摘要:

New outcrop and subsurface data from SW Iran have permitted a review of the stratigraphy of the area to the SW of the Zagros Crush Zone and a comparison with neighbouing areas. The Triassic sequence consists mainly of an evaporite and dolomite sequence in the coastal areas of the Persian Gulf which is the extension of the evaporite basin of Saudi Arabia and Iraq. Towards the high Zagros in the northeast, the evaporites are replaced by dolomites. Two unconformities are found at the base and top of the Triassic.The Jurassic in Fars and eastern Khuzestan consists of an argillaceous interval representing early Liassic time, overlain by a thick development of neritic carbonates of early to late Jurassic age. An evaporite unit developed in the upper Jurassic is present in coastal/subcoastal areas of Fars and eastern Khuzestan and is the north‐eastwards extension of Hith Anhydrite of Saudi Arabia. The end of the Jurassic was marked by uplift and erosion, giving rise to an unconformity over a large area. In western Khuzestan and Lurestan, the Lower Jurassic is a sequence of alternating evaporites and dolomites. The Middle Jurassic is represented by deeper water bituminous shales and argillaceous limestones of the Sargelu Formation, which is cut by a regional unconformity in this area. The Upper Jurassic is represented by the evaporites of the Gotnia Formation which is terminated by the possible Upper Jurassic unconformity. The Jurassic sequence of this area can be correlated well with that of eastern Iraq. In the high Zagros area to the south of the Crush Zone, the Jurassic consists of a thick development of shelf carbonates with no evaporites.The Cretaceous System in SW Iran is divided into Lower (Neocomian‐Aptian), Middle (Albian‐Turonian) and Upper (Coniacian‐Maastrichtian). The Lower Cretaceous is mainly made up of two shelf carbonate unit separated by shales in Fars and eastern Khuzestan. Towards Lurestan, the carbonates pass into deeper water black shales and limestones with radiolaria. The top of the Lower Cretaceous is marked by a regional unconformity in Fars and the Persian Gulf area. The Middle Cretaceous began with a transgression forming the shales and limestones of the Kazhdumi Formation which was followed by a shallowing of the sea and the deposition of Cenomanian and Turonian shelf carbonates over the entire area of Fars and Khuzestan. The Lurestan basin retreated northwards and northwestwards and covered only central Lurestan during Albian‐ Turonian time, with the deposition of dark grey to black shales and pelagic limestones of the Garau and the Oligostegina bearing limestones of the Sarvak Formation. At least two pronounced regional unconformities have been recognized, between the Cenomanian and Turonian and between the Turonian and Coniacian. The Upper Cretaceous is represented by limestones at the base and a transgressive shale unit at the top, which is terminated by a regional unconformity at the Cretaceous/Tertiary boundary.Isopach and lithofacies maps of various units and correlations of outcrop and subsurface sections indicate several important unconformities and facies changes in SW Iran during the course of the Mesozoic. The general stratigraphy of the region shows similarities to the Mesozoic sequence of Iraq and Saudi Arabia, with a gradual facies change from carbonates to sandstone towards Saudi Arabia. This change is most evident in the Upper Triassic and in the Barremian‐Cenomanian. The Upper Cretaceous sequence of SW Iran changes from mainly argillaceous sediments of deeper marine environment into carbonates of shallow water origin towards Saudi Arabia. The correlation of the Mesozoic sequence of SW Iran with those to the northeast of the Zagros Crush Zone indicates a rather abrupt change from the Upper Trias

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00599.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

This is a record of an attempt to understand the geological structure of an area of several thousand square kilometres where the main interest lies in formations concealed under some 750 to 2500m of unconformable terrestrial sediments. Various fracture trace techniques have been used in an attempt to understand the stress system in the underlying rocks, and to distinguish between movements caused by horizontal and vertical forces. The study resulted in the interpretation of possible anticlines, domes, and drape folds in the underlying rocks, whereas the surface rocks were found to be mainly deformed by differential compaction during diagenesis.

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00600.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The Northern North Sea basin is a relatively narrow, grabenal or half‐grabenal, northsouth trending feature. The trapping structures are tilted fault blocks. In the southern part of the basin these are mainly westwards tilted blocks formed by down to the east throw faults trending north‐south, parallel to the basin margins. This could fit with general plate tectonic theory, but in the northern part of the area this faulting is complicated by a pronounced NE‐SW trend. This is parallel to the old Caledonian trend and it is postulated that strike‐slip faulting may have been reactivated during the Mesozoic. This strike‐slip movement on the NE‐SW fault trend gave a tendency for individual fault block rotation resulting in a variety of block tilt directions in the northern part of the basin.The overall half‐graben feature probably started forming in early Triassic, but the faulting leading to the individual fault block formation mainly started during the Middle Jurassic, continuing through the Upper Jurassic. A further period of fault movement occurred during the Upper Cretaceous, but this is not associated

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00601.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Permian to Tertiary faunas along the eastern margin of Africa, and on Madagascar, are presented, described, and discussed. Presentation of the faunas is made in four charts: Permo‐Triassic, Jurassic, Cretaceous, and Tertiary. A correlation chart provides tentative time‐rock units. Paleogeography northeast and east of Africa is derived from the writer's analysis of marine invertebrate fauna, and is delineated in sketches for Late Permian, Jurassic, and Cretaceous times. Limitations exist on the conclusions that can be drawn from fauna alone. Pelagic waters can be indicated, but their extent cannot be specified, and lack of diversification in some of the pelagic genera results in unavoidable ambiguities of interpretation. Nothing in the faunal evidence so far available, however, disproves unequivocally the existence of an ancestral Indian Ocean from Late Permian onward. Even if such an ancestral ocean did not exist the pattern of pelagic waters that can be inferred from marine invertebrate fauna constitutes an impediment to models that suture Australia or India to Africa or Madagascar. Peninsular India, on readings of its own geology across the foreland‐orogen boundary, may have occupied its present position through the whole of geologic

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00602.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

A newly compiled tectonic map of Ireland and part of the offshore area can be used to show that a pattern of rejuvenated Caledonian structures was superseded by newly imposed structures at about the time of the opening of the northern North Atlantic Ocean. There are three distinct patterns of structural control: 1. Older Caledonian structures, 2. Younger Caledonian structures and 3. ‘Oceanic’ structures. Younger structural patterns are each superimposed on older, so that locally interference patterns are developed. Each of the structural regimes has controlled sedimentation in particular zones, and where superimpostion has occurred, mixed shelf‐continental and ‘oceanic’ sedimentation can be expected at different structural levels.One of the major control structures in and immediately off NW Ireland is the Great Glen Fault system, which has been repeatedly rejuvenated since its development in Caledonian times. Other major control structures are associated with the Porcupine Seabight, which probably developed during the initiation of the immediately adjacent North Atlantic Ocean basin. Where these structural systems intersect at the head of the Seabight, sedimentational provinces can be defined.A poorly defined E‐W structural line at about 53° 25′ across the northern part of the Seabight may reflect deep wrench faulting related to a subjacent transform. Major structures along this line would have influenced sedimentation and consequent growth structures. This line may be an eastward analogue of the Gibbs Fracture Zone against which the axial zone of ‘quasi‐oceanic’ or attenuated continental crust in the Porcupine Seab

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00603.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00604.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00605.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

This section is intended to provide a facility to subscribers for pursuit of brief enquiries or for response to enquiries of others, for solicitation of information or views, for announcement of forthcoming events or of innovations in services, etc.

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00606.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Book reviewed in this article:“A Geologist in the Service of the Raj”: published br C. T. Barber. Henfield, West Sussex.“Developments in Petroleum Geology”. ed. G. D. Hobson.“Pétroles de Mesopotamie et d'Afrique du Nord”. b

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00607.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1978.tb00608.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY