Plio-Pleistocene Age Research Articles

The retention of primary oxygen isotope compositions of fossil elephant skeletal phosphate

Fossil elephant remains from sediments of Plio-Pleistocene age in the vicinity of Lake Turkana, Kenya, provide insights into the ability of the phosphate-oxygen system to preserve original δ 18 O values ( δ 18 O p ) in the depositional environment. Individual fossil specimens exhibit systematic variations in the δ 18 O p values of their various tooth and bone components. Differences in δ 18 O p values between these skeletal components can be as high as 3.6%., despite the fact that equivalent phases for individual modern elephants have δ 18 O p values which vary by less than 0.6%.. XRD traces of the different skeletal phases of modern and fossil samples, also infer differential preservation of primary apatite crystallinities among the various fossil phases. Fossil samples of dentine, cementum and bone have X-ray spectra with sharper and more intense peaks compared to their modern counterparts, but little change in crystallinity is observed for fossil enamel samples. A model based on the premise that the enamel phase preserves primary isotope signatures and that the accompanying skeletal phases are partially re-equilibrated with the fluids associated with the microbial decomposition of the elephant's carcass is consistent with the features of the 18O p dataset. This isotopic evidence, in conjunction with the physical and chemical attributes of enamel, has led us to postulate that enamel could be preserving primary isotope signatures while other skeletal components are affected to varying degrees by alteration processes in the burial environment.

Tectonics and geology of spreading ridge subduction at the Chile Triple Junction: a synthesis of results from Leg 141 of the Ocean Drilling Program

An active oceanic spreading ridge is being subducted beneath the South American continent at the Chile Triple Junction. This process has played a major part in the evolution of most of the continental margins that border the Pacific Ocean basin. A combination of high resolution swath bathymetric maps, seismic reflection profiles and drillhole and core data from five sites drilled during Ocean Drilling Program (ODP) Leg 141 provide important data that define the tectonic, structural and stratigraphic effects of this modern example of spreading ridge subduction. A change from subduction accretion to subduction erosion occurs along-strike of the South American forearc. This change is prominently expressed by normal faulting, forearc subsidence, oversteepening of topographic slopes and intensive sedimentary mass wasting, overprinted on older signatures of sediment accretion, overthrusting and uplift processes in the forearc. Data from drill sites north of the triple junction (Sites 859–861) show that after an important phase of forearc building in the early to late Pliocene, subduction accretion had ceased in the late Pliocene. Since that time sediment on the downgoing oceanic Nazca plate has been subducted. Site 863 was drilled into the forearc in the immediate vicinity of the triple junction above the subducted spreading ridge axis. Here, thick and intensely folded and faulted trench slope sediments of Pleistocene age are currently involved in the frontal deformation of the forearc. Early faults with thrust and reverse kinematics are overprinted by later normal faults. The Chile Triple Junction is also the site of apparent ophiolite emplacement into the South American forearc. Drilling at Site 862 on the Taitao Ridge revealed an offshore volcanic sequence of Plio-Pleistocene age associated with the Taitao Fracture Zone, adjacent to exposures of the Pliocene-aged Taitao ophiolite onshore. Despite the large-scale loss of material from the forearc at the triple junction, ophiolite emplacement produces a large topographic promontory in the forearc immediately after ridge subduction, and represents the first stage of forearc rebuilding.

Geological setting and styles of mineralization, north arm of Sulawesi, Indonesia

The north arm of Sulawesi consists of a Neogene island arc (North Sulawesi Arc) built upon Paleogene volcanic-sedimentary basement and underlain by oceanic crust, which is followed to the west by an arcuate, highly deformed terrane (neck of Sulawesi) characterized by metamorphic rocks and felsic granitoids belonging to the Sundaland continental margin. These two terranes have been contiguous during the Tertiary. The evolution of the North Sulawesi Arc is divided into two stages separated by collision of the north arm with the Sula Platform microcontinent in mid-Miocene time. During the Early Miocene a calc-alkaline andesitic arc developed in relation to west-directed subduction. Arc-continent collision resulted in back-arc thrusting, clockwise rotation of the north arm, and inception of subduction along the North Sulawesi Trench. Post-collisional magmatism in the North Sulawesi Arc produced felsic to mafic volcanic suites that are thought to be related primarily to rifting of the former arc rather than directly to subduction. In the neck of Sulawesi,LILE and LREE-element enriched, potassic granites (Dondo suite) of continental affinity (Sr 87/Sr 86 0.71) were generated. The north arm of Sulawesi is comparatively well mineralized. Porphyry CuAu and porphyry Mo mineralization is approximately 2–4 Ma old based on preliminary KAr dating and geological relationships. The former developed in an oceanic terrane following collision-related arc reversal, whereas the latter developed in a continental terrane that underwent lower crustal melting during extension following the same collision. Porphyry CuAu mineralization in the North Sulawesi Arc is associatedwith clusters of small hornblende diorite or quartz diorite stocks, but the specific volcanic environment above these intrusions and their magmatic affinity remain unknown. Mineralization related to porphyry CuAu districts includes CuAu skarn, polymetallic vein and high sulphidation epithermal Au (+enargite). Porphyry Mo mineralization in the neck of Sulawesi is related to small stocks or roof apophyses of the Dondo batholith. Cogenetic granites are exposed over 5000 km 2 and are intruded in an arcuate belt, more than 400 km long, parallel to the Sula Platform collision zone. Unimodal felsic volcanics of Plio-Pleistocene age, which occur locally along the inner side of the north arm and further to the south, are probably the extrusive equivalents of the Dondo granites. Epithermal Au mineralization (typically quartz-calcite veins ± adularia) is associated mainly with the Early Miocene andesitic arc but there are important exceptions, and in general the age of mineralization is poorly known. A district-wide correlation between epithermal Au mineralization and porphyry CuAu mineralization is not apparent. The most important epithermal Au district (Kotamobagu) is inferred to be associated with a long-lived volcanic center represented by the Moat caldera. Epithermal gold systems in the North Sulawesi Arc are generally eroded deeply, typically with chlorite-epidote wallrock alteration, and little is known about their associated volcanic environment. In addition to high sulphidation Au mineralization related to porphyry systems, other styles and settings of Au mineralization in the north arm are exemplified by the Gunung Pani rhyolitic dome, the Patung diatreme breccia, the Mesel jasperiod, hosted partly by carbonate rocks, and sedimentary replacement Au-base metal mineralization at Doup. Diversity of mineralization in the north arm is further illustrated by VMS mineralization in volcanic basement to the Neogene arc, and by metamorphogenic quartz vein Au mineralization in the neck of Sulawesi.

Geochronology and distribution of silicic volcanic rocks of Plio-Pleistocene age from the central sector of the Main Ethiopian Rift

Plio-Pleistocene silicic volcanoes, calderas, and their eruptive products are common throughout the Main Ethiopian Rift (MER). A compllation of KAr and 40 Ar 39 Ar dating results for the central sector of the MER demonstrate that the most voluminous and widespread ignimbrites of this region are Pliocene in age, between 4.2 and 3.5 Ma. These units occur in and around: (1) The Awasa and Wagebeta calderas, (2) the Guraghe and Munesa escarpments, where a major buried caldera is believed to occur in the adjacent rift floor, (3) the Addis Ababa-Nazret area, and (4) the foothills and shoulders of the northern sector of the Main Ethiopian Rift. The older units are overlain by less volumious and in most cases, rift-bound late Pliocene and Pleistocene pyroclastic rocks. The Pliocene ignimbrites in this area are likely to be the near-source equivalents of widespread a ash-fall units associated with fossil hominid deposits of the Turkana and Afar sedimentary basins.

Post Mid-Cretaceous Seismic Stratigraphy and Geologic History, Deep Gulf of Mexico Basin

The deep Gulf of Mexico basin is underlain by up to 10 km of sedimentary rocks. This section is subdivided into two megasequences separated by a prominent, basinwide, mid-Cretaceous sequence boundary (MCSB), which marks a major turning point in the history of the Gulf basin. The post-MCSB section consists of the more distal portions of large siliciclastic wedges that partially fill the basin. A detailed seismic stratigraphic analysis has subdivided the post-MCSB, pre-Pleistocene section into 12 new sequences, which have been mapped throughout the entire deep basin using UTIG and all available industry seismic data. Correlation with two published Exxon seismic lines on the northeastern shelf provides tentative age control for the five youngest sequences. The correlation across the slope was made using a dense grid of UTIG and industry seismic data with minimum interference from salt structures. These ages were further confirmed by correlation with DSDP sites 90 and 91 in the western Gulf. This study suggests that the base of the Mississippi Fan is Upper miocene in age, which is older than the Plio-Pleistocene age proposed by previous studies. Isopach maps of each new sequence document the progressive filling of the deep basin and the shift of majormore » deep water depocenters from the west and northwest to the north. This corresponds to the shift of the deltaic depocenters along the northern Gulf margin. A tentative correlation of the deep Gulf sequences with the major northern Gulf coast depositional episodes is proposed.« less

Bois plio-pléistocènes du gisement de saropée plateau de khorat, est de la Thaïlande

Alluvial deposits from the Mue Nam Mum river at Saropée, Khorat Region, Thailand, yielded about 60 wood specimens, attributed to Araucarioxylon sp., Shoreoxylon thaïlandense n.sp., Careyoxylon pondicherriense Awasthi, Terminalioxylon coriaceum Prakash and Awasthi, Terminalioxylon burmense Mädel-Angeliewa and Müller-Stoll, Pahudioxylon sahnii Ghosh and Kazmi, Cynometroxylon schlagintweitii Müller-Stoll and Mädel, and Albizzinium eolebekkianum Prakash. This association, attributed to a Plio-Pleistocene age, evokes a mixed deciduous forest, probably not far from a river and ancient volcanoes. The presence of Araucariaceae in South-Eastern Asia at a relatively recent epoch is pointed out. A comparison with other fossil wood localities reveals close floristic resemblance with Burma, Western Bengal and Kachchh.

Slope Morphology Controlled by Hydro-Geological Conditions in the Western Part of the Tama Hills, West of Tokyo

The Tama Hills, located in the western edge of the Kanto Plain, are mainly composed of semi- or unconsolidated shallow marine sediments of Plio-Pleistocene age, which, named the Kazusa Group, consist of several clay-silt, sand and gravel beds. On the hilltop gentle slopes in the western part of the Tama Hills, the mid Pleistocene Gotentoge Gravel Bed rests unconformably upon the Kazusa Group. And the Hills are covered with airborne tephras named the Kanto Loam. The lower part of the Kanto Loam is full-weathered and rich in clay.The purpose of the present study is to clarify the distribution and formation of detailed- to micro-scale landforms composing small tributary basins, in connection with the hydro-geologic conditions in the western part of the Tama Hills.In valley-head areas, head hollow and head floor defined by Tamura (1974) are distributed and their location seems to be controlled by the hydro-geologic conditions. The maximum height of each head hollow and the position of springlet correspond well to the height of bedding plane of clay-silt bed in the Kazusa Group or the lower part of the Kanto Loam, both of which have less permeability. Head floor develops on the surface of less-permeable beds. Because of the less permeability, surface and sub-surface flow often occurs and marsh is sometimes formed on this slope unit.Locations of valley-head slopes on the hillsides are also affected by the distribution of less permeable beds. Here the development of the slopes seems to have been initiated by the landslides. Present head hollows were formed by slide type failure. Each mass movement occurs along the bedding plane upon the less-permeable beds.Valley-head slopes are considered to have been formed by surface failures occurred during heavy storms. In addition to the occurrence of pipeflow and returnflow which are also related to hydro-geologic conditions, groundwater itself seems to play an important role in landforming process accompanied by surface failure.It is concluded that the distribution and formation of slope units in the Tama Hills are strongly controlled by the hydro-geologic conditions.

Geology of the Kathmandu fluviatile lacustrine sediments in the light of new vertebrate fossil occurrences

The fluviatile lacustrine sediments of the Kathmandu Valley have been restudied. New fossil discoveries in the southern part of the valley sheds light on the geology of the Kathmandu Valley.
 The finds comprise, diverse vertebrate fossils represented by elephant, deer, bovine and pig belonging to Plio-Pleistocene age. The paper mainly deals with stratigraphy of the Lukundol Formation and evolution of the Kathmandu sediments.

Evidence for a cooler and drier climate in the Ethiopian uplands towards 2.5 Myr ago

In east-central Ethiopia (7° N–39° E), at 2,300 m, Pliocene diatomites underlying sediments bearing Acheulian artefacts have provided a rich pollen microflora. The pollen diagram with a Plio-Pleistocene age (2.5–2.35 Myr) is dominated by grasses, Ericaceae and Myrica, whereas the modern pollen rain is dominated by forest taxa. The weak representation of montane forest trees and the abundance of heath moorland and grassland pollen indicate a cooler and drier climate during a time period known to include episodes of global cooling.

Heat flow in the southwestern Okinawa Trough

Lying to the southeast of the East China Sea continental shelf, the Okinawa Trough is believed to have been formed by crustal spreading behind the Ryukyu island arc. It has the highest mean heat flow among the Pacific marginal basins. The mean of 18 reliable measurements is3.34±2.75HFU. The next highest mean heat flow for a marginal basin is2.53±1.60HFU for the Fiji Plateau. The high mean value for the Okinawa Trough may be partially attributable to a sampling bias because most measurements were made in or near the well-sedimented central “rift” or graben. The reported values range from 0.36 to 10.49 HFU, with low values probably resulting from hydrothermal circulation in an area of large relief. The high heat flow suggests that the age of the Okinawa Trough may be as young as 2 Ma. Such an estimate is in gross agreement with the inferred Plio-Pleistocene age for the drifting in the Okinawa Trough. The opening of the Okinawa Trough may continue onto Taiwan but the relation between the opening of the trough and the occurrence of a nearby, onshore geothermal resource area remains unsolved.

Onshore marine Cenozoic along southwest Pacific coast of Mexico

Reconnaissance exploration along the Pacific coast of Mexico from the Isthmus of Tehuantepec to Puerto Vallarta in the northwest, beginning in 1977, has shown the presence of at least seven previously unreported areas with late Cenozoic sedimentary deposits. In addition marine Pleistocene deposits on the coast of Oaxaca were previously reported. In four of the newly discovered areas marine sediments occur. All of these occurrences, excepting the two southeastern ones, were encountered along the Federal coastal highway, route F 200. Beginning in the northwest these areas are: along the Rio Ameca, 10 km north of Puerto Vallarta; 10 km south of Puerto Vallarta; Tomatlan Basin (named herein), 79 km south of Puerto Vallarta, with fossil vertebrates; Campo Acosta Basin (named herein) beginning 115 km south of Puerto Vallarta, sediments at least partly marine; La Mira Basin (named herein), straddling the mouth of the Rio Balsas, with at least two marine incursions; San Nicolas Basin (named herein) about 200 km southeast of Acapulco, marine sediments encountered in water well; Colotepec Formation, marine, along the coast of Oaxaca between Puerto Angel and Puerto Escondido; marine deposits near Santa Cruz, Oaxaca, about 100 km southwest of Salina Cruz, Oaxaca. Of the seven new areas, only the La Mira Basin has been examined in more than a most cursory manner. In the La Mira Basin four formations are recognized: Ferrotepec Formation (named herein), marine, late early to middle Miocene in age; Barranca del Perro Muerto Formation (named herein), nonmarine; El Bordonal Conglomerate (named herein), nonmarine; Abanico Brisa Mar Formation (named herein), at least partly marine, of undifferentiated Plio-Pleistocene age. If the attitudes observed in the Ferrotepec Formation continue seaward, the total thickness of the sediments in the basin might attain 1,500 m. The fossils from the Ferrotepec Formation mostly belong to the “Tertiary Caribbean Province” of Woodring, but a few show affinities to north Pacific coast Miocene faunas. The La Mira Basin sediments indicate that the Rio Balsas has existed since early Miocene time. The few fossils from the San Nicolas Basin suggest a late Miocene to Pliocene age. The few fossils from the beds near Santa Cruz are suggestive of a Plio-Pleistocene age. Insofar, as is known, the sediments in the areas northwest of the La Mira Basin only attain a few meters in thickness. Offshore from the San Nicolas Basin, at Deep Sea Drilling Project (DSDP) Site 493, about 670 m of early Miocene to Pleistocene sediments are reported. The Santa Cruz beds appear to be about 50 m thick, and Palmer reports a 15 m thickness for the Colotepec Formation.

The chemical and mineralogical changes accompanying the laterization of basalt at Kerikeri, North Auckland

Abstract Aluminous laterites which occur above basalts of Plio-Pleistocene age in the Kerikeri area of North Auckland have been formed by processes initiated in the late Pliocene and continuing during the interglacial periods. Initial alteration leached the parental basalt of alkalis and about half its silica to produce a saprolite composed of halloysite, amorphous to subcrystalline iron oxides and oxyhydroxides, and relict magnetite and ilmenite. Continued leaching removed further silica from halloysite to yield gibbsite while dehydration of the upper layers aided crystallisation of the iron oxyhydroxides. Resilicification appears to have occurred at one locality.

Marine terrace deformation, san diego county, California

Abstract The NW—SE trending southern California coastline between the Palos Verdes Peninsula and San Diego roughly parallels the southern part and off-shore extension of the dominantly right-lateral, strike-slip, Newport—Inglewood fault zone. Emergent marine terraces between Newport Bay and San Diego record general uplift and gentle warping on the northeast side of the fault zone throughout Pleistocene time. Marine terraces on Soledad Mt. and Point Loma record local differential uplift (maximum 0.17 m/ka) during middle to late Pleistocene time on the southwest side of the fault (Rose Canyon fault) near San Diego. The broad Linda Vista Mesa (elev. 70–120 m) in the central part of coastal San Diego County, previously thought to be a single, relatively undeformed marine terrace of Plio—Pleistocene age, is a series of marine terraces and associated beach ridges most likely formed during sea-level highstands throughout Pleistocene time. The elevations of the terraces in this sequence gradually increase northwestward to the vicinity of San Onofre, indicating minor differential uplift along the central and northern San Diego coast during Pleistocene time. The highest, oldest terraces in the sequence are obliterated by erosional dissection to the northwest where uplift is greatest. Broad, closely spaced (vertically) terraces with extensive beach ridges were the dominant Pleistocene coastal landforms in central San Diego County where the coastal slope is less than 1% and uplift is lowest. The beach ridges die out to the northwest as the broad low terraces grade laterally into narrower, higher, and more widely spaced (vertically) terraces on the high bluffs above San Onofre where the coastal slope is 20–30% and uplift is greatest. At San Onofre the terraces slope progressively more steeply toward the ocean with increasing elevation, indicating continuous southwest tilt accompanying uplift from middle to late Pleistocene time. This southwest tilt is also recorded in the asymmetrical valleys of major local streams where strath terraces occur only on the northeast side of NW—SE-trending valley segments. The deformational pattern (progressively greater uplift to the northwest with slight southwest tilt) recorded in the marine and strath terraces of central and northern coastal San Diego County conforms well with the historic pattern derived by others from geodetic data. It is not known how much of the Santa Ana structural block (between the Newport—Inglewood and the Elsinore fault zones) is affected by this deformational pattern.

Plio-Pleistocene age of high-potassium volcanism in the northwestern part of the hellenic arc

Two newK/Ar dates firmly establish that the high potassium volcanic rocks of Thessaly are of late Pliocene and Pleistocene age, considerably younger than the geochemically similar rocks of the Dodecanese.

Geology and geochemistry of bauxite deposits in the lower Amazon Basin

Aluminous laterites north of the Amazon River have formed on poorly consolidated clayey terrestrial sediments of Pliocene or Plio-Pleistocene age. The essential processes affecting the major elements were leaching of the surficial portion of kaolinitic sedimentary rocks causing a reduction of nonquartz silica in the entire laterized zone, downward transport in solution of aluminum and iron, and concentration of aluminum and iron as hydroxides and hydrated oxides at the base of the laterized zone.Measurement of the vertical distribution of 20 elements through the laterized profile shows large variations in their concentrations. Leaching has predominated in the upper portion and strong enrichment of many elements is characteristic of the aluminum- and iron-rich lower parts of the zone. When compared with the subjacent material, Fe, V, P, Ga, and Mn are strongly enriched and Pb, Sr, and Ba are strongly depleted in the laterized zone. Enrichment of minor elements in the principal mineral phases is marked for Cr, Ga, K, P, Mg, and V (in iron oxides) and Ba, Pb, and Sr (in kaolin). None of the minor elements measured show a preference for gibbsite. The distribution of the elements in the laterized zone is not consistent with a geochemcial control related to their ionic potential.

Chronology and biology of the South African australopithecines

Based on a 10 months' visit to Southern and Eastern Africa, an attempt is made to contribute to the faunal correlation and the palaeecology of the Transvaal cave deposits; conclusions are mainly drawn from evidence of the fossil Cercopithecoids, but light is shed on the sympatric Australopithecines of Makapansgat, as well. It is suggested that Early Man could have lived only underneath rock-shelters near the ancient cave entrances; the highly diversified fossil fauna of the Makapansgat breccia indicates a very varied biotope; the fossil Cercopithecoids of this site are very primitive and correlate well with a Plio-Pleistocene age.

Limnische Huntit-Hydromagnesit-Magnesit-Lagerst�tten in Mazedonien/Nordgriechenland

Lacustrine sediments of Plio-Pleistocene age in the intramontanous Servia basin /Northern Greece contain so-called microcrystalline magnesite in different areas of the basin. Dressing extremely finely “magnesites” from Aiani/Servia is very difficult. Looking for suitable methods of dispersion and using X-ray analysis, it appeared, that magnesite in the area of the Servia basin forms only a small amount of the total magnesium-carbonatic mineralization, and that huntite and hydromagnesite are predominant. Following analysis preliminary calculation of reserves of seamlike deposits in the area of Servia and Aiani have been made. Both deposits will at least amount to 50 mill. tons in an area of 15 km2. The amount of reserves of the total basin should reach several 100 mill. tons. — The following types of ore could be distinguished: 1. Clayey-silty huntite magnesite ores (most common type). 2. Hydromagnesite-huntite ores (50% of hydromagnesite are normally of gravel size). 3. Huntite ores (nodules in clayey matrix, mainly illites and saponite group minerals). 4. Magnesite ores (nodules with obvious shinkage cracks; relatively rare; can be mined selectively). — The Servia-Aiani Type of deposit is of limnic-sedimentary, Plio-Pleistocenic genesis, which received its Mg- and Ca- content through fluviatile transport from the ultramafic and serpentinized Vourios Mountains. Almost certainly the Servia-Aiani type of deposit has been overlooked because of its insignificant silty-clayey exterior, but it is by no means unique.

A discussion on the structure and evolution of the Red Sea and the nature of the Red Sea, Gulf of Aden and Ethiopia rift junction - Tectonic significance of regional geology and evaporite lithfacies in northeastern ethiopia

Mesozoic and Precambrian rocks are exposed in the Danakil Alps of coastal Eritrea, but the Danakil Depression between the Alps and the Ethiopian plateau is covered by Tertiary-Quaternary rocks. The physiography, structural geology, regional stratigraphy and evaporite lithof acies distribution of this area all suggest that it is underlain by an asymmetrically subsided block of old sialic crust. The western edge of this block has subsided deeply along the Ethiopian rift and is covered, in the Danakil Depression, by an evaporite-basalt veneer, but its eastern edge has been uplifted as the Danakil Alps. These are bounded on the east by a rift escarpment facing the Red Sea. Although geologic data here is sparse compared to the Danakil region, certain features suggest that a similar asymmetrically subsided block of older sialic rocks, with an evaporite-basalt veneer, may also lie beneath much of the Red Sea. This tectonic evolution apparently commenced in Miocene time with rifting near the centre of an earlier Mesozoic-Paleogene sedimentary basin. Uplift along this central rift caused tensional failure along a secondarily induced rift to the west, and east-side-down subsidence along this structure formed the asymmetrically subsided block. There were apparently two successive cycles of this tectonic activity. The earlier, of Miocene age, formed the easterly (Red Sea) block with a thicker veneer of older evaporitebasalt, and the later, of Plio-Pleistocene age formed the westerly (Danakil) block with a thinner veneer of younger evaporite-basalt. The separation of Arabia from Ethiopia across the southern Red Sea would thus be relatively minor, presumably represented by the width of the Red Sea’s axial trough plus a few kilometres across each of the Danakil Alp and Ethiopian rifts. Similar tectonic developments may accompany initial rifting and separation in the development of ocean basins by seafloor spreading, and might explain why oceans like the Atlantic, that have apparently developed in this manner, are fringed by shallow continental shelves with thick evaporite sequences and steep walled submarine canyons.

Quaternary stratigraphy of Panchkhal valley, Central Nepal

The Panchkhal Valley is one of intermontane basins in the Central Nepal east of Kathmandu with two sets of neo-tectonic lineaments sited from satellite imagery and aerial photographs. One extending NNW-SSE east of the valley results the old Panchkhal Valley uplifting along south during Plio-Pleistocene age and second one NE-SW has ultimately uplifted the old valley. The Panchkhal Clay, Ratopairo Formation, Rampur Formation and Tamaghat Formation are four depositional lithostratigraphical units. Similarly, Tamaghat, Rampur, Thumka, and Chisapani surfaces are depositional and Basukidada, Sano-Tinghare, Sumara-Thulo Tinghare, Dhulikhel, Koiralathumka and Bhamarkot surfaces are erosional morphostratigraphic geomorphic surfaces. Geomorphic terrace cutting level is around 1400-1440 m and all surfaces and deposits above and below are relatively young. doi: 10.3126/bdg.v10i0.1415 Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 10, 2007, pp. 1-8

The Osaka Group

In Kinki and Tokai districts, the eastern part of southwest Japan, there are three Plio-Pleistocene sedimentary basins, where are the Osaka, Kobiwako and Tokai Groups, respectively. The Osaka Group is composed of the cyclic sediments of lacustrine and bay in the upper part, and of lacustrine in the lower. The other Groups are composed of lacustrine sediments only. In the upper part of Osaka Group, the cyclic sedimentation caused by transgression and regression corresponding to climatic change.The stratigraphical summary of the three Groups was figured in terms of tephrochronology, paleomagnetic chronology, fission-track and K-A ages and fossil ranges. Then the climatic changes of Plio-Pleistocene age were introduced. The ages of cold climate were determined as follows.Terasho 3-3.1m.y. Saidera 1.2±m.y.Shimakumayama 2.3-2.4m.y. Gokenya 0.75-0.8m.y.Kamimura I 1.5+m.y. Manchidani 0.45±m.y.Kamimura II 1.5-m.y.In the Manchidani cold age, the coldest climatic age among them, the annual mean temperature was estimated to be about 10°C. The warmest climatic age of Pleistocene is the Shinkori warm age, 0.35m.y.. The climate of that time was mild in winter and had sufficient rainfall as in the southern part of Kyushu, being about 17°C in annual mean temperature.