Composition of fossil manganese nodules from Costa Rica

Horizons of several types of Upper Jurassic to Lower Cretaceous manganese nodules occur locally in sequences of radiolarian cherts within the Nicoya Ophiolite Complex (NW Costa...多种晚侏罗世至早白垩世的锰结核（manganese nodules）层位，在尼科亚蛇绿岩套（Nicoya Ophiolite Complex，哥斯达黎加西北部……）内的放射虫燧石（radiolarian cherts）序列中局地产出。