GEOLOGICAL SETTINGPorphyry deposits

GEOLOGICAL SETTING
Porphyry deposits, as the name suggests, are spatially and genetically related to small intrusive stocks which typically have a porphyritic texture. Gold rich deposits are preferentially found in monzodiorite-monzogabbro porphyries, but also occur in diorite and quartz diorite porphyries. A generalised model of deposits typical of those that occur in the southwest Pasific.
These mineralised stocks are invariably related to magmatism at convergent plate margins, those of calc-alkaline chemistry being related to subduction zones and potassic lithologies occuring where there has been a collision involving a subduction zones, and post-date active subduction. Gold rich porphyries (>0.5g/t, and excluding skarn and supergene concentrations) are common in the southwest Pasific.
The intrusives directly associated with porphyry deposits are typically small (

Results (Indonesian) 1:

GEOLOGICAL SETTINGPorphyry deposits, as the name suggests, are spatially and genetically related to small intrusive stocks which typically have a porphyritic texture. Gold rich deposits are preferentially found in monzodiorite-monzogabbro porphyries, but also occur in diorite and quartz diorite porphyries. A generalised model of deposits typical of those that occur in the southwest Pasific.These mineralised stocks are invariably related to magmatism at convergent plate margins, those of calc-alkaline chemistry being related to subduction zones and potassic lithologies occuring where there has been a collision involving a subduction zones, and post-date active subduction. Gold rich porphyries (>0.5g/t, and excluding skarn and supergene concentrations) are common in the southwest Pasific.The intrusives directly associated with porphyry deposits are typically small (<1km2 in outcrop). Generally they are shown as simple stocks in most models but can have much more complicated morphologies with concurrent complications in the distribution of ore. They are frequently multi-stage, with mineralisation associated with only some of the stages of intrusion. Often the earliest stages of intrusion are the best mineralised. Thus post-mineralisation dykes or stocks are common. Mineralised porphyries frequently occur around the margins of much larger unmineralised intrusives which have an equigranular texture. The mineralised intrusives commonly occur in groups, such that the most prospective area for a porphyry type deposit in in the immediate vicinity of a known deposit. Similary, obscured economic mineralisation may occur in the vicinity of exposed sub-economic mineralisation. Halaman 7.The intrusive is generally emplaced with its top in the range 2-5 km below the surface. Gold rich intrusives are shallow, to the extent they can be hosted by coeval volcanics. Since in the island arc setting these volcanics usually form high relief volcanoes, which are subject to strong erosion, particularly by sector collapse, the mineralised intrusives can be found after overlying parts of the volcano have been removed.Intrusion-related and hydrothermal breccias are common in porphyry deposits, most particularly around the margins of the intrusive and the immediately surrounding country rocks, and can be genetically connected with mineralisation by providing permeable pathways for fluid flow. Thus ore bodies in some cases are annular in form, with a barren or sub-economic intrusive core(figure 4). Selective mineralisation of certain host rocks can be enhance this situation.

Results (Indonesian) 2:

SETTING GEOLOGI
deposito Porfiri, seperti namanya, secara spasial dan genetik yang berhubungan dengan saham mengganggu kecil yang biasanya memiliki tekstur porfiritik. Emas deposito kaya istimewa ditemukan di porphyries monzodiorite-monzogabbro, tetapi juga terjadi pada diorit dan kuarsa porphyries diorit. Sebuah model umum deposito khas mereka yang terjadi di barat daya Pasifik.
Ini saham mineralisasi yang selalu terkait dengan magmatisme di margin lempeng konvergen, mereka kimia calc-alkaline yang terkait dengan zona subduksi dan satuan batuan potasik yang terjadi di mana telah terjadi tabrakan yang melibatkan sebuah zona subduksi, dan pasca-tanggal subduksi aktif. Emas porphyries kaya (> 0,5 g / t, dan tidak termasuk skarn dan supergen konsentrasi) yang umum di barat daya Pasifik.
The intrusives terkait langsung dengan deposito porfiri biasanya kecil (<1km2 di singkapan). Umumnya mereka ditampilkan saham yang sederhana dalam kebanyakan model, tetapi dapat memiliki jauh lebih rumit morfologi dengan komplikasi bersamaan dalam distribusi bijih. Mereka sering multi-stage, dengan mineralisasi yang berhubungan dengan hanya beberapa tahapan intrusi. Seringkali tahap awal intrusi adalah mineral terbaik. Dengan demikian pasca-mineralisasi tanggul atau saham yang umum. Porphyries Mineralised sering terjadi di sekitar margin intrusives unmineralised jauh lebih besar yang memiliki tekstur equigranular. Intrusives mineral umumnya terjadi dalam kelompok, sehingga paling prospektif daerah untuk deposit Jenis porfiri di di sekitar langsung dari deposit diketahui. Similary, mineralisasi ekonomi dikaburkan dapat terjadi di sekitar sub-ekonomi mineralisasi terkena.
Halaman 7.
The mengganggu umumnya emplaced dengan puncaknya di kisaran 2-5 km di bawah permukaan. Emas intrusives kaya yang dangkal, sejauh mereka dapat diselenggarakan oleh batuan vulkanik sebaya. Karena dalam busur pulau pengaturan volkanik ini biasanya membentuk gunung berapi lega tinggi, yang tunduk pada erosi yang kuat, terutama oleh runtuhnya sektor, intrusives mineral dapat ditemukan setelah atasnya bagian dari gunung berapi telah dihapus.
Intrusion terkait dan breksi hidrotermal yang umum di deposito porfiri, paling terutama di sekitar margin dari mengganggu dan bebatuan negara yang mengelilingi, dan dapat secara genetik terhubung dengan mineralisasi dengan menyediakan jalur permeabel untuk aliran fluida. Dengan demikian badan bijih dalam beberapa kasus annular dalam bentuk, dengan inti mengganggu tandus atau sub-ekonomi (gambar 4). Mineralisasi selektif batuan host tertentu dapat meningkatkan situasi ini.