestone. Many of the primary phreatic caverns have been modified by collapse , and collapse domes and passages are common .Cave diving has demonstrated the existence of extensive underwater cave systems , and it appears that in the southern part of the region the bulk of the cave development may well be below the present water table , though these passages would have been at least partly drained during the lower sea levels of the last glacial period.
V. N. KATAEV, Cand. Sc.
Perm State University , Russia
The elements of structural control ( the form of tectonic fold ,the pattern of faults and the pattern of joints in the rocks of the tectonic fold ) have a relationship in geological space and time. The tectonic development of area ,the lithological and the deformation characteristics of rocks are influenced by the peculiarities of these elements of structural control.
In combination with other forms of control ( hydrodynamic , lithological , mineralogical and chemical ) the structural control in an area is defined by the dynamic and development conditions of karst process in geological space. The analysis of this control may be undertaken during the prognosis stage of karst investigation. The most advantageous structural conditions necessary to promote karst process were as follows: elongation in the direction of the regional underground water movement ,which provided the hydrodynamic connection between different water tables and with the surface drainage system .Moreover ,the efficiency of faults and joint zones as karst controlling features will depend on the actual fault (or joint zones ) angle and the direction of main movement of underground water.The faults ( or jointing) configuration , as a rule ,determines the degree of stream energy losses. For investigation of karst process the joints and faults will be analyzed as elements of the physical structural and the hydrodynamical anisotropic parameters of the massif.
As an illustrative example of the different role of joints for karst process is presented the analysis of jointing conditions in the Juravlinskii limestone massif (Urals) and Cloford Quarry area (Mendips, England) . The scheme of common variant mechanisms of tectonic fold formations and possible patterns of karst active faults is presented too in the text of the actual review.
THE GEOMORPHOLOGICAL SIGNIFICANCE OF THE NEWLY
DEFINED "DALY POINT" AND "DAVIS POINT" ON CORAL
REEF FORMATION AND DISTRIBUTION IN THE WORLD
HORI , Nobuyuki
Faculty of Integrated Arts and Sciences ,
Hiroshima University , Hiroshima , Japan
Coral reefs have been formed under the control of sea level changes during the Quaternary period. Especially ,present coral reefs have been controlled by the Holocene transgression. HORI(1977) proposed a new explanatory model for the distribution and formation of coral reefs of the world . The basal depths of outer reef slope (Rd) is most important in this model , for it indicates the sea level at the beginning of the coral reef formation.
The zone of the present coral reef formation is divided into the following two subzones. One is the core zone which indicates the zone of coral reef formation during the glacial period. The other is the peripheral zone of postglacial times. The core zone shows the constant value (ca. 100-150 m) of Rd , but the peripheral zone shows the geographical gradient of Rd.
Following DALY's idea of the glacial control theory , I would like to introduce the term "Daly point" for the maximum depth of Rd ,and "Dailyline" for the geographical gradient connecting these points (HORI , 1983) . And taking DAVIS' idea of the marginal sea , I would like to introduce the term "Davis point" for the marginal site of coral reef distribution which shows the minimum depth of Rd , and "Davis line" for the geographical marginal line connecting these points.
GEOGRAPHICAL VARIATIONS OF GROWTH RATES OF SPELEOTHEMS
AND ITS CLIMATIC GEOMORPHOLOGICAL SIGNIFICANCE
ARAKAWA , Tatsuhiko1 , HORI , Nobuyuki1 and MIURA , Najime2
1 Faculty of Integrated Arts & Sciences , Hiroshima University , Japan
2 Dep.of Geography , Faculty of Education , Yamaguchi University, Japan
Karst landforms have presented many good examples for climatic geomorphology. Absence of quantitative analysis , however , has been felt as a great lack.
Analysis of carbonate speleothems offers an interesting field for climatic geomorphology in karstic regions. A lot of speleothems such as stalagmites , stalactites and columns were collected from different climatic areas:
Hokkaido , Akiyoshi and the Ryukyu Islands (from the northern to the southern part of Japan). Many speleothem rings (growth rings) were dated by ESR , the volume of each layer of growth rings was calculated , and the formations of each layer were analyzed using an electron microscope.
In the Ryukyu Islands , as an example for the subtropical zone , most of the growth rings showed ages of around and after 25,000 yr. B. P. Their growth rates were more rapid than those of other areas. They consist of soft materials.
In the Akiyoshi limestone plateau , as an example for the temperate zone ,speleothems showed the oldest dates. They consist of very fine material.
In the Tohma Cave area , as an example for the subpolar zone , they consist of a very pure material , and the growth rate has been the slowest of all.