According to the passage the widely held view
问题详情
According to the passage, the widely held view of Archean- age gold-quartz vein systems is that such systems______
A．were formed from metamorphic fluids
B．originated in molten granitelike bodies
C．were formed from alluvial deposits
D．generally have surface expression
E．are not discoverable through chemical tests请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：A
解析：ThebestanswerisA.Inlines5-6theauthormentions“thewidelyheldviewthatthe(Archean-agegold-quartzvein)systemsweredepositedfrommetamorphicfluids.”Thisviewissaidtobecontrarytotherecenttheorythatthesesystemsoriginatedinmoltengranitelikebodies,sochoiceBisnotcorrect.Alluvialdepositsarementionedinthepassageashavingaidedsimpleprospectingmethods,butsuchdepositsarenotsaidtohaveformedthatArchean-agegold-quartzveinsystems(choiceC).Accordingtotheauthor,“mostdepositsnotyetdiscoveredhavegoneundetectedbecausetheyareburiedandhavenosurfaceexpression”(lines14-16,sochoiceDisnotcorrect.AndchoiceEisincorrectbecausetheauthorsaysthatchemicaltestscanaidthediscoveryofgolddepositsiftheyareconductedinareaswheremineralizationislikelytohavetakenplace(lines23-27).
