ABSTRACT
This study deals with the tectonic evolution of Tethys during the Mesozoic. A critical question concerning Tethyan geology is how far the Tethys ocean extended westwards in the Mediterranean region. Because this question can only be answered by studying in detail the opening history of the Alpine ocean, a critical area involving Triassic and Jurassic sediments was mapped in the Albula Pass area in eastern Switzerland. The mapping shows that the main rifting in the Alps took place during the Lias with a very weak extensional event during the medial Triassic. The record of these events is now found in the Lower and Middle Austroalpine units, which deformed through a complex sequence of events involving a hitherto unknown early south-vergent folding of the Middle Austroalpine Aela Nappe. The stratigraphic analysis undertaken during this study demands that the Aela Nappe be placed farther north than hitherto believed, near the Lower Austroalpine facies realm, mainly because of the demonstration that the typically Lower Austroalpine Alv Breccia also occurs in the Aela Nappe. In order to place the Jurassic and the Triassic rifting events into their appropriate tectonic settings, a regional tectonic synthesis of the Mediterranean Alpides was undertaken. This synthesis shows that the Triassic and Jurassic rifting events in the Alps was related to the opening of Neo-Tethys and to the opening of the Atlantic ocean respectively. Because only Jurassic rifting eventually led to generation of ocean-floor, the Alpine ocean and the Mesozoic-Cainozoic oceans west of it formed as parts of the Atlantic Ocean and are tectonically unrelated to Tethys. The two oceanic systems merged in the western Carpathians. Neo-Tethyan opening, which controlled the Triassic rifting events in the Alps was controlled and was largely coeval with the closing of the Palaeo-Tethys, described in detail for the first time in this dissertation. The closure of Palaeo-Tethys generated an orogenic belt, extending from the Carpathians to the Pacific Ocean. It is herein named the Cimmerides and follows closely the later Alpides, products of Neo-Tethys, throughout southern Eurasia. This spatial association resulted in complex overprinting of the Cimmerides by the Alpides, which hindered the recognition of the former for nearly a century. The Cimmeride orogenic system was completed by the latest Jurassic with some late events during the early Cretaceous along the Great Khingan-Shitka suture in the Far East. An important result of this study is the recognition of the dominating effect of the Palaeo-Tethys on the tectonic evolution of the Mediterranean Alpides until the latest Triassic.

Sengor, A.M.C., 1982. The geology of the Albula Pass area, eastern Switzerland in its Tethyan setting: Palaeo-Tethyan factor in Neo-Tethyan opening.
Unpublished PhD dissertation, State University of New York at Albany. 405pp., +xviii; 8 folded plates (maps)
University at Albany Science Library call number:  SCIENCE MIC Film QE 40 Z899 1982 S46
Copies of this PhD dissertation can be ordered from Proquest UMI

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