Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support

Solenoporacean Stromatolites

Jobst Wendt
PALAIOS
Vol. 8, No. 1 (Feb., 1993), pp. 101-110
DOI: 10.2307/3515224
Stable URL: http://www.jstor.org/stable/3515224
Page Count: 10
  • Read Online (Free)
  • Cite this Item
If you need an accessible version of this item please contact JSTOR User Support
Solenoporacean Stromatolites
Preview not available

Abstract

In the Upper Permian reef complex of southern Tunisia and in Triassic (Ladinian, lower Carnian) carbonate platforms and patch reefs of the Dolomites (Italy) cushion- and pillar-shaped finely laminated structures occur which in growth form and structure strongly resemble cyanobacterial stromatolites. They consist of regular alternations of micritic (or cement) and microsparitic layers. Micritic and cement layers are 0.09 to 0.9 mm thick, with the thickness of the microsparitic layers varying from 0.05 to 5 mm. The latter show a patchily preserved structure of parallel-arranged polygonal cells which are 0.04 to 0.12 mm wide. The majority of these layers consists of one cell-layer only, but some are composed of several cell-layers. The faintly preserved calcitized cell walls are obviously recrystallized. The cell structure is similar to that of solenoporacean algae which occur in the same environment as the stromatolites. In contrast to the generally assumed Mg-calcitic composition of the Solenoporaceae, the cell walls of crustose solenoporaceans from the Carnian of the Dolomites are still aragonite. Judging from their poorly preserved wall structure, the examined Permian and Triassic stromatolitic Solenoporaceae were also probably originally aragonitic. It appears that prior to, or during an early stage of calcification, these solenoporacean algae were capable of trapping fine sediment. The muddy veneers were periodically resettled by the algae. The regular lamination and the periodical influx of muddy sediment probably reflect annual fluctuations of precipitation in nearby land areas. Growth form and lamination of the solenoporacean stromatolites resemble the Problematicum Collenella Johnson (1942) which is a common frame-building organism in the Permian reef complex of Texas/New Mexico (USA). Due to its poorly preserved internal structure, the systematic position of Collenella has hitherto remained enigmatic.

Page Thumbnails

  • Thumbnail: Page 
101
    101
  • Thumbnail: Page 
102
    102
  • Thumbnail: Page 
103
    103
  • Thumbnail: Page 
104
    104
  • Thumbnail: Page 
105
    105
  • Thumbnail: Page 
106
    106
  • Thumbnail: Page 
107
    107
  • Thumbnail: Page 
108
    108
  • Thumbnail: Page 
109
    109
  • Thumbnail: Page 
110
    110