摘要:

A model is presented that traces quantitatively the history of geodynamic processes, from the time of origin of the Earth to the present time. Initially, the Earth underwent a slow, cool, homogeneous accretion, then a non‐catastrophic formation and melting of the core. Thereupon, the gravitational interaction of the Moon and core produced a thermal power of about 1013watts. It is this power that creates the buoyant force for the upflow of convection. The convection is shown to serve three function: (1)the transference of heat from the mantle base to the surface for radiation to space: (2)the uplift to the surface and separation from the convection cycle of “incompatible” constituents: and (3) the redistribution of heat from the mantle's base to its body by conductive transfer. The “incompatible” constituents include continental, oceanic, atmospheric. Petroleum and radionuclide materials. They are stored initially in the asthenosphere region up to a limiting capacity that ensures the thermal integrity of the lithospheric shell. The capacity range is regulated by a periodic relief mechanis: namely, a controlled penetration of the lithosphere and eruption of continental and other “incompatible” material to the surface. The transfer of radionuclides to the surface region acts to regulate the conductive thermal loss from the Earth's interior in order to maintain a steady state. Mantle heat lost by removal of radionnuclides is replaced via conductive transfer from the hot, upflowing convection. The mechanisms of cooling in the 400‐km deep surface leg of the convection, the formation of the continents, and the pattern of heat flow from the Earth's surface are analysed in detail. A thermodynamic analysis of the convection cycle is presented, as well as detailed power analyses for the various work functions that are involved in the convection. Values obtained for power input and out put of the convection are in agreeme

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00218.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Recent progress in structural and stratigraphic analysis of the allochthonous units situated north of Hazro in the Border Fold zone of SE turkey has shed light on the nature and signijicance of the Gondwanan margin there. Allochthonous material consists of several superimposed units ranging in age from the Early Trias to the Late Senonian (Hezan units), in which the transition between neritic carbonates and the pelagic and detrital facies is well indicated by an Ammonitico‐rosso facies of mid Jurassic age. Above it, ophiolitic material and radiolarites represent the former Tethyan crust and cover. The Hezan units thus belong to the former Gondwanan margin thrust southwards in Lute Cretaceous times, and a tentative reconstruction of its Mesozoic evolution there is facilitated by the absence of later major tectonic events.This reconstruction shows marked diferences compared with the more complex nearby margins described in the Hellenides or Zagrides, where parallel ridges and troughs reflect crustal extension. By contrast, the simple “staircase”geornetry of the present margin is best interpreted as the result of the fracturing of the Gondwanan continent, separating the Apulian and African Plates as early as the

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00219.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A thick calcareous shale of Early/Middle Kimmeridgaiann age is the principal source rock for the oils discovered in the Jeanne d'Arc Basin of the Grand Bankks. This Upper Jurassic source rock forms a geological marker throughout the basin, but is not a stratigraphic marker. Its regional distribution is controlled by the tectonic and sedimentary history and the depositional enviornment.Rift tectonics in the Grand Banks during Oxfordian/Kimmeridgian times formed a series of silled, anoxic basins, which received low input of terrigenoous material from the adjacent continent. This favoured the accumulation of a thick sequence of calcareous shales rich in oil‐prone, amorphous organic matter. The principal source‐rock unit is generally 200‐300m (656–984 ft) thick in the southern and western part of the basin and thickens in the NE to more than 700m (2,296ft). Anoxic conditions were maintained in the NE area throughout the Late Kimmeridgian. While the SW area underwent uplift and was flooded by terrigenous clastics.Detailed geochemical analysis of oils and condensates discovered in many wells allows distinction of two principal oil families of different origins: one of Jurassic source, and the other of a probable Teritary origin. Most oils found in the basin belong to the Jurassic oil family.Distinct regional variations in the maturity and composition of the Jurasssic oil family are evident. These can be explained by the regional maturity pattern of the principal source rock, and by the co‐contribution of a secondary, slightly younger source‐rock interval, which contains a predominantly terrestrial type of organic matter. This secondary source input is recognized in areas where the younger source rock reaches fully‐mature conditions. Condensates in the centre of the basin are derived from the deeply‐buried source beds at present in late‐ to overmature conditions.The Adolphus oil in the centre of the basin represents the second oil family, and is probably derived from a Teritary source rock. No oil‐source correlation could be established due to lack of data and proper cutting samples. However, geological and heat‐flow considerations suggest a Teritary source. Heat‐flow values are high in the Adolphus structure as a result of salt diapirsm and the base of the Tertiary shale section is

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00220.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

An integrated stratigraphic study was made of the La Peña Formation, which is penetrated by a number of wells in NE Mexico. the study was conducted with the aid of ammonites (Cheloniceratidae, Deshayestidae, Acanthohoplitidae), microfossils (Colomiella, Nannoconus), and radioactivity logs to investigate the age of the unit ‐ late Aptian.A series of wells extending 400 Km NW ‐ SE were studied. The results show that the stratigraphic ranges of Colomiella recta, C. mexicana, and certain Nannoconus species are greater than currently believed. In contrast, the ammonite groups mentioned above are present only in the La Peña Formation.The formation is composed of a condensed section of limestone and shale in this area. The La peña and the units below it are cut by normal faults, in particular the Paras Fault System, which is described here for the firs

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00221.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The age of the so‐called Sakaka Sandstone exposed in the al‐Jawf area, northern Saudi Arabia, has in the past been disputed. It is assigned here to the Middle‐ Late Devonian and middle Cretaceous. This age has been established from correlations of surface ‐ subsurface sections utilising palynological and litholgical data, and also from the regional geological framework. The sequence is divided into two units. The lower unit, consisting of clastic and mixed fine‐clastic and calcareous shoreline‐ shallow marine deposits, is considered to be part of the Middle Cretaceous Wasia Formation.The name “Sakaka Formation” is now restricted to the lower unit of the Middle ‐ Upper Devonian sequence. This formation forms a well‐exposed and lithologically‐distinct mappable unit. The type section of the Formation can be designated from a traverse in the al‐ Jawf area, where a thickness of 215.5 m is exposed. The Sakaka Formation conforably overlies the Lower Devonian Jauf Formation, and uncomformably underlies the Middle Cretaceous Wasia Formation. At depth, in the subsurface, the sakaka Formation underlies conformably the Lower Carboniferous Berwath Formation.Reliable relative age‐dating of the sakaka Formation has contributed to investigations of both the history of the Hail Arch, and the economic prospects of the area. This Arch extends throughout the al‐Jawf area, and is probably of PreCambrian age: it was rejuvenated in pre Middle Devonian and pre‐middle Cretaceous times. The Arch separates the Widyan Basin to the east from the Tabuk Basin to the west. The former basin is promising in terms of petroleum exploration owing to its great possible thickness, and the presence of favourable lateral facies changes, and potential source and reservoir rocks; moreover, tectonic activity has resulted in the generation of many traps, including stratigraphic traps. The Sakaka Formation and the overlying Berwath Formation could serve as potential reservoir rocks, capped uncomfortably by fine, argillaceous rocks of the Upper Carboniferous ‐

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00222.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Kerogen maturation, estimated from pyrolysis Tmax values is compared with the smectite laayer‐content of the illite/smcetite mineral derived from sediments in six suites from different basins with different ranges of statographic age. The most significant correlations are made when camparing Tmax and estimated percentage kerogen transformation with sample age for the same smecite layer‐content (iso‐smectite content or stage of clay maturation) the percentate transformation of Type III kerogen and smectite layer‐content shows a regulare relationship at the end of the clay reaction series (10 smectite content), which includes the oil and gas potential range for sediments in the 200‐100 MM year age groups. Relations between less mature, more smectic illite/smectite clay minerals and kerogen maturation are not at pre

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00223.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Huntsberger ans Lerche (1987) recently presented a method of obtaining on information on the varaition paleo heat‐flux with time in sedimentary basins by use of fission tracks on apatie. While this paper has the merit of drawing attention to the advantages of Apatite Fission Track Analyis over more convential paleotemperature indicators, we suggest that it is flawed in various important respec

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00224.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00225.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00226.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Book reviewed in this article:“Microscopic study of organic matter”Statistics on discCraters on the Ocean floorJurassic stratigraphy in the LevantALSO RECE

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1989.tb00227.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY