Suluktin Fm

Synonym: Suluktinskaya suite

Reference section:

Combines the coal-bearing deposits of the lower-middle Jurassic. Among them, complexes of plant remain are established.

1. The lower-middle Triassic is undivided, represented by breccias, conglomerates, gravelites, sandstones, claystones, and clays, forming a cyclic section. The thickness of the layer is up to 100 m.

2. The lower Triassic (Toarcian) consists of an alternation of clays, sandstones, claystones, and carbonaceous slabs. The thickness of the layer is 50 m.

3. The Aalenian horizon of the middle Jurassic is represented by a cyclically built layer of interbedded gravelites, sandstones, claystones, clays, and coal beds, patties are common. The power of the layer is 85-135 m.

4. The Bajocian deposits have a clearly pronounced cyclic structure. The rocks forming cycles are regularly replaced from gravelites and sandstones, through claystones to clays and coal beds. The power of the Bajocian deposits is from 80 to 200 m.

1. Among the plant remains, ferns Clathropterais obovata Oishi, Dictyophyllum nilssonii Brongn., Hausmannia forchhammeri Bart., Phlebopteris braunii Goepp., and rare ferns of the genera Coniopteris and Cladophlebis are common; gymnosperms and ginkgos are often found, but are monotonous in terms of species.

2. The plant complex is characterized by significantly greater diversity of forms. Only Hausmannia is encountered among the dicotyledons, the number of ferns of the genus Coniopteris increases. Broadly developed are ferns Cladophlebis (C. haiburnensis, C. denticulata, C. hirsuta, etc.) and Todites, cycadophytes Taeniopteris (T. ferganensis, T. asiatica), Nilssonia, Anomozamites. The first Ptilophyllum cutchense appear. Ginkgos and gymnosperms are in about the same proportions.

3. In the plant complex, ferns of the genera Coniopteris (C. spectabilis, C. ferganensis, C. hymenophylloides, C. karatjubensis) and Cladophlebis prevail, as well as cycadophytes of the genera Nilssonia and Ptilophyllum, horsetails Equisetum ferganensis and ginkgos Sphenobaiera spect are common.

4. Plant remains are represented by an even greater number of Coniopteris (C. pulcherrima, C. angustiloba, C. spectabilis, etc.), abundance of Cladophlebis, Eboracia, Sagenopteris phillipsii. Characteristic is the replacement of entire-edged Nilssonia by forms with dissected leaf blades: Nilssonia acuminata, N. mediana, N. compta, N. muensteri, N. serrata, N. variabilis, which is one of the features of the Bajocian flora. Horsetails Equisetum beanii are widely developed, as well as Ptilophyllum cutchense.