Staropaleozoiczne złoża apatytów w Wietnamie Północnym oraz uwagi o możliwościach poszukiwawczych podobnego typu złóż w Polsce
Abstract
OLD PALAEOZOIK APATITE DEPOSITS IN NORTH VIET-NAM AND POSSIBILITIES OF SEARCHING FOR SIMILAR TYPE OF DEPOSITS IN POLAND
Summary
In the Lao-Cai region (Democratic Republic of Viet-Nam) there occur large apatite deposits or world-wide importance. The area of the deposits is estimated to be about 150 km2, the entire resources being 1,2 milliard tons. Content of P2O5 in the first quality ore ranges from 35 to 40 per cent.
The apatite series occur within the folded and metamorphozed Cambro-Ordovician deposits (Koc-San series) approximately 300 m in thickness. The series contains numerous lamprophyre dikes concordantly folded together with the beds of Koc-San series. Here three horizons are apatite-bearing, the middle one – the so-called ore-bearing horizon, 10-12 m in thickness – being of economic value. The ore-bearing horizon consist of carbonate-apatite deposits and constitutes the exploitation seam. The monomineral apatite ores occurring in the weathering zone of the deposit are of greatest economical importance.
The apatites from Lao-Cai region have undoubtedly originated, within geosynclinal formations, as a result of sedimentary-chemical activity. The deposits are of sedimentary type, syngenetic one in the relation to adjacent rocks. However, the ultimate mineralogic-chemical character of the apatites was greatly influenced by secondary factors, mainly by metamorphic processes (transition of phosphorites into apatites) and by rock weathering, which led to an enrichment in P2O5 in the deposit. Taking into consideration a fact that the apatite deposits are closely connected with the horizon of carbonate rocks, we may assume that they were formed in the shallow zones of shelf area.
On palaeogeographical and tectonical data an attention was paid to a possibility of searching for such type deposits in the Cambro-Ordovician formations in Poland, particularly in Sudetes, where trace of apatite occurrence have recently been ascertained.
Summary
In the Lao-Cai region (Democratic Republic of Viet-Nam) there occur large apatite deposits or world-wide importance. The area of the deposits is estimated to be about 150 km2, the entire resources being 1,2 milliard tons. Content of P2O5 in the first quality ore ranges from 35 to 40 per cent.
The apatite series occur within the folded and metamorphozed Cambro-Ordovician deposits (Koc-San series) approximately 300 m in thickness. The series contains numerous lamprophyre dikes concordantly folded together with the beds of Koc-San series. Here three horizons are apatite-bearing, the middle one – the so-called ore-bearing horizon, 10-12 m in thickness – being of economic value. The ore-bearing horizon consist of carbonate-apatite deposits and constitutes the exploitation seam. The monomineral apatite ores occurring in the weathering zone of the deposit are of greatest economical importance.
The apatites from Lao-Cai region have undoubtedly originated, within geosynclinal formations, as a result of sedimentary-chemical activity. The deposits are of sedimentary type, syngenetic one in the relation to adjacent rocks. However, the ultimate mineralogic-chemical character of the apatites was greatly influenced by secondary factors, mainly by metamorphic processes (transition of phosphorites into apatites) and by rock weathering, which led to an enrichment in P2O5 in the deposit. Taking into consideration a fact that the apatite deposits are closely connected with the horizon of carbonate rocks, we may assume that they were formed in the shallow zones of shelf area.
On palaeogeographical and tectonical data an attention was paid to a possibility of searching for such type deposits in the Cambro-Ordovician formations in Poland, particularly in Sudetes, where trace of apatite occurrence have recently been ascertained.