ORE DEP (OCEANIC CRUST)

Question 1

Another term for Podiform Chromite

Answer 1

Alpine Type Chromites

Question 2

Ages of Podiform Chromites

Answer 2

<1.2 Ga Proterozoic to Phanerozoic

Question 3

Layer 1

Answer 3

Deep Sea Siliceous or ocherous Sediments w/ Radiolarian cherts (Cm to m)

Question 4

Layer 2

Answer 4

Layered Pillow Basalts and Sheeted Dikes (100s to 1000s m)

Question 5

Layer 3

Answer 5

Massive Gabbro, layered Gabro serpentinized mafic to ultramafic rocks (10-15 km)

Question 6

In which layer is Chromite formed?

Answer 6

Dunite and Harzburgite Sequence (Layer 4)

Question 7

Alpine Type Ophiolites in the world

Answer 7

Philipines
New Caledonia
Cuba
Cyprus
Oman

Question 8

Origin of Podiform chromite

Answer 8

1) An exotic melt reacts with mantle harzburgite to produce a more silica saturated melt and a dunite envelope
(Kakainin ng exotic magma ang Opx sa Harzburgite kaya may dunite na mafofofrm)
2) The secondary melt enriched in Si and Cr will then be mixed with a primitive melt melt yielding an magma oversaturated with spinel which effectively precipitate chormitite (Hybrid Melth)
The Dunite Envelope is of replacive origin

Question 9

Known Philipines Examples

Answer 9

Acoje and Masinloc Zambales

Question 10

IN what settings are harzburgite type of ophiolite form?

Answer 10

Back Arc and MORB

Question 11

Common morphology of Podiform Chromite

Answer 11

Nodular
Leopard Skin surrounded by Olivine

Question 12

IN what type of subduction zones occurs higher degree of partial melting of the oceanic crust and mantle?

Answer 12

Suprasubduction Zone

Question 13

Low degrees of partial melting associated with

Answer 13

Lherzolite

Question 14

Other known Podiform Chromite

Answer 14

Kempirsai, Kazakhstan