Lava Formation
The Lava Formation is a Mesozoic geologic formation in Lithuania. Fish remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus. The Jotvingiai Group Toarcian deposits were deposited likely in a shallow lacustrine basin or a near sea freshwater lagoon, with the other environment of the formation consisting of shallow marine conditions, seashore barriers and dunes, on a hot and humid climate. Due to the abundant presence of deltaic sedimens on the upper part it is considered to be related to the retry of the sea level, as in the Polish equivalent formation, the Ciechocinek Formation.The climate at the time of deposition was strongly seasonal, probably with moonsonal periods. There is a great amountof kaolinite content, being present laterally in the basin, decreasing and lefting space to increasing smectite to the south-west of the formation. On the other hand, there is a great amount of coarsest sediments, what consist mostly on sands.
Paleogeography
While most of Europe was occupied by sea, Lithuania has a dominated continental regime, which lasted about 32 million years. The low elevation lands where flooded along the Toarcian rise and fall of the sea level, measured also on the Ciechocinek Formation, where the decomposition products were taken to separate depressions where they accumulated lagoon sediments, along with marine deposition of the sea basin lying on southwest of Lithuania. The southwest was composed mostly by a series of deltaic successions, along with several unidentified water bodies.The deposition of the formation shows a transition from deltaic to basinal facies at the west, where the sea shallow bays flooded the region, while in the north-east the land remained. The Lava Formation shelf had a depth of 200–250 m. The climate was humid, slightly warmer than in average latitudes, with a drier climate periods. In this climate, lush vegetation grew on the edges of the basins, leading to
the formation of brown coal interlayers. Aalenian-Oxfordian marine activity led to changes, with the rise of the sea level, until it retreat back on the southwest near the Cretaceous strata.
Spores
Plantae
Actinopterygii
| Genus | Species | Stratigraphic Position | Material | Notes | Images |
Pholidophoridae | Pholidophoriformes Indeterminate | Nida, Curonian Split | Teeth & Scales | Bony fishes of the family Pholidophoriformes inside Pachycormiformes. Fishes of small size, the most abundant on the strata along the Toarcian European Realm. | |
Semionotidae | Semionotiformes Indeterminate | Nida, Curonian Split | Teeth & Scales | bony fish of the family Semionotiformes | |
Macrosemiiformes | Macrosemiiformes Indeterminate | Nida, Curonian Split | Teeth & Scales | Bony fish of the family Semionotiformes |