A highly altered carbonate rock was recovered from the mount, off Calicut, Kerala. Bulk chemical analysis of the rock showed that it contains ~ 21 % P2O5. The rock consists of fine to coarse lithic and bio-clasts embedded in brown to the yellow coloured phosphatic matrix. Detailed SEM-EDS of the rock piece indicates micro-globular and nodular growth of phosphorite around calcite to form a core-rim structure, with P2O5 as high as 31.67 weight percentage. The X-ray elemental mapping carried out using EPMA indicates highest P2O5 (29.87 %) on the altered surfaces. Microstructural and geochemical analyses suggest authigenic/diagenetic precipitation of phosphorite on the carbonate rock.

中文翻译：

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印度拉克沙威海 (Lakshadweep Sea) 喀拉拉邦附近卡利卡特山上磷矿的出现

从喀拉拉邦卡利卡特附近的山上发现了一块高度改变的碳酸盐岩。岩石的整体化学分析表明，它含有约 21% 的 P2O5。岩石由细到粗的岩屑和嵌入棕色到黄色磷酸盐基质中的生物碎屑组成。岩石块的详细 SEM-EDS 表明磷矿在方解石周围微球状和球状生长，形成核缘结构，其中 P2O5 重量百分比高达 31.67。使用 EPMA 进行的 X 射线元素映射表明改变表面上的 P2O5 最高 (29.87%)。微观结构和地球化学分析表明，在碳酸盐岩上磷矿自生/成岩沉淀。