Significance of U-Pb detrital zircon geochronology for mudstone provenance

Abstract Detrital zircon U-Pb studies of mudstone provenance are rare but may preferentially fingerprint distal sources. To examine this issue, Pierre Shale and Trinidad Sandstone deposited in a Late Cretaceous deltaic environment the Raton Basin, Colorado (USA), were measured for detrital age by laser ablation–inductively coupled plasma–mass spectrometry. Two major peaks at ca. 70 1690 Ma found both inversely varying proportions: 68% 16%, respectively, finest fraction (~15–35 ?m) shale, 25% 32%, coarsest (~60–80 sandstone. Proximal sources Sangre de Cristo Mountains, directly west contain coarse-grained, zircon, whereas Laramide uplifts basins Colorado, New Mexico, Arizona fine-grained, zircon. The results indicate that reflects availability volcanic other fine-grained source rocks rather than simply should routinely include units because these identify more reliably sandstones alone.