| Lava Formation | |
| Type: | Geological formation |
| Age: | Lower Toarcian [1] |
| Period: | Toarcian |
| Prilithology: | Sandstone and clay with a coaly admixture and the inclusion of wood remains.[2] [3] |
| Otherlithology: | Shallow, continental basins with sandy-clayey sediments deposited with traces of breaks and weathering. Upper part is dominated by argillaceous sediments. Cemented sandstones with interlayers of kaolinite-hydromica clays.[4] |
| Namedfor: | Lava River |
| Country: | |
| Unitof: | Jotvingiai Group[5] |
| Underlies: | Skalviai Group |
| Overlies: | Neringa Formation |
| Thickness: | 45 m [6] |
The Lava Formation is a Mesozoic geologic formation in Lithuania and Kaliningrad, being either the sister or the same unit as the Ciechocinek Formation.[7] [8] It represents the outcrop of Lower Toarcian layers in the Baltic Syncline and in the Lithuanian-Polish Syneclise (C8-borehole in Gdańsk Bay). It is known by the presence of Miospores and Pollen, as well Plant remains.[9] The formation contains grey, greenish, and dark grey silt and clay with interealatians and lenses of fine-grained sand, pyritic concretions and plant remains (carbonised wood fragments).[10] The Jotvingiai Group Toarcian deposits represent deposits laid down in fresh water and brackish basins, possibly lagoons or coastal plain lakes.[11] The Bartoszyce IG 1 of the Ciechocinek Formation shows how at the initial phase of the Toarcian there was a regional transgression in the Baltic Syncline, indicated by greenish-grey mudstones, heteroliths and fine-grained sandstones with abundant plant fossils and plant roots, what indicates a local delta progradation between the Lava and Ciechocinek Fms.[8] Then a great accumulation of miospores (+2500 specimens) indicates a local concentration, likely due to a rapidly decelerating fluvial flow in a delta-fringing lagoon forming a “hydrodynamic trap”, with the wave and currents stopping the miospores to spread to the basin.[8] Latter a marsh system developed with numerous palaeosol levels, being overlayed by brackish-marine embayment deposits that return to lagoon-marsh facies with numerous plant roots (Radicites sp) and palaeosol levels in the uppermost section, ending the succession.[8] Overall the facies show that the local Ciechocinek-Lava system was a sedimentary basin shallow and isolated, surrounded by a flat coastal/delta plain with marshes, delivering abundant spores and Phytoclasts, indicators of proximal landmasses with high availability of wood and other plant material.[8] This climate at the time of deposition was strongly seasonal, probably with monsoonal periods.[12] Due to the abundant presence of deltaic sediments on the upper part, it is considered to be related to the retry of the sea level. The Lava Formation was deposited on a mostly continental setting, with its upper part, dominated by argillaceous sediments, corresponding to the Ciechocinek Formation.[8] There is a great amount of kaolinite content, being present laterally in the basin, decreasing and lifting space to increasing smectite to the south-west of the formation. On the other hand, there is a great amount of coarsest sediments, which consist mostly of sands.[13]
__TOC__
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
| Leiotriletes |
|
| Miospores | Affinities with Botryopteridaceae, Cooksoniaceae, Schizaeaceae, Sermayaceae and Zosterophyllaceae. Likely reworked from Devonian-Permian layers | |
| Acanthotriletes[14] [15] |
|
| Miospores | Affinities with the Botryopteridaceae and Selaginellaceae. Reworked from primitive ferns found in Devonian and Carboniferous rocks of Europe | |
| Staplinisporites |
|
| Miospores | Affinities with the family Encalyptaceae inside Bryopsida. Branching Moss Spores, related with high water-depleting environments | |
| Lycopodiumsporites |
|
| Miospores | Affinities with the family Lycopodiaceae inside Lycopodiopsida. | |
| Foveosporites |
|
| Miospores | Affinities with the family Lycopodiaceae inside Lycopodiopsida. Lycopod spores, related with herbaceous to arbustive flora common on humid environments | |
| Uvaesporites |
|
| Miospores | Affinities with the Selaginellaceae inside Lycopsida. | |
| Densoisporites |
|
| Miospores | Affinities with the Selaginellaceae inside Lycopsida. Relatively abundant | |
| Heliosporites |
|
| Miospores | Affinities with the Selaginellaceae inside Lycopsida. Herbaceous Lycophyte flora, similar to Ferns, ralated with Humid Settings. This Family of Spores are also the most diverse on the Formation. | |
| Leiozonotriletes |
|
| Miospores | Uncertain Affinities with the Pteridopsida. | |
| Cingulatisporites |
|
| Miospores | Affinities with Cibotiaceae and Selaginellaceae inside Pteridopsida. Relatively abundant | |
| Leptolepidites |
|
| Miospores | Affinities with the family Dennstaedtiaceae inside Polypodiales. Forest Fern Spores | |
| Pilosisporites |
|
| Miopores | Affinities with Schizaeaceae and Lygodiaceae inside Pteridophyta. Either from herbaceous or climbing ferns | |
| Klukisporites |
|
| Miospores | Affinities with the family Lygodiaceae inside Polypodiopsida. Climbing fern spores | |
| Clathropterisospora |
|
| Miospores | Affinities with Dipteridaceae inside Polypodiales. | |
| Dictyophyllidites |
|
| Miospores | Affinities with Dipteridaceae inside Polypodiales. Dictyophyllum is a common Dipteridacean genus of the mid-Mesozoic | |
| Marattiopsis |
|
| Miospores | Affinities with the Marattiaceae inside Polypodiopsida. | |
| Matonisporites |
|
| Miopores | Affinities with the Matoniaceae inside Polypodiopsida. Fern spores from lower herbaceous flora | |
| Cyathidites |
|
| Miospores | Affinities with the family Cyatheaceae inside Cyatheales. Arboreal Fern Spores | |
| Tripartina |
|
| Miospores | Affinities with Dicksoniaceae inside Cyatheales. Common cosmopolitan Mesozoic Tree fern genus. | |
| Camptotriletes |
|
| Miospores | Affinities with the Lepidodendraceae and Botryopteridaceae. Reworked Carboniferous Palynomorphs | |
| Hymenozonotriletes |
|
| Miospores | Affinities with the Lepidodendraceae. Reworked | |
| Protopinus |
|
| Pollen | Pollen from the Family Caytoniaceae inside Caytoniales. Caytoniaceae are a complex group of Mesozoic Fossil floras, that can be related to both Peltaspermales and Ginkgoaceae. | |
| Chasmatosporites[16] |
|
| Affinities with the family Cycadaceae inside Cycadales. Is among the most abundant flora recovered on the upper section of the coeval Rya Formation, and was found to be similar to the pollen of the extant Encephalartos laevifolius. | ||
| Paleoconiferus |
|
| Pollen | Affinities with the Voltziaceae, Pinaceae, Cupressaceae and Araucariaceae inside Pinopsida. | |
| Pseudopinus |
|
| Pollen | Affinities with the Voltziaceae inside Pinopsida. | |
| Protopodocarpus |
|
| Pollen | Affinities with the Voltziaceae inside Pinopsida. | |
| Paleopicea |
|
| Pollen | Affinities with the Pinaceae and Voltziaceae inside Pinopsida. | |
| Pseudopicea |
|
| Pollen | Affinities with the Pinaceae inside Pinopsida. Relatively abundant Pinaceae Pollen, appears specially on Kaolinite-abundant strata. | |
| Cerebropollenites |
|
| Pollen | Affinities with the Sciadopityaceae or Miroviaceae inside Coniferales. This Pollen resemblance with extant Sciadopitys suggest that Miroviaceae can be an extinct lineage of sciadopityaceaous-like plants.[17] | |
| Perinopollenites |
|
| Pollen | Affinities with the family Cupressaceae inside Pinopsida. Pollen that resembles extant genera such as the Genus Actinostrobus and Austrocedrus, probably derived from Dry environments. | |
| Cupressacites |
|
| Pollen | Affinities with the family Cupressaceae inside Pinopsida. | |
| Taxodiites |
|
| Pollen | Affinities with the family Cupressaceae inside Pinopsida. | |
| Classopollis |
|
| Pollen | Affinities with the Cheirolepidiaceae inside Pinopsida. Indicator of Dry settings | |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
| Phlebopteris |
|
| Isolated pinnae | Affinities with Matoniaceae inside Gleicheniales. | |
| Ginkgoites |
|
| Leaves | Affinities with Ginkgoaceae inside Ginkgoales. Large to medium Arboreal trees, common on the Fennoscandinavian realm, but also on the Siberian strata | |
| Picea? |
|
| Cones | Affinities with the Piceoideae inside Coniferales. | |
| Pinus? |
|
| Cones | Affinities with the Pinaceae inside Coniferales. | |
| Podozamites |
|
| Leaves | Affinities with Krassiloviaceae inside Voltziales. The local Podozamites show a rather great range of Growth, reflecting Tropical to subtropical conditions. | |
| Elatocladus |
|
| Leaves | Affinities with the Cupressaceae inside Coniferales. | |