| The object of this study focuses on similarities and differences of element enrichment metallogenic regularity between Zhexi (western Zhejiang province) and Nanling regions. We keep closely to the point that elements may act as "genes" of mineralization, which is a recently springing-up metallogeny proposition. We believe that both the quality and quantity are inseparable geochemical properties for an element, and such two properties have a threefold expression in geochemistry:time, space and geology-geochemical processes. By extension, energy (reserves) of ore mineralization reflects the ensemble of ore formation; while mineralization potential (fractal dimension) is used to describe the central tendency of energy; metallogenic intensity, efficiency and scale, on the other hand, are different aspects of energy.Of these, a model of anisotropic multifractal spectrum is firstly proposed, and it makes fractal dimension pegged to the rock-control and ore-control structures. We also makes reference to the concept of "efficiency" in economics, and believe that the ratio between the left and the right opening length of a multifractal spectrum can be interpreted as "metallogenic efficiency index"-EEI, because the former denote the anomalous "output", while the latter denote the background "input". And then, total opening length should be defined as "metallogenic intensity index"-EII.As significant ore-concentrated areas along the Qin-Hang metallogenic belt, both Zhexi and Nanling regions have relatively different types, scales and minerals of ore deposit. In order to reflect these differences, the elemental geochemical information hidden in their1:200000stream sediment data was thus further considered, based on several data-mining techniques, in this work, its statistical characteristics as well as its corresponding tectonic background, magmatic activities, sedimentary formation and so on were together used to compare the regularity of enrichment and mineralization in both areas. All of them are the general technical route of this article.Findings show that:such a comparison between both regions appears as "less intersection","more complement (difference)", and "great disparities".Firstly, a "great disparity" between both areas accords just with the well-known Matthew Effect or Pareto’s Law. Only Hg, Au and La’s metallogenic efficiencies in Nanling region are smaller than in Zhexi area; and only As, Au, Cu, F, Fe’s metallogenic potentials in Nanling are lower than in Zhexi. As to other ore-controlling factors, e.g., metal reserves, metallogenic scale, outcropped area of granitoid, amount of interjunction of different tectonic systems, fracture density, elemental background of abundance, high heat production granites and etc, Nanling region always has advantages compared to Zhexi,no matter in quantity or in quality. Due to a thicker sedimentary cover of Zhexi region in the Qiantang basement geotectogene, the ore-forming energy that produced by deep structure related to subduction can hardly transmit to superficial crust, leading to poor mineralization associated with an insignificant "Tidal-Resonance" effect in this area. While Nanling’s deep tectionic energy can do it, which brings huge metal reserves within a rather short time-span. Secondly, as to the reason why "less intersection" and "more complement"? Different ore-forming geological conditions in both areas inherited and developed subsequently by all kinds of ore-making processes must account for. The "less intersection" and "more complement" mean Qin-Hang metallogenic belt as a whole has a colorful and well-ordered metallogenic landscape. Most mineral spots in Zhexi spatiotemporally distributes into much older and much younger strata, while Nanling complementarily distributes into the early-to-mid period of late Paleozoic. In Zhexi, the essential ore-and rock-conrolling structure is points of interjunction between regional north-east fracture and secondary north-west fracture, while the most essential structure in Nanling area is of NE-NNE trending, and EW trending followed by. The subduction may exert great influence on the magmatic-metallogenic events in Zhexi area, but there is a change of subduction angle from gentle to steep, namely a transformation of regional tectonic settings, from150to140Ma. Before and after such a transformation, various mineralization associated with hyperthermal I-type (at adjacent northeastern Jiangxi province), hypothermal I-type, S-type, ferruginous A-type granites occurs in succession. And therefore, Fe, Au, Ag, Hg, Cu, Mo, Zn and other metals related to MT type (type I) granites do have a relatively considerable mineralization potential in Zhexi area. Nanling’s Mesozoic mineralization, on the other hand, is likely to be linked to transformation of lithosphere, dominated by S-type (BELIF granites) and I-type followed by. Elements of IL type (S) granites such as Be, Bi, W, Sn, Nb, Ta, U and Pb all have an extremely higher mineralization potential, scale and reserves in Nanling area. These regularities themselves likely provide a series of further guidance about regional exploration in both areas. |
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