Tectonic-sedimentary evolution during Late Triassic-Jurassic period in the eastern part of the Qiangtang basin, Tibet

AbstractRadiolarians were extracted from siliceous sediments of the northern Pindos Mountains, in an attempt to establish the chronology of tectonic and stratigraphic events related to the evolution of the Pindos ocean basin. Three separate phases of siliceous sedimentation were identified: (i) (mid-) late Triassic; (ii) mid-late Jurassic and (iii) mid-late Cretaceous. The first two phases are also known from the Pindos and Sub-Pelagonian zones of southern and central Greece, and elsewhere in the Dinarides andHellenides. However, the occurrence of Cretaceous radiolarites in the west central Tethyan region is somewhat unusual. Field observations suggest thatfrom the mid-late Triassic through to the mid Jurassic, radiolarites were deposited on volcanic basement, or were interbedded with sediments associated with the late rifting/spreading stages in the development of the Pindos ocean. Radiolarites of mid-late Jurassic age are commonly interbedded with clastic sediments of ophiolitic derivation. This coincides with a phase of significant compression within the Hellenides, which caused intra-oceanic deformation of the Pindos ophiolite. The ophiolite was subsequently emplaced onto the margin of the Pelagonian microcontinent in latest Jurassic time (Kim-meridgian-early Tithonian), as evidenced by transgressive marine carbonates. However, the Pindos basin survived in reduced form until the early Tertiary, allowing radiolarites to accumulate again within Cretaceous post-tectonic clastic sequences.

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Sequence stratigraphy of a Mesozoic carbonate platform-to-basin system in western Sicily

Open Geosciences ◽

10.2478/v10085-009-0021-8 ◽

2009 ◽

Vol 1 (3) ◽

Cited By ~ 3

Author(s):

Luca Basilone

Keyword(s):

Continental Margin ◽

Carbonate Platform ◽

Late Eocene ◽

Late Triassic ◽

Sedimentary Evolution ◽

Subaerial Exposure ◽

Platform Margin ◽

Western Sicily ◽

Physical Stratigraphy ◽

Basin System

AbstractSequence stratigraphic studies of the Triassic through Paleogene carbonate successions of platform, slope and basin in western Sicily (Palermo and Termini Imerese Mountains) have identified a sedimentary cyclicity mostly caused by relative oscillations of sea level. The stratigraphic successions of the Imerese and Panormide palaeogeographic domains of the southern Tethyan continental margin were studied with physical-stratigraphy and facies analysis to reconstruct the sedimentary evolution of this platform-to-basin system.The Imerese Basin is characterized by a carbonate and siliceous-calcareous succession, 1200–1400m thick, Late Triassic to Eocene in age. The strata display a typical example of a carbonate platform margin, characterized by resedimented facies with progradational stacking patterns. The Panormide Carbonate Platform is characterized by a carbonate succession, 1000–1200 m thick, Late Triassic to Late Eocene, mostly consisting of shallow-water facies with periodic subaerial exposure.The cyclic arrangement has been obtained by the study of the stratigraphic signatures (unconformities, facies sequences, erosional surfaces and stratal geometries) found in the slope successions. The recognized pattern has been compared with coeval facies of the shelf. This correlation provided evidence of sedimentary evolution, influenced by progradation and backstepping of the shelf deposits.The stratigraphic architecture of the platform-to-basin system is characterized by four major transgressive/regressive cycles during the late Triassic to late Eocene.These cycles, framed in a chronostratigraphic chart, allows the correlation of the investigated shelf-to-basin system with the geological evolution of the African continental margin during the Mesozoic, showing tectono-eustatic cycles. The first cycle, encompassing the late Triassic to early Jurassic, appears to be related to the late syn-rift stage of the continental margin evolution. The following three cycles, spanning from the Jurassic to Eocene, can be related to the post-rift evolution and to thermal subsidence changes.

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