Eustatic versus tectonic control on the development of Neoproterozoic and Cambrian stratigraphic sequences of the Lublin-Podlasie Basin (SW margin of Baltica)

A sequence stratigraphy is applied for the Neoproterozoic to Cambrian sedimentary fill of the Lublin-Podlasie Basin (LPB). The main goal of the study is to discriminate between eustatic and tectonic control on the development of sedimentary sequences. The Neoproterozoic and Cambrian sedimentary succession is subdivided into two second-order depositional sequences, separated by a major regional unconformity. The lower sequence A is poorly recognised. It is presumably of the early Neoproterozoic age and is characterized by continental to coastal shallow marine deposition. Sequence B comprises a time span of the (?late Neoproterozoic) to Middle Cambrian. The lowermost part of the sequence B is composed of a lowstand system tract (LST). A low relative sea-level (RSL), associated to the LST development, was controlled by regional thermal doming, followed by a rapid clastic and volcanogenic deposition, exceeding rate of subsidence of extensional grabens. The terminal Ediacaran was a time of a transgressive system tract I (TST I) development. Increase of the RSL was induced by a transition from syn-rift to post-rift subsidence. During the development of a following highstand system tract I (HST I) the RSL remained high. Significant local supply of sediments, exceeding in rate the basement subsidence, caused progradation of shoreline. The higher up-section TST II is characterized by gradual increase of the RSL and represents continuing thermal sag phase of the LPB. It was coeval with a global transgression and controlled mainly by eustatic sea level rise. The beginning of the Middle Cambrian corresponds to development of a HST II, controlled by decelerating rate of RSL rise, even though it coincides with the Hawke Bay regression. The HST II is therefore interpreted as controlled by local tectonic processes, superimposed on continued post-rift thermal subsidence of the passive margin.