“Structural Study of a Gold Prospect using Core Orientation Techniques - Case Study of Bundulipu Gold Prospect, Gorontalo, Indonesia”

Abstract
In mineral exploration, collection of structural data is important in order to understand the
intricate interplay of structures and their impact on the mineralisation. Valuable
structural information can be gained from drill cores and it is important to extract all these
information. The best way to maximise the structural data from drill core is through core
orientation. Various methods are currently available for core orientation including:
Spear, Ezy Mark®, Ball Mark®, and Ace Core Tool®. The current study used simple
Spear-method utilising Chinagraph pencil. A procedure was developed in-house in
marking, preserving marks, drawing bottom of hole lines, and alpha and beta readings of
structures. Processing and analysis of alpha and beta readings is facilitated through
GeoCalc and GeoOrient softwares.
The core orientation procedure was applied in the definition drilling of the Bundulipu
Gold prospect in Avocet’s Totopo Project, Gorontalo, Indonesia. Combined with logging
of vein mineralogy, vein textures and cross-cutting relationships, Avocet geologists were
able to come-up with a feasible interpretation of the structural paragenesis and its impact
on the gold mineralisation.
The Bundulipu prospect is characterised by epithermal quartz-sulphide veins hosted by
Pliocene dacitic to rhyolithic pyroclastic rocks. It was originally interpreted that these
veins were developed within a pair of NW-SE trending sinistral faults forming a small
pull-apart basin. Mineralised quartz-sulphide veins form within this pull-apart basin.
Structural measurements in drill cores showed that mineralised veins occur as moderate
to steep, northwest dipping veins trending ENE-WSW to NE-SW. Unmineralised veins,
on the other hand, have gentle to moderate dips to the north-northeast and west. The
structural readings of these veins and their spatial distribution confirmed the regional
structural interpretation of a dominant E-W stress field and the development of veins in a
small pull-apart basin. Vein paragenesis and fault readings indicate that this stress field
has a protracted history that outlived the mineralisation event. This interpretation helped
significantly in the delineation of the vein system at Bundulipu.

 

By: Eddy Da Costa/ Boyet Bautista
PT. Avocet Bolaang Mongondow
Jl. Kol Sugiono no 24 – Kotabangon
Kotamubagu – Sulawesi Utara
Phone : 0434 – 2628776
Fax : 0434 – 22965

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Introduction geology

From Wikipedia, the free encyclopedia

Geology (from Greek: γη, gê, "earth"; and λόγος, logos, "speech" lit. to talk about the earth) is the science and study of the solid matter that constitutes the Earth. Encompassing such things as rocks, soil, and gemstones, geology studies the composition, structure, physical properties, history, and the processes that shape Earth's components. It is one of the Earth sciences. Geologists have established the age of the Earth at about 4.6 billion (4.6x10⁹) years, and have determined that the Earth's lithosphere, which includes the crust, is fragmented into tectonic plates that move over a rheic upper mantle (asthenosphere) via processes that are collectively referred to as plate tectonics. Geologists help locate and manage the Earth's natural resources, such as petroleum and coal, as well as metals such as iron, copper, and uranium. Additional economic interests include gemstones and many minerals such as asbestos, perlite, mica, phosphates, zeolites, clay, pumice, quartz, and silica, as well as elements such as sulfur, chlorine, and helium. Geology is also of great importance in the applied fields of civil engineering, soil mechanics, hydrology, environmental engineering and geohazards.

Planetary geology (sometimes known as Astrogeology) refers to the application of geologic principles to other bodies of the solar system. Specialised terms such as selenology (studies of the moon), areology (of Mars), etc., are also in use. Colloquially, geology is most often used with another noun when indicating extra-Earth bodies (e.g. "the geology of Mars").

The word "geology" was first used by Jean-André Deluc in the year 1778 and introduced as a fixed term by Horace-Bénédict de Saussure in the year 1779. The science was not included in Encyclopædia Britannica's third edition completed in 1797, but had a lengthy entry in the fourth edition completed by 1809.An older meaning of the word was first used by Richard de Bury to distinguish between earthly and theological jurisprudence.

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