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Atlantic

A Regional Synthesis Paul E. Schenk

Volume 11, Number 1, April 1975

URI: https://id.erudit.org/iderudit/ageo11_1rep04

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Publisher(s) Maritime Editorial Board

ISSN 0843-5561 (print) 1718-7885 (digital)

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Cite this article Schenk, P. E. (1975). A Regional Synthesis. Atlantic Geology, 11(1), 17–24.

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A Regional Synthesis

PAUL E. SCHENK, Department of Geology, Dalhousie University, Halifax, Nova Scotia

Introduction southern zone (the Meguma Belt). The Avalon Plat­ form is composed of Late Cryptozoic and Early The Devonian Acadian orogeny divides the Nova Paleozoic shelf sedimentary rocks and volcanics. Scotia section into two contrasting assemblages: In contrast, the Meguma Belt contains an Early to (1) the pre-orogenic units, which are mainly marine; Middle Paleozoic succession which shows evidence and (2) the post-orogenic units, which are mainly of shoaling upwards from deep- fans to paralic redbeds with later marine overlap. The stratigraph­ lithosomes. The Belt extends seaward 200 km toward ic section is applied to Folk's tectonic cycle and the present continental slope. The two pre- plate tectonic events is shown in Figure 1. orogenic belts are separated structurally by the Glooscap Fault system - a major geostructure of The pre-orogenic assemblages can be separated questionable age and slip (Fig. 2). into a northern belt (the Avalon Platform) and a NOVA SCOTIA - A CHIP OF AFRICA ! Nouvelle Maroc Plate Units Event LATE PALEOZOIC my CEN0Z0IC

UPPER spread MESOZOIC ing TRIASSIC rifting -200 PERMIAN seal t MABOU o WINDSOR -330 Africa- HORTON N. Am. T0RBR00K collision KNOYDART KENTVILLE closing ARISAIG 420 WHITE ROCK subduct -•440 MEGUMA spread -ing CAMBRIAN OF C. BRETON FOURCHlT rifting •560 collision jOOO GEORGE R. closing ■1500

FIG . 1. Nova Scotian stratigraphic section as applied to Folk’s FIG . 2. Presumed paleogeographic position of Atlantic tectonic cycle, with plate-tectonic events. Canada and Northwestern Africa during the late­ st Paleozoic. Earliest Mesozoic strike-slip com­ ponent on faults not considered but argued mini­ mal in text. Note the disruption in the Mauritan- ide Eugeocline, possibly represented by the Meg­ uma Belt through the Ifni Gap. 18

The post-orogenic rock is distributed in two along the platform at this time. Although the Siluro- belts differing with respect to location both in Devonian is not preserved on Cape Breton Island, time and space. The northern belt of Late Devon- outcropping, Devonian granites suggest emplacement ian to Late Triassic rock forms part of the mainland and enclosing metamorphism at ">10km" depth (i.e. bedrock, consisting of redbeds and minor carbonate, a Silurian cover has since been eroded) (Wiebe, all deposited in intermontane basins of a rift- 1972). The older rocks were deformed and metamor- valley setting. This belt subcrops southward under phosed in the later Ordovician (Taconic) and possibly the present . The southern belt through the Lower Silurian (Wiebe, 1972; Helmstaedt is almost entirely offshore, on the Scotian Shelf, and Telia, 1973). and consists of a wedge of Mesozoic to Holocene age paralic sediments that generally thicken toward In the western segment of the Platform, the shelf edge. This belt is the miogeocline of successions of Lower Ordovician volcanics and the present East Coast Geosyncline (King( et al. , Silurian-Lower Devonian shallow marine and continent- 1975), al clastics cap an older tectonized terrain. Pre- ceding Acadian tectonism, a lower Devonian (?) pile The following sections outline the geologic of andesitic volcanics accumulated on the western evolution of these belts by a preliminary plate- (Cobequid) fringe of the Platform,, The Acadian tectonic. model. In brief, the pre-Acadian Avalon deformation was mild in this belt but is profound Belt was a Late Precambrian sialic block extensively north and south of the belt. modified by Early Paleozoic along its "northwestern" flank. The Meguma belt was a deep- Southern Belt - The Meguma Belt sea fan passing upward into shallow-water complexes, and deposited off northwestern Africa. The Acadian The Meguma Group forms most of the present geo- orogeny marks the initial impact of continental morphic massif. The Group is a complex, atv least collision which sandwiches the Avalon between 10 km thick, consisting basically of alternating Africa and North America. The northern belt of layers of quartz metawacke and slate. Conventional post-orogenic redbeds record Carboniferous shear stratigraphic classification is essentially based as the impact of continental collision passed south- on the /shale ratio - the sandier, supposedly ward, and Triassic rifting when Atlantic Canada was basal Goldenville Formation, and the shaly, suppos- a triple junction between the American, African, edly upper Halifax Formation (Fig. 3). Goldenville and European plates. The southern belt also con- lithosomes are channel deposits of former deep- tains a record of this rifting, but mainly of drift sea complexes derived from the present southeast as the present Atlantic widened. The Meguma (Fig. 4) . Belt is unique in the Appalachians for.being the only outcropping remnant of Africa left in North America (Fig. 2). dispersal patterns bend to the right, from northerly to easterly. This deflection could be due to: (1) an offshore bathymetric high (the Avalon Platform?) (Fig. 5), (2) the effect in the southern hemisphere; or (3) vector rotation PRE-OROGENIC ROCKS due to the strain induced by Acadian folding. Fluidized sediment flow was the main transport Northern Belt - The Avalon Platform mechanism for thicker sand layers, and turbidity currents for the thinner strata. The source area The Avalon Platform is a sialic residual of was a broad, low-lying, metasedimentary/meta- the cryptozoic (Pig. 2). On Cape Breton Island igneous terrane of presumed Cryptozoic age. A the oldest known rocks are (miogeoclinal) carbonates continent-sized source is required because the and arenites (George River Group) possibly 1400 to Meguma volume probably exceeds 1.3 x 10 km (see 1700 my in age (Wiebe, 1972). The Group has been Harris and Schenk, this volume). Siliclastics from intruded by diorites (Wiebe, 1972) which are, in this source were well-sorted both texturally and 03 turn, overlain by Eocambrian metavolcani (the compositionally before introduction into the fan Forchu Group). These volcanics are related to system„ either an episode of proto-Atlantic rifting (Schenk, 1971), or an arc-type volcanism (Helmstaedt Water depth over the Meguma lithotope is and Telia, 1973). The Forchu may include the wide- questionable but probably great. Transported, spread Eocambrian tillites (A.F. King, personal angular pebbles of phosphate within some thick communication). Notably all of these rocks were may have been derived from an outer shelf or penetratively deformed by the Eocambrian "Avalonian" upper slope regime similar to the area where phos- orogeny and intruded by epizonal granites (560 my) phate is known to precipitate today (200 to 1500 m, (Wiebe, 1972; Helmstaedt and Telia, 1973). Recent marine depth). These clasts may have been eroded dating of granites may reveal a similar history in by headward migrating canyons. Persistence of a the Cobequid Mountains. uniform, consistent current pattern throughout 10 km of the Group is characteristic of deep water Intermittant volcanism, shallow-water clastic fans and "troughs". Absence of large-scaled deposition, and frequent hiatuses continued through cross-stratification and predominance of massive Cambrian and Early Ordovician. A record of an- to graded layering also suggest deep water. Massive desitic (?) volcanic accumulation in this period coalescing carbonate concretions which occur in is preserved in the Antigonish-Pictou Highlands the middle of thick sand layers may have concentrat- (Brown's Mountain Group)„ Benson (1974) suggested ed from dissolving shell debris due to acidic inter- that this represents a that formed stitial marine water below the carbonate compen- 19

FIG. 3. Meguma Group outcrop, boxed area on u j (/ i Eastern Shore is Fig. 1 of Harris and C d id 0 3 <_> Schenk (this volume). \ SANDS FUNNELED DOWNSLOPE BY TURBIDITY CURRENTS \ VERY LARGE, LOWLYING THROUGH CANYONS TO LOWER \ DEEPLY ERODED, RISE AND . GNEISSIC SOURCE FLOWS DEFLECTED BY TOPO- \ AREA, 7PRECAMBRIAN GRAPHIC HIGHS OF OFFSHORE AGE AVALON PLATFORM BLOCKS. BOTTOM CURRENTS ON LOWER RISE ARE IMPORTANT.

SANDS WELL-SORTED AND WINNOWED ON \ WIDE SHELF

DISPERSAL- PROVENANCE FIG. 4. Dispersal and provenance of the Meg­ MEGUMA GROUP uma Group. 20

FIG. 5. Speculative setting along the “ eastern” Paleozoic North Atlantic during deposition of the Meguma Group. Delta complex from Algeria; continental shelf in Morocco; upper Meguma perhaps a lower ; lower Meguma perhaps an abyssal fan. Rotation of diagram 180 degrees restores setting to Recent along the western North Atlantic with the sialic block as the Bermuda Rise (after Horne et al., 1971).

sation depth (4 km). Several of the Halifax litho- (polar ) in spite of evidence of somes probably accumulated in relatively shallow (phosphate). If the Moroccan Anti-Atlas was the water as indicated by trace fauna, flaser structures, Meguma Shelf, Meguma deposition began in the and similarity to slates intimately associated with Middle Cambrian (Schenk 1971). The Anti-Atlas paralic sediments of the overlying White Rock area (Fig. 2) was a site of carbonate deposition Formation. through the Infra-Cambrian and Early Cambrian.

The shaley Halifax lithosomes are much more Younger and slightly more fossiliferous units complex than the relatively simple Goldenvilles. of the Belt overlie the Meguma Group only along Halifax lithologies both intertongue with, and over- the northwestern border. These units include lie Goldenville layers. Possible lithotopes for quartz arenites, mixed quartzites, siltstones and the Halifax range from the abyssal plain, through shales, and black shales of the White Rock, Kent- a deep-sea fan, and to the continental shelf. ville and Torbrook Formations. The formations span "Distal" in this complex need not occur the time interval from Late Ordovician through only downcurrent from more proximal Goldenville Early Devonian (Fig. 6). facies, but also on the northwestern flanks of easterly turning channels. Intercalations up to The White Rock Formation is a paralic to near­ 1 km in thickness of Halifax within Goldenville shore complex of lithosomes (Lane, this volume). lithologies are levee, overbank, and interchannel The most distinctive and common type is quartz facies of either the fan or the upper slope. Al­ arenite; however, silty shales, mixed quartzites- though turbidity currents undoubtedly were common, siltstones, phosphatic dark shales, volcaniclastics much of the thin, ungraded, fine sand and coarse and limited lime beds and paraconglomerates also silt were related to bottom current origin. occur. The Meguma Group-White Rock Formation contact (Caradocian(?) or younger) varies from a complex, Graptolites occur in outcrops of the Halifax folded, angular unconformity to presumably conform­ Formation approximately 2 km below the contact with able relations. In the area of unconformity, a the overlying White Rock Formation.along the north­ thin unit of pebbles has drop-stone features and western edge of the Meguma Belt. The fauna indicate the pebbles have shapes and surface textures an Earliest Ordovician age. Others in the upper­ suggestive of glacial origin (Fig. 7; Schenk, 1972) . most Goldenville along the southeast are question­ The beds of this formation and the preceding Halifax ably Early Ordovician. Thus far, acritarchs and and succeeding Kentville slates are poorly to non- chitonozoans have been recovered almost entirely fossilferous. This absence or great scarcity of in graptolitic rock. The absence of fauna in the fossils suggests a hostile environment to life Meguma Group tentatively suggests refrigeration (because of cold?). Curiously, northward, across 21

IH3 • Extent of late Ordovician Ice Sheet \\\ Area of main glacial fluctuations ^ Direction of glacial movement

\ ?i

FIG. 6. Late Ordovician glaciation of Northwestern Africa with offshore Meguma-White Rock sediment-stack.

the Glooscap Fault system, time-equivalent strata evolving complex of offshore mud, sandy storm of a similar environment contain a rich tropical shoals, muddy embayments and river mouths, and to subtropical fauna (Arisaig Group-Bambach, 1969). sub- to intertidal regimes of mixed sand and mud. Equally notable, the massive quartz arenite beds of (Jensen, this volume). Sedimentation closely pre- the White Rock Formation are particularly concen- dated Acadian tectonism here and occurred simultane- trated along the lower boundaries of two transgres- ously as other regions of the Appalachians were up- sions. These levels may be integrally related to lifted and deformed. Apart from the textural eustatic changes from deglaciations (Lane, this evidence of its shoaling nature and small tuffaceous volume). Similar impressive marine quartzite content, the sediment is petrologically mature. accumulations are known from the Coastal Meseta of What is most distinctive about the formation is Morocco and northward along Western Europe (Beuf its unusual Rhenish(European) fauna. In the Avalon et al, 1971). Platform, some of the rocks of the Upper Stonehouse Formation at Arisaig are of equivalent age and Much of the Kentville Formation is a classical similar sedimentary facies to the Lower* Torbrook graptolitic black shale, particularly near the base; Formation, but possess a very different fauna. however, silty shale, interbedded siltstones and This is a critical point which strongly supports limestones also occur both vertically and laterally. an eastern origin for the Meguma Belt. Lateral variability in thicknesses and litho.somes would suggest a variable, neritic marine origin. POST-OROGENIC ROCKS Of the few fossils found, some bivalves and brachio- pods were probably native to shallow regimes. The The Northern Belt Kentville is reminiscent of the black shales of the Ross Brook Formation of Arisaig where shallow The Late Devonian through Triassic sedimentary water fauna (Eocoelia brachiopods) are common. pattern is one of alluvial fans grading laterally into fluvial plains spotted with lakes, all within In contrast to the underlying sequence, the a structurally complex intermontane system. The Torbrook Formation is a richly fossilferous sources for these very thick, siliclastic deposits succession of Lower Devonian silty shales, mud- were mainly horsts of the Avalon Belt, and to a stones, and limestones. These sediments lesser extent, the Meguma Massif. Recall that the were deposited in a paralic marine zone - an Mid-Devonian Acadian orogeny marks initial contin- 22

FIG. 7. Mid-Paleozoic cross-section of Northern Nova Scotia. The Cobequid (Glooscap) Fault probably represents a great separation. ental collision with Africa at our latitude (Nova Carboniferous strata underlie large areas of the Scotia), Regionally, this collision occurred at Gulf of St. Lawrence, Laurentian Channel and different times, to the north of our area earlier, southeastward under Mesozoic-Cenozoic sediments 0f to the south, later. During the Mid-Carboniferous, of the Scotian Shelf (Howie and Barss, 1975, In press). a rapidly narrowing seaway to the south repeatedly Modern sedimentologic-tectonic analogues might be flooded the tortuously interconnected, graben found on the southewestern shore of the "shrinking" basins. Resulting sediments are cyclothems, each Persian Gulf, or, somewhat similar geographically of carbonate, sulfate, and redbeds. Carbonates to the Afar Triangle of the rifting Red Sea. show progressive increase in salinity, culminating in intertidal algal stromatolites disrupted by In the Atlantic Provinces, the Permian is diagenetic, supratidal sulfate (see Schenk, this poorly developed and both Lower and Middle volume). Metallic sulfide and sulfate deposits Triassic are absent on land. During the Early are related to initial concentration by hydro- Mesozoic, Nova Scotia was close to the triple thermal activity related to volcanism. Subse- junction from which the American, African and quent concentration was by evaporation both in European plates separated. Late Triassic uparching, shallow lagoons, beneath adjacent salt flats, and probably due to peripheral rifting (and upwelling within salinas or playa lakes. The climate was mantle plumes), uplifted the area. "Basin and arid; the setting mid-continental. Paleomagnetic Range" topography was renewed as much larger grabens data from Mid-Carboniferous lavas at faulted basin- were created. The faulted margins coincide with margins place Nova Scotia at 10 degrees south old lines of weakness, mainly along the juncture latitude (Roy and Robertson 1968). between the Meguma and Avalon belts. This linea- ment is now called the Glooscap Fault System (King At the end of the Carboniferous, these thick et al, 1975). During Jurassic drift, the Glooscap basin successions (locally >13 km) were deformed was reactivated (probably with no strike slip - during the Maritimes Disturbance, equivalent to the francheteau and LePichon, 1972), and extended sea- Allegheny-Hercynean orogeny. Multiple continental ward to form the southwestern edge of the Grand collisions have been proposed for this event, but Banks and the Newfoundland . Figure 2 it may more simply represent translated movements shows that other possibly reactivated lines of weak- during ultimate collision between North America ness may have been important. The Mauritanide and Africa. The Carboniferous rift valley setting mountain belt is the mirror image of the Appala- may be due to alternating tension and compression chians, and is the eastern side of the split due to shearing along a sinusoidal fracture zone orogen of Paleozoic age. The eugeocline of the reactivated later as the Glooscap Fault System. Mauritanides is discontinuous only in southern 23

Morocco (Fig„ 2). This area is also the location supported warm water forms. Silurian deglaciation of the Ifni Gap, the largest mis-match (after flooded the African shore. Distances between the Bahama Overlap in Bullard's et al. (1965) cratons decreased as was subducted continental fit. Dietz and Sproll (1970) attempt- and basins closed on either side of the Avalon Plat- ed to fill this gap with supposed sial of the Canary form. At the latitude of Nova Scotia initial closing Islands. Figure 2 shows that the Meguma belt may was in the Middle (?) Devonian, but was earlier be the missing segment °f the Maurintanide eugeo- further to the north and later to the south. The cline, and may be responsible for the Ifni Gap. Meguma Belt met the Avalon Platform along the present line of the Glooscap Fault - a continually active The Southern Belt zone even today. During shearing closure through the Carboniferous, lateral slip on splays of the Since the initial rifting in the Early Jurassic, Glooscap fault raised block-fault mountains. Atlantic Canada has moved westward and subsided These blocks were the sources for very thick, inter- away from the uparching Mid-Atlantic Ridge. Above montane, redbed deposits. During the Mid-Carbonifer- the depressed Paleozoic basement, miogeoclinal ous, repeated floodings of hypersaline sediments record a variety of environments ranging into both Nova Scotia and Morocco are the last from restricted marine to carbonate and deltaic. records at this latitude of the Paleozoic Atlantic. These sediments of latest Triassic through Cretaceous The Late Carboniferous Maritime Disturbance and Cenozoic ages describe a wedge that thickens (Allegheny-Hercynian) marks the final closure to about 3.5 to 4 km at the shelf edge. Seaward between Africa and North America. The position of the shelf extends another wedge of equal thick- of Nova Scotia was then mid-continental and ness, the eugeocline of the East Coast Geosyncline equatorial. (King et al, 1975). It is composed of coalescing deep-sea fans. Sediment on the present shelf is Late Triassic rifting resulted in large-scale relict till and outwash from the regressive inter- grabens and fissure eruptions preceding the Early vals of Pleistocene glaciations, covered by a veneer Jurassic drifting of Atlantic Canada from North- of winnowed sands and gravels derived from the western Africa. Configurations of the new ocean Holocene transgression of the Atlantic. The history basin were inherited by rifting along old lines of of the East Coast Geosyncline may be analagous to weakness (e0g. the Zemmour Fault, and the Glooscap- that of the Meguma Belt. The coalescing deep Newfoundland Fracture Zone),, Some of these sea fans of the eugeocline are similar to those fractures initiated great transform faults (e.g. of the Meguma. Dispersal patterns of Cenozoic fans Kelvin Fault and Glooscap-Newfoundland Fracture show both deflection of turbidity currents by sea- Zone). The Maruitanide eugeocline segmented,, bottom highs as well as smoothing of the lower rise leaving a portion (the Meguma Belt) attached to a by geostrophic contour currents. Upper parts of part of the Avalon Platform (Fig. 2). the Halifax Formation are composed of muds similar to those of the upper continental slope. Reworked REFERENCES glacial sediments capping the East Coast miogeocline are reminiscent of the White Rock Formation. Melt- BAMBACH, R.K., 1969, Bivalvia of the Siluro- ing of the Wisconsin ice-sheet has submerged parts Devonian Arisaig Group, Nova Scotia, unpubl. of the Scotian Shelf under 300 m of seawater. Could Ph.D. thesis, Yale Univ. 376 p„ very slow sedimentation today on the Shelf be a present-day analogue to deposition of the Silurian BENSON, D.Go, 1974, Geology of Antigonish Highlands, Kentville black shale? Nova Scotia. Geol. Surv. Canada, Mem. 376 p.

SUMMARY BEUF, S., BIJOU-DUVAL, B., CHARPAL, de O., ROGNON, P., GARIEL, 0., et BENNACEF, A., 1971, Les Gres Provenance and dispersal study suggest that du Paleozoique Inferieur au Sahara. Sedi- the Meguma Group was a Cambro-Ordovician deep-sea mentation et discontinuities. Evolution fan complex built offshore of Morocco. As such, structurale d'un craton. Inst. Francais the Meguma was a segment of the Mauritanide eugeo- Petrole, Coll. Sci. et Tech. Petrole No. 18, cline. The Meguma may be that segment missing 464 p. today between the coastal Meseta of Morocco to the north, and the coastal belt of the Spanish BULLARD, E., EVERETT, J.E., and SMITH, A.G., 1965, Sahara-Mauritania to the south. The Early Paleozoic The fit of the continents around the Atlantic: continental slope may be marked by the continuing in A Symposium on Continental Drift, Phil. weak lineaments of the South Atlas and Zemmour Trans. Roy. Soc. London, Ser. A, v. 258, p„ Faults. If so, the Zemmour should mark the eastward 41—51. limit of the Meguma Belt near the Scotian Shelf edge. DIETZ, R.S. and SPROLL, W.P., 1970, East Canary Islands as a micro-continent within the Africa- Deep-water sedimentation of the Meguma changed North America continental drift fit. Nature, upward to upper-slope deposition as the eugeoclinal v. 226, p. 1043-1045. prism prograded seaward with extension of the Moroccan shelf. Latest Ordovician glacio-eustasy FRANCHETEAU, J. and LEPICHON, X., 1972, Marginal lowered , resulting in the sudden appearance fracture zones as structural framework of of paralic and glacio-genetic lithosomes on the continental margins in south Atlantic Ocean. African shore and shelf. Cold water probably Am. Assoc. Petrol. Geol., Bull., v. 56, p. 991- restricted fauna within this succession while at 1007. the same time the (remote?) Avalon Platform 24

HELMSTAEDT and TELLA, 1973, Pre-Carboniferous SCHENK, P.E., 1970a, Carbonate-sulfate-redbed facies Structural History of Southeast Cape Breton and cyclic sedimentation of the Windsorian Island, N.S., Maritime Seds., v„ 9, p. 88-89. Stage (Middle Carboniferous), Maritime Pro- vinces. Can. J. Earth Sci. 6, p 1037-1066. HOWIE, RoDo and BARSS, M.S., 1975, Upper Paleozoic rocks of the Atlantic Provinces, Gulf of St. , 1970b, Regional variation of the Lawrence and adjacent continental shelf; in flysch-like Meguma Group (Lower Paleozoic) van der Linden, W.J.M. and Wade, J.A. (eds.) of Nova Scotia compared to Recent sedimentation Offshore Geology of Eastern Canada, Geol. off the Scotian Shelf. Geol. Assoc. Canada Surv. Canada, Paper 74-30, Vol. 2, p. 35-50. Spec. Paper 7, p 127-153.

HOWIE, R.D. and BARSS, M.S., In press, Paleogeography , 1971, Southeastern Atlantic Canada, and sedimentation in the Upper Paleozoic, northwestern Africa, and continental drift. Eastern Canada, Can. Soc„ Petrol. Geologists, Can. J. Earth Sci. 8, p 1218-1251. Memoir 4. , 1972, Possible Late Ordovician HURLEY, P.M., and BOUDDA, A., KANES, W.H„ and glaciation of Nova Scotia. Can. J. Earth Sci. NAIRN, A„E.M„, 1974, A plate-tectonics origin 9, p 95-107. for the Late Precambrian-Paleozoic orogenic belt in Morocco. Geology, v.2, p. 343-344. WIEBE, R.A., 1972, Igneous and Tectonic Events in NE Capte Breton Island, N.S., Can. J. Earth KING, L.H., HYNDMAN, R.D., and KEEN, C.E., 1975, Sci., v. 9, p. 1262-1277. Geological development of the of Atlantic Canada. Geosci. Canada, v. 2, p. 26-35.

ROY, J.L. and ROBERTSON, W.A., 1968, Evidence for diagenetic remnant magnetism in the Maringouin Formation, Can. J. Earth Sci., v. 5, p. 275- 285.