National ASTER Map MgOH group composition

1. Band ratio: B7/B8 Blue-cyan is magnesite-dolomite, amphibole, chlorite Red is calcite, epidote, amphiboleuseful for mapping: (1) exposed parent material persisting through "cover"; (2) "dolomitization" alteration in carbonates - combine with Ferrous iron in MgOH product to help separate dolomite versus ankerite; (3) lithology-cutting hydrothermal (e.g. propyllitic) alteration - combine with FeOH content product and ferrous iron in Mg-OH to isolate chlorite from actinolite versus talc versus epidote; and (4) layering within mafic/ultramafic intrusives. useful for mapping: (1) exposed parent material persisting through "cover"; (2) "dolomitization" alteration in carbonates - combine with Ferrous iron in MgOH product to help separate dolomite versus ankerite; (3) lithology-cutting hydrothermal (e.g. propyllitic) alteration - combine with FeOH content product and ferrous iron in Mg-OH to isolate chlorite from actinolite versus talc versus epidote; and (4) layering within mafic/ultramafic intrusives. useful for mapping: (1) exposed parent material persisting through "cover"; (2) "dolomitization" alteration in carbonates - combine with Ferrous iron in MgOH product to help separate dolomite versus ankerite; (3) lithology-cutting hydrothermal (e.g. propyllitic) alteration - combine with FeOH content product and ferrous iron in Mg-OH to isolate chlorite from actinolite versus talc versus epidote; and (4) layering within mafic/ultramafic intrusives.

1. 波段比值：B7/B8。蓝青色对应菱镁矿-白云石（magnesite-dolomite）、角闪石（amphibole）与绿泥石（chlorite）；红色对应方解石（calcite）、绿帘石（epidote）与角闪石。该波段比值可用于以下地质填图工作：(1) 识别穿透"覆盖层"的裸露母质；(2) 碳酸盐岩中的白云岩化蚀变：结合MgOH产物中的亚铁含量，辅助区分白云石与铁白云石（ankerite）；(3) 穿切岩性的热液蚀变（如青磐岩蚀变（propylitic））：结合FeOH产物含量与Mg-OH中的亚铁含量，将绿泥石、阳起石（actinolite）、滑石（talc）与绿帘石区分开；(4) 基性/超基性侵入岩体（mafic/ultramafic intrusives）内部的层理构造。该波段比值可用于以下地质填图工作：(1) 识别穿透"覆盖层"的裸露母质；(2) 碳酸盐岩中的白云岩化蚀变：结合MgOH产物中的亚铁含量，辅助区分白云石与铁白云石；(3) 穿切岩性的热液蚀变（如青磐岩蚀变）：结合FeOH产物含量与Mg-OH中的亚铁含量，将绿泥石、阳起石、滑石与绿帘石区分开；(4) 基性/超基性侵入岩体内部的层理构造。该波段比值可用于以下地质填图工作：(1) 识别穿透"覆盖层"的裸露母质；(2) 碳酸盐岩中的白云岩化蚀变：结合MgOH产物中的亚铁含量，辅助区分白云石与铁白云石；(3) 穿切岩性的热液蚀变（如青磐岩蚀变）：结合FeOH产物含量与Mg-OH中的亚铁含量，将绿泥石、阳起石、滑石与绿帘石区分开；(4) 基性/超基性侵入岩体内部的层理构造。