MISSISSIPPI VALLEY TYPE (MVT) DEPOSIT

Sejarah MVT Amerika Utara (Galena ,Sphalerite, sedikit Kalkopirit )

Banyak ditemukan terbentuk di waktu PROTEROZOIKUM - CRETACEOUS

Pertama kali ditemukan 70 tahun yang lalu (Bastian 1939)

Apa sih MVT (Mississippi Valley Type) itu ?

Endapan MVT terdiri dari kumpulan tubuh bijih dimana silfida Fe, Pb, dan Zn mengisi rongga pada termokarst atau larutan breksia pada platform karbonat kebagian

cekungan sedimen

Ukuran rata – rata Deposit 7.0 Mt

32,5 g/t Ag

0.23 % Cu

6,0 % Zn

1.9 % Pb

Berikut kareteristik mvt :

1) kebanyakan deposito terjadi di batuan karbonat, dengan biasa kuat pada dolomites dan batugamping

2) deposito terjadi di kebanyakan cekungan sedimen di seluruh belahan dunia. Hors rock kisaran usia dari Proterozoikum-kapur (createceous)

3) Kebanyakan horst rock yang di temukan berada pada zaman protezoic sedangkan sedikit ditemukan pada zaman proterozoikum

4) deposit cenderung ditemukan di dekat tepi cekungan, atau pada lengkungan antara cekungan

5) tiap deposit itu sendiri , kejadiannya mirip dengan satu sama lain, cenderung terjadi di daerah-daerah yang dapat didistribusikan seratus sampai seribu meters.

6) Jenis intrusinya konkordan

7) batu-batuan karbonat host tidak berubah bentuk.

Source / Sumber

Transportation

The Trap

Exploration

Mineralisasi

Types of Sulfide Mineralization

There are at least five types of sulfide mineralization present in the Lavrion district.

1. Porphyry-style mineralization

2. Skarn-style mineralization are spatially associated with the Plaka granodiorite

3. Breccia-style mineralization

4. Carbonate-replacement Pb-Zn-Ag mineralization

5. Vein-style Pb-Zn-Ag mineralization is present at Adami

Photos of various types of mineralization and rock types in the Lavrion district. a. Multiple crosscutting quartzmolybdenite- pyrite (Qtz-Mlb-Py) veins in the Plaka granodiorite (PG). b. Hornfels on the margin of the Plaka granodiorite porphyry. c. Upper Marble (UM) and interbedded schists (S) near the southern margin of the Plaka granodiorite. Massive epidote (E)-bearing skarn is outlined. d. Massive carbonate-replacement ore along the contact of the Kaesariani schists and the Lower Marble (LM), Jean Baptiste mine (Kamariza area). e. Massive sphalerite (Sph) and calcite (Cal) in carbonate-replacement ore from Kamariza. f. Intergrown massive pyrite (Py) and sphalerite (Sph) with crosscutting calcite (Cal) veins in massive ore from Plaka (Villia). g. Brecciated sphalerite-galena ore with clasts of Upper Marble in Vein 80 at the Adami mine. Note the hornfels on the upper portion of the vein. h. Vein 80 from Adami mine showing bands of galena (Gn), siderite (Sd), and calcite (Cal).

Jenis-jenis pengisian (open-space filling)

A. Crackle breccia with disseminated

sphalerite crystals in white dolomite

cement, Robb Lake, BC.

B. Mosaic breccia with sphalerite crystals

in white dolomite cement, Robb Lake,

BC.

C. Rubble breccia consisting of variably

altered dolostone fragments and shale

fragments in white dolomite cement.

Note the dolostone fragments with

zebra texture, Robb Lake, BC.

D. Rock-matrix breccia with dolostone,

shale, and white sparry dolomite

fragments in dark grey fragmental

matrix, Robb Lake, BC.

E. Aggregates of massive sphalerite

crystals and white sparry dolomite

along small fractures, Pine Point, NWT.

F. Aggregates of colloform sphalerite and

skeletal galena completely replacing

the carbonate, Polaris, Nunavut; scale

bar is 1 cm.

Various ore textures from

Polaris, Nunavut, NWT; scale

bar is 1 cm.

A. Keel ore: sphalerite and

skeletal galena are

replacing the carbonate

clasts.

B. Keel ore: crystalline

sphalerite in solution

collapse breccia.

C. Ocean zone: Massive

galena and sparry

dolomite in

pseudobrecciated

carbonate host rock.

Peta deposit MVT di seluruh dunia

.

Distribution of Mississippi Valley-type deposits/districts plotted on a simplified geological map of Canada

(Map D1860A). Districts shown are,Cornwallis;Nanisivik, Pine Point, Prairie Creek, Robb Lake, Monarch-

Kicking Horse, Blende, Bear-Twit, Gayna River, Goz Creek, Gays River, Jubilee, Walton, Newfoundland Zn,

Upton, and Esker

Pine Point

Summary of the characteristics of three Mississippi

Valley-type districts

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