Jinju Formation

The Jinju Formation (Korean: 진주층; Hanja: 晋州層; RR: Jinju-cheung), also known as the Dongmyeong Formation (Korean: 동명층; Hanja: 東明層; RR: Dongmyeong-cheung) in some literature is a Lower Cretaceous formation in South Korea. Lithology of the Jinju Formation could be distinguished from overlying and underlying formations by lack of red beds in the entire formation. The depositional age of this formation spans from approximately 112.4 ± 1.3 to 106.5 million years ago (early Albian) based on detrital zircon U-Pb dating. It predominantly consists of black shale, with sandstone packets, deposited in a fluvial-lacustrine setting. The entire paleoenvironment of the Jinju Formation is interpreted as a balanced-fill lake basin, with deltas and streams. A diverse arthropod fauna, including isopods, spiders, and insects, is known from the formation. Other notable fossils known from the formation include several freshwater fishes, ostracods, and plants. This formation has also "attracted global ichnological attention" for the variety of important ichnofossils. Columnar and rod-shaped stromatolites have also been found here.