摘要
In the present study,we present the occurrence and emplacement of chromite ore deposits from two abandoned mines（Kankavali[Janoli]and Wagda） in the Sindhudurg district of Maharashtra,India.These ores,that occurred as lenses and are associated with metamorphic and ultrabasic rocks,consist of octahedral grains of chromite,while clinochlore is present between the interstices of these grains.The Kankavali（Janoli） and Wagda ores revealed a dominance of Cr_2O_3 followed by FeO and variable proportions of A1_2O_3,MgO,and SiO_2.The former deposits have a slightly higher Cr_2O_3（average 52 wt%） and FeO（～18 wt%） than those from Wagda（Cr_2O_3～50 wt%,FeO～25 wt%）.The similar Cr~# values（0.73 for Kankavali[Janoli],0.74 for Wagda） correspond to those reported for typical podiform-type chromite deposits.We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest-southeast trend.We postulate the continuation of the fold structure from Janoli to Wagda（～4.5 km apart） and the probable （sporadic） occurrence of chromite along this stretch.The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out.
In the present study,we present the occurrence and emplacement of chromite ore deposits from two abandoned mines（Kankavali[Janoli]and Wagda） in the Sindhudurg district of Maharashtra,India.These ores,that occurred as lenses and are associated with metamorphic and ultrabasic rocks,consist of octahedral grains of chromite,while clinochlore is present between the interstices of these grains.The Kankavali（Janoli） and Wagda ores revealed a dominance of Cr_2O_3 followed by FeO and variable proportions of A1_2O_3,MgO,and SiO_2.The former deposits have a slightly higher Cr_2O_3（average 52 wt%） and FeO（～18 wt%） than those from Wagda（Cr_2O_3～50 wt%,FeO～25 wt%）.The similar Cr~# values（0.73 for Kankavali[Janoli],0.74 for Wagda） correspond to those reported for typical podiform-type chromite deposits.We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest-southeast trend.We postulate the continuation of the fold structure from Janoli to Wagda（～4.5 km apart） and the probable （sporadic） occurrence of chromite along this stretch.The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out.
基金
a part of the National Programme on"Capacity Building for Beach Placer Mining"a Network Project(CMM 0023) of the Council of Scientific and Industrial Research(CSIR),New Delhi
support of Dr.J.Shaoqing are much appreciated.NIO contribution no.4650.
