Impossible! Or not? What would be your answer? Well, read the facts on my website, and let us come back to this hypothesis at the end:
Most of China’s bauxite production is derived from karst deposits. One example of a bauxite mining province is western Guangxi in the South China Block, where resources comprise more than 500 Mt including Permian bauxite ore and its quaternary derivatives ( Liu et al. 2017). The bauxite province is adjacent to the mantle-plume-related Emeishan Large Igneous Province ...
Read more on my website http://www.walter-pohl.com/news.html .......
Back to the Emeishan mantle plume: I suggest that indeed, its activity caused (1) directly the emergence of the marine carbonate platform; (2) indirectly, by emission of CO2, the elevated temperatures and rainfall of the Capitanian greenhouse favouring karstification; and (3) the provision of basalt-derived sediments.
Liu, Xuefei, Wang, Qingfei, Zhang, Qizuan et al. (2017) Genesis of the Permian karstic Pingguo bauxite deposit, western Guangxi, China. Miner. Deposita (yet no volume no. attributed).
DOI 10.1007/s00126-017-0723-y
Dear Walter,
An interesting question, no doubt about it. We are working now on karstic bauxite deposits from the Dominican Republic, in the southern Peninsula. You can download our last article from my website (Ore Geology Reviews, in press). In our case, research revolves mainly around the promising REE resources in this bauxite province. The interesting point here is that we envisage the Dumisseau Formation (mantle-plume derived and tectonically emplaced previously to the formatin of the bauxites there; Lithos, v. 254-255, p- 67-83) as a potential source of aluminosilicate materials to be lateritized and then, bauxitized. However, at least in our case, mantle-plume volcanism had nothing to do with the emergence of the carbonate sequence nor with its karstification as you propose for Xinese bauxites. Hope you enjoy the reading.
Thank you for answering my question. More arguments that speak for a genetic connection are the coincidence in time and the proximity. But I do admit that coincidence is not a proof of causation.
Can you help me by explaining your 'no'?
Dear Dr Pohl:
I mean that bauxite is a product of laterite formed by weathering of aluminum-rich minerals at the surface. Bauxite cannot be formed by high-T mantle plume. Otherwise, how can 'OH' components in bauxite (i.e. hydroxyl aluminum oxide mixture) survive such high-T condition of the plume?
Regards,
Xue-Ming Yang
Dear Dr. Pohl: your idea sounds right. In the Deccan Trapps, in India, the bauxite amounted to 3 billion tons of reserves, developed in a weathering horizon in the plume generated basaltic plateau. So, if in China, the Emeishan LIP produced a similar plateau in the Paleozoic, conditions could have been similar to those in India to generate bauxite horizons. The entrapment of bauxite in karst depressions could have happened after the extrusion of the LIP, due to the deposition of the carbonate platforms, as you correctly state, so this would be a transported pisolitic bauxite, similar to the one in Jamaica, generated by the weathering, in this case, of Cretaceous rhyolitic tuffs and lavas of the Great Arc of the Caribbean. In Venezuela the largest bauxite deposit of Los Pijiguaos, is associated to a large weathered pluton of rapakivi granite, the Parguaza Granite, of Mesoproterozoic age, whose origin is probably also related to a mantle plume. Minor bauxite deposits are also found associated to the Avananavero Province LIP, of Paleoproterozoic age, obviously the corresponding basaltic plateaus have long ago been eroded, and only some thick diabase sills have remained. With regards. Sebastian. UCV-Caracas.Venezuela.
Dear,
The bauxite is among the most deposit sought by industrialists.
Best regards.
Dear Dr. Pohl,
An article (Deng et al., 2010, Journal of Asian Earth Science) elucidate the relationship between the formation of the bauxite deposits in Western Guangxi and the Emeishan plume.
Deng et al., 2010. Genetic relationship between the Emeishan plume and the bauxite deposits in Western Guangxi, China: Constraints from U–Pb and Lu–Hf isotopes of the detrital zircons in bauxite ores. Journal of Asian Earth Science, 37(5-6): 412-424.
Dear Colleague Lu Lu, thank you for this citation. So geochemical data of zircons in the bauxite do indeed point to a derivation of the bauxitized material from the Emeishan. Here is the Abstract of Deng et al., 2010:
The formation processes and alumina sources of the large and super-large bauxite deposits that have developed in West Guangxi in the Yangtze Block have been debated for a long time. SHRIMP zircon U–Pb dates, combined with in situ Hf isotopic data of the detrital zircons from Permian bauxite ores in the Western Guangxi province, China, provide new constraints on the genesis of the bauxites in West Guangxi. U–Pb dating ages of the detrital zircons cluster around 256 Ma and 261 Ma; this is consistent with the emplacement age of the Emeishan plume. Thus, it has been determined that the detrital zircons come from magmatic rocks related to the Emeishan plume and that the Emeishan plume has significant control on the formation of bauxites. In addition, this work presents new evidence for the evolution of the Emeishan plume. Most of the εHf(T) values of the zircons around 256 Ma and 261 Ma are negative, varying widely from −1.3 to −16.1. This data indicates the melting of Yangtze Block basement rocks and the mixing of magmas generated both from the mantle and from the crust occurred at the periphery of the plume in the main phase of Emeishan LIP magmatism. This study verified that the plume-induced uplift exposed carbonates, as well as the mafic and felsic rocks generated by the Emeishan plume to long periods of intense weathering under humid tropical conditions. The weathering remnants of the high-alumina magmatic rocks and carbonates were deposited on, or transported to, the paleokarst surface and converted to bauxites.
Allow me a general observation: Increasingly, metallogenetic models comprise the whole system from the source to deposit formation, preservation and eventual supergene enrichment. In the case of bauxite, supergene processes are, of course, the direct agents of ore formation, as Xue Ming Yang correctly stated. Thank you all for your contributions to the matter.
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