Deep-freeze petrology of Lena River sand, Siberia

Modern sand from the vast (2 430 000 km(2)), high-latitude Lena River water shed occupies a low-lying, mostly unglaciated craton covered by thick, wide spread permafrost-totally different from the watersheds of large temperate and tropical rivers, whose sands have been previously studied to establish modern baselines for the interpretation of ancient sandstones. Fifty-nine L ena sands are rich in rock fragments and feldspar and reflect well the thre e major tectonic provinces that underlie it-platform, shield, and collision al suture, although the platform and shield sands are still very immature. Long exposure to cool middle Tertiary climates at first, and dry sub-Arctic to Arctic climates later, is the underlying cause of the mineralogically i mmature river sands of the Lena River.