U.S. Geological Survey Bulletin
Colin F. Williams · David Z. Piper · Hugh McLean · Jeffrey L. Howard · Samuel Y. Johnson · Caroline M. Isaacs · M. D. Medrano · Peter S. Galanis · Frederick V. Grubb · Thomas H. Moses
Jan 1983 · U.S. Government Printing Office
e-Buku
12
Halaman
reportRating dan ulasan tidak disahkan Ketahui Lebih Lanjut
Perihal e-buku ini
Phosphatic concretions occur within diatomite in the upper part of the Miocene Monterey Formation near Lompoc, Calif. Absence of disruption of fine laminar bedding in the associated sediment by the concretions shows that they formed after complete compaction of the enclosing sediment.The concretions exhibit a strongly concentric color, chemical, and mineralogic zonation. Many of them are composed of a nucleus in which vivianite is the dominant mineral. Amorphous ferric phosphate, mitridatite, and francolite are the dominant phosphatic phases in successive layers toward the surface of the concretions. Cd and As contents increase tenfold from the nucleus outward, reaching a maximum of 2,000 ppm, whereas Ni content, with a maximum of 720 ppm, and Co content show the opposite trend. This mineralogy and elemental composition favor accretion under conditions of continuously increasing Eh and pH, during uplift into the fresh-ground-water zone of the terrestrial environment. Shale-normalized rare-earth-element patterns, however, suggest a marine source for the elements biogenic debris consisting of opal-A, organic matter, and carbonates of the enclosing sediment.
Berikan rating untuk e-Buku ini
Beritahu kami pendapat anda.
Maklumat pembacaan
Telefon pintar dan tablet
Pasang apl Google Play Books untuk Android dan iPad/iPhone. Apl ini menyegerak secara automatik dengan akaun anda dan membenarkan anda membaca di dalam atau luar talian, walau di mana jua anda berada.
Komputer riba dan komputer
Anda boleh mendengar buku audio yang dibeli di Google Play menggunakan penyemak imbas web komputer anda.
eReader dan peranti lain
Untuk membaca pada peranti e-dakwat seperti Kobo eReaders, anda perlu memuat turun fail dan memindahkan fail itu ke peranti anda. Sila ikut arahan Pusat Bantuan yang terperinci untuk memindahkan fail ke e-Pembaca yang disokong.
