Provenance Tracking Study Of City Wall’s Earth In The Neolithic Liangzhu City Based On XRD Analyses Of Clay Minerals

On the basis of previous researching, this article is mainly discussing the provenances of city wall’s rammed layers of the Neolithic Liangzhu City, around the core content of the Neolithic Liangzhu City and the coupling process of geomorphic environment. By expanding the scope of the sampling, we obtain five cross-sectional samples in the distribution area of the ancient city, namely initially recognized source MT2, HN2and Possible provenances SCI, QH1, NMS1. Through comparing them to the rammed layers of Neolithic Liangzhu City’s city wall from the aspect of clay minerals, geochemical elements, whole-rock minerals, we conclude the provenances of city wall’s rammed layers and its soil characteristics. And on this basis, the paper further analysis the processes of soil forming and which lead to differences in the content of clay minerals reasons. Primary conclusions are as follows:(1) Clay minerals experimental results show that, the differences between the content of the walls of rammed earth layer’s illite, kaolinite, smectite and MT2, HN2, SCI, QH1, NMS1’s is small, the main difference is that the mineral content of1.4nm.1.4nm mineral content of rammed earth walls layer is12%-27%; most samples of MT2, HN2, SC1cross-sectional is between14%to25%; while the QH1, NMS1sectional is14%or less.Other indicators such as whole rock minerals, oxides ratio, also reflects that the sample distributions of MT2, HN2, SCI are consistent with the layer of rammed earth walls’s, while there exists a clear dividing line between NMS1, QH1. The above analysis shows that MT2, HN2, SCI are the sources of the ancient city walls of rammed earth material layer, while QH1, NMS1are not its provenance.(2) According layered soil profile, compared the samples of SCI, MT2, HN2profile’s deposition layer, humus layer, leached layer, deposited layer, parent material layer to the rammed layers respectively, the results show that except the parent material, the other layers are more similar with Nh sample. Thus furthering indicates that the provenances of city wall’s rammed layers of the Neolithic Liangzhu City is the upper layer of the soil parent material weathering crust of SCI, MT2, HN2cross-section, Liangzhu ancestors did not use the parent material layer to build the walls.(3) The content of quartz and oxides SiO2, Al2O3, Fe2O3of MT2, HN2, SCI are higher than QH1,NMS1’s, up to95%and90%respectively. And it Reflects the maturity of the mineral soil is higher, the material composition more stability.Similarly,1.4nm mineral content of MT2, HN2, SCI are much higher, and mainly in the vermiculite-based, with green/vermiculite mixed, excluding chlorite.The vermiculite as a lightweight material, is widely used in the construction field, and it has a thermal insulation function which can make the house cool in summer, warm in winter. On the other hand, it is still a very good adsorbent and fireproof material. The1.4nm mineral content of parent materials of MT2, HN2, SC1sectional, namely reticulate red clay is small or none, with green/vermiculite mineral in the main.Perhaps it is for this reason that in the prevailing circumstances, the Liangzhu ancestors chosen the more stability and high levels of soil vermiculite materials to build walls by virtue of their wisdom.(4) Experimental indicators show that the provenance SCI section is in intense chemical weathering stage, the soil is strongly acidic, with better oxidation and higher kaolinite content, obvious desilication allitic, its parent material is petterned red earth. Due to the low-lying terrain, MT2, HN2cross-sections are in lower-middle stages of chemical weathering and belong to burial weathering crusts, soils are acidic or neutral, poor oxidation conditions, their parent materials are also the petterned red earth. QH1, NMS1cross-sections are in the middle stages of chemical weathering. QH1cross section is yellow soil, NMS1cross section is mountainous limestone weathering crust weathered residual soil slope sediments formed by pedogenesis, and soil parent material is not obvious. The biggest difference of the sources SCI, MT2, HN2and non-sources QH1, NMS1is the soil parent materials. The soil parent materials of the sources SCI, MT2, HN2are similar, all develpoed on the petterned red earth, the oxide content, mineral content of the whole rock are closely, especially the1.4nm mineral content is also close to.