Phosphine-catalyzed [3 + 2] cycloaddition of Morita-Baylis-Hillman carbonates with sulfamate-derived cyclic imines has been developed, affording sulfamate-fused dihydropyrroles in moderate to good yields.

Introduction: Carbonate minerals observed in primitive meteorites are products of either terrestrial weathering or aqueous alteration in the early solar system. Most of the carbonate minerals in carbonaceous chondrites occur primarily as isolated grains in matrix, as crosscutting veins, or as replacement minerals in chondrules [e.g., 1, 2]. A few calcium-aluminum-rich inclusions (CAIs) have bee...

In recent times sedimentation data have become increasingly relevant in modeling sedimentation operations such as filtration, fluidization, two-phase flow operations and in environmental engineering. In this study, the effects of reactants concentrations and size of settling vesselson the sedimentation rates of strontium and barium carbonates, in aqueous medium, were studied by a modified appro...

Records of past changes in lake levels and lake water isotopic composition in closed basins provide key insights into past variations in the hydrological cycle; however, these records are often limited by dating precision and temporal resolution. Here we present data from lacustrine cave carbonates, a previously unexplored class of carbonates that comprise a promising new archive of past hydrol...

Understanding the extreme carbon isotope excursions found in carbonate rocks of the Ediacaran Period (635–541 Ma), where dC of marine carbonates (dCcarb) reach their minimum ( 12&) for Earth history, is one of the most vexing problems in Precambrian geology. Known colloquially as the ‘Shuram’ excursion, the event has been interpreted by many as a product of a profoundly different Ediacaran carb...

A 4.5 Ma record of fluvial and lacustrine deposits is well exposed at Gona, in the Afar Depression of Ethiopia. We use isotopic values of pedogenic carbonate and fossil teeth to reconstruct Plio^Pleistocene environmental change at Gona. An increase in N13C values of pedogenic carbonates since 4.5 Ma points to a shift from woodlands to grassy woodlands in the early Pliocene, 310.4 to 33.9x (VPDB...

Calcium carbonate precipitation associated with biotic activity is first recorded in Archaean rocks. The oldest putative fossils related to hydrothermal vents have been dated at ~3.77 Ga (possibly 4.29 Ga). Stromatolites, the 3.70 Ga, since occurred through Earth history, despite dramatic changes physical and chemical conditions aquatic environments. A key question is: what advantages do photos...