Sanidine spherules at the Cretaceous–Tertiary boundary indicate a large impact event

  title={Sanidine spherules at the Cretaceous–Tertiary boundary indicate a large impact event},
  author={Jan Smit and Gerard Th. Klaver},
The hypothesis that a catastrophic impact of an extraterrestrial body caused the terminal Cretaceous mass extinctions of dinosaurs, planktonic foraminfera and other species is now accepted as respectable following the discovery of a worldwide iridium enrichment in the Cretaceous–Tertiary (K–T) boundary clay1–5. In the basal lamina of the K–T boundary clay of Caravaca (Spain)7 numerous spherules were discovered composed of finely crystallized, almost pure K-feldspar in the structural state of… 
Siderophile-rich magnetic spheroids from the Cretaceous–Tertiary Boundary in Umbria, Italy
The magnetic fraction of some Cretaceous–Tertiary (K–T) boundary sediments sampled at two locations in Italy, contains a spheroidal component which has retained some relict mineral textures and,
Dark green spherules occur in the lower part of a turbidite in Section 603B-22-3, at the 70 cm level. In all probability these spherules originally consisted of massive glass, but now appear to have
The oldest impact deposits on Earth - First confirmation of an extraterrestrial component
The chromium isotopic compositions of samples from an early Archean (3.22 Ga) spherule bed (S4) from the Barberton Greenstone Belt, South Africa, are distinct from that in background rocks and other
Review of the mineralogy of the Cretaceous-Tertiary boundary clay: evidence supporting a major extraterrestrial catastrophic event
Abstract The proposed impact event at the end of the Cretaceous resulted in mass extinctions and subsequently significant variations in the geochemical and mineralogical composition of the sediments
Tektites in Cretaceous‐Tertiary boundary rocks on Haiti and their bearing on the Alvarez Impact Extinction Hypothesis
Relic tektites are associated with a Pt-group metal abundance anomaly and shocked minerals in a thin marl bed that marks the K-T boundary on Haiti. The presence of these three impact-produced
Chemostratigraphy across the Cretaceous-Tertiary Boundary and a Critical Assessment of the Iridium Anomaly
The elevated concentration of iridium-one of the platinum-group elements (PGE)-at the Cretaceous-Tertiary boundary is still the most generally accepted evidence that a large bolide struck the earth
Geochemical evidence for an impact origin for a Late Archean spherule layer, Transvaal Supergroup, South Africa
A Late Archean layer rich in sand-sized spherules of former silicate melt in the Monteville Formation (Transvaal Supergroup, South Africa) has Ir concentrations as high as 6.4 ppb and is clearly


Extraterrestrial Cause for the Cretaceous-Tertiary Extinction
A hypothesis is suggested which accounts for the extinctions and the iridium observations, and the chemical composition of the boundary clay, which is thought to come from the stratospheric dust, is markedly different from that of clay mixed with the Cretaceous and Tertiary limestones, which are chemically similar to each other.
An extraterrestrial event at the Cretaceous–Tertiary boundary
Closely spaced samples from an uninterrupted calcareous pelagic sequence across the Cretaceous–Tertiary boundary reveal that the extinction of planktonic Foraminifera and nannofossils was abrupt
A Major Meteorite Impact on the Earth 65 Million Years Ago: Evidence from the Cretaceous-Tertiary Boundary Clay
The major extinction of life on the earth at the end of the Cretaceous Period may be related to the meteorite impact, as the enriched noble metals in the clay are present in cosmic proportions, indicating that the impacting celestial body had not undergone gross chemical differentiation.
Siderophile-enriched sediments from the Cretaceous–Tertiary boundary
Siderophilic element concentrations are high in sediments from the Cretaceous–Tertiary boundary. An extraterrestrial source is indicated. Concentrations are too high to be understood in terms of the
Syngenetic Sanidine Beds from Middle Ordovician Saint Peter Sandstone, Wisconsin
Syngenetic sanidine beds are described from three localities in Wisconsin and three localities are recognized from the literature. Other localities in the Upper Mississippi Valley region appear
Physics of Magmatic Processes
While the chemical aspects of igneous petrology have dominated research for many years, the physical processes associated with the generation, transport, and crystallization of magma have been
Potassium-Feldspar Phenocrysts in the Surface of Colomera, and Iron Meteorite
Observations of glass nodules in the interior of the medium octahedrite Colomera are evidence that some iron meteorites formed as segregations within a silicate matrix and did not originate in a metallic core.
A Study of Authigenic Feldspars
Samples from forty localities were examined and include monoclinic potash feldspar, microcline, albite, and the first reported example of naturally occurring soda feldspar structurally intermediate