دانلود رایگان ترجمه مقاله مشروح سیر تکامل یک ایالت اپی ترمال بزرگ – Geoscienceworld 2011
دانلود رایگان مقاله انگلیسی + خرید ترجمه فارسی | |
عنوان فارسی مقاله: |
مشروح سیر تکامل یک ایالت اپی ترمال بزرگ: Hauraki Goldfield، نیوزلند |
عنوان انگلیسی مقاله: |
Punctuated Evolution of a Large Epithermal Province: The Hauraki Goldfield, New Zealand |
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مشخصات مقاله انگلیسی (PDF) | |
سال انتشار | 2011 |
تعداد صفحات مقاله انگلیسی | 23 صفحه با فرمت pdf |
رشته های مرتبط با این مقاله | زمین شناسی |
گرایش های مرتبط با این مقاله | سنگ شناسی |
چاپ شده در مجله (ژورنال) | زمین شناسی اقتصادی – Economic Geology |
رفرنس | دارد ✓ |
کد محصول | F1134 |
نشریه | Geoscienceworld |
مشخصات و وضعیت ترجمه فارسی این مقاله | |
وضعیت ترجمه | انجام شده و آماده دانلود |
تعداد صفحات ترجمه تایپ شده با فرمت ورد با قابلیت ویرایش | 10 صفحه با فونت 14 B Nazanin |
ترجمه عناوین تصاویر و جداول | ترجمه نشده است ☓ |
ترجمه متون داخل تصاویر | ترجمه نشده است ☓ |
ترجمه متون داخل جداول | ترجمه نشده است ☓ |
درج تصاویر در فایل ترجمه | درج شده است ✓ |
درج جداول در فایل ترجمه | درج شده است ✓ |
کیفیت ترجمه | کیفیت ترجمه این مقاله خوب میباشد |
توضیحات | ترجمه این مقاله به صورت خلاصه انجام شده است. |
فهرست مطالب |
چکیده
معرفی
زمین شناسی منطقه
زمین شناسی محلی
مواد و روش ها
نتایج
بحث
سیر تکامی ولکانیکی و ساختاری
نتیجه گیری
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بخشی از ترجمه |
چکیده |
بخشی از مقاله انگلیسی |
Abstract The Hauraki goldfield in the Coromandel volcanic zone contains approximately 50 adularia-sericite epithermal Au-Ag deposits in a 200-km-long by 40-km-wide north-south−trending belt. These deposits have produced approximately 320,000 kg Au and 1.5 Mkg Ag and formed from Miocene to Pliocene subaerial hydrothermal systems. The goldfield has been divided into three provinces (northern, eastern, and southern), based on the host rocks and geologic setting of the deposits (Christie et al., 2007). In the northern province of the goldfield, adularia from Paritu yields a single 40Ar/39Ar plateau date of 16.32 ± 0.13 Ma, and adularia from Opitonui yields a preferred 40Ar/39Ar age of 13.15 ± 0.03 Ma. Two Re-Os dates of molybdenite from porphyry-style mineralization at Ohio Creek overlap within error and yield dates of 11.87 ± 0.06 and 11.97± 0.08 Ma; geologic relationships suggest that this is the likely age of mineralization in the nearby Thames epithermal deposits. In the eastern province, adularia from the Ohui deposit gives a preferred 40Ar/39Ar age of 8.29 ± 0.25 Ma, adularia from the Broken Hills deposit gives a preferred 40Ar/39Ar age of 7.12 ± 0.02 Ma, and adularia from the Wharekirauponga prospect yields a preferred 40Ar/39Ar age of 6.32 ± 0.12 Ma. In the southern province, adularia from quartz veins at the Maratoto deposit provide a preferred 40Ar/39Ar age of 6.41 ± 0.04 Ma, and adularia from a quartz vein at the Sovereign deposit yields a preferred 40Ar/39Ar age of 6.70 ± 0.16 Ma. Two dates from vein adularia at the world-class Martha deposit overlap within error, and we interpret a preferred age for the deposit of 6.16 ± 0.06 Ma. Two samples of molybdenite from veins in the Martha deposit yield discrete Re-Os dates of 6.37 ± 0.03 and 6.51 ± 0.03 Ma. Adularia from one quartz vein from the Favona deposit yields a 40Ar/39Ar date of 6.05 ± 0.04 Ma. Host rock and vein adularia from the Karangahake deposit yield 40Ar/39Ar plateau dates that range from 6.90 ± 0.20 to 5.71 ± 0.13 Ma, which may reflect more than one stage of mineralization or protracted fluid flow. Adularia from veins at the Waiorongomai deposit yields a preferred 40Ar/39Ar age of 5.71 ± 0.03 Ma, and adularia from a vein at the Eliza deposit yields a preferred age of 4.47 ± 0.06 Ma. The southernmost deposit in the Hauraki goldfield, Muirs Reef, has adularia in quartz veins that yield 40Ar/39Ar plateaus dates of 2.12 ± 0.11 to 1.78 ± 0.16 Ma. Combined with previous work, these results indicate that mineralization in the Hauraki goldfield ranges from 16.3 Ma in the north to 2 Ma in the south, and clusters into two distinct groups that correlate with location, volcanic stratigraphy, and mineralization style. The first group, from ~16.3 to ~10.8 Ma contains epithermal veins, including bonanza-style veins, and porphyry-style mineralization that formed in the northern province in an arc that was dominated by andesitic volcanism. The second period of mineralization occurs primarily from 6.9 to 6.0 Ma in the eastern and southern provinces, when precious metals were deposited into thicker colloform-crustiform banded veins that formed in extensional settings in an arc that was erupting bimodal andesite-rhyolite compositions. Therefore, even though volcanism in the Coromandel volcanic zone was active from 18 to 2 Ma, Au-Ag mineralization was focused into two discrete periods of this arc formation, and the style of mineralization changed through time, coinciding with a change in style of volcanism. In addition, while Hauraki goldfield mineralization discontinuously lasted more than 11 m.y., greater than 80 percent of the known gold endowment was deposited in a relatively brief 0.9 Ma window between 6.0 and 6.9 Ma. These changes through time likely reflect, at least in part, reorganization of the Miocene Northland and Colville volcanic arcs in the New Zealand region of the southwest Pacific.. 1- Introduction EPITHERMAL Au-Ag deposits form from hydrothermal systems that most commonly develop in active volcanic regions (e.g., Simmons et al., 2005). Epithermal provinces occur in remnant and active volcanic arcs worldwide, including the Great Basin of the western United States (e.g., John, 2001; Saunders et al., 2008), the Mexico silver belt (e.g., Albinson et al., 2001), Japan (e.g., Hishikari: Izawa et al., 1990), the Patagonia province of Argentina (e.g., Sillitoe, 2008), and the Hauraki goldfield of New Zealand (e.g., Christie et al., 2007). Work in these, and in other epithermal provinces has focused mainly on descriptions of individual deposits, and yet few integrated studies have documented the temporal evolution of volcanic systems and the relationships between tectonics, volcanism, hydrothermal activity, and the formation of epithermal gold deposits. Here, we document the regional chronology of the Hauraki goldfield, providing new 40Ar/39Ar dates of hydro thermal adularia and Re-Os dates of molybdenite from veins. Regional Geology In the last 25 m.y., the North Island of New Zealand has undergone a considerable shift in the locus of volcanism, from the north- to northwest-trending Northland arc between 25 and 15 Ma, to the Coromandel volcanic zone between 18 and 2 Ma, and then to the currently active northeast-striking Tonga-Kermadec-Taupo Volcanic Zone arc (Fig. 1; Adams et al., 1994; Ballance, 1999; Hayward et al., 2001; Carter et al., 2003; Briggs et al., 2005). Although there is wide consensus on this overall evolution, important details remain unclear, including the timing of the significant clockwise rotation of the arc from north-northwest to northeast trending. |