# Lava Formation

The Lava Formation is a Mesozoic geologic formation in Lithuania and Kaliningrad, being either the sister or the same unit as the Ciechocinek Formation. 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. 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). The Jotvingiai Group Toarcian deposits represent deposits laid down in fresh water and brackish basins, possibly lagoons or coastal plain lakes. 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. 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. 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. 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. This climate at the time of deposition was strongly seasonal, probably with monsoonal periods. 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. 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.

## Palynology

| Genus | Species | Stratigraphic position | Material | Notes | Images |
| Leiotriletes | Leiotriletes rotundiformis | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with Botryopteridaceae, Cooksoniaceae, Schizaeaceae, Sermayaceae and Zosterophyllaceae. Likely reworked from Devonian-Permian layers | |
| Acanthotriletes | Acanthotriletes elatus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Botryopteridaceae and Selaginellaceae. Reworked from primitive ferns found in Devonian and Carboniferous rocks of Europe | |
| Staplinisporites | Staplinisporites caminus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the family Encalyptaceae inside Bryopsida. Branching Moss Spores, related with high water-depleting environments | Example of extant Encalypta specimens, Staplinisporites come probably from similar genera |
| Lycopodiumsporites | Lycopodiumsporites semimuris | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the family Lycopodiaceae inside Lycopodiopsida. | |
| Foveosporites | Foveosporites microreticulatus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the family Lycopodiaceae inside Lycopodiopsida. Lycopod spores, related with herbaceous to arbustive flora common on humid environments | Extant Lycopodium specimens. Genera like Foveosporites probably come from a similar plant |
| Uvaesporites | Uvaesporites argenteaeformis | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Selaginellaceae inside Lycopsida. | |
| Densoisporites | Densoisporites crassus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Selaginellaceae inside Lycopsida. Relatively abundant | |
| Heliosporites | Heliosporites altmarkensis | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Selaginellaceae inside Lycopsida. Herbaceous Lycophyte flora, similar to Ferns, related with Humid Settings. This Family of Spores are also the most diverse on the Formation. | Extant Selaginella, Heliosporites probably come from a similar or a related Plant |
| Leiozonotriletes | Leiozonotriletes sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Uncertain Affinities with the Pteridopsida. | |
| Cingulatisporites | Cingulatisporites scabratus Cingulatisporites sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with Cibotiaceae and Selaginellaceae inside Pteridopsida. Relatively abundant | |
| Leptolepidites | Leptolepidites major Leptolepidites sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the family Dennstaedtiaceae inside Polypodiales. Forest Fern Spores | Example of extant Dennstaedtia specimens, Leptolepidites come probably from similar genera |
| Pilosisporites | Pilosisporites brevipapillosus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miopores | Affinities with Schizaeaceae and Lygodiaceae inside Pteridophyta. Either from herbaceous or climbing ferns | |
| Klukisporites | Klukisporites sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole C8-borehole | Miospores | Affinities with the family Lygodiaceae inside Polypodiopsida. Climbing fern spores | Example of extant Lygodium, Lygodioisporites come probably from similar genera or maybe a species from the genus |
| Clathropterisospora | Clathropterisospora obovata Clathropterisospora "sp. 1" Clathropterisospora "sp. 2" | Nida-44 Borehole Kybartai-29 Borehole | Miospores | Affinities with Dipteridaceae inside Polypodiales. | |
| Dictyophyllidites | Dictyophyllidites sp sp. nov. | Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with Dipteridaceae inside Polypodiales. Dictyophyllum is a common Dipteridacean genus of the mid-Mesozoic | Dictyophyllum nilssonii specimen |
| Marattiopsis | Marattiopsis scabratus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Marattiaceae inside Polypodiopsida. | |
| Matonisporites | Matonisporites phlebopteroides | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miopores | Affinities with the Matoniaceae inside Polypodiopsida. Fern spores from lower herbaceous flora | Example of extant Matonia specimens, Matonisporites come probably from similar genera |
| Cyathidites | Cyathidites minor | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the family Cyatheaceae inside Cyatheales. Arboreal Fern Spores | Example of extant Cyathea, Cyathidites come probably from similar genera |
| Tripartina | Tripartina variabilis Tripartina sp sp. nov. | Nida-44 Borehole C8-borehole | Miospores | Affinities with Dicksoniaceae inside Cyatheales. Common cosmopolitan Mesozoic Tree fern genus. | Coniopteris specimen |
| Camptotriletes | Camptotriletes anagrammensis Camptotriletes cerebriformis Camptotriletes triangularis | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Lepidodendraceae and Botryopteridaceae. Reworked Carboniferous Palynomorphs | |
| Hymenozonotriletes | Hymenozonotriletes dalinkevidiusi Hymenozonotriletes speciosus | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Miospores | Affinities with the Lepidodendraceae. Reworked | |
| Protopinus | Protopinus sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | 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 | Chasmatosporites apertus Chasmatosporites hians Chasmatosporites sp. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole C8-borehole | | 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. | Extant Encephalartos laevifolius. Chasmatosporites maybe come from a related plant |
| Paleoconiferus | Paleoconiferus sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Pollen | Affinities with the Voltziaceae, Pinaceae, Cupressaceae and Araucariaceae inside Pinopsida. | |
| Pseudopinus | Pseudopinus oblatinoides | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Pollen | Affinities with the Voltziaceae inside Pinopsida. | |
| Protopodocarpus | Protopodocarpus sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Pollen | Affinities with the Voltziaceae inside Pinopsida. | |
| Paleopicea | Paleopicea sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Pollen | Affinities with the Pinaceae and Voltziaceae inside Pinopsida. | |
| Pseudopicea | Pseudopicea sp. sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole | Pollen | Affinities with the Pinaceae inside Pinopsida. Relatively abundant Pinaceae Pollen, appears specially on Kaolinite-abundant strata. | Extant Picea. Pseudopicea maybe come from a related plant |
| Cerebropollenites | Cerebropollenites dalinkeviciusi | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole C8-borehole | 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. | Extant Sciadopitys. Cerebropollenites likely come from a related plant |
| Perinopollenites | Perinopollenites sp sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole C8-borehole | 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. | Extant Austrocedrus. Perinopollenites maybe come from a related plant |
| Cupressacites | Cupressacites coriaceus Cupressacites subgranulatus | C8-borehole | Pollen | Affinities with the family Cupressaceae inside Pinopsida. | |
| Taxodiites | Taxodiites pallens | C8-borehole | Pollen | Affinities with the family Cupressaceae inside Pinopsida. | |
| Classopollis | Classopollis corniculatus Classopollis sp.1 sp. nov. Classopollis sp.2 sp. nov. Classopollis sp.3 sp. nov. | Nida-44 Borehole Belyj Jar-1 Borehole Uljanovo-3 Borehole Kybartai-29 Borehole C8-borehole | Pollen | Affinities with the Cheirolepidiaceae inside Pinopsida. Indicator of Dry settings | |

## Megaflora

| Genus | Species | Stratigraphic position | Material | Notes | Images |
| Phlebopteris | Phlebopteris cf. smithii | Nida-44 Borehole | Isolated pinnae | Affinities with Matoniaceae inside Gleicheniales. | Example of Phlebopteris specimen |
| Ginkgoites | Ginkgoites acuta Ginkgoites "sp. 1" | Nida-44 Borehole Belyj Jar-1 Borehole | Leaves | Affinities with Ginkgoaceae inside Ginkgoales. Large to medium Arboreal trees, common on the Fennoscandinavian realm, but also on the Siberian strata | Ginkgoites specimen |
| Picea? | Picea? sp sp. nov. Picea? sp.1 sp. nov. Picea? sp.2 sp. nov. | Nida-44 Borehole Uljanovo-3 Borehole | Cones | Affinities with the Piceoideae inside Coniferales. | Example of extant Picea cones |
| Pinus? | Pinus? sp sp. nov. | Nida-44 Borehole | Cones | Affinities with the Pinaceae inside Coniferales. | Example of extant Pinus cones |
| Podozamites | Podozamites sp sp. nov. | Nida-44 Borehole | Leaves | Affinities with Krassiloviaceae inside Voltziales. The local Podozamites show a rather great range of Growth, reflecting Tropical to subtropical conditions. | Podozamites reconstruction |
| Elatocladus | Elatocladus sp. | Nida-44 Borehole | Leaves | Affinities with the Cupressaceae inside Coniferales. | Elatocladus |