NOTES ON THE GEOMORPHIC HIST0RY OF SOUTHERN NUEVA
VIZCAYA AND THE GENESIS OF THE TAAN IRON DEPOSIT 0F
STA. CECILIA CONSOLIDATED MINES


FROILAN C. GERVASIO

 

 

 

 

ABSTRACT

 

 

The Taan iron deposit is a sedimentary bog iron consisting of an upper layer of
crispy limonite with floral imprints which grade down to limonite and poorly sorted
limonitic conglomerate. The deposit lies unconformably above the truncated surface
of a metamorphosed sequence of volcanic flows and clastic rocks and forms a mantle
fringing the slopes within the watershed of the Taan River.


Geomorphic indications together with features of the deposit seemingly indicate
that iron deposition took place in a ponded drainage basin developed as a consequence
of t.he down-faulting of the headwater portion of the former San Juan River. The
iron have probably been derived from the weathering of pyritic rocks and volcanic
rocks within the neighborhood of the present day deposit, taken in solution and trans-
ported by streams and slope wash into the basin, possibly both as ferrous and ferric
ions. The iron ions were later further oxidized, precipitated and settled in areas free
of currents and thereon lithified to form the present deposit.

 

 

 

Geological Society of the Philippines

Unit 250, 2nd Floor, Cityland Pioneer, 128 Pioneer Street, Mandaluyong City, Philippines

Tel: +(63-2) 633-9025