AUSTRALIA'S vigorous and burgeoning literature began drawing large numbers of readers outside specialist American circles in 1973, when Patrick White won the Nobel Prize for Literature. Since then a steady stream of engrossing, sometimes tantalizingly mysterious Australian fiction has appeared here, and readers who have gotten hooked are scanning Forthcoming Books for titles by writers like Peter Carey and Randolph Stow, whose singular, arch-strange Visitants should acquire cult following any day now. Thea Astley, an Australian writer with a quieter but equally personal voice, has also attracted a coterie of American admirers with her elegant style and ironical eye.

Her new novel, Beachmasters, treats a subject which also fascinates Stow: the denaturing that occurs when Western-style rule is imposed on the alien cultures of the South Pacific islands. She surveys it with equal pessimism but without Stow's mystical overtones. The island of Kristi, where the novel is set, is governed jointly by the British and the French, who are tolerated but not loved by the inhabitants, many of whom are hapkas, half-castes, of confused ethnic allegiance. Other intruders have come and gone, most notably the Americans, who made a trash dump of the island before pulling out at the end of World War II, "shovell ing tons of food ammunition guns tractors jeeps still in their crates demountable buildings radios . . . into the Pacific on a mound so high that the driving cabins of the monster waste-heap could be seen at low water."

The British and French overlords are scarcely more respectful, and Astley lampoons them relentlessly in their smug incompetence. The cowardly and ineffectual British District Agent Cordingley is despised by everyone, including his far more capable American wife, and Resident Commissioner Trembath speaks condescendingly in pidgin to islanders whose English is as good as his own. "What Trembath didn't realize," Astley confides, "was that the fractured words he used were part of a slave language developed out of desperation on the cane fields of Australia, on the pearling ships, on the sandalwood runs -- a language developed to give men from half a dozen different language belts a lingua franca. Boil it down, it was the islanders' parody but the parodees -- the government officials, the traders and planters -- too lazy and too dull to learn native dialects, seized on it as if it were their own vile joke."

The French are more subtle, but just as destructive. For four years the cynical Colonel Mercet has been collaborating on the sly with a shady American fundamentalist firm called the Salamander Corporation "to carve up great tracts of Kristi and turn it into a mini Florida" ruled by France. To bring this about he is conspiring with a clique of half-castes and malcontents of foreign descent to instigate a takeover by an independent government to be headed by Tommy Narota, a "naive, manipulable" half-caste who is admired by the islanders for his warmth and sincerity, but is clearly no match for those who wish to control him. ASTLEY counterpoints the island's dilemma with that of one of its half-caste inhabitants, the boy Gavi Salway, whose personal catastrophe reproduces that of the island culture. When he happens on certain facts, previously concealed from him, about his lineage, at first Gavi is furious, but soon he is stirred by nascent political feelings springing from his new identity as a native, and these are reinforced by his unquestioning naivete'. He is drawn into the takeover plot, helping to run smuggled guns to the rebels. Yet when one of the guns accidentally kills the one Westerner who has truly made the transition from intruder to islander, Gavi recognizes the gravity of what he has done and is overwhelmed with guilt.

The takeover is a fiasco for all concerned, and Astley is at her best chronicling the chaos of its collapse. Even those foreigners who have been on the island for many years, teaching the islanders in school and bestowing the questionable blessings of Western-style refinement on them, are appalled at the speed with which the Kristi rebels drop these acquired mannerisms and at the genuineness of their hostility. Headmaster Woodful, who knows the rebels as his former students, finds one of them grinding something into the ground with his foot on the property of District Agent Cordingley's ruined house:

"On the ground was a child's white plastic doll, broken into a dozen pieces by the sedulous boot which was now working it deliberately and with great attentiveness into the coral drive.

"It was more an attempt at obliteration.

"Woodful was shocked at the concentration on the boy's face, the mashing action that pasted the flattened bits of leg, arm, head and belly into the gravel, the screwing motion of the heel and over all these movements a fog, a fog of rejection and contempt . . . "

Journalists descend on Kristi, and their bored comments as they listen to Tommy Narota's speech form a cynical chorus on the importance of the island's politics in the worlds's eyes. "Christ," says the man from Reuters after sweating through the new leader's unsophisticated rhetoric, "twelve thousand miles for that?"

Before long the inevitable British troops and French garde-mobile show up to quell the tiny revolution but find it already spent, undermined and exhausted by its Western perpetrators. Foreigners like Mercet who had had a part in the insurrection are removed from Kristi; Tommy Narota is jailed, and the hapkas islanders like Gavi Salway, who were briefly seduced by way of their innocence and idealism, are exiled.

It is characteristic of Astley's ironic approach that the revolution's only casualty is Lorimer, an Englishman gone native, who has isolated himself from Kristi's expatriate community and made the island his real home. Lorimer also gives the book's most impassioned defense of Kristi's culture in its pristine form, unpolluted by imported civilizing, and celebrates, in a private journal, the unbounded wealth of beauty nature has bestowed on the island: "The softness of it all, the draped clouds on the great ranges to the north and west and the Pic thrusting like a needle with the sun coming up, stretching the grey into blue as it comes. The moisture is wonderful then -- infinite small glister-bubbles of light that spit color."

Beachmasters is a slender novel, so gracefully written that it invites reading at a single sitting. And although its characters will be familiar to readers who have any acquaintance with other novels of its type, they are vividly drawn and fill the book with their energy. Astley has infused her novel with feelings of anger and sadness that give it unusual emotional weight. Like Randolph Stow, she makes it difficult to ignore the irreversible loss brought about by the cultural homogenization of colonial politics.

Bob Halliday writes frequently about contemporary literature and music.