caa a22 4500 386402841 CHVBK 20180307112206.0 cr unu---uuuuu 161130e198901 xx s 000 0 eng 10.1017/S0016756800006166 doi S0016756800006166 pii (NATIONALLICENCE)cambridge-10.1017/S0016756800006166 Basal Cambrian reworked phosphates from Spitsbergen (Norway) and their implications [Elektronische Daten] Several phosphatic zones are associated with the oldest remains of shelly fossils on the arctic island of Spitsbergen. The phosphate occurs as reworked nodules and layers associated with a disconformity. A gap in the acritarch biostratigraphic record supports a hiatus associated with the phosphatic zone. Palaeogeographic positions for Svalbard, both (1) as a single unit, and (2) as three isolated parts prior to Caledonian tectonism are consistent with conditions favourable to at least minimal amounts of upwelling. However, upwelling may not have been a prerequisite for development of these phosphate deposits. These phosphates were deposited in a nearshore shelf environmnt which contrasts with the outer shelf setting of many modern and recent phosphate deposits. Geochemistry of the Lower Cambrian phosphates of Spitsbergen varies with the mode of phosphate occurrence. Concretionary phosphate clasts are chemically zoned such that their centres are enriched in P2O5 and CaO and are depleted in A12O3, SiO2, and K2O. Laminated and thinly bedded phosphate shows no chemical zonation within clasts. Phosphate cements are the most pure with respect to calcium phosphate. This thin phosphatic zone of Svalbard is minor when compared with thicker and richer Lower Cambrian phosphate deposits, particularly those in the Soviet Union, Southeast Asia, and Australia. Coupled with the near absence of phosphate in some extensive Proterozoic to Lower Palaeozoic successions (e.g. western North America), this emphasizes the fact that widespread Lower Cambrian phosphate deposition was unevenly distributed. Althouth the Upper Proterozoic and Lower Cambrian are characterized by enhanced phosphogenesis, palaeogeographic position was also apparently critical to deposition of phosphatic sediments. Copyright © Cambridge University Press 1989 Kidder D. L. Department of Geology, University of California, Davis, CA 95616, U.S.A. Swett K. Department of Geology, University of Iowa, Iowa City, IA 52242, U.S.A. Geological Magazine Cambridge University Press 126/1(1989-01), 79-88 0016-7568 126:1<79 1989 126 GEO https://doi.org/10.1017/S0016756800006166 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0016756800006166 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kidder D. L. Department of Geology, University of California, Davis, CA 95616, U.S.A NATIONALLICENCE 700 1- Swett K. Department of Geology, University of Iowa, Iowa City, IA 52242, U.S.A NATIONALLICENCE 773 0- Geological Magazine Cambridge University Press 126/1(1989-01), 79-88 0016-7568 126:1<79 1989 126 GEO CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge